1,4-Butanediol (BDO) can be manufactured from formaldehyde and acetylene via the Reppe process. BDO can also be manufactured from other processes using key starting raw materials such as n-butane or propylene oxide. The major markets for BDO are tetrahydrofuran (THF), polybutylene terephthalate (PBT), gamma-butyrolactone (GBL), and polyurethanes. THF is used primarily to produce polytetramethylene ether glycol (PTMEG); solvent applications account for the remainder. PTMEG is used in the manufacture of cast and thermoplastic urethane elastomers, spandex fibers, and high-performance copolyester-ether elastomers. The production of N-methyl-2-pyrrolidone, a solvent in lube oil extraction, electronics applications, paint strippers, magnetic wire coatings, and engineering resins, consumes approximately 70% of GBL. GBL can be used as a solvent as well as in the manufacture of 2-pyrrolidone/N-vinyl-2-pyrrolidone/polyvinyl-pyrrolidone. Automotive markets and electrical/electronic components and parts ultimately use PBT resins.