Process for preparing dihydric phenol derivatives

A process for preparing a dihydric phenol having the formula:

• ##STR15## wherein R represents a lower alkyl radical having 1-6 carbon atoms and each R may be the same or different, and n represents zero or an integer of 1 to 4 and when n is 3 or 4 not all of the 2-, 4- and 6-positions are occupied with the said alkyl radicals,
• which comprises oxidizing a monohydric phenol having the formula:
• ##STR16## wherein R and n have the same meanings as above, with a ketone peroxide at a temperature of from 45.degree. to 200.degree. C. in the presence of a catalyst selected from the group consisting of sulfuric acid and a salt thereof and a sulfonic acid and a salt thereof, the amount of peroxide P per millimole of the monohydric phenol being a value of from 0.01 to 0.50, said ketone peroxide being obtained by reaction of hydrogen peroxide and a ketone selected from the group consisting of (i) and (ii), following:
• i. a ketone having 3-20 carbon atoms represented by the following formula:
• R.sub.1 --CO--R.sub.2
• wherein R.sub.1 and R.sub.2, which may be the same or different, and which represent straight or branched alkyl groups of 1-18 carbon atoms or a phenyl group, or
• ii. a cycloketone having the following formula:
• ##STR17## wherein n.sub.1 represents an integer of 4-11, inclusive, or a ketone peroxide derived from a secondary alcohol having the following formula:
• iii. a secondary alcohol having 3-30 carbon atoms and represented by the following formula:
• ##STR18## wherein R.sub.1 and R.sub.2 have the same meanings as above