Method of bisphenol manufacture

A method of manufacture of a bisphenol of chemical structure:

• wherein each R1 is independently selected from the group consisting of hydrogen, halogen, methoxy, and C1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl;
• each R2 is independently selected from the group consisting of hydrogen, halogen, and C1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl, and each R3 is independently selected from the group consisting of hydrogen, halogen, and C1-11 hydrocarbyl, the method comprising:
• heating a monohydric phenol of chemical structure:
• wherein R1 and R2 are as defined above, to a first temperature sufficient to melt the monohydric phenol;
• adding a carbonyl compound of chemical structure:
• wherein R3 is as defined above, to 2.0 to 2.5 molar equivalents, based on the moles of carbonyl compound, of the monohydric phenol in the presence of catalytic amounts of an organosulfonic acid catalyst and a reaction promoter at a second temperature sufficient to maintain unreacted monohydric phenol in a molten state;
• increasing the temperature to a third temperature higher than the second temperature, and mixing for a time sufficient to produce the bisphenol in a yield of 80 to 100%, based on the amount of carbonyl compound;
• wherein mineral acids, Lewis acids, and ion exchange resins are not used.