What is GBL?

(for explanation of unfamiliar scientific terms, we recommend www.britannica.com )
Description

gamma-Butyrolactone (GBL) is a colorless liquid, free of suspended matter. It is miscible (capable of being mixed; specifically: capable of mixing in any ratio without separation of two phases) with water, alcohols, ketones, esters and aromatic hydrocarbons. Solubility is limited in aliphatic and cycloaliphatic hydrocarbons.
Safety
•gamma-Butyrolactone (GBL) is a strong mucous membrane irritant, as well as a mild skin irritant.
•GBL can penetrate the epidermis and cause rashes or eczema.
•GBL has a narcotic effect.
•This product is neither explosive nor spontaneously flammable in air. However, it is combustible. Materials recommended for storage tanks are carbon steel, stainless steel and nickel. Always refer to the Material Safety Data Sheet (MSDS) for detailed information on handling and disposal.
Applications
•GBL serves as a chemical intermediate in the manufacture of all pyrrolidones. It can be used in the production of pesticides, herbicides and plant growth regulators. GBL may be formed as an intermediate in the production of vitamins and pharmaceuticals.
•As a solvent, GBL can be used in/with:
•pesticides
•photochemical etching
•electrolytes of small batteries or capacitors
•viscosity modifiers in polyurethanes
•surface etching of metal coated plastics
•organic paint disbursements for water soluble inks
•pH regulators in the dyeing of wool and polyamide fibers
•foundry chemistry as a catalyst during curing
•curing agents in many coating systems based on urethanes and amides

Graph of GBL Specification as reported by BASF