(Stranger)
12-17-02 21:45
No 390298
(Rated as: excellent)
The following text was taken from book titled "Industrial Chemicals", wich is all about industrial processes for making chemicals for organic industry. I cant remember name of the author, but I have copied few pages from it and re-writen them:
ACETIC ANHYDRIDE (CH3CO)2O
Reaction:
CH3CHO + O2 ----> CH3COOOH (peracetic acid!)
CH3COOOH + CH3CHO ----> (CH3CO)2O + H2O
70-75% yield
Material Requrements:
Basis -1 ton acetic anhydride:
Acetaldehyde 2400 lbs Diluent 3300 lbs
Catalyst 2 lbs Air variable
Process:
Air is bubbled trough liquid acetaldehyde in a reactor in the presence of 2% (based on the weight of acetaldehyde) catalyst, such as a mixture of copper and cobalt acetates or manganese acetate, wich prevents the formation of explosive amounts of peracetic acid. Approximately 1.4 parts of acetic acid per part of acetaldehyde is present as a diluent to promote acetic anhydride formation. Methyl or ethyl acetate, triacetin, or benzene may also be used as diluents, and the last is generally utilized in conjuction with acetic acid as a withdrawing agent in subsequent vacuum distilation to allow separation of the reaction mixture from water at lower temperatures.
The reactor is maintained at a temperature of 50-60 °C, and the pressure is approx. 60 psi. The overhead from the crude vacuum coulumn is fractionated in a aldehyde column, yielding acetaldehyde for recycle as the overhead and water and diluent as bottoms. The diluent is returned to reactor after the water is separated.
The dehydrated mixture of acetic anhydride and acetic acid from the bottom of the crude vacuum column is separated by distillation. Acetic acid is removed as overhead, and the acetic anhydride is withdrawn from a bottom plate. The catalyst is taken from the bottom to be re-used. The acetic anhydride may be further purified by vacuum distillation.
Variations of this process involve type and amount of diluent, and several stages in reactor (with oxygen injection in each stage) under milder reaction conditions.
Present trends are away from air and toward oxygen. In one continuous process using ethyl acetate as diluent and a catalyst concentration of 1% (cobalt acetate and copper acetate in a weight ratio 2:1), the reaction is carried out at 50°C and 45 psi. Oxygen is injected at various points along the path of liquid travel, with overall oxygen supply limited to 1-2% excess. Under these conditions, 95% conversations of acetaldehyde are obrained. Both acetic anhydride and acetic acid are produced in a 50:50 weight ratio.
The same process carried out in the absence of diluent gives a higher oxidation rate but yields a lower acetic anhydride-acetic acid ratio(ca. 2:3)
Now the most interesting part of this process is when the peracetic acid reacts with acetaldehyde to form acetic anhydride + water
CH3COOOH + CH3CHO ===> (CH3CO)2O + H2O
We know that peracetic acid can be made with CH3COOH + H2O2 + H2SO4 so I propose next:
1. React CH3COOH + H2O2 + H2SO4 to get 15% solution of CH3COOOH in acetic acid (wich also acts as a diluent for next step)
2. React acetaldehyde with our 15% solution of CH3COOOH to get acetic anhydride (with a higher molar ratio of acetaldehyde to insure higher conversation of peracetic to anhydride)
Now, I know they operate this process @45-60 psi but IMO this is just to promote CH3CHO + O2
===> CH3COOH convertion.
I bet you 10$ if we react acetaldehyde with peracetic at atmospheric pressure we should get some aceic anhydride. Even if the yield would be some 30-50% it is still dirt cheap process, and MOST OF ALL totally OTC!
The only real problem I see here is that if we make peracetic acid via H2O2/CH3COOH we can only get something like 15% solution, can this be too diluted for step no.2?
P.S. how did all you beez miss this synthesis from all those books you read? As far as I could understand from this book, this process very largely used in industry, and it should be found most books about organic industry.
(Chief Bee)
12-17-02 23:58
No 390327
Very interesting! However, if ascetic anhydride and water is formed, why does this not equal two molecules of acetic acid?
(Stoni's sexual toy)
12-18-02 01:55
No 390363
Acetaldehyde has a boiling point of 21°C. How do you want to produce it? Chemical oxidation is too expensive.
I'm not fat just horizontally disproportionate.
(Master Searcher)
12-18-02 02:08
No 390367
Ye Olde Tube Furnace.
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Stranger)
12-18-02 11:13
No 390481
Acetaldehyde has a boiling point of 21°C. How do you want to produce it?
Welll, maybe we could use an autoclave, or in the worst case a pressure cooker like those mushroom guys do. It`s not that expensive and lot of people have it just sitting at home.
Rhodium, what do you mean when you say two molecules of acetic acid???
This is the reaction mechanism:
CH3COOOH + CH3COH ==> (CH3CO)2O + H2O
(Stranger)
12-18-02 12:20
No 390490
He means: why isn't the acetic anhydride going to be hydrolyzed? Acetic anhydride is used as a dehydrating agent: Ac-O-Ac + H20 --> 2 AcOH
(Stranger)
12-18-02 13:04
No 390494
Maybe we can use some drying agent that uses chemisorption (CaO) rather than hydration (MgSO4, etc...)
I have seen in one patent about amines/imines(us 702 985), they use calcium oxide as a dehydrating agent wich works like this:
CaO + H2O ==> Ca(OH)2
This forms a calcium hydroxide, but I dont know if it reacts with a anhydride...
(Stranger)
12-18-02 14:50
No 390504
The Ca(OH)2 base will most certainly react with the acetic anhydride. It 's probably a better idea to throw in a 4A molecular sieve for the water absorption.
(Stranger)
12-18-02 21:30
No 390571
hmmm... well anyway, it seems that in the process described they do it without any drying/absorbing agents, but I cant really understand how they separate water becoause it is not described very well.
I have scanned the picture of this process, but it doesent tell me much, maybe Rhodium or somebody would like to take a look at it coz I can`t post it.
(Master Searcher)
12-19-02 02:50
No 390655
Maybe this would work for
EtOH --> CH3CHO
Patent US3884776
Note the use of the Cr redox couple.
Also see
Post 182782 (PolytheneSam: "Re: potassium dichromate", Chemicals & Equipment)
Patent US3423300
Patent US3450623
Patent US3726914
Patent US3824160
Patent US5127999
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Stranger)
12-19-02 09:52
No 390748
What does that "?" stand for?
(Hive Addict)
12-19-02 16:22
No 390813
The question mark punctuation was just Polythene's way of saying that the following post is just a bunch of suggestions and ideas that may or may not work. It's a matter of stating Sam's uncertainty. Sam is just asking for opinions on some of what is posted.
(Stranger / Eraser)
12-21-02 00:50
No 391191
acetaldehyde can be made from acetylene using HgSO4. It´s just a normal alkyne hydration forming an enol CH2=CH-OH, wich isomerises to CH3CHO.
(Stranger)
12-21-02 23:28
No 391523
OK,I dont think the main problem here would be obtaining acetaldehyde, but rather this forming of H2O that would decompose acetic anhydride, so i`m going to ask two questions:
1. does anybody know how fast acetic anhydride reacts with water? (i.e. will it react within a second, or slowly within a few minutes?)
What I mean by this is: maybe we can use some drying agent that will absorb water faster than it takes it to react with anhydride...
2. If we use drying agent that uses absorption of water, that means that water will still be present in a form of a cristal (example MgSO4 * XH2O), now the question here is: can anhydride still react with this water that is attached to our drying agent?
(Chief Bee)
12-22-02 01:29
No 391546
The reaction of acetic anhydride with water at 25°C takes place over several minutes, not instantly - at higher temps the rate is higher.
Yes, water adsorbed to for example MgSO4 is still available for reaction with Ac2O, but the rate is slower than with free water in solution.
(Hive Bee)
12-23-02 08:57
No 391938
Ullmann's Encyclopedia of Industrial Chemistry:
[Love this book!]
Oxidation of Acetaldehyde
Acetic anhydride can be obtained directly by liquid-phase oxidaton of acetaldehyde. The peracetic acid formed from oxygen and acetaldehyde reacts under suitable conditions with a second molecule of acetaldehyde to form acetic anhydride and water [64]:
Rapid removal of the reaction water and the use of suitable catalysts are essential in this process. Mixtures of acetic acid and acetic anhydride are always obtained; their ratio can be varied within wide limits by changing the reaction conditions. Generally, the highest possible anhydride yield is sought.
Because of the rapid hydrolysis of acetic anhydride above 60 °C, the process is operated preferably between 40 °C and 60 °C [65]. Suitable catalysts are combinations of metal salts [66]. Particularly important are mixtures of manganese acetate and copper acetate [67], of cobalt acetate and nickel acetate, and of cobalt and copper salts of higher fatty acids [68]. Manganese acetate should hinder the formation of explosive amounts of peracetic acid during the oxidation of acetaldehyde. For increasing the rate of oxidation, the use of pure oxygen at a pressure of several hundred kilopascals instead of air has been proposed [69].
The strongly exothermic reaction requires efficient cooling. For this purpose, the addition of low-boiling solvents has been found to be of assistance. Methyl and ethyl acetates are favored because they form azeotropic mixtures with water (but not with acetic acid or acetic anhydride) and hence allow a rapid, continuous separation of the water formed in the reaction. The ratio of acetic anhydride to acetic acid in the product depends on the ratio of ethyl acetate to acetaldehyde in the initial mixture (Table (1)).
In practice, a 1 : 2 mixture of acetaldehyde and ethyl acetate is oxidized with the addition of 0.05 to 0.1 % cobalt acetate and copper acetate at 40 °C; the ratio of Co:Cu is 1:2. The ratio of acetic anhydride to acetic acid obtained is 56:44, whereas on oxidizing in the absence of ethyl acetate this ratio is only 20:80 [16]. The optimization of other reaction conditions can also lead to an increase in the acetic anhydride-acetic acid ratio. For example, at 55 °C and atmospheric pressure, a ratio of 80:20 was achieved[70]. At a higher temperature (62 – 90 °C, 200 – 300 kPa, acetaldehyde concentration in the final mixture of up to 40 %) a ratio of 75:25 was obtained at high aldehyde conversion [71].
Other suitable low-boiling solvents are methylene chloride, diisopropyl ether, cyclohexanone, or ethylidene diacetate. Nonvolatile esters also can be used as diluents, provided they do not have to be removed from the reaction zone. These include alkyl benzoates and alkyl phthalates [72].
The acetaldehyde oxidation is illustrated in Figure (5) by the process of Usines de Melle [73]. The gas mixture containing oxygen and acetaldehyde is pumped into the reactor (a). The oxidation takes place in the liquid phase and in the presence of catalysts. The reactor effluent is sent through a water-cooled condenser (b) constructed as a separator; non-condensable gases are sent to the packed column (c). Fresh acetaldehyde is introduced at the top of this column. The condensates from both the cooler (b) and the column (c) are distilled to obtain the product. Acetaldehyde is recovered from the branch stream (d) of the non-condensable gas. The other part of the gas flow is supplemented with air and returned to the reactor.
Both towers and vessels are suitable as reactors if the heat of reaction can be dissipated. The process of Distillers Co. [69] is shown in Figure (6) as an example. The off-gas contains combustible low-boiling products, such as acetaldehyde, and solvents, such as methyl acetate and ethyl acetate. These can be flared off.
[64] Wacker-Chemie, DE 867 689, 1940 (A. Krug, J. Sixt).
Table 1:
Initial Ethyl Acetate/Acetaldehyde 20:80 30:70 60:40 70:30
Acetaldehyde conv. % 80 80 80 80
% Acetic Anhydride based on Acetaldehyde 13.5 57 64 68.5
Mountain Boy
(Stranger)
12-23-02 13:10
No 391970
Now we are finally going somewhere!
Can you please PM me illustration of this process? Thnx
(Stoni's sexual toy)
12-23-02 13:30
No 391973
[whisper]
Ketene lamp! Acetone pyrolysis! 1kg Ac2O per day! Unsupervised operation!
[/whisper]
I'm not fat just horizontally disproportionate.
(Stranger)
12-23-02 14:13
No 391980
Yes, there is also a ketene synth in that book, it goes like this:
From Acetic Acid (Ketene)
Reaction
CH3COOH ==> CH2=C=O + H2O
CH3COOH + CH2=C=O ==> (CH3CO)2O
85-89% yield
Material Requrements:
Basis-1 ton Acetic Anhydride
Acetic Acid 2700 lbs
Catalyst small
Process
Vapors of GAA containing 0.2 to 0.3 % triethylphosphate (TEP) are passed into a tubular (chrome-iron alloy) reactor heated to 700 - 800 °C uder reduced pressure (200mm). As reaction gasses leave the converter , ammonia gas (1lb per 4.2 lb TEP) is injected into the stream to prevent reversion of the ketene in the product.
The reactor exit vapors containing acetic anyhidride, acetic acid, ketene, and water are led to a series of condensers where weak aceic acid (30%) is condensed before it can react with ketene. The uncondensed ketene is absorbed in acetic acid to give acetic anyhidride (90% purity), wich is then fractioned to yield a specification product.
From Acetone
CH3COCH3 ==> CH2=C=O + CH4
Process
Acetone vapors are passed through a void chrome-iron tube. The temperature of the tube is 650 - 670 °C, and contact time is about 0.25 - 5 sec. The unchanged acetone is condensed and recycled. The gaseous ketene is absorbed in GAA to give acetic anhydride.
Yields based on acetone are about 80 to 95 %. Conversion per pass varies from 15 to 25 %.
Hmmm... this seems lot more complicated than procedure from peracetic acid.
I know that there are not many people who are willing to build a chemical reactor that operates @ 700°C vapor fase...
Unless... there are some easyer methodes of preparing ketene... or even OTC sources of ketene. Are there any?
(Hive Addict)
12-23-02 14:32
No 391985
> Unless... there are some easyer methodes of preparing ketene...
> or even OTC sources of ketene. Are there any?
have you tried to UTFSE!?!?
some people (cough) have been succesful, afaik others (acetyl)
had problems with their insulation.
(Stoni's sexual toy)
12-23-02 15:23
No 391991
In other words,
Post 271991 (hypo: "first encouraging ketenelamp experiment", Methods Discourse)
Post 247901 (Osmium: "Re: Acetic Anhydride", Chemicals & Equipment)
Post 200799 (Osmium: "Re: Relativly simply Acetic Anhydride Synth.", Chemistry Discourse)
I'm not fat just horizontally disproportionate.
(Hive Addict)
12-23-02 15:24
No 391993
why not just use the new acid chloride synth for some acetyl chloride and use it for the AA?
(Stoni's sexual toy)
12-23-02 15:40
No 392000
> why not just use the new acid chloride synth for some
> acetyl chloride and use it for the AA?
Dunno which one you mean, but consider this:
acetone, electricity and distilled water, the only required chems and reagents in this synth are very cheap and OTC. This process is also not very demanding, it can in principle run continuously without attention.
Read the above links!
Maybe there is a way to simplify hypo's ketenelamp experiment even further?
What if the flask contained refluxing GAA, and acetone was slowly, dropwise added to it? Since the result has to be distilled anyway it doesn't matter if all the crap ends up in the boiling GAA/AA mixture, this will simplify the design considerably. Acetone is cheap, so just burn all the shit that manages to escape from the top of the condenser.
Ketene absorption will without a doubt be less efficient, but by adding a simple wash bottle with GAA this can be overcome. Otherwise, consider that acetone is cheap and for small amounts and for the glassware-challenged among us this easier version might be good enough.
When you believe that enough of the GAA is converted into AA, simply remove most of the stuff in the boiling flask, distill it and fill it up again with the AA foreruns plus some of the GAA/AA /acetone/whatever mix from the final absorption washbottle.
The really crazy ones among us can even use the generated gasses to heat the whole synth!
Just kidding.
I'm not fat just horizontally disproportionate.
(Official Hive Translator)
12-23-02 17:40
No 392044
(Rated as: excellent)
Check out this:
Patent US2259895
It explains pretty much everything.
Simple, undemanding, perfectly OTC. IMHO, a good way.
OTOH, some equipment is definitely required. In this way it's similar to the acetone pyrolysis thing.
Antoncho
(Stoni's sexual toy)
12-23-02 18:36
No 392063
Nice, especially for bees interested in propionic anhydride.
I think the ketene procedure is hard to beat in ease, cost, yield and simplicity.
I'm not fat just horizontally disproportionate.
(Hive Addict)
12-25-02 02:43
No 392593
Hey Antoncho, it's nice when aurelius actually has time to do work. here's your patent- in text (the pertinent parts anyway)
US Patent 2259895
Process for the manufacture of aliphatic carboxylic acid anhydrides
(Antoncho: Post # 392044)
The present inverntion related to the production of organic carboxylic acid anhydrides such as acetic anhydride and other simple aliphatic anhydrides. (listed through butyric)
It is known that in the oxidation of aldehydes the corresponding carboxylic acid anhydrides are formed over the intermediate existence of per-compounds. These anhydrides are obtained by known measures such as distillation in vacuo, whereby the anhydrides are preserved from the saponifying influence of the water formed at the oxidation. Generally metal salts, especially the acetates of copper, cobalt, or manganese are used in the dissolved or suspended form. The yields and the reactions velocity are very unsatisfying so that a technical process is nearly impossible.
It is an object of my invention to provide such catalysts as accelerate the reactions so that the process may be well practiced.
My invention consists in carrying through the said process with catalysts to which stronger acids, or those acids which are able to form complex compounds or other acidic substances are added. Te catalysts to which these substances according to my invention are added are the salts of the metals with organic acids.
I prefer to employ polyvalent metals salts and to use the free organic acids of the salt as solvent or suspending agent. The salts of copper, silver, cobalt, nickel, iron chromium and the like are used, preferably I the presence of substances with large surface such as silica gel, active-carbon, or cellulose.
As strong acids I use sulphuric acids, alkali bisulfates, perchloric acid, phosphoric acid, acid phosphates, sulpho-acetic acid, benzene sulphonic acid, chlorinated carboxylic acids and so on.
In the same way, weaker acidic substances which form strong acidic comples compounds by reactions with a corresponding carboxylic acids, such as boric acid, zinc chloride, vanadium acid, molybdic acid and the like my be employed.
The effect obtainable by my invention is quite surprising. One would have supposed that in the presence of such strong acids, which are well known hydrating catalysts, that the acetic anhydride would hydrolyze to the respective acid.
Copper sulphate is not a great catalyst for the reaction. owever, have shown to me, that by using a catalyst which was obtained by adding sulphuric acid to a solution of copper acetate the yields and the velocity of reaction are much improved.
Oxygen containing gas (such as air) is bubbled through the reaction mixture to keep the solution at a maintainable heat level. Adding esters of such acid/anhydride will also increase the velocity of the reaction. This process can be carried out as a continuous process by removing ½ the reaction volume and distilling out the product. The remaining substances are reintroduced to the reaction flask with additional catalyst.
Example 1:
In a stirring vessel, which is provided with a good cooling system and which enables the reaction liquid to circulate 30 parts of glacial acetic acid, 0.15 parts of cobalt acetate, and 0.2 parts of copper acetate are introduced. At 44-45*C, 34.5kg of acetaldehyde are treated with the equivalent of quantity of oxygen, within 2-1/2 hours. After one hour the reaction liquid contained 26% acetic anhydride and from that time the liquid was removed gradually in the rate as acetaldehyde was introduced. 55% of the reacted acetaldehyde was turned to acetic anhydride.
Example 2:
In the same way as in Ex. 1, by using 0.15parts cobalt acetate and 0.2 copper sulfate within 2 hours, 17.6 parts acetaldehyde entered into the reaction, whereby a yield of 52% acetic anhydride was obtained.
Example 3:
I used 0.15 parts of cobalt acetate, 0.2 copper acetate and 0.02 part sulfuric acid. Within one hour 17.5 parts of acetaldehyde are reacted with a yield of 63% acetic anhydride.
Example 4:
I used 0.15part of cobalt acetate, 0.2 part of copper acetate and 0.03 parts benzene sulfonic acid. Within one hour, 18.8kg acetaldehyde are reacted, whereby a 61% yield of 3kg of acetic anhydride) is obtained.
Example 5:
when using 0.15part of cobalt acetate, 0.2 part copper acetate and 0.03part boric acid, 18.2 parts acetaldehyde were reacted per hour and 13.1kg AA/hour were formed. 61% yield.
Example 7:
In a stirring vessel as in Example 1 to a solution of 30 parts of ethyl acetate, 0.15 part cobalt acetate, 0.1 part copper acetate and 0.3 part boric acid in 500ml GAA pure acetaldehyde was introduced with the equivalent quantity of oxygen at a rate corresponding to the velocity of the oxidation. 18.4 kg acetaldehyde were reacted/ hour and 15.4 kg of AA were obtained. yielded 72% !!!! The reaction liquid had a content of 32% AA, the reaction temperature was kept at 44-45*C
There are more examples, only one with higher yields (73% AA, but more reactants needed)
eatly advised not to use Manganese catalysts as they reduce the yield to consistant 20% ranges.
Other simple aliphatic acids may be used to obtain their respective anhydrides.
(Stranger)
12-26-02 11:26
No 392930
I`m a bit confused here about use of catalysts.
In process described by me, and latter by Mountain Girl, use of manganese and copper acetate are to prevent forming of explosive amounts of peracetic acid.
But in US Patent 2259895 catalysts are used to accelerate the reactions.
Quote: "...accelerate the reactions so that the process may be well practiced."
So according to the patent if we don use catalysts we get a crappy yied.
Any thougts on that?
(Master Searcher)
12-26-02 17:23
No 392995
I wonder if this would bee of help.
Patent US6387238
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Hive Addict)
12-26-02 18:53
No 393023
Aurelius was going to step up for that patent too, but DAMN SAM!! it's 21 pgs!! forget that (at least for now). does anybody have text for that one?
(Chief Bee)
12-26-02 20:02
No 393040
Abstract
An electrolysis unit has an anode and a gas diffusion cathode. Air is fed to the cathode to generate peroxide species, such as hydrogen peroxide, peroxide ions, or peroxide radicals by electrolysis of oxygenated water. A peracetic acid precursor, such as acetyl salicylic acid, reacts with the peroxide to form peracetic acid. An ion selective barrier optionally separates the unit into two chambers, an anodic chamber and a cathodic chamber. By selecting either a proton permeable membrane or an anion exchange membrane for the barrier, the peracetic acid may be formed in either an alkaline electrolyte in the cathodic chamber or in an acid electrolyte in the anode chamber, respectively.
US Pat 6,387,238 - Full Text:
http://patft.uspto.gov/netacgi/nph-Parse
(Master Searcher)
12-26-02 22:17
No 393075
http://patft.uspto.gov/netahtml/srchnum.
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Stranger)
12-30-02 23:05
No 394273
About that ketene lamp... seems like a great thing, but what about acetone autoignition temp?
I have looked thru some data sheets on acetone autoignition point, and found that info on that varies from 465-540°C, and acetone pyrolysis operates @ 695–705° (Org.Syn.)
So how come the whole thing dident just blow up?
I know that ketene lamp works, but swim wants to bee 100% sure b4 he tries anything
(Hive Addict)
12-30-02 23:15
No 394277
> So how come the whole thing dident just blow up?
no O2 => no explosion. the trick is to have a
very heavy reflux before turning on current.
(but yes, first time it _is_ unnerving)
be careful! the gases are extremely toxic!
(Master Searcher)
12-31-02 00:11
No 394293
Flush out the air with N2 or CO2.
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Stranger)
12-31-02 00:54
No 394300
be careful! the gases are extremely toxic!
What Hypo said is certainly not an understatement. Ketene is a poisonous gas having a toxicity comparably with phosgene
. If you observe a pungent odour resembling acetic anhydride, you 'd better run for your life since this means that there is a leak in the apparatus. It goes without saying that this procedure must be done in an efficient fume cupboard. If you 're a first time chemist, it is not the procedure I would recommend.
(Stranger)
12-31-02 01:11
No 394303
uhmm... could on use a simple toaster wire for that? It glows red...
If one opens toaster and uses his mechanism for ketene lamp, there`s no need for current regulator.
( I sopouse one would use a current regulator to set it right)
Lets say i toaster mechanism for it. How would I know the temp. is right?
By the gass forming I soupose?
(Hive Addict)
12-31-02 01:36
No 394311
> uhmm... could on use a simple toaster wire for that? It glows red...
i don't think so, but it's possible. check the web for nichrome wire
or resistance wire. 2 types of resistance wires were tried, one worked
(the expensive one for about $2/m) and the other one didn't work ($1.5/m).
use the one that goes >1200°C.
> there`s no need for current regulator
you really want a way to control the ketene production rate.
> How would I know the temp. is right? By the gass forming I soupose?
yes, ketene / methane production goes fast.
note one thing though: acetyl had major problems with the insulation.
(the stopper couldn't stand the heat). my experimentator didn't have
the problem. the grey eu-stopper showed signs of chemical reaction (the
bottom got dark - not really strange at several hundred °C in an
agressive ketene atmosphere), but it didn't brittle or something.
(Stranger)
12-31-02 11:03
No 394457
hmmm... i have searched on the web for toaster wire, and it seem that it is mostly nicrome wire!
Check this: http://www.howstuffworks.com/toaster1.ht
(Hive Bee)
01-04-03 01:56
No 395232
Yup, toaster wire is nichrome. Same with the wire in blow driers.
(Hive Bee)
01-04-03 04:42
No 395259
Captin_Mission: any references for your claim or text where you make your claim.........I would be interested to read as I'm looking for an easy synthesis for acetaldehyde ...........java
(Moderator)
05-26-03 20:43
No 435660
From Thorpes's
Preparation.
LABORATORY METHODS.-The classical method for preparing acetaldehyde is by dierct oxidation of ethyl alcohol, for example by air presence of platinum black (Dobereiner, Gm. 8 274), by manganese dioxide and sulphuric acid (Liebig, Annalen, 1835, 14, 133), by potassium dichromate and sulphuric acid (Staedeler, J 1859, 329). Improved methods and apparatus for converting alcohol into acetaldehyde am described by Boult (Patent GB3998;. J.S.C.I. 1896, 15, 668), Fournier (Patent GB7887, J.S.C.I. 1897, 16, 695), and Lang (ibid. 1903, 571). Wertheim recommended the oxidation alcohol with a mixture of sulphuric acid, nitric acid, and sodium bichromate in a stream carbon dioxide (J. Amer. Chem. Soc. 1913, 35 689, 698), whilst Adams and Williams.(ibid. 1921. 43, 2420) stated that the yield of aldehyde by the ordinary chromic oxidation is greatly improved by very vigorous stirring of the mixture. Other methods of preparation are: distillation of calcium acetate with calcium formate (Limpricht, Annalen, 1856, 97, 369), distillation of lactic acid with manganese dioxide and sulphuric acid (Stadeler, Annalen, 1851, 79, 333„ or by the action of dilute sulphuric acid alone (Erlenmeyer, Zeitsch. f. Chemie, 1868, 4, 343).
Ethylene oxide, yields acetaldehyde on heating either alone (Nef, Annalen, 1904, 335, 201), or better in presence of aluminium oxide at 200°C. (Ipatieff and Leontowitsch, Ber. 1903, 36, 2017). Acetaldehyde is also produced by treating ethylene glycol with Fenton's reagent, by treating ethylene diamine with nitrous acid (Neuberg and Rewald, Biochem. Z. 1914,67,127), and from pyruvic acid by heating to 150°C. with dilute sulphuric acid (Beilstein and Wiegand, Ber. 1884, 17, 841) it is also formed on heating an alcoholic solution of an ethyl halide with hexamethylene tetramine or with formaldehyde and ammonia (Fabriques de Laire, Patent GB5533. Various aliphatic acids such as succinic, glyceric, maleic, fumaric, tartaric, etc., yield acetaldehyde on treatment with Fenton's reagent in sunlight (Neuberg, Biochem. Z. 1914, 47, 50).
The most interesting and convenient method, as well at the most important practically, is based on the discovery of Sabatier and Senderens (Compt. rend. 1903, 136, 738; cf. also Bouveault, Bull. Soc. chim. 1908 [iv], 3, 117) that on passing the vapour of alcohol over a heated metallic catalyst, preferably copper or silver, hydrogen is readily split off with production of acetaldehyde in high yield. Snelling Patent US1124347) has also claimed a method which consists in passing the vapour of alcohol into a heated porous earthenware tube containing platinum or palladium and drawing off the hydrogen produced which diffuses through the walls of the tubes. It is doubtful if this is a practicable method. The Sabatier-Senderens method has, however, in recent years become the basis of a very important branch of the organic chemical industry which is demonstrated both by the number of patent applications and by the erection of large works in Great Britain, Germany, the United States and elsewhere, for the manufacture of acetaldehyde from ethyl alcohol.
The effect of various catalysts on the conversion of ethyl alcohol into acetaldehyde has been examined by Engelder (J. Physical Chem. 1917, 21, 676). Martineau (Compt. rend. 1931, 193, 1189) has described the production of acetaldehyde by passing a mixture of alcohol and air over a copper-carbon catalyst at 63°C. Patterson and Day (Ind. Eng. Chem. 1934, 26, 1276) examined the effect of pressure on the reaction, using a silver catalyst, and showed that under atmospheric pressure the optimum yield was at 415°C, while increase of pressure diminished the yield of acetaldehyde. The addition of 0.2% Sm203 to the silver increased the yield 3-4%.
Kagan and Shneerson examined the yields and obtained 88-96% with a copper catalyst, and 94-97% using a silver catalyst; Kagan and Podurovskaya recommended the use of CuO heated to 900°-950° before reduction and found that the presence of moisture increased the amount of acetic acid formed (J. Appl. Chem. Russia, 1932, 5, 378, 389).
Calvert (Patent GB132120) claims the oxidation of alcohol to acetaldehyde in an apparatus identical with that described in Patent GB126479 for converting methyl alcohol to formaldehyde. Groombridge, Oxley, and British Celanese Ltd. introduce oxygen and alcohol vapour into the reaction zone through perforated conduits at several points parallel to the line of flow of the reaction mixture (Patent GB391444), whilst water may be removed by cooling the issuing vapours to 40°-70C°, the acetaldehyde being then absorbed directly in glacial acetic acid for oxidation (Patent GB390186, Patent GB390211); the same inventors also claim the use of a heat-interchange system in which the reaction bed exchanges heat with a climbing film of cooling liquid (Patent GB390186, Patent GB390504).
H. Dreyfus, in a series of patents, describes the use of suitably cooled annular reaction vessels for the oxidation of alcohol to aldehyde and at least its own weight of steam being passed over a silver or copper catalyst (Patent GB389134). The use of silver deposited upon copper as a catalyst is described in Patent GB425550. The water produced in the reaction may be partially removed by treatment with a dehydrating agent such as calcium chloride, etc. (Patent GB389135), or the water and unchanged alcohol may be removed as a ternary mixture by treatment with benzene, the acetaldehyde remaining in vapour form (Patent GB389145), or the moist acetaldehyde vapour may be cooled to 40°-70° to condense the water with only a small amount of acetaldehyde (Patent GB390211); lastly the acetaldehyde itself may be separated by extraction at 100°-150° with a solvent miscible with water, such as chlorobenzene or paraffin oil (Patent GB390506).
Du Pont de Nemours & Co., Ltd. (with Bond, Smith, and lazier) claim that on heating ethyl alcohol at 350°/270 atm., in presence of copper containing traces of
magnesium or manganese, a mixture is obtained of ethyl
acetate, n-butyl alcohol, and a lesser amount of acetaldehyde (Patent GB287846); again, on passing alcohol vapour over a catalyst consisting essentially of a basic zinc chromite, copper chromite, manganese chromite, etc., the product consists mainly of acetaldehyde and n-butyl alcohol, with lesser amounts of n-butyl alcohol (Patent GB313575. Cf. also Adkins, Folkers, and Kinsey, J. Amer. Chem. Soc. 1931, 53, 2714, 4220 ; Ind. Eng. Chem. 1932, 24, 314). For the normal process a catalyst is recommended consisting of electrolytic silver crystals impregnated with a small amount (e.g. 1%) of the oxides of Al, Cr, Ce, Mo, Th, V, W, or Zn (Patent US1968552). Scalione and Frazer effect the oxidation of alcohol in presence of free oxygen, by using a metal oxide catalyst which has been prepared by drying below 150° or in a current of neutral gas below 200° (Patent GB166285). Holzverkohlungs Industrie A.-G. claim a 92.3% conversion by using a silver gauze catalyst, a similar method being claimed by Goldschmidt in Patent GB290523, using a silver catalyst at 400°-420°C. Woolcock and Imperial Chemical Industries, Ltd., pass alcohol vapour with air through silver gauze discs contained in a copper tube (Patent GB325105), whilst Boehringer and Soehne recommend the addition of 0.2% of CeO2 to the reduced copper catalyst. Wiesler, Peake, and British Industrial Solvents, Ltd., obtain acetaldehyde by passing alcohol vapour, steam and air over copper at 420°-440° or silver gauze at 450°-500°, or over the AgVO3 or Cu(N03)2 at 350°-400°C. (Patent GB353071). Monsanto Chemical Works claim the use as catalysts of vanadyl zeolites prepared by forming complex silicates containing vanadium in non-exchangeable form, with or without other chemical groups such as boric, phosphoric, tungstic, molybdic, stannic, or plumbic acids, combined with zinc, aluminium, chromium, etc. (Patent GB298142). In Patent GB294037 Fuchs and Holzverkohlungs Industrie A.-G. dry the reaction products by cooling, and then extract the aldehyde by means of a solvent such as aldol, acetic acid, alcohol, etc., the resultant solutions being then polymerised, oxidised, or reduced to yield more aldol, acetic acid, or alcohol respectively. Young and Carbide and Carbon Chemicals Corpn., in Patent US1977750, pass the vapour of alcohol at 225°-350°C. over a reduced copper catalyst containing not more than 5% of Cr, prepared by impregnating an inert carrier with a concentrated solution of 545 parts cupric nitrate and 118 parts chromic nitrate, the mass being dried, roasted at 600°, and then heated at 250°C. in a stream of alcohol vapour.
A large works has been erected on a 45-acre site at Salt End, near hull, by British Industrial Solvents, Ltd., for the manufacture of glacial acetic acid, n-butyl alcohol, etc., from acetaldehyde. Alcohol vapour with air is passed over silver gauze maintained by the heat of the reaction at a dull red heat under rigidly controlled conditions, and very high yields of aldehyde are obtained (cf. Chem. Age, Sept. 27, 1930). Unchanged alcohol is fractionated off and returned to the process, the aldehyde being then collected and stored. It is found preferable to employ a number of comparatively small catalytic units rather than a smaller number of larger units, as the process then becomes more flexible and capable of readier control. During the last quarter of a century the large-scale manufacture of acetaldehyde from acetylene has become an important branch of applied organic chemistry, mainly as an intermediate for the manufacture of glacial acetic acid and of n-butyl alcohol.
Chemistry is our Covalent Bond
(Moderator)
05-26-03 20:59
No 435662
The basic process depends upon the original discovery of Kutscherow (Ber. 1881, 14, 1540 ; 1884, 17, 13), that in the presence of mercury salts, such as mercuric chloride or sulphate, acetylene reacts with water to give acetaldehyde. In accordance with the analogy of the formation of vinyl acetate from acetylene and acetic acid we may assume that the penultimate stage in the synthesis is the formation of the labile vinyl alcohol, which at once isomerises to acetaldehyde. The exact role played by the mercury catalyst is still obscure. Hofmann (Ber. 1898, 31, 2212, 2783 ; 1899, 32, 874 ; 1904, 37, 4459 ; 1905, 38, 663 ; 1908, 41, 312; 1909, 42, 4232) and Biltz and others (Ber, 1904, 37, 4417 ; 1905,38, 133; Annalen, 1914, 404, 219) investigated, the white precipitate formed by passing acetylene into an aqueous solution of mercuric chloride.
Hofmann considers that the first product of the reaction is a substance having the constitutional formula: which is rapidly hydrolysed by water to trichloromercuriacetaldehyde, (CIHg)3C•CHO. Bilts and his co-workers have shown that the white precipitate almost certainly has the constitution of trichloromercuriacetaldehyde, but they regard the evidence for the formation of Hofmann's intermediate compound as unsatisfactory. Brame (J.C.S. 1905, 87, 427), however, has shown that a white substance observed by Biginelli (Chem. Zentr. 1898, i, 926) to be formed in small quantities by the action of acetylene on mercuric chloride in dilute hydrochloric acid solution can be obtained in a pure crystalline condition; it is an additive compound and has the constitution and is decomposed by water, yielding acetaldehyde, free hydrochloric acid, and a little trichloromercuriacetaldehyde.
Chapman and Jenkins (J.C.S. 1919, 115, 847) and Jenkins (J.C.S. 1921, 119, 747) have confirmed Brame's results and have succeeded in preparing the additive compound in quantity (50 g. from 72 g. of mercuric chloride) by the action of acetylene on a saturated solution of mercuric chloride in absolute alcohol containing hydrogen chloride. It is a crystalline compound, m.p. 129°, and soluble in most organic solvents. Decker has discussed the theoretical basis of the hydrolysis of vinyl ethers to acetaldehyde (Helv. Chim. Acta, 1930, 13, 666).
(a) Process.-The first British Patent dealing with the subject is by the Chem. Fabrik Griesheim Elektron (Patent GB29073), in which a process is claimed consisting in passing acetylene into a solution of a mercury salt in an organic or inorganic acid below 70°C. (e.g. sulphuric, phosphoric, acetic, chloracetic acids). The use of 45% sulphuric acid mixed with mercuric oxide is
recommended. Owing to the war and the unexpected importance of processes for the manufacture of acetaldehyde, for conversion to acetic acid and thence to acetone, N. Gruenstein's original German Patent Application (G. 40228 of July 2, 1913) remained in abeyance for 13 years and the complete Patent DE425665, was only granted on Feb. 11, 1926, with extension of "life"; it was later acquired by I.G. Farbenind. A.-G. This patent covered the process for the production of acetaldehyde by passing a continuous stream of acetylene through dilute sulphuric acid containing a mercury catalyst. A general discussion of the priority of earlier patents is given in Z. angew.
Chem. 1918, 31, 148, 180. Chem. Fabrik Griesheim Elektron (Patent GB15669) claim the use of a 20-35% aqueous solution of sulphuric, phosphoric, or an organic sulphonic acid, etc., containing a mercury salt, the temperature being kept below the boiling-point. The Consort. f. Elektrochem. Ind. G.m.b.H. describe a modification consisting in passing acetylene through sulphuric acid solutions of mercury oxide, containing less than 60 parts SO4 per 1,000 parts of water, at temperatures above 70°C. (Patent GB6000). The aldehyde distils off as it is formed and mercury is deposited at the bottom of the liquid; the patent also claims an electrolytic process for re-oxidising the mercury which is gradually formed by reduction during the process. In Patent GB16848, the same firm describe a process in which the acetaldehyde is swept out of the solution as it is formed, by a stream of excess acetylene, the aldehyde being removed and the residual gas recirculated (see also Patent GB208689). Fr. Bayer and Co. (Patent GB6527) claimed a similar process, the sulphuric acid being replaced by an organic sulphonic acid, e.g. benzene sulphonic acid (di- or tri-sulphonic acids), etc., the object being to avoid the condensation and polymerisation of the acetaldehyde which is caused by the prolonged action of stronger acids, such as mineral acids.
Boiteau in Patent GB15919 recommends the production of a catalytic liquid by dissolving a mercuric salt in a suitable solvent and then forming the sulphate in situ, by the addition of sulphuric acid; the process is,
however, mainly concerned with the production of ethylidene diacetate.
A further improvement claimed by the Consort. f. Elektrochem. Ind. G.m.b.H. (Patent GB16957) consists in so adjusting the rate of flow of the acetylene and the temperature of the reaction vessel that the heat
evolved by the reaction is balanced by the heat lost by
evaporation of water, thus attaining a state of approximate thermal equilibrium, fresh water being added continuously to keep the volume constant. The use of thermally insulated and water-jacketed vessels is recommended. A further patent (Patent GB5132) is concerned mainly with the use of solvents such as glacial acetic acid, ethylidene diacetate, etc., in the presence of mercuric oxide and a strong acid, water being added continuously in the theoretical proportions.
A continuous process using 6% sulphuric acid containing
mercuric oxide in suspension, at 40°-65°C., and at pressures slightly above atmospheric, is claimed by Matheson and Canadian Electroproducts, Ltd., in Patent GB132557; continuity is maintained by the periodic
addition of water, acid and mercuric oxide.
Dreyfus (Patent GB105064) recommends the use of sulphuric acid of 5-20% at a temperature below 60°C., the acetylene being led in at such a rate that all is absorbed. The acetylene is introduced slowly at first until all the mercury compound present (5-20%) has become grey or greyish-black. The acetaldehyde formed may be removed periodically either by distillation or by extraction with solvents such as tetraehlorethane, etc., water being added at intervals. In Patent GB106483Dreyfus modifies his process by using sulphuric acid of more than 20% and extracting the acetaldehyde with suitable solvents.
The removal of acetaldehyde from mixed reaction products by extraction with a solvent such as methyl-cyclohexanone, benzene, etc., in stages, at or above its boiling-point, is claimed by Usines de Melles in Patent GB380928.
The formation of undesirable by-products is largely prevented, according to Hibbert and Morton (Patent US1213486, Patent US1213487, Patent US1247270; Patent CA181655), by the introduction of a salt of a weak acid, e.g. a borate, into the catalytic mercury solution ; the absorption of the acetylene and distillation of the acetaldehyde is stated to be more complete. A claim is also made for the use of several catalytic baths arranged in series to ensure complete absorption. In Patent GB260305 the Consort. f. Elektrochem. Ind. G.m.b.H. recommend the catalytic hydration of acetylene in presence of a solvent for the gas, such as phenols, ketones, acetals, esters, etc. I.G. Farbenind. A.-G. claim the catalytic production of acetaldehyde from acetylene in presence of mercuric salts, at pressures exceeding 2 atm., the method being especially applicable to mixtures containing dilute acetylene obtained by the thermal decomposition of hydrocarbons ([patent]GB 278324[patent]); they also claim the use of a catalyst comprising a solution of an alkali metal bi-sulphate, containing a mercury salt, or a salt of a heavy metal of the 1st or the 8th groups of the periodic system, such as copper or iron (Patent GB312716), whilst in Patent GB319542 a claim is made for the use of a solution of mercuric and ammonium salts for effecting the hydration; the use of slightly increased pressures, temperatures above 85°C., and an excess of acetylene is recommended in Patent GB349022. The same inventors claim the use of heated concentrated aqueous solutions of salts having a slightly acid reaction, such as the chlorides of zinc, chromium, magnesium, calcium or ferric iron, in presence of mercuric oxide or uranyl nitrate (Patent GB313864); this last process may be modified by the use of increased pressure with the addition of a small amount of water, insufficient to destroy the acid reaction but enough to lower the boiling-point to at least 4°C. below the boiling-point of the corresponding saturated solution (Patent GB393690).
Chemistry is our Covalent Bond
(Moderator)
05-26-03 21:10
No 435664
Regeneration and Recovery of Mercury Catalyst.-
One great difficulty found in the early years of this branch of chemical industry lies in the fact that the mercury catalyst gradually becomes reduced and is deposited as a heavy tarry sludge at the bottom of the vessel, the solution thus gradually losing its catalytic activity.
Hilditch and Crosfield suggested overcoming this trouble by reoxidising the sludge to mercuric oxide by the periodic addition of small amounts of suitable oxidising agents such as manganates, permanganates or hydrogen peroxide (Patent GB124702, Patent GB125926); or by lead peroxide, manganese dioxide, or ceric oxide (Patent GB131084). The Soc. Chem. Ind. in Basle regenerate the catalyst by electrolysis in presence of a suitable oxygen carrier such as an iron salt (Patent GB130138); more generally, however, the formation of mercury sludge is prevented or delayed by the introduction into the catalytic liquor of oxidising agents such as chromic acid, chromates, or in particular ferric salts (Meister, Lucius, and Briining, Patent GB24153; Patent DE293070; Patent US1151928, Patent US1151929). Riley and Imperial Chemical Industries, Ltd., recommend the use as a catalyst of a mercury salt solution containing ferric sulphate, a portion of the liquor being continuously removed, reoxidised by oxygen, and returned to the process (Patent GB346883). Alternatively, the catalyst may be prepared by mixing mercury with a suitable oxidizing agent such as ferric oxide, and then adding dilute sulphuric acid (Soc. Anon. de Prod. Chim. Etabl. Maletra, Patent GB140785). A continuous regeneration process using electrolytic oxidation with a platinum anode and mercury cathode is described by the Chem. Fabr. Griesheim-Elektron in Patent GB143891. Again, the spent reaction liquor of Patent GB140785 (v.s.) may be regenerated by first removing all aldehyde present, precipitating the mercury from the solution by means of iron filings, and finally reoxidising the ferrous salt solution by electrolysis (Soc. Anon. de Prod. Chim. ]tabl. Maletra, Patent GB165085). As an alternative the sludge itself may be removed and treated in various ways to revivify it or to recover the mercury: thus the Chem. Fabr. Griesheim-Elektron advise carbonising the residue by heat or else mixing the sludge with caustic lye and electrolysing (Patent GB10140). Matheson also recommends letting the sludge settle, neutralising with alkali and heating to 125°C.; the liquid mercury is then run off, the residue being ground up and carbonised by heating it to 100°-500°C. (Patent GB132559). Riley, Rowell, and Imperial Chemical Industries, Ltd., recover the mercury by treating the sludge with chlorine and removing the resultant mercuric chloride solution (Patent GB332106); whilst Hirst, Rowell and Imperial Chemical Industries, Ltd., suggest treating the sludge with strong nitric acid and then adding concentrated sulphuric acid to precipitate mercuric and ferric sulphates (Patent GB309888). The Chem. Fabr. Worms A.-G. advise heating the spent catalytic material with iron powder or other reducing agent to 200°C. for several hours (Patent GB156187).
The preparation of the requisite mercuric oxide for the
production of the fresh catalyst may be carried out
electrolytically, according to Matheson (Patent GB132560; cf. Canad. Chem. J. 1919, 3, 259); mercury and dilute aqueous caustic soda are placed in a large cast-iron pan, 6 ft. in diameter and 15 ins. high, oxidation being effected with current density of about 55 amps. per sq.
ft., at 8-10 volts, using an iron or nickel cathode (cf. also Daniell and Elektrizitatswerk Lonza, Patent DE311173)
Chemistry is our Covalent Bond
(Moderator)
05-26-03 21:29
No 435670
Use of Other Catalysts.-
A number of attempts have been made to effect the hydration of acetylene by the passage of steam and acetylene over heated dry catalysts which may or may not contain non-volatile mercury compounds; the Deuts. Gold- u. SilberScheidenanstalt vorm. Roessler pass a mixture of acetylene and steam over contact agents such as molybdic acid on asbestos, at high temperatures (Patent GB107584). The Chemische Fabrik Rhenania suggest passing the same mixture over bog iron ore at 400°-420°C., or over hydrated iron oxide, bauxite, hydrated aluminium silicates, or compounds of copper, nickel, chromium, vanadium, etc. (Patent GB109983; cf. also [patent]GB 107585[patent]). I.G. Farbenind. A.-G. claim the production of acetaldehyde by passing acetylene and steam over non-volatile mercuric compounds such as the phosphate, vanadate or sulphate in presence, if desired, of silver or tin vanadates ; in presence of air acetic acid is formed (Patent GB321241). Again, the catalyst may consist of silico-tungstic acid deposited on clay, or basic zinc tungstate (Patent GB329867), or it may comprise alumina activated by dehydrogenating catalysts such as cadmium oxide, zinc oxide, cadmium sulphide, or zinc sulphide together with the corresponding chromates, tungstates, molybdates, etc. (Patent GB332635). Acetaldehyde may also be obtained by passing a mixture of approximately equal volumes of acetylene and steam over a catalyst comprising, for example, zinc oxide, manganese dioxide and chromic acid, at 180°-200°C. (Mittasch, Pier, Winkler, and I.G. Farbenind. A.-G., Patent DE415686). In a later patent by the same firm it is proposed to pass a mixture of acetylene, steam and oxygen, saturated with mercury vapour at 200°-260°C., over a mixed catalyst such as mercuric phosphate with other heavy metal oxides and/or salts, deposited on pumice, clay, etc. (Patent GB364255). Wohl (Patent GB154579) recommends passing a mixture of air, steam, and acetylene over a heavy metal salt which is stable below 300°-400°C., such as basic zinc chloride, basic zinc vanadate, molybdate or chromate; the product consists of acetaldehyde with some acetic acid. A similar process of the Consort. f. Elektrochem. Ind. A.-G. (Patent GB373893) consists in passing acetylene and steam through molten zinc chloride, with or without the addition of (BaSO4+ZnO) or a mixture of oxides such as CeO2, ZnO, Cr Os, MnO, BaO, TiO2, etc., at 300°-450°C., the exit vapours being then passed over a heated solid catalyst to complete the conversion, if desired. In a modified process acetylene and oxygen, together with small amounts of nitrogen oxides and in substantial absence of steam, are passed over heated quartz or porcelain at 287°-407°, to yield acetaldehyde and acetic acid Gutehoffnungshutte Oberhausen A.-G., Patent GB376045). Horsley, Tanner, and Imperial Chemical Industries, Ltd., recommend the use of a catalyst composed of zinc oxide and a molybdate, at 300°-350°C. (Patent GB334427), or of bismuth salts such as the phosphate or molybdate, using a large excess of steam in the process (Patent GB344638), whilst by the use of cadmium phosphate at 300°-400°C. acetaldehyde and crotonaldehyde are produced (Patent GB346288), or the catalyst may consist of boron trioxide and phosphoric acid ("boron phosphate") at 200 -400°C. (Patent GB351016). Traun's Forschungslaboratorium proposes to obtain acetaldehyde by hydrating acetylene with steam at 250°-300°C./5-10 atm. in presence of small quantities of acetic, sulphuric, or organic sulphonic acids, etc. (Patent GB156152), whilst I.G. Farbenind. A.-G. propose passing gases containing acetylene through concentrated aqueous solutions of neutral salts at 140°, the salts having an acid reaction in concentrated solutions (e.g. salts of zinc, cadmium, chromium, etc.), and the residual gases are then further catalytically hydrated, for example, by passage at 300°400°C. over a mixture of the oxides of aluminium, tungsten, and zinc (Patent GB313864, Patent GB425069). I.G. Farbenind. A.-G., in Patent GB340787, claim a process for the purification, prior to conversion to acetaldehyde, of acetylene-rich gases produced thermo-electrically, by passing the gases over porous carbon or silica gel; they also claim the use of mercuric phosphate, at temperatures above 120°C., for the hydration of crude dilute acetylene, or the use of silver vanadate on active carbon at 250°C. or over (Patent GB304855). The production of acetaldehyde from dilute mixtures containing 2-10% of acetylene, by washing the gases in a counter-current with a suitable mercuric sulphate catalyst solution, is claimed by Hirst and Imperial Chemical Industries, Ltd., in Patent GB302515. The same problem is also dealt with in Patent GB414347 (Murphree and Standard Oil Co.).
In a somewhat different category are the following: I.G. Farbenind. A.-G. claim the production of acetaldehyde by passing ethylene oxide over a catalyst obtained by heating together copper carbonate and magnesium ammonium phosphate, etc.. (Patent GB331185); the same firm in Patent GB334223 describes the manufacture of ethyl alcohol by leading acetylene, saturated with water vapour at 90°C., first over zinc oxide or silica gel, etc., at 380°C., and then, admixed with hydrogen, over nickel at 200°C. A general description of preparing acetaldehyde from acetylene is given by Thommen in Chem.-Ztg. 1934, 58, 797. Benson and Cadenhead note the occurrence of diacetyl, and of other potentially valuable by-products in the synthesis of acetaldehyde from acetylene (J.S.C.I. 1934, 54, 40T).
Apparatus and Plant.-
The use of acid resisting silicon-iron vessels for the process is recommended by Dreyfus in Patent GB115899. Comp. de Prod. Chim. d'Alais describe the production of acetaldehyde from acetylene in an apparatus in which the reaction liquid is subjected continuously to a vacuum so as to remove the acetaldehyde as it is formed (Patent GB130650). As originally carried out on the large scale at the Shawinigan works of Canadian Electro-products, Ltd., acetylene gas was led into dilute sulphuric acid containing mercuric oxide in pension, the oxide being added continuously and the acetaldehyde carried off in the excess of acetylene used (Canad. Chem. J. 1919, 3, 260). Seller, Hotz, and the British Cellulose and Chemical Co. recommend that parts of the apparatus exposed to the action of sulphuric acid shall be of lead, coated electrolytically with lead peroxide (Patent GB151086) (cf. also Patent GB105064, Dreyfus). In Patent GB155776 and Patent GB217747 Brutkus describes apparatus for producing acetaldehyde from acetylene and water vapour in a type of compressor in which they are brought to reaction during compression strokes, temperature and pressure being maintained constant by injection of a spray of water. In Patent GB294227 (void) (Karpiti and Hilbsch a plant is described in which the acetylene and the absorbing solution are maintained in separate circulatory systems having the reaction chamber in common. I.G. Farbenind. A.-G. in Patent GB299234 (grant of patent refused) claim the use of chromium-nickel steel for the construction or lining of the apparatus, whilst in Patent GB298108Harter describes a form of vessel including a rotating fan, or impeller, made of, or coated with, platinum so that a stream of acetylene, steam, and oxygen may be impelled through the vessel and caused to react with production of acetaldehyde. Small amounts of acetaldehyde are formed, together with ethylene glycol, on hydrolysing dichlorethane with water and barium carbonate at 160°-180°C. for 1 hour (Askenasy and Heller, Patent US1928240). Emeleus (J.C.S. 1929, 1733) states that acetaldehyde is formed to the extent of about 10% in the phosphorescent cold flame of ether, whilst Marie and Lejeune (Anal. Ffs. Quim. 1930, 27, 447) describe a method of electrolysing ether in presence of perchloric acid which affords acetaldehyde in 30% yield.
H. Dreyfus claims the production of mixtures of acetic acid, acetaldehyde and acetone by passing a mixture of methane, carbon monoxide, and carbon dioxide under pressure (e.g. 12-50 atm.) and below 500° over various catalysts such as copper, iron, nickel, cobalt, palladium, etc. (Patent GB226248, Patent GB337409). Walker and the Empire Gas and Fuel Co. also claim the production of methanol, formaldehyde and acetaldehyde by a similar process from natural gas, coal gas, shale gas, oil gas, etc. (Patent GB295356, void). In Patent GB304623 the I.G. Farbenind. A.-G. claim the production of acetaldehyde, formaldehyde and formic acid from hydrocarbons and air under the influence of the silent electric discharge; the same firm also notes the production of acetaldehyde as a byproduct obtained on passing hydrocarbon mixtures, together with steam and air, over catalysts such as oxides of manganese, vanadium, chromium, aluminium, etc., at 500°-800°C. (Patent GB305603). In Patent GB267925 the same firm describes the preparation of acetaldehyde by passing carbon monoxide and acetic acid vapour at 200°-550° over a mixture of iron and cobalt; whilst Dreyfus reduces waste or dilute acetic acid to acetaldehyde by catalytic reduction with hydrogen, using finely divided nickel, iron, zinc, tin, lead, pumice, etc., as catalysts (Patent GB273810). The formation of acetaldehyde as a by-product during the catalytic oxidation of various gaseous hydrocarbons at 350°-600° is noted in Patent GB321494 (Arnold and Standard Oil Development Co., Ltd.), whilst Gutehoffnungshutte Oberhausen A.-G. note the production of acetaldehyde and formaldehyde by treating a mixture of methane and carbon dioxide with a high-frequency field of 20,000 volts or over, at cycles greater than 10,000 per second (Patent GB353455). Behrens describes the production of acetaldehyde by mixing the gases obtained by distilling coal, wood, turf, etc., with 5-6% of carbon dioxide and heating the mixture for some time (Patent DE276764). Aldehyde is also formed to some extent by heating charcoal saturated with acetylene to 350°C. with water (Degriz, Ann. Chim. Phys. 1894 [vii], 3, 216). I.G. Farbenind. A.-G. claim the production of acetaldehyde by passing ethylene oxide over a reduced catalyst such as one prepared from copper carbonate and magnesium ammonium phosphate, at 180°-200°C. (Patent GB331185). A more unusual claim is made by Curme consisting in passing ethylene into a solution of a mercuric salt, the compound produced being then subjected to anodic oxidation to produce acetaldehyde, which is removed continuously by distillation (Patent US1315543, Patent US1315546).
Chemistry is our Covalent Bond
(Hive Bee)
06-17-03 12:38
No 440509
Very interesting. I need literature about the etylene process
Monograph Number: 40
Title: Acetaldehyde
CAS Registry Number: 75-07-0
Additional Names: Ethanal; "aldehyde"; acetic aldehyde; ethylaldehyde
Molecular Formula: C2H4O
Molecular Weight: 44.05.
Percent Composition: C 54.53%, H 9.15%, O 36.32%
Line Formula: CH3CHO
Literature References: Produced by oxidation of alcohol with Na2Cr2O7 and H2SO4; usually from acetylene, dil H2SO4 and mercuric oxide as catalyst; also by passing alcohol vapor over a heated metallic catalyst. Lab procedure from ethanol: Wertheim, J. Am. Chem. Soc. 44, 2658 (1922); Fricke, Havestadt, Angew. Chem. 36, 546 (1923); Gattermann-Wieland, Praxis des organischen Chemikers (de Gruyter, Berlin, 40th ed., 1961) p 180; from acetylene: Gattermann-Wieland, op. cit. 183; from paraldehyde: A. I. Vogel, Practical Organic Chemistry (Longmans, London, 3rd ed., 1959) p 324; by catalytic oxidation of ethylene in aq soln: J. Smidt et al., Angew Chem. 71, 176 (1959); by oxidation of ethylene in fuel cells in the gas phase: K. Otsuka et al., Chem. Commun. 1988, 1272. Manuf: Faith, Keyes & Clark's Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley-Interscience, New York, 4th ed., 1975) pp 1-7. Toxicity data: Smyth, Arch. Ind. Hyg. Occup. Med. 4, 119 (1951). Review: H. J. Hagemeyer in Kirk-Othmer Encyclopedia of Chemical Technology vol. 1 (John Wiley & Sons, New York, 4th ed., 1991) pp 94-109.
Properties: Flammable liquid; characteristic, pungent odor. d416 0.788. mp -123.5°. bp 21°. nD20 1.3316. Flash pt, closed cup: -36°F (-38°C). Miscible with water, alcohol. Keep cold. Chill thoroughly before opening. LD50 orally in rats: 1930 mg/kg (Smyth).
Melting point: mp -123.5°
Boiling point: bp 21°
Flash point: Flash pt, closed cup: -36°F (-38°C)
Index of refraction: nD20 1.3316
Density: d416 0.788
Toxicity data: LD50 orally in rats: 1930 mg/kg (Smyth)
CAUTION: Potential symptoms of overexposure are eye, nose and throat irritation; conjunctivitis; coughing; CNS depression; eye and skin burns; dermatitis; delayed pulmonary edema. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 2. See also Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section II, p 186. This substance is reasonably anticipated to be a human carcinogen: Ninth Report on Carcinogens (PB2000-107509, 2000) p III-65.
Use: Manuf paraldehyde, acetic acid, butanol, perfumes, flavors, aniline dyes, plastics, synthetic rubber; silvering mirrors, hardening gelatin fibers. Flavoring agent in foods and beverages.
(Hive Bee)
06-22-03 14:07
No 441677
I need the following literature:
catalytic oxidation of ethylene in aq soln: J. Smidt et al., Angew Chem. 71, 176 (1959); by oxidation of ethylene in fuel cells in the gas phase: K. Otsuka et al., Chem. Commun. 1988, 1272.
Is there a bee, who can copy this literature ?
(Chief Bee)
06-22-03 20:30
No 441727
(Rated as: good read)
roger2003: Angew. Chem. 71(5), 176-182 (1959) has already been posted in Post 417762 (Rhodium: "Isosafrole Wacker - MDP2P in 69% yield", Novel Discourse) for other reasons - it deals with the Wacker oxidation of a whole lot of alkenes, not just ethylene.
J. Chem. Soc. Chem. Commun. 1272-1273 (1988) (../rhodium/pdf /ethene2ethan
The circular Palladium electrodes were 1 mm thick, 21 mm in diameter and the ethene/oxygen gas flow ~30 mL/min. With a current of 30mA/1V applied between the Pd electrodes, the rate of acetaldehyde formation was 0.01 mmol/min, and without any current applied ~4 mA was actually produced by the fuel cell, but the rate of aldehyde formation dropped by 90%.
It is clear that this fuel cell needs to be scaled up considerably or the surface area otherwise increased, as even if it generates no waste and runs on air and water, the current setup produces at most 150mg acetaldehyde per hour
(Hive Addict)
06-23-03 11:38
No 441901
Yields, yields, yields.....
What are you after? The highest acetone or ethanol conversion per pass because of the high costs per hour your chemical plant has? And the 25 million dollar investment for the technics must pay back soon? The high costs and hard availability of the compounds used?
Reality check.
For acetaldehyde and acetic acid a apparatus is easily buildt from scrapyard materials, the starting compounds are cheap and OTC. The apparatus runs for itself once adjusted and tested. Where please is the importance for how high the conversion is actually as long you have an half or one or more liters of the desired compound after a night of unwatched processing? It is much easier to install a second tube or three, five, nine.... More tubes make heat distribution even easier btw.
Yields, yields, yields...
What fetish is this? There are enough phantastic 90%+ synths on the HIVE one more phantastic than the other. I confess that I regard every 90%+ synth as made up first and that there has to be very good proof for to make me change my mind.
This leads only to fake IMHO.
Back to the tubes:
Acetaldehyde by the dehydrogenation of EtOH is not hard to do over a copper/zinc catalyst on kieselguhr made by precipitating the metaloxides/hydroxides from their salts and reducing them to the metal short before used already in the tube. Temperatures from 230°C to 330°C can be used, 270°C gives the best result. RESULT not yield. 15%-20% per pass conversion what is complete irrelevant as the relevant point is: virtually no byproducts. EtOH + acetaldehyde + hydrogen come outa the tube. Those who actually do chemistry will agree the others may shut up.
Ketene: Obviously nobody has done this in a way of production of acetic anhydride and not only as proof of principle experiment. (This is was Hypo did and he helped me a lot with what he told me about his experiment - by no way I take down this).
Others bragging with amounts with ease made overnight do this without actual knowledge. How to tell? Why does nobody mention the black tar? The fact that nickel and iron catalyse polymerisation of ketene? That ketene doesn´t even need such an catalyst, the fuck polymerises without also in a unbelievable speed?
And together with other nifty things this makes obvious:
Bla, bla, bla.
I throw in only one patent now. But it is choosen from many and provides actual information - data. The Patent GB425973 names contact time at different temperatures and related conversion. More important it tells the density of the actone vapours at about 75°C and gives a an example to calculate flow contact time etc.
A hint: If somebody thinks he can blow the ketene/acetone/methane mix through a condensor to condense relaxed the acetone, I promise him he will soon know what this tar is I spoke about.
End: Glassware is the wrong material whats obvious. You want as less openings and joints as ever possible as acetone burns and ketene is a wargas. So solder some coppertubes together or you will be haunted by leaks and bad dreams without ending.
Yields are the devil - nothing good came outa this, only lies and reagents with unspeakable names.
On the other side this provides an excellent (what a pour abused word this is) way to decide who dreams his dreams and who only dreams of dreaming his dreams.
I want to allow myself a little joke to finish my post:
What´s the most excellent lab-technique?
Copy & paste.
(Hive Addict)
06-23-03 19:58
No 441970
> Obviously nobody has done this in a way of production of
> acetic anhydride and not only as proof of principle experiment.
depends on the scale you are thinking about. 50ml have been made in two
sessions. it's not the l per day that osmium speaks about, but i'm
pretty sure a few hundred ml per day is possible, when you do things like
stirring the recipient or use a good gas dispersion tube. personally i
wouldn't let the thing run unattended, so expect a week's work for a
liter of Ac2O. not too bad imho (if you can't get it from a chem company).
and don't expect a "good" yield either, but come on - acetone in larger
quantities is so dirt cheap it's not even funny. most of the unreacted
AcOH is recovered by distillation.
the only thing that has to be worked out is the insulation of the
lamp. i've heard of bees having problems with this. the rest is sound.
> Why does nobody mention the black tar?
which black tar? the only thing my test subject encountered was
the yellow/dirty condensate in the recipient of the second condensor
i've mentioned. maybe you aren't cooling it fast enough?
> Glassware is the wrong material whats obvious. You want as less
> openings and joints as ever possible as acetone burns and ketene is a wargas.
i disagree. glass is the perfect material for this. ground joints are
flexible and seal very well. the only thing that is problematic is the
insulation of the lamp itself. if you know a glass blower, let him make you
a special item, otherwise the best method i know of is euro-rubber-stoppers
(the ones that don't go brittle) and teflon tape. works so-so.
the patent you quote is from '33. did they even know ground glass joints
and nichrome wire back then?
note that our reaction chamber doesnot have 700°C, only the wires do. i think this is what makes the ketene-lamp
so favorable over the 24 burners bullshit.
anway, if you manage to make the metal catalyst method viable,
more power to you!
the advantage i see is thatthe gasses are less toxic, but on the other hand, it does sound
like more work...
(Hive Addict)
06-23-03 23:17
No 442029
as copper is perfect, easy to work on and still the best joint is no joint at all IMHO.
Each of us should make a religion out of his point of view and we can have crusades and other fun, whatta think?
I think the black tar is diketene-polymerisation product - something like this was mentioned in other patents as I remember. You won´t have mentioned it because of the in relation huge amounts of acetone purging permanently the system. Did you purify/distill the anhydride and how much diketene was produced?
Be careful talking bad about my patent, yes? Oldies are goldies.... The technologie was complete ten years before I would like to say.
Later came some methods like bubbling the acetone through molten metal - something for you?The black tar appeared only once at mine up to now - I blame running to hot for this responsible as the cooling can be regarded as quick and efficient - the ketene enters directly after the tube a kind of washtube filled with hot GAA/acetic acid - the anhydride can be removed at the bottom together with GAA and acetone boils away at top. Yes, exactly! In the middle fresh acetic is refilled. How else.
Catalyst isn´t involved as it is a pure pyrolysis. Metal salts can be used to hinder a too early decomposition of the acetone (MgSO4 for example) in the preheating part. A device which could or should be applied in a glassware layout is a kind of nozzle between boiler and actual hot area: This works as flameback inhibitor - not a bad idea I wanna say.
Main problem is nearly the same as yours was the days: A sudden change in my aquisitional situation made the anhydride obsolete. It is only a gadget by now. (and a reserve for times will change again....)
"euro rubber stoppers and teflon tape..." You should integrate a life after death feature in your new religion, you might need it....
(Hive Addict)
06-23-03 23:37
No 442031
> Each of us should make a religion out of his point of view and
> we can have crusades and other fun, whatta think?
no, i'm not that kind of guy. (at least when it comes to chemistry.
now emacs vs. vi, we could discuss that)
> Did you purify/distill the anhydride and how much diketene was produced?
of course. first of all there was the stuff condensed by the second condenser.
this was thrown away. dunno what this was (diketene + acetone + crap?)
then the product was distilled giving basically 3 fractions: mysterious
stinking shit at about 80°, GAA and Ac2O. (all of this from the top of my
head, so take with a grain of salt)
> the ketene enters directly after the tube a kind of washtube filled with
> hot GAA/acetic acid - the anhydride can be removed at the bottom together
> with GAA and acetone boils away at top. Yes, exactly! In the middle fresh
> acetic is refilled. How else.
whoa, this is quite a different layout. so your reaction mixture is so hot,
that the acetone boils away? and of course you take up all the crap in the
acetic acid. which might not be very bad, since you have to distill it anyway.
hmm... i can see how this layout has some merits.
> Catalyst isn´t involved as it is a pure pyrolysis.
i know, i was talking about your acetaldehyde plans.
> You should integrate a life after death feature in your new religion, you might need it...
gee, thanks for the head ups.
but don't forget, i'm talking about one single place in the system. everything else
is ground joints.
(Hive Bee)
07-10-03 17:47
No 446212
The "Consortium" patents:
Patent DE1049845
Patent DE1061767
Patent DE1080994
roger2003
(Soothsayer)
11-01-03 01:44
No 468044
Yes, I think with such a hieness gas produced,
No joints would be the way to go, for the Clandestine Chemsit,.
Copper tubing sounds ideal, and as safety here is tantamount, then fuck yeh,
Seal the bastard up,.
What does ketene react with, would be my only issues here,
If copper is unaffected, well, that would be my first choice,
Hey, if steel works, I would give that an even higher preference,
And even if it does react,
God who am I kidding, Of course it won't matter,
I mean if a 700c nichrome wire is good for it, hey, steel should be ok,.
I think we could change our thinking in regards to the ketene production. Osmium, had a good point,.
How about a nice SS pressure cooker to boil the acetone, then running the acetone vapour through a nice copper still head that is jammed full of heated wire, with a larger contact area of wire, all sealed, welded, letting that sweet ketene flow into the Gaa, all in a selaed section,.
There can be no leaks,.And this would guarentee it,.
hm
Every time I make love to my sister, I feel that this truly is a drug within itself
(Chief Bee)
11-01-03 16:12
No 468123
a nice copper still head that is jammed full of heated wire
Have you heard of the phenomenon called "short-circuiting"? The nichrome wire must neither touch itself nor any other exposed metal. You definitely need glass tubing, and the wire must be wound into a coil.
(Moderator)
08-02-04 01:31
No 523145
(Rated as: good read)
These pages on aldehyde synthesis from Gattermann's Laboratory Methods in Organic Chemistry explain the synthesis of acetaldehyde from acetelyne in the laboratory, as well as some other aldehydes
Chemistry is our Covalent Bond