Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2000-02-17
2002-04-09
Carr, Deborah D. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C554S068000
Reexamination Certificate
active
06369250
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for preparing and/or purifying amido acid phenyl ester sulfonates. More particularly, the present invention relates to a process for the preparation of purified 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate salts.
BACKGROUND OF THE INVENTION
The synthesis of ingredients for use in low unit cost consumer goods such as laundry detergents, fabric softeners, and the like is of considerable interest to manufacturers. Indeed, the low cost synthesis of ingredients is typically the rate limiting step in the course of bringing a consumer product to the market. Due to the large number of ingredients in consumer goods such as laundry detergents, the expense of individual ingredients must be minimized in order to keep the cumulative product cost within acceptable ranges. The expense associated with the manufacture of consumer goods ingredients is often due to either the cost of the raw materials used to make such ingredients or to the complex reaction and processing chemistry which is required in their manufacture. Accordingly, manufacturers conduct a continuing search for both inexpensive raw materials or simplified reaction sequences.
Amido acid phenyl ester sulfonates form a class of materials which can serve as bleach activators in laundry detergents and other types of bleach-containing cleaning compositions. Such activators have several desirable attributes including excellent bleaching performance with minimal color damage on fabrics dyes, good washing machine compatibility and a good odor profile in the wash. While these materials are potentially obtainable from inexpensive raw materials, the synthesis is somewhat complicated and typically involves the use of solvents. Problems can also arise in the formation of color forming impurities in the end product. Thus, the synthesis of amido acid phenyl ester sulfonates is not straightforward and can be surprisingly problematic.
Processes for the preparation of amido acid phenyl ester sulfonates have been known. U.S. Pat. No. 5,466,840 teaches a 5 step process for the preparation of the compounds. Other processes are disclosed in U.S. Pat. Nos. 5,391,780; 5,414,099; 5,534,642; 5,153,541; 5,650,527; 5,286,879 and 5,523,434.
Accordingly, the need remains for a simple, inexpensive yet effective process for the production of amido acid phenyl ester sulfonates.
SUMMARY OF THE INVENTION
This need is met by the present invention wherein an improved process for preparing a purified amido acid phenyl ester sulfonate is provided. The present invention employs a water-based purification system to remove color forming compounds and other impurities from the amido acid phenyl ester sulfonate. The use of the water-based purification system removes a greater percentage of color forming impurities than the acetic acid based system of the prior art. The use of the water-based purification system also allows for a greater degree of flexibility to a process for the synthesis of amido acid phenyl ester sulfonate salts due to its ability to purify or crystallize the salt in the presence of large quantities, i.e. greater than 10% and typically more than 20-40%, of the reaction solvent which is required in the synthesis and, thus, eliminates the necessity for a solvent removal step. In addition, the water-based purification system adds flexibility to the synthesis process by providing the ability to work on either a slurry or a homogeneous solution. Accordingly, the purification process of the present invention may be employed on either slurries of crystallized product salt or homogeneous solutions of dissolved product salt which would then allow a controlled recrystallization.
According to a first embodiment of the present invention, a process for the preparation of a purified salt of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate is provided. The process comprises the steps of:
(a) providing a source of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate;
(b) admixing the source with a water-based purification system to form a purification mixture, the water-based purification system having water present at a ratio of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate to water ranging from about 1:0.05 to about 1:50, preferably from about 1:0.1 to about 1:40;
(c) separating a purified salt of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate from the purification mixture; and
(d) collecting the purified salt of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate.
Preferably, the source of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate includes a polar aprotic reaction solvent selected from the group consisting of dialkylacetamides, dialkyl sulfoxides, dialkyl ethers of polyethylene glycol and cyclic or acyclic alkyl sulfones and most preferably is tetrahydrothiophene-1,1-dioxide.
The water-based purification system preferably further comprises a processing aide such as one selected from the group consisting of linear or branched C
1
to C
6
alcohols or diols, linear or branched C
1
to C
6
ketones, linear or branched C
1
to C
6
esters, cyclic or acyclic C
1
to C
6
ethers, linear or branched, cyclic or acyclic C
1
to C
6
sulfoxides and sulfones and mixtures thereof. Most preferably, the processing aide is selected from the group consisting of ethyl alcohol, propyl alcohol, isopropyl alcohol, acetone and mixtures thereof. In highly preferred scenarios, the processing aide has a density of less than or about that of tetrahydrothiophene-1,1-dioxide and is present at a ratio of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate to processing aide ranging from about 1:0.1 to about 1:50 and most preferably from about 1:1 to about 1:20. If desired, the step of admixing further comprises the step of heating the purification mixture to a temperature of from about 30° C. to about 100° C.
According to a second embodiment of the present invention, the process for preparing the purified salt of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate comprises the steps of:
(a) reacting a salt of 4-hydroxybenzene sulfonic acid with a carboxylic anhydride in a reaction solvent to form a reaction mixture having a salt of 4-acyloxybenzenesulfonic acid and a carboxylic acid;
(b) adding a [(1-oxyalkanoyl)amino]alkanoic acid and at least one transesterification catalyst to the reaction mixture and heating at a temperature of from about 120° C. to about 220° C. for from about 0.5 to about 10 hours and a pressure sufficient to maintain reflux of the reaction solvent to form a reaction product containing a salt of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate;
(c) admixing the reaction product with a water-based purification system to form a purification mixture, the water-based purification system having water present at a ratio of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate to water ranging from about 1:0.05 to about 1:50;
(d) separating a purified salt of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate from the purification mixture; and
(e) collecting the purified salt of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate.
According to a third embodiment of the present invention, a process for preparing the purified salt of 4-sulfophenyl-[(1-oxyalkanoyl)amino]alkanoate comprises the steps of:
(a) reacting an alkali metal salt of 4-hydroxybenzene sulfonic acid with a C
2
to C
4
carboxylic anhydride at a sufficient temperature and time in a reaction solvent to form a reaction mixture having an alkali metal salt of 4-acyloxybenzenesulfonic acid and a C
2
to C
4
carboxylic acid, wherein the alkali metal salt of 4-hydroxybenezenesulfonic acid and C
2
to C
4
carboxylic anhydride are present in a mole ratio of 1:1 to 1:40, respectively, and the reaction solvent is present in a weight ratio of 1:1 to 20:1 based on the weight of the alkali metal salt of 4-hydroxybenzenesulfonic acid, provided that excess carboxylic anhydride is removed under reduced pressure from the reaction vessel;
(b) adding a [(1-oxyal
Burns Michael Eugene
Dupont Jeffrey Scott
Dykstra Robert Richard
Carr Deborah D.
Cook C. Brant
Echler Sr. Richard S.
Procter & Gamble Company
William Zerby Kim
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