Monoester compound of 2,2-alkylidene bis(4,6-di-substituted phenol)

A method of preparing a compound which comprises reacting a 2,2'-alkylidene bis(4,6-di-substituted phenol) of the formula (II), ##STR27## wherein R.sub.1 and R.sub.2, which may be the same or different, each represents a C.sub.1-4 alkyl group, a C.sub.5-6 cycloalkyl group, or a methyl-substituted C.sub.5-6 cycloalkyl group;

• and one of R.sub.3 and R.sub.4 represents a hydrogen atom and the other represents a hydrogen atom or a C.sub.1-10 alkyl group or both of them represent a methyl group, with an esterifying agent selected from the group consisting of the compounds of the formulae (III) and (IV),
• R.sub.5 COCl (III)
• and
• (R.sub.5 CO).sub.2 O (IV)
• wherein R.sub.5 represents a C.sub.4-9 alkyl group, a C.sub.3-7 cycloalkyl group, a phenol group, a C.sub.1-4 alkyl-substituted phenyl group, a C.sub.1-4 alkoxy-substituted phenyl group, a mono- or di-C.sub.1-4 alkyl-substituted hydroxyphenyl group, a benzyl group or a pyridyl group, substantially at an equimolar amount in the presence of a reaction medium while maintaining the reaction temperature at from about 0.degree. C. to about 30.degree. C. until about 50% of the 2,2'-alkylidene bis(4,6-di-substituted phenol) is converted to the compound of the formula ##STR28## wherein R.sub.1 and R.sub.2, which may be the same or different, each represents a C.sub.1-4 alkyl group, a C.sub.5-6 cycloalkyl group or a methyl-substituted C.sub.5-6 cycloalkyl group;
• and one of R.sub.3 and R.sub.4 represents a hydrogen atom and the other represents a hydrogen atom or a C.sub.1-10 alkyl group or both of them represent a methyl group;
• R.sub.5 represents a C.sub.4-9 alkyl group, a C.sub.3-7 cycloalkyl group, a phenyl group, a C.sub.1-4 alkyl-substituted phenyl group, a C.sub.1-4 alkoxy-substituted phenyl group, a mono- or di-C.sub.1-4 alkyl-substituted hydroxyphenyl group, a benzyl group or a pyridyl group and thereafter raising said reaction temperature to range from about 50.degree. C. to about 100.degree. C.