What are the key production routes and quality considerations for tetrahydrofuran?

What are the key production routes and quality considerations for tetrahydrofuran?
The dominant commercial route for THF is dehydration cyclization of 1,4-butanediol (BDO), which accounts for most Chinese capacity. Alternative routes include maleic anhydride hydrogenation and furfural decarbonylation. After BDO dehydration, THF requires purification to remove unsaturated impurities like 2,3-dihydrofuran and 2-methylfuran, which cause color degradation. Hydrogenation is employed to meet industrial standard GB-T 24772-2009, which caps APHA color at 5 for premium grade. Catalyst aging can lead to off-spec color, a common issue for producers. For laboratory use, THF is typically dried with sodium and benzophenone under nitrogen until a blue or purple indicator forms, ensuring ultra-low moisture for organometallic reactions. Quality control is critical for both industrial and high-purity applications.