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AssigneeGeneral Electric Company
InventorsPatrick Joseph McCloskey, Timothy Brydon Burnell, Daniel Joseph Brunelle, Elliott West Shanklin, Paul Michael Smigelski, Jr., Ganesh Kailasam
Estimating the term…
High yields of ester-substituted diary carbonates such as bis-methyl salicyl carbonate were obtained by the condensation of methyl salicylate with phosgene in the presence of a phase transfer catalyst (PTC) in an interfacial reaction system in which the pH of the aqueous phase was greater than 9.3. Using the method of the present invention conversions of greater than 99% were obtained whereas under standard conditions using triethylamine as the catalyst conversions were limited to 70-75% of the methyl salicylate starting material even with a 20 mole % excess of added phosgene. The optimized conditions of the of the present invention use only a slight excess of phosgene and represent an attractive route for the manufacture of bis methyl salicyl carbonate and ester-substituted diaryl carbonates generally.
A method of preparing ester-substituted diaryl carbonates, said method having a contact time, said method comprising contacting an ester-substituted phenol with phosgene and a phase transfer catalyst in the presence of an organic solvent and an aqueous phase wherein the aqueous phase is maintained at a pH of at least about 9.3 throughout the contact time, said phosgene being used in an amount corresponding to between about 0.95 and about 1.20 moles of phosgene per mole of product ester-substituted phenol diarylcarbonate.
A method of preparing ester-substituted diaryl carbonates, said method having a contact time, said method comprising contacting an ester-substituted phenol with phosgene, a phase transfer catalyst, and a tertiary amine, in the presence of an organic solvent and an aqueous phase wherein the aqueous phase is maintained at a pH of at least about 9.3 throughout the contact time, said phosgene being used in an amount corresponding to between about 0.95 and about 1.10 molar equivalents based on said product ester-substituted phenol diarylcarbonate, whereby at least 90% of the ester-substituted phenol is converted into product ester-substituted diaryl carbonate.
A method of preparing bis-methyl salicyl carbonate said method comprising contacting a two phase mixture of a solution of methyl salicylates in methylene chloride and an aqueous phase, with from about 0.95 to about 1.10 molar equivalents of phosgene and from about 0.1 to about 2 molar equivalents of a quaternary ammonium compound, said molar equivalents of phosgene and quaternary ammonium compound being based on the number of moles of methyl salicylate employed, said aqueous phase being maintained at a pH of between about 9.3 and about 12 by the addition of aqueous sodium hydroxide solution, whereby at least 90% of the methyl salicylate is converted into product bis-methyl salicyl carbonate.
Dependencies are inferred from the claim text.