05-19-03 03:23
No 434063
I put 90.1g 1,4-butanediol, 4g of copper chromite catalyst and 0.15g of powdered sodium hydroxide in a 500ml flask and set up for refluxing. I heated to 200C slowly and expected some lively evolution of hydrogen, but nothing evolved. I continued heating at 210-215C for 3,5h and after cooling I found only this black viscous liquid in the flask, which did't seem to be GBL at all. Rather BDO, but it didn't freeze in the refrigerator as BDO. I expected to find at least some smell on GBL or taste or a liquid with same viscosity, but nothing. Just this weird black stuff a little less viscous than BDO... And I also didn't notice any gas evolution.
Can anybody please comment what could have gone wrong? I think the catalyst was wrong or needed some modification. I used Aldrich CC-Catalyst, CAS 12053-18-8 (Cr2Cu2O5).
(Chief Bee)
05-19-03 04:15
No 434071
Did you heat the mixture to reflux? Did you distill the resulting reaction mixture to verify if any reaction happened?
(Old P2P Cook)
05-19-03 04:32
No 434073
I have used homemade copper chromite to prepare hexaldehyde from hexanol as per Vogel and it worked very well but the temperature specified by Vogel is 330°C. Where did you get the temperature of 200° ? As I remember the reaction did require this temperature and you could watch the hydrogen evolution begin as the reaction tube reached temperature.
Also, what is the reason for the NaOH?
All those moments will be lost in time, like tears in rain.
(arrogant bee of the day)
05-19-03 10:47
No 434114
Describe how the catlyst was made. The way on Rhodium's site is easier and known to work. The NaOH is not necessary.
http://www.whatreallyhappened.com
(Stranger)
05-19-03 10:49
No 434115
From 200C it was boiling and refluxing. I used 400mm reflux condenser with cold water, also magnetic stirring. Unfortunately I was too disappointed and didn't even bother to distill, which I should have as I now understand. I thought I had used a wrong catalyst.
The temp 200C and NaOH is from the Rhodium's site. The catalyst I used was bought, CAS 12053-18-8 (Cr2Cu2O5).
But if you guys say the catalyst is right, I'll try again and this time try to distill it.
(arrogant bee of the day)
05-19-03 11:49
No 434127
I heated to 200C slowly and expected some lively evolution of hydrogen, but nothing evolved.
Then..
From 200C it was boiling and refluxing.
So hydrogen was evolving?
Do a search for BDO to GBL in serious chem forum for a rundown on the whole thing.
http://www.whatreallyhappened.com
(Stranger)
05-19-03 19:43
No 434164
To get an answer weather I have the right catalyst or not, I did some searching and concluded the following:
1.I had used Copper Chromite Catalyst (Synonym: Copper-chromium oxide), CAS 12053-18-8, Cr2Cu2O5. Sigma-Aldrich
And failed.
2.The correct catalyst to be used is Copper Chromite (Synonym: Lazier catalyst, can also be Barium promoted etc), CAS 12018-10-9, Consists of 62-64% Cr2CuO4, 22-24% CuO, can also contain 6%BaO, 0-4% Graphite, 1% CrO3, 1% Cr2O3. There are many variations. Preparation of this catalyst is on the Rhodium's site.
I suggest it be mentioned somewhere, that Copper Chromite and Copper Chromite catalyst are two different things. By Sigma-Aldrich's definition Copper Chromite Catalyst is actually Copper-Chromium Oxide Cr2Cu2O5 [12053-18-8] and is probably not suitable for BDO to GBL conversion.
(Newbee)
06-08-03 23:06
No 438694
Weird...
SWIM has used Copper Chromite Catalyst from Acros (With the correct CAS 12018-10-9) with great results.
At least 95% yield could be expected... Distillation is essential!
Make Drugs - Not War!
The White House needs Acid!
(Stranger)
07-21-03 16:45
No 448822
I tried the BDO->GBL procedure using Acros CAS 12018-10-9 catalyst. 90,1g BDO + 4g copper chromite + 150mg NaOH. At 200C evolution of hydrogen began at a rate, which filled a condom in 2-3 minutes. After an hour the pressure was so low that it couldn't fill a condom at all (beacause it also pulled air back after pushing), but gave bubbles when the tube from the condenser was put under water. The bubbling rate was as before 1x/1s. With every drop of reflux liquid back into the flask a bubble of hydrogen came up. At temperatures above 230C the bubbling ceased untill cooled to 210C. I let it reflux for various lenghts of time, longest was 8h when I waited for the bubbling to stop (which it practically did). But every time the result was a oily liquid which smelled and tasted very similar to BDO after distillation and had only minimal burning taste of GBL.
My opinion is that only a small amount of BDO converted to GBL and maybe some 3-5 liters of H2 evolved instead on 39. I also tried with 200mg of NaOH and without NaOH and with double amount of copper chromite, but nothing changed.
My question is what could be the reason? I used clean precursors with dry glassware. Stirring was maximum, but maybe it requires even more violent stirring? I noticed that letting it boil with no stirring for some 15s and then turning on stirring causes increase in bubbling rate (H2 evolution) for another 15s. Maybe my 400mm condenser is too long? I'm clueless. I tried with 250ml and 500ml flasks with the same results. Hydrogen evolves, but probably not enough. Could somebody with experience describe how intense is the evolution of hydrogen and what setup do they use? Is the GBL recognizable by smell and taste after distillation? How important is the temperature? Is there a maximum temp? I'm desperate. Please help.
(Old P2P Cook)
07-24-03 03:58
No 449371
I already gave you the answer.
Post 434073 (terbium: "Temperature?", Chemistry Discourse)
All those moments will be lost in time, like tears in rain.
(Chief Bee)
07-24-03 04:22
No 449374
(Rated as: good read)
The boiling points of 1,4-BD and GBL is ~204-206°C, so keeping the temp at 300°C will be a problem without special equipment.
Besides, both JACS 68, 1385 (1946) (../rhodium /bd2gbl
Also, Microgram 33(11), 321-324 (2000) (../rhodium /gbl.sy
(Old P2P Cook)
07-24-03 06:25
No 449409
The boiling points of 1,4-BD and GBL is ~204-206°C, so keeping the temp at 300°C will be a problem without special equipment.
Yes, it would be vapour phase reaction in an inclined tube. Liquid BDO would be dripped in at the top of the tube and the vapour pass over the supported catalyst packed in the tube.
Perhaps there is some reason why BDO will dehydrogenate at a much lower temperature than hexanol but my experience with hexanol was that there was very little hydrogen evolution until the temperature got to around 300°C.
All those moments will be lost in time, like tears in rain.
(Chief Bee)
07-24-03 07:05
No 449422
(Rated as: good read)
Catalyst for preparing lactone and a method for preparing lactone
Patent US6323347
Abstract
The present invention relates to a catalyst for preparing a lactone, which is prepared by supporting a cupric compound, a zinc compound and at least one alkaline earth metal compound on the supporter. The present invention also relates to a method for preparing a lactone, which comprises a dehydrocyclization reaction of a diol under a gas phase in the presence of the aforementioned catalyst after activating said catalyst. The catalyst for preparing lactone of the present invention is quite economic because of its high activity, long lifetime and high selectivity of products.
The catalyst of the present invention used for preparing a lactone is prepared according to the following method. The supporter is immersed in the above aqueous cupric salt and zinc salt solutions, and the value of pH is adjusted between 8 and 11 using ammonia water, while the hydroxides of copper and zinc are precipitated on the supporter. The precipitate is washed with water and dried. The precipitate is immersed in the above aqueous salts solution selected from one or two alkaline earth metal compound(s) consisting of magnesium, calcium and barium, and then calcined for 3 to 5 hours at 400-500°C. In such resultant catalyst, each metal component exists in the form of oxide. Therefore, before the dehydrogenation reaction of diol, the catalyst must be reduced and be activated at a temperature ranging from 180-250°C for 6-20 h with hydrogen gas wherein the ratio of hydrogen gas to nitrogen gas starts between 5-10% by volume, then gradually adjusts to all hydrogen gas.
In the dehydrocyclization reaction of the method for preparing lactone such as gamma-butyrolactone used in the present invention, the reaction temperature usually ranges from 160-280°C., preferably 180-250°C. If the reaction temperature is too low, the conversion of 1,4-butylene glycol may be decreased. Although the higher temperature may increase the conversion of 1,4-butylene glycol, the selectivity of gamma-butyrolactone may be substantially decreased.
In the dehydrocyclization reaction of the method for preparing lactone such as gamma-butyrolactone used in the present invention, the reaction pressure usually ranges from 0-10 atm., preferably from 1-5 atm. However, the higher reaction pressure may easily carry out an undesired reaction, decreasing the yield.
Reference Example 1 - Activation of the catalyst
A commercially available copper-chromium catalyst (30 ml) (copper oxide 42% and chromium oxide 28% by weight, 5 mm diam.) was packed in the stainless steel reactor having an inside diameter of 23.5 mm. After the temperature was elevated to 150°C with nitrogen gas, the mixed gas of 10 vol % hydrogen gas was passed into the reactor, then the catalytic reduction reaction was initiated. The temperature and the concentration of hydrogen gas were gradually elevated until the reduction temperature of catalyst was 200°C. and the concentration of hydrogen gas was 100 vol %. When the temperature of catalyst bed was confirmed to be the same as that of the heating equipment, the reduction reaction was terminated.
(Chief Bee)
01-06-04 10:58
No 480719
The Preparation of Copper-Chromium Oxide Catalysts for Hydrogenation
R. Connor, K. Folkers, H. Adkins
J. Am. Chem. Soc. 54, 1138-45 (1932) (../rhodium/pdf /copper.chrom
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