1,4BDO -> GBL byproducts

[fierceness]

What are the byproducts of the 1,4BDO -> GBL reaction with copper chromite catalyst (besides the obvious unreacted 1,4BDO).  I'm wondering if distillation afterwards is necessary (after filtration of the catalyst).  Correct me if I'm wrong, but since the dosage of 1,4BDO and GBL are about the same by volume (1ml), no separation of these two are really needed.

If there are some impurities formed that are soluble in the GBL/BDO mix, what about converting the GBL portion to NaGHB and doing an ethanol recrystalliztion of it to rid it of impurities?

Thanks!

[Rhodium]

UTFSE for the patents posted on the products to find out what the byproducts are. You definitely need to perform a fractional distillation as some of the chromium/copper salts are soluble in the reaction mixture, and some really nasty butanal/butyric acid is formed as by products.