ANCS (Stranger)
07-14-03 18:47
No 447118
      1,4-BD -> GBL need some help  Bookmark   

1) The following procedure was used to make GBL. A mixture of 540.6g (6 moles) 1,4-Butanediol, 24g of Copper Chromite
catalyst and 0.90g of KOH was stirred and heated under reflux using a 1l beaker, Pyrex bowl filled with water to fit above the
beaker, variable heat source, and an accurate thermometer. At about 200C, evolution of hydrogen gas began and the
temperature dropped about 10-15C and the dehydrogenation proceeded. The evolution of gas ceased about 3hrs-4hrs later.
The reaction mixture was cooled to room temperature, filtered from the catalyst using coffee filters starting with one filter element
and progressively increase the number of filter elements to increase filtration.The remaining liquid has a dark greenish type colour
and slight solvent type smell. (more than usual GBL). Is this proceedure accurate and are these results to be expected and what
other compounds are present after dehydrogenation ?
2) The filtered liquid was than poured in a 2l Erlenmyer flask to which a 3/8" stainless steal home made condensor was installed.
The setup was heated to about 200C, upon reaching the temperature the liquid started to change colour from dark greenish to
red oxide before the vapour started to condensed. The condensed liquid was clear as water with again a slight solvent smell
more than usual GBL. Note that reduced pressure distillation equipment was not available, are these results to be expected and
what other compounds are present after distillation ?
(Active Asperger Archivist)
07-14-03 20:36
No 447150
      Distill  Bookmark   

Do a distillation to separate everything and save the fraction for GBL.  You should also recover a decent (~5-15% original) amount of 1,4-BD.  it's worth keeping/recovering.  If you've distilled everything, try converting to the lactone to the salt.  The other products will probably be some polymerization and dehydration products in small proportion.  Distillation will take care of these.

Act quickly or not at all.