Synthesis of bisphenol compounds from non-edible cashew nut shell liquid

Cardanol, main component of cashew nut shell liquid (CNSL) which is an unused non-edible phenolic derivative, was hydrogenated, and subsequently converted to bisphenol compounds (Bis-CNSL) for the industrial intermediates in a variety of fields by reacting with carbonyl compounds in the presence of an acid catalyst without a solvent. It was found that Bis-CNSL was successfully obtained with high selectivity using aldehydes with alkyl chains of 2 or more carbons. We have established a large-scale preparation process using propionaldehyde by reducing the amount of aldehyde to 0.25 equivalents to suppress the formation of multimers to obtain Bis-CNSL with a purity of over 99% by recrystallization from methanol.