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ACCELERATED ESTER PRODUCTION UTILIZING TWO-STEP WATER REMOVAL

IP.com Disclosure Number: IPCOM000031190D
Publication Date: 2004-Sep-16

Publishing Venue

The IP.com Prior Art Database

Abstract

An improved method of making an ester by reacting acrylic acid or methacrylic acid with an alcohol wherein the ester has a boiling point higher than that of water includes distilling out at least a portion of the by-product water from a reaction mixture consisting essentially of the reactant acid, reactant alcohol, an ester product, by-product water, a polymerization inhibitor and a catalyst followed by adding a solvent to the reaction mixture which forms an azeotrope with water and azeotropically distilling out by-product water from the reaction mixture.

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ACCELERATED ESTER PRODUCTION

UTILIZING TWO-STEP WATER REMOVAL

In the production of acrylic esters there is a need for a high efficiency process that removes substantially all of the water byproduct and that result in an improved yield of product, while demonstrating increased efficiency of ester production, both in terms of conversion times and energy consumption.

Summary

            We have discovered such a method of making an ester by reacting acrylic acid or methacrylic acid with an organic alcohol in the presence of an acid catalyst and a polymerization inhibitor wherein the ester has a boiling point higher than that of water, the improvement which includes distilling out at least a portion of the by-product water from a reaction mixture consisting essentially of the reactant acid, reactant alcohol, an ester product, by-product water, polymerization inhibitor and including a catalyst followed by adding a solvent to the reaction mixture which forms an azeotrope with water.  The azeotrope is then distilled out of the mixture to remove the remaining by-product water.  Typically the organic alcohol has four carbon atoms or more, such as from four to twelve carbon atoms or is a polyol.  In one embodiment, the alcohol has at least 6 carbon atoms.

            While any suitable alcohol may be employed, 2-ethylhexyl alcohol is used to produce a preferred ester with acrylic acid. 

            In another aspect of the invention there is provided a method of esterifying an acid selected from the group consisting of acrylic acid and methacrylic acid.  The product includes:  a) reacting the acid with an alcohol wherein the ester formed has a boiling point higher than that of water, in a reaction mixture consisting essentially of the acid, the alcohol, an acid catalyst, an ester product, a polymerization inhibitor as well as by-product water.  After the reaction begins, at least a portion of the by-product water is distilled from the reaction mixture, which at this point consists essentially of the acid, the alcohol, the acid catalyst, the ester product, the polymerization inhibitor and the by-product water.  Following distilling at least a portion of the by-product water from the mixture, an organic solvent is added to the mixture, the solvent being capable of forming an azeotrope with water.  More by-product water is then azeotropically distilled from the reaction mixture.  Generally, at least about 15% of the by-product water is removed prior to adding solvent to the reaction mixture.   

            The alcohol may be selected from the group consisting of butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, 2-ethylhexyl alcohol, nonyl alcohol, decyl alcohol, dodecyl alcohol, hexadecyl alcohol and stearyl alcohol or a polyol.  So also, any suitable organic solvent may be used as the azeotroping solvent.  Solvents such as cyclohexane, benzene, heptane, toluene, xylene...