Process for producing esters of monohydric alcohols and carboxylic acids by esterification thereof and removal of acidic impurities from the resulting product

Claim 2

A PROCESS FOR THE PRODUCTION OF ESTERS FROM MONOHYDRIC ALCOHOLS CONTAINING FOUR TO 12 CARBON ATOMS AND MONO- OR POLY- BASIC CARBOXYLIC ACIDS OR ANHYDRIDES THEREOF, CONSISTING IN THE STEPS OF: A. ESTERIFYING SAID CARBOXYLIC ACIDS OR ANHYDRIDES THEROF WITH SAID ALCOHOLS BEING USED IN AN AMOUNT IN EXCESS OF THE STOICHIOMETRIC AMOUNT WITH RESPECT TO SAID ACIDS OR ANHYDRIDES UNTIL A LEVEL OF ACIDS-TO-ESTERS CONVERSION OF AT LEAST 90 9S REACHED; B. DISPERSING THE RESULTING ESTERIFICATION PRODUCT CONTAINING IMPURITIES OF NON-ESTERIFIED ACID ANC ACIDIC ESTER, WHEN POLYBASIC ACID IS USED, INTO DROPS OF 1.0-10 MM SIZE IN AN AQUEOUS CAUSTIC ALKALI SOLUTION HAVING A CONCENTRATION IN THE RANGE OF FROM 2 TO 20 PERCENT BY WEIGHT, BASED ON THE PARTICULAR ACID OR ANHYDRIDE BEING EMPLOYED, AT A TEMPERATURE OF FROM 40* TO 100*C. SAID SOLUTION BEING DISPOSED IN A LAYER OF A THICKNESS SUFFICIENT TO COMPLETE THE DIFFUSION OF SAID IMPURITIES FROM INSIDE OF SAID DROPS ONTO THE SURFACE OF SAID DROPS DURING THE TIME OF THE ASCENSION OF SAID DROPS THROUGH SAID LAYER; SAID IMPURITIES BEING NEUTRALIZED ON THE SURFACE OF SAID DROPS BY THE AQUEOUS CAUSTIC ALKALI SOLUTION AND FORMING SALTS WHICH PASS INTO THE AQUEOUS CAUSTIC ALKALI LAYER, AND SAID DROPS COALESCING OVER SAID LAYER OF CAUSTIC ALKALI SOLUTION AND FORMING A CONTINUOUS LAYER OF PRODUCT FREE FROM NON-ESTRIFIED ACID, ACIDIC ESTER, WHEN A POLYBASIC ACID IS USED, AND SALTS THEREOF; C. REMOVING THE REMAINING ALCOHOL FROM THE PRODUCT D. AND DISCOLORING AND ENSURING THE REQUIRED DIELECTRIC PROPERTIES IN THE PRODUCT BY DISTILLING OR CONTACTING THE PRODUCT WITH SORBENTS.

Claim 3

A process according to claim 1, wherein the dispersing of the esterification product is effected at a temperature in a range of 50* - 70* C.

Claim 4

A process according to claim 1, wherein the dispersing of the esterification product is effected in drops of 1-3 mm size.

Claim 5

A process according to claim 1, wherein the dispersing of the esterification product is effected in an aqueous caustic soda solution.

Claim 6

A process according to claim 1, wherein the dispersing of the esterification product is effected in an aqueous caustic potash solution.

Claim 7

A process for the production of esters from monohydric alcohols containing four to 12 carbon atoms and mono- or polybasic carboxylic acids or anhydrides thereof, consisting in the steps of: a. esterifying said carboxylic acids or anhydrides thereof with said alcohols, the alcohols being used in an amount in excess of the stoichiometric amount with respect to said acids or anhydrides until a level of acids-to-esters conversion of at least 90 percent is reached, in the presence of an acidic catalyst selected from the group consisting of sulphuric acid, benzene sulphonic acid and para-toluene sulphonic acid; b. dispersing the resulting esterification product containing impurities of non-esterified acid, acidic ester, when polybasic acid is used, and said acidic catalyst into drops of 1.0-10 mm size in an aqueous caustic alkali solution having a concentration in the range of from 2 to 20 percent by weight, based on the acid or anhydride and catalyst employed for the esterification and at a temperature of from 40* to 100* C. said solution being disposed in a layer of a thickness sufficient to complete the diffusion of said impurities from inside of said drops onto the surface of said drops during the time of the ascension of said drops through said layer; said impurities being neutralized on the surface of said drops by the aqueous caustic alkali solution and forming salts which pass into the aqueous caustic alkali layer and said drops coalescing over said layer of caustic alkali solution, and forming a continuous layer of product free from non-esterified acid, acidic ester when a polybasic acid is used and salts thereof; c. removing the remaining alcohol from the esterification product; d. and discoloring and ensuring the required dielectric properties in the product by distilling or contacting the product with sorbents.

Claim 8

A process for the production of esters from monohydric alcohols containing four to 12 carbon atoms and mono- or polybasic carboxylic acids or anhydrides thereof, consisting in the steps of: a. esterifying said carboxylic acids or anhydrides thereof with said alcohols, the alcohols being used in an amount in excess of the stoichiometric amount with respect to said acids or anhydrides until a level of acids-to-esters conversion of at least 90 percent is reached, in the presence of an acidic catalyst selected from the group consisting of sulphuric acid, benzene sulphonic acid and para-toluene sulphonic acid; b. dispersing the resulting esterification product containing impurities of non-esterified acid, acidic ester, when polybasic acid is used, and said acidic catalyst into drops of 1.0-10 mm size in an aqueous caustic alkali solution having a concentration in the range of from 2 to 20 percent by weight, based on the acid or anhydride and catalyst employed for the esterification and at a temperature of from 40* to 100* C. said solution being disposed in a layer of a thickness sufficient to complete the diffusion of said impurities from inside of said drops onto the surface of said drops during the time of the ascension of said drops through said layer; said impurities being neutralized on the surface of said drops by the aqueous caustic alkali solution and forming salts which pass into the aqueous caustic alkali layer and said drops coalescing over said layer of caustic alkali solution, and forming a continuous layer of product free from non-esterified acid, acidic ester when a polybasic acid is used and salts thereof; c. removing the remaining alcohol from the esterification product; d. and discoloring and ensuring the required dielectric properties in the product by distilling or contacting the product with sorbents.

Claim 9

A process according to claim 6, wherein the dispersing of the esterification product is effected at a temperature in a range of 50* to 70* C.

Claim 10

A process according to claim 6, wherein the dispersing of the esterification product is effected in drops of 1 to 3 mm size.

Claim 11

A process according to claim 6, wherein the dispersing of the esterification product is effected in an aqueous caustic soda solution.

Claim 12

A process according to claim 6, wherein the dispersing of the esterification product is effected in an aqueous caustic potash solution.

Claim 13

A process according to claim 1, wherein the level of acids-to-esters conversion of at least 92 percent is reached.