Trouble with BDO->GBL

[ShaiGuy]

This is actually a 3 part question.
Firstly which is the best copper chromite catalyst for this reaction 12018-10-9,12018-10-8 or something else?
Secondly, do these catalysts require any special activation? If so, how? or even better is there a catalyst that won't require such a procedure.
Finally, As far as temperature goes is it sufficent to reflux at slightly above 200 degrees, or is it necessary to go to 300? I've read many posts each with conflicting statements and I would appreciate any and all help in clearing up these issues.
Thanks
ShaiGuy

[elifoner]

SWIM is trying the same procedure (1,4 or BDO -> GBL), and is finding MANY conflicting sources of information.  Many supplier type sources list that the

CAS#12018-10-9
Cr2Cu2O5
2CuO.Cr2O3
F.W. 311.07
EINECS 234-634-6
TSCA

is the correct item, but then in a post by placebo, it was stated that

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.

SWIM's question is three-fold:
1) Are these two compounds (Cr2Cu2O5 and 62-64% Cr2CuO4, 22-24% CuO, with 6%BaO, 0-4% Graphite, 1% CrO3, 1% Cr2O3) the same?

2) SWIM currently tried with CAS# 11104-65-7, [CrCuO3] and is not getting the desired results.  Does anyone have any helpful info on this?  SWIM is refluxing at 200c for approx 120-180 min., then performing a pressure distillation WITHOUT additional heating.  Although there have been a few ways to do this that have been posted, SWIM thinks the preparation withOUT NaOH will produce the greatest yield.

3) With ANY of these catalysts, is ACTIVATION needed?  If so, are there any catalysts out there that react with 1,4 without an "activation" process?

Someone PLEASE help!

[placebo]

I hate typing redundant shit so all I'm going to say is read my post in serious or novel (UTFSE) about this shit and do it that way, it is the easiest and it works!

[roger2003]

Here you find a lot of samples to convert 1,4 butanediol to GBL in vapour or liquid phase and a lot of samples for preparing catalysts.

Patent DE699945

[elifoner]

SWIM is preparing gbl by dehydrogenating BDO with copper chromite catalyst. The reaction is proceeding perfectly, but a few issues remain. Does one have to stop after 3 hours, or should one wait for the evolution of hydrogen to stop completely? The copper chromite seems really soluble in the product - how should one go about filtering it out of the product. Will the catalyst also reduce the GBL, or can one do a straight temperature distilation after the reaction is completed??

[Rhodium]

Does one have to stop after 3 hours, or should one wait for the evolution of hydrogen to stop completely?

What is your yield after three hours? I think you should continue as long as the hydrogen evolution continues at a reasonable speed, as long as it doesn't seem like you are getting a lot of byproducts instead. 

Will the catalyst also reduce the GBL, or can one do a straight temperature distilation after the reaction is completed??

If the catalyst is soluble in the GBL, you cannot filter it out, naturally. I'd suggest you isolate your product through vacuum distillation. The catalyst will not reduce the GBL, as there is no hydrogen available to do that - it is all carried away into the atmosphere during the dehydrogenation of 1,4-BD to GBL.

What brand of copper chromite do you use (or is it self-made)?

[elifoner]

The copper chromite catalyst being used is 12018-10-9.
During the synthesis, the temperature dropped 10-15 degrees as others have said, then near the 3-hour mark, started to increase in temp. again.  After more heating, the solution went up to 212, then slowly back down to 204-205 where it stayed.

After this synthesis, my question is about the pressure distillation; should it be done at 25C @ 1atm or should HEAT BE ADDED?  Any answers on the subject of the actual pressure distillation would be great (looking to finish everything soon).

Thanks,

[Rhodium]

Huh? The boiling point of GBL is ~204°C/1 atm... either you need to heat it and/or lower the pressure to be able to distill.

It seems like you need to read this:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/equipment/distillation4dummies.html

[Chromic]

Distill it under reduced pressure.