Process for the preparation of mono-alkylcarbonate of bisphenols

A process for the preparation of mono-alkylcarbonate of bisphenols of formula I ##STR3## where R.sub.1 represents an ispropylidene, hexafluoroispropylidene, cyclohexane, sulphone, keto, ether, phthaline or phthalimide group, R.sub.2 represents an alkyl group with 1-8 carbon atoms, X is selected from straight or branched, chain alkyl groups of 1 to 4 carbon atoms, a phenyl group and halogen atoms and n is from 1 to 4 which comprises reacting a bisphenol of the formula II ##STR4## where R.sub.1 represents an ispropylidene, hexafluoroispropylidene, cyclohexane, sulphone, keto or phthalimide group, X is selected from straight or branched chain alkyl groups of 1 to 4 carbon atoms, a phenyl group and halogen atoms and n is from 1 to 4 with a dialkylcarbonate in the presence of a catalyst selected from organometallic compounds from the group consisting of di-n-butyltin oxide, di-n-butyltin diacetate, tri-n-butyltin hydroxide n-butyltin tributoxide, di-n-butyltin dimethoxide, tin oxalate, di-n-butyltin dilaurate, tri-n-butyltin halides, stannoxanes, titanium isopropoxide, titanium butoxide, and titanium aryl oxides, under inert atmosphere at a temperature in the range 60.degree.-150.degree. C.