Gamma-butyrolactone â also known by its product name âGBLâ or CAS No. 96-48-0 â is a versatile cyclic ester used throughout many applications. Rather than seeing GBL on its own, most will employ GBL to produce derivative chemicals. GBL is also a popular solvent in several cosmetic products. The need for gamma-butyrolactone in industries throughout North America is significant. To order kindly call/Text