10-18-03 18:25
No 465428
Hi,
i must wash one solution with Sodium-chloride. But I donīt understand how. Can anybody please help me?
(Chief Bee)
10-18-03 18:41
No 465431
Washing a solution is precisely like extracting it, only that you discard the washing as opposed to keeping it when you extract.
Separatory Funnel Extraction Procedure (http://orgchem.colorado.edu/hndbksuppor
(Hive Addict)
10-18-03 18:49
No 465433
don't post your friggin' ICQ number for gods sake!!
n'importe quoi
(Orgasm Donor)
10-19-03 04:09
No 465525
I removed it.
Topdowner: Don't post personal information in the public forums.
On time is when I get there.
(Hive Addict)
10-19-03 10:37
No 465569
he still has it in his other post though
i don't know much about those instant messanger thingies,
but don't they have a P2P mode, which would make it very
easy to find out his IP-address??
(i'm not suggesting he is harvesting IPs, but: one should never ever
contact any other bee over ICQ or IRC or things like that. (imho)
thanks to the PM function it's unecessary anyway, so no need to risk
it. (use common sense, people!))
n'importe quoi
(Stranger)
10-19-03 12:45
No 465585
I have understand what you said. But i have a new question. I want made 2,5 DMA and i must wash the solution (Consists of:2,5-dimethoxybenzaldehyde, Acetic Acid, Nitroethane and ammonium acetate) with Sodium Chloride. But the Salt will be dissolve in the solution. How can i extract the salt when its dissolved?
(Hive Bee)
10-19-03 13:20
No 465589
the salty water will form a separate layer from the nitroethane, 2,5DMBA, 2,5DMP2NP. After shaking, allow the layers to form, separate off the salty water layer and proceed to the next step of your procedure with the organic layer.
(Stranger)
10-19-03 14:04
No 465591
How can I recognize the salty layer??? i think, i write the part of the text which one i donīt understand!
"A solution of 10.0 g 2,5-dimethoxybenzaldehyde in 50 mL glacial acetic acid was treated with 6.8 g of nitroethane and 4.0 g of anhydrous ammonium acetate. This mixture was heated on the steam bath for 3 h and then the reagent/solvent was removed under vacuum. The residue was suspended in H2O and extracted with CHCl3. Removal of the solvent from the pooled extracts yielded 11.2 g of an impure 1-(2,5-dimethoxyphenyl)-2-nitropropene which, on recrystallization from 75 mL boiling MeOH, gave 6.7 g of product with a mp of 73-75 deg C. Anal. (C11H13NO4) C,H,N. This nitrostyrene has been periodically available commercially from a number of sources."
Nad how do i remove the solvent under vacuum?
please help me...
Thanx
(Stranger)
10-19-03 16:27
No 465603
(Rated as: good read)
How can I recognize the salty layer???
You should really study some organic chemistry before SWIY starts to synthesize 2C-B. It's definately not the easiest synthesis to start with. You will encounter extraction and washing all the time while cooking. Master the theory on extraction and washing before you proceed, it will save you a lot of money on chemicals.
I can recommend James W. Zubrick's book "The Organic Chem Lab Survival Manual". I will give you some free hints you can find in this excellent book.
I quote "
Never, never,never,never,
ever throw away any layer, until you are absolutely sure you'll
never need it again. Not very much of product can be
recovered from the sink trap!"
This may sound silly but is is very useful!
I think it is better to call the "salty" layer the aqueous layer. [Extraction can only be done between two immiscible liquids, organic layer/aqueous layer] To know which layer floats on top you need to know what the density of your organic solvent is. The lighter layer floats on top of the heavier layer. Logic isn't it? You can assume that a dilute NaCl solution has the same density as pure water (about 1g/ml @25°C). Check the density of your organic solvent and you know if the layer will be on top or not.
An experimental way I quote directly from Zubrick's book:
""Which layer is the water layer?" This is so simple, it confounds everyone. Get a small (10x75 mm) test tube and add about 0.5-1.0 ml water. Now add 2-4 drops of the layer you thinks is aqueous, and swirl the tube. If the stuff doesn't dissolve in the water, it's not an aqueous (water) layer. The stuff may sink to the bottom, float on top, do both, or even turn the water cloudy! It will not however, dissolve."
Good luck and study hard!
To fly or not to fly that's only a matter of time...
(Stranger)
10-19-03 17:04
No 465610
Nad how do i remove the solvent under vacuum?
Reading the question I think I can assume that you don't have a rotary evaporator (Rotovap). A Rotovap is commonly used to remove low boiling organic chemicals, usually solvents, from a mixture of compounds. The solvents or low boiling compounds are removed by a simple distillation. The Rotovap is designed to be operated under a vacuum (to lower a compound's boiling point) and to heat the sample at the same time. A cold finger is used to condense the vapors to a liquid, which are trapped in a separate flask.
Of course if you don't have a Rotovap, you could set up for vacuum distillation and use magnetic stirring to substitute for the rotation in a Rotavap.
The higher the vacuum the lower the boiling point of the solvent will be. You can calculate the boiling point of your solvent under vacuum using a Nomograph. Visit the following link on Rhodium's page for enlightment.
../rhodium /equipme
I don't have shares in Zubrick's book
, but again I can recommend the book to gain understanding about several kinds of distillation techniques.Buy the book man and study!
To fly or not to fly that's only a matter of time...
(Stranger)
10-19-03 18:05
No 465618
In the text is written "...wash the solution with NaCl and put it into the seperation funnel (used before) to wash it..." I think that I donīt have to wash it at all, or am I wrong?
(Hive Bee)
10-19-03 18:29
No 465620
if it says to wash with NaCl solution, then that is what is meant to happen. You can't just go cutting out steps in a procedure and expect it to work. At best you will end up with a low yield, or impure product. At worst you will end up with nothing. Purification steps are incredibly important if you want to succeed.
Not being rude, but judging by the level of your questions, you will undoubtedly be unsuccessful with this synthesis unless you do some real learning first. As suggested, buy some books and start reading. Otherwise you will waste inordinate amounts of time and money.
(Newbee)
10-19-03 18:31
No 465622
I think that I donīt have to wash it at all, or am I wrong?
You are wrong. If your cooking book says to wash then you wash. Unless of course you are a very skilled cook with lots of experience and the capability to judge the necessity of a certain purification you'd better stick to the recipe.
You cannot skip every step you are not sure of! Take my advice first read and learn then start to cook, not the other way around!
To fly or not to fly that's only a matter of time...
(Stranger)
10-19-03 18:36
No 465623
Yes youīre right with that what you said.But i think to try goes studying over. Thanxx
(Stranger)
10-19-03 18:38
No 465625
If someone has it please reply.
(Newbee)
10-19-03 19:01
No 465628
I don't think I know what exactly you understand as a "pressure diagram of chloroform".
I figure that you might want to know the boiling point of chloroform at a reduced pressure. The boiling point of chloroform at atmospheric pressure is 61.2°C. If you know the vacuum your pump pulls you can calculate the boiling point under vacuum using the nomograph.
If you meant something else, please clarify your question and I'll try to help you.
To fly or not to fly that's only a matter of time...
(Stranger)
10-19-03 19:04
No 465629
i donīt understand the nomograph. And we in Germany calculate with bar not torr. And the nomograph says me nothing. I canīt read this kind of diagram.
(Hive Addict)
10-19-03 19:07
No 465631
> And we in Germany calculate with bar not torr
nah, german chemists use torr as often as others.
n'importe quoi
(Stranger)
10-19-03 19:11
No 465633
Can somebody help me to red the nomograph??? I donīt understand how to read it.
(Newbee)
10-19-03 19:59
No 465642
Conversion of bar to torr is easy:
1 atm = 1.013 bar = 1013 hPa = 760 torr (Torricelli
)Now 1 mm Hg = 1 torr, so you can easily find that
1 torr = 1.3 x 10-3 bar
Concerning the use of the nomograph I cannot explain it better than on Rhodium's site. Nevertheless in your case you cannot use the nomograph since the bp of chloroform at atmospheric pressure is below 100°C.
If you want to know more use Google and search on Clausius-Clapeyron equation (mathematical background of the nomograph).
To fly or not to fly that's only a matter of time...