Tetra-alkyl bisphenols prepn. - by reaction of (2,6)-dialkyl phenols with formaldehyde using oxalic acid as catalyst

摘要

Prepn. of 4,4'-dihydroxy 3,31,5,51-tetraalkyl diphenyl methanes (tetra-alkyl bisphenols) of formula (I) is described (where R1 and R2 are 1-6C alkyl). The process comprises condensing 2,6-di-alkyl phenols with formaldehyde in presence of oxalic acid as catalyst. The prods. are raw materials for plastics, e.g., hydrolysis-resistant polycarbonates or after hydrogenation to idols for hydrolysis-resistant polyesters. Almost quantitative yields are obtd. in short reaction times without loss of HCHO. The oxalic acid does not have to be sepd., since it decomposes into gaseous components at >150 degrees C. The prod. is sufficiently pure for direct catalytic hydrogenation.