2,2-Bis(4-hydroxyphenyl)-alkyl onium salt and process for the preparation thereof

A process for the preparation of 2,2-bis(4-hydroxyphenyl)alkyl onium salts of formula (1), the said process comprising the steps of:

• a. mono brominating alkyl dialcohol by reacting it with a brominating agent in an organic solvent, at a temperature in the range of 40-150° C. to obtain α,ω-bromoalkylalcohol of formula (2):
• b. alkylating acetoacetate with α,ω-bromoalkylalcohol of formula (2) in dry organic solvent in the presence of base and accelerating agent, at a temperature in the range of 0-80° C. to obtain hydroxyl alkyl acetoacetate of formula (3):
• wherein R═CH3, C2H5, and n=1 to 36,
• c. dealkoxycarbonylating the compound of formula (3) either by first hydrolysing the compound of formula (3), followed by decarboxylation or, in a single step, dealkoxycarbonylation by adding alkali metal salt or ammonium salt along with an equivalent amount of water to a non-aqueous solution of compound of formula (3), at a temperature in the range of 40-250° C., cooling the abovesaid reaction mixture to a temperature of 20-30° C., and pouring it into water, followed by extraction with diethyl ether and washing with water, brine and finally drying the resultant product to obtain ω-hydroxyalkan-2-one of formula (4):
• wherein N=1 to 37,
• d. reacting the compound of formula (4) with phenol in the presence of acidic catalyst, under stirring, at a temperature in the range of 10° C. to 60° C., for a period of 10-15 hrs, dissolving the resultant reaction mixture in ethyl acetate followed by washing with water, NaHCO3 and brine and finally drying and removing the excess phenol under vacuum at about 60° C. to obtain 2,2-bis(4-hydroxyphenyl)alkanol of the formula (5), where n=1 to 37:
• e. brominating the compound of formula (5) by reacting with a brominating agent in dry organic solvent, at a temperature in the range of −10 to 100° C., under stirring, to obtain 2,2-bis(4-hydroxyphenyl)alkyl bromide of the formula (6):
• f. alkylating compound of formula (6) by reacting it with an alkylating reagent in presence of organic solvent, at a temperature in the range of 35-110° C. to obtain the salts of the formula (1).