METHOD FOR PREPARING STERICALLY HINDERED BIS- OR POLYPHENOLS

A method for preparing sterically hindered bis- or polyphenols of the formula: R" - CH - R"' R' wherein R' is hydrogen, a C1-C4 alkyl, R" and R"' the same or different and are each: or wherein R is a tertiary C4-C8 alkyl, R1 and R2 are the same or different and represent a C1-C8 alkyl or a C6-C8 cycloalkyl, or a C7-C9 aralkyl, which comprises reacting the starting sterically hindered 2,4,6-trialkylphenols of the formula: wherein A is a C1-C8 alkyl or a C6-C8 cycloalkyl or a C7-C9 aralkyl or a 3,5-dialkyl-2-hydroxybenzyl of the formula: B is a C1-C8 alkyl, or a C6-C8 cycloalkyl, or a C7-C9 aralkyl, or a 3,5-dialkyl-4-hydroxybenzyl of the formula: wherein R1 and R are as identified above, with acetals, aldehydes or donors of C1-C5 aldehydes in an acidic medium at a temperature within the range of from 60 to 200.degree.C in the presence of an acidic catalyst, followed by isolation of the desired product. The method according to the present invention makes it possible to prepare sterically hindered bis- or polyphenols in a single stage, whereby the process technology is substantially simplified as compared to those of the prior art. The method of the present invention precludes formation of waste waters and atmosphere pollutants. The method ensures preparation of the desired products possessing a high quality in a high yield without any additional crystallization.