Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
1999-02-26
2001-06-12
Killos, Paul J. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S485000, C562S593000, C562S580000
Reexamination Certificate
active
06245942
ABSTRACT:
BACKGROUND
1. Field of the Invention
This invention relates to reduction of carbonyl values in compositions containing carboxylic acids, derivatives of carboxylic acids or both.
2. Description of Related Art
Carboxylic acid and carboxylic acid derivative containing compositions have a multitude of uses as intermediates in the production of materials and as final products. Various processes have been used to produce carboxylic acids and derivatives thereof. These products are then stored or subject to further processing. The processing and storage of these products can result in degradation of the carboxylic acids and contamination of the products. For example, production of azelaic acid or pelargonic acids by ozonolysis of oleic acid is known to lead to a mixture of oxidation products containing carboxylic acids and carbonyl-containing species such as aldehydes and ketones. The presence of aldehydes and ketones may be considered undesirable since they may impart discoloration, odors and tastes to such products. Indeed, processing and storage of fatty acids and derivatives of fatty acids may lead to aldehyde and ketone degradation products resulting from oxidation.
The combined concentration of aldehydes and ketones is known interchangeably as the carbonyl content or carbonyl value. In the present context, the carbonyl value is also a measure of oxidation and may be expressed as milligrams of carbonyl functionality per gram of sample. Carbonyl value is abbreviated COV and may also be expressed in parts per million.
Since aldehydes, ketones and oxo-carboxylic acid derivatives thereof may be considered undesirable contaminants in compositions containing carboxylic acids and derivatives thereof, certain processes have been developed to lower the COV. Typically, keto-acids and aldo-acids are contaminants which are difficult to remove from the carboxylic acid end products, especially on industrial scales. One removal process involves reaction of ketones and aldehydes with oxygen in the presence of a metal ion catalyst such as cobalt and manganese. Unfortunately, treatment with oxygen may result in degradation of the product and toxic manganese or cobalt waste products. The presence of manganese or cobalt in waste streams can present environmental problems.
Consequently, there exists a need for methods of lowering COV, but which eliminates the need for manganese compounds and oxygen for the removal of aldehydes and ketones.
SUMMARY OF THE INVENTION
A process is provided for lowering the carbonyl value of a composition containing carboxylic acid or carboxylic acid derivative which includes contacting the composition containing carboxylic acid with an amount of a catalyst and an active methylene compound effective to lower the carbonyl value of the composition.
Also provided is a process for reducing the amount of carbonyl group containing impurities in a composition which includes carboxylic acid or carboxylic acid derivative, the process including contacting the composition containing carboxylic acid or carboxylic acid derivative with an amount of a catalyst and an active methylene compound effective to form a condensate and to reduce the carbonyl value of the composition and separating the condensate from the composition.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention provides an efficient, environmentally friendly method of lowering the amount of certain undesirable contaminants in compositions including carboxylic acid and derivative of carboxylic acid without degrading the compositions. As a result, stable carboxylic acid containing compositions are facilitated which have reduced amounts of undesirable colors, odors, tastes and other unwanted properties attributable to such contaminants. The present invention eliminates the need for manganese or cobalt compounds and oxygen for removal of aldehydes and ketones including oxo-carboxylic acids from other carboxylic acid which leads to higher product yields through the reduction of manganese or cobalt soaps and product degradation from oxygen sparging. It should be understood that use of the terms “carboxylic acid” or “carboxylic acid derivative” herein is meant to encompass both singular and plural species, i.e., one or more carboxylic acid molecules or one or more carboxylic acid derivative molecules.
It is contemplated that any carboxylic acid or carboxylic acid derivative containing composition may be subjected to decontamination according to the present invention. The composition may consist entirely of carboxylic acid and/or derivative of carboxylic acid, or the composition may contain other chemical entities. Such carboxylic acid include any carboxyl group containing compound such as saturated and unsaturated aliphatic carboxylic acids, unsaturated and saturated aromatic carboxylic acids and mixtures thereof, e.g., C
4
monoacids to C
20
, saturated or C
12
to C
20
unsaturated, fatty acids and the like. Diacids, triacids, etc. are also contemplated. It is also contemplated that compositions containing derivatives of carboxylic acids can be decontaminated according to the present invention. Such derivative of carboxylic acid are compounds that yield carboxylic acid upon reaction with water and include acid halides, acid anhydrides, esters, amides, and nitrites.
Reduction of the carbonyl value of a composition containing carboxylic acid or carboxylic acid derivative is achieved by contacting such a composition with a catalyst and an activated methylene compound. Without wishing to be bound by any theory, the reaction appears to involve Knoevenagel condensation which is the reaction of an aldehyde or ketone with a compound that has a hydrogen alpha to two activating groups (such as C═O or C≡N) using a catalyst to form a condensate, i.e., two molecules combine into a larger molecule. Ketones are typically less reactive than aldehydes and more acidic compounds such as active methylene compounds are preferred to facilitate condensation of ketones. Examples of such methylene compounds are provided below. While reference has been made to Knoevenagel condensation herein, the carbonyl value may actually be lowered by formation of undefined products. Suitable catalysts for use in accordance with the present invention include amine, ammonia, ammonium salt, titanium tetrachloride (TiCl
4
) and aluminum oxide (Al
2
O
3
) or combinations thereof. Suitable amines include primary amines and secondary amines including alkyl amines, arylamines, arylakylamines and the like. A preferred amine is n-octylamine.
Active methylene compounds are well-known in the art. Any compound having the formula X-CH
2
-Y wherein X and Y may be the same or different and are electron withdrawing groups is suitable for use herein. Examples of suitable X and Y substituents may be represented by the following formulas:
wherein R is alklyl or aryl. Common names of suitable active methylene compounds include malonitrile, benzoylacetonitrile, 2,4-dimethylbenzoylacetonitrile, pivaloylacetonitrile, cyanoacetamide, p-nitrophenylacetonitrile and p-cyanophenylacetonitrile. Particular examples include:
Particularly preferred are cyanoactive methylene compounds such as cyanoacetic acid and ethylcyanoacetate.
The amounts of catalyst and active methylene compound to be added to a composition containing carboxylic acid or carboxylic acid derivative depends on the COV of the composition. For example, the greater the COV, the higher the relative amount of methylene compound and catalyst. Those with skill in the art can determine appropriate amounts of methylene compound and catalyst based upon COV. For example, the amount of catalyst can be greater than about 0.001% by weight of the entire composition and is preferably about 0.01 wt % to about 10 wt % and more preferably about 0.01 wt % to about 0.5 wt % of the composition. The amount of active methylene compound may generally be greater than about 0.1 molar equivalent and is preferably about 0.1 molar equivalent to about 6 molar equivalents and more preferably about 1.5 molar equivalents to about 4
Drach John E.
Henkel Corporation
Killos Paul J.
Steen Jeffrey S.
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