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IMPROVED METHOD FOR PURIFYING DIBASIC ESTER COMPOSITIONS

IP.com Disclosure Number: IPCOM000242930D
Publication Date: 2015-Aug-31

Publishing Venue

The IP.com Prior Art Database

Abstract

The present disclosure provides an improved method for treating compositions comprising dibasic esters. It also provides stable compositions of dibasic esters virtually devoid of entrained impurities which cause color and turbidity.

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IMPROVED METHOD FOR PURIFYING DIBASIC ESTER COMPOSITIONS

FIELD OF THE DISCLOSURE


[0001]The present disclosure relates to an improved method for treating compositions comprising dibasic esters. More particularly, the disclosure relates to an improved method for treating compositions comprising dibasic esters whereby entrained impurities which cause color and turbidity are removed by passing the composition through a particular ion exchange resin at specific conditions, followed by passing the composition through a filtration material comprising a particular activated carbon at specific conditions. Even more particularly, the disclosure relates to a highly purified dibasic ester composition with certain desirable properties.

BACKGROUND OF THE DISCLOSURE


[0002]Meeting product specifications regarding color and turbidity in compositions comprising dibasic esters has long been a problem in the industry. Such compositions contain radical compounds such as nitrates, nitrites, sulfates, metals such as vanadium, copper, iron, and organic radicals capable of further reacting to form colored or turbid complexes which can affect the purity of the compositions.


[0003]Over time many steps have been taken to solve this complex problem. As an example of this continuing effort, U.S. pat. No. 3,991,100 discloses a process for manufacturing alkyl esters from various dibasic acids which are typically from waste streams of a process for manufacturing adipic acid and dodecanedioic acid via nitric acid oxidation. The process comprises esterifying the dibasic acid in the presence of an acid catalyst and alcohol followed by removing substantially all water formed, then distilling off alkyl esters formed in the esterification step. A further example is disclosed in U.S. Pat. No. 4,321,407 and Canada Pat. No. 1,168,262, disclosing a method for reducing color-forming


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tendency of such esters by contacting them with various alkali metal borohydride, permanganate or methylate. Also, U.S. Pat. No. 4,365,080 discloses a process for producing methyl esters of C4 -C6 carboxylic acid components contained in an aqueous filtrate which is a waste byproduct stream derived from the production of adipic acid by nitric acid oxidation of cyclohexanone/cyclohexanol. The latter process comprises steps of (1) concentrating the volume of the aqueous filtrate medium by the partial removal of water and the volatile components which co-distill with water to provide a concentrate solution; (2) admixing the concentrate solution with methanol, and heating the solution at a temperature form 60 to 90 oC to form methyl esters of the C4 -C6 carboxylic acid components; (3) extracting the methyl esters by contacting the esterification medium with a water-immiscible organic solvent at a temperature from 40 to 90 oC; and (4) separating the immiscible organic solvent phase and aqueous phase.


[0004]U.S. Pat. No. 4,331,812 discloses a method for reducing the color- forming t...