Plant protecting and regulating compositions – Plant growth regulating compositions – Plural active ingredients
Reexamination Certificate
2001-06-01
2002-12-24
Carr, Deborah D. (Department: 1621)
Plant protecting and regulating compositions
Plant growth regulating compositions
Plural active ingredients
Reexamination Certificate
active
06498124
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an improved process for the isolation of phenyl ester salts from mixtures comprising sulfolane (tetrahydrothiophene-1,1-dioxide), such as a crude reaction mixture in which a phenyl ester salt is synthesized.
BACKGROUND OF THE INVENTION
Phenyl ester salts, as known in the art, have been used in detergents and as bleach activators for fabric laundering and cleaning applications. The synthesis, isolation, and purification of phenyl ester salts which are used as bleach activators, is described in U.S. Pat. Nos. 5,717,188, 5,650,527 and 5,523,434. The isolation of these phenyl ester salts is typically by techniques such as filtration or centrifugation.
In most cases, the isolation or separation steps must be done at low temperatures in order to minimize or avoid unacceptable losses of product. Centrifugation is usually done at temperatures below about 100° C. In fact, equipment rated for use above about 100° C. is difficult to obtain. However, by collecting the product at temperatures lower than about 100° C., several problems are encountered. For instance, allowing the mixture to cool to temperatures below 100° C. or to ambient temperature as described in the art, is not a satisfactory method for the isolation of many phenyl ester salts. Although filtration or centrifugation at these temperatures may be possible, the process is often too slow to be economical for large scale production. At typical reaction concentrations, the mixture becomes almost solid and cannot be readily moved for isolation. While the mixture may be made more tractable by dilution with a solvent, the result is loss of product due to increased solubility as well as a large downstream flow of solvent, which must be purified and recovered.
Another approach used to isolate detergents and bleach activators is to remove the solvent by vacuum distillation at temperatures up to 200° C. This approach is usually unsatisfactory for several reasons. Particularly for large scale production, the evaporation of the reaction solvent is expensive. Further, impurities present in the reaction mixture remain with the product, and must be removed in subsequent steps. In addition, degradation of the solvent and reaction components at the high temperatures required for drying imparts undesired color and impurities to the product. When the phenyl ester salts are made in a reaction mixture comprising sulfolane as the solvent, the degradation of the solvent is a particular problem at elevated temperatures.
Another problem associated with the isolation of phenyl ester salts from reaction mixtures occurs when the product is in the form of very fine crystals. These fine crystals rapidly form a layer upon the filter medium that is virtually impervious to the penetration of liquid, thus blinding the filter or centrifuge. When the mother liquid is viscous, these types of crystals do not settle well on sedimentation style devices. Separation is problematic when the density of the solid and the reaction solvent are similar. Slurries of fine crystals are also difficult to pump or transfer from one vessel to another at typical reaction concentrations and low temperatures.
Patents that describe techniques for the isolation of phenyl ester salts using filtration or centrifugation are discussed below, however, these techniques are typically carried out at temperatures of less than 100° C. The abstract of Japanese Patent Number 8,245,549 describes the isolation of a sulfonate from a solvent having a boiling point of less than 100° C. by centrifugation. The Abstract of Japanese Patent No. 58,157,760 describes the preparation of m-xylene-4-sulfonic acid in which centrifugation is used in product recovery after crystallization. Japanese Patent No. 4,103,567 describes the separation of alkoxybenzene sulphonic acid salts, such as sodium 5-chloro-2-(2-methoxyethoxy) benzenesulfonate, in which the product is recovered by centrifugation. The Abstract of East German Patent DD 295, 349 describes the production of basic phenolate-containing calcium sulfonates, which involves centrifuging or filtering to remove solid oil-insoluble components. U.S. Pat. No. 5,429,773 relates to the centrifugation or isolation of an alkyl ester sulfonate surfactant composition at a temperature of 10-43° C. U.S. Pat. No. 5,523,434 teaches a process for manufacture of phenol sulfonate esters of N-nonanoyl-6-aminocaproic acid, which includes centrifugation at low temperatures for isolation. U.S. Pat. No. 5,650,527 describes a method of isolation wherein the reaction solvent is removed by either evaporation, or crystallization followed by filtration.
Accordingly, what is needed is a process for the isolation of phenyl ester salts from reaction mixtures comprising sulfolane which avoids the following: high temperatures, excessive dilution with cosolvent, excessive problems with pumping or transferring the mixture, blinding of the filter medium, and undesirable solvent interactions. The invention described below answers this need.
SUMMARY OF THE INVENTION
The invention discloses an improved process for the isolation of a phenyl ester salt directly from a mixture comprising sulfolane (tetrahydrothiophene-1,1-dioxide). For example, the invention relates to the improved isolation of a phenyl ester salt from the crude reaction mixture in which the phenyl ester salt is synthesized. Any of the following steps, taken alone or in combination will improve the isolation of a phenyl ester salt from a mixture comprising sulfolane: (i) centrifugation or filtration within an optimal temperature range of about 110-150° C., (ii) addition of a solvent in amounts of about 2-4% based on weight of the crude reaction mixture to reduce the viscosity and/or density of the mother liquid prior to filtration or centrifugation, and (iii) slow cooling of the crude reaction mixture at a rate of about 8-10° C. per hour. Advantageously, the invention avoids excessive dilution with sulfolane, excessive problems with pumping the mixture, problems related to viscosity and/or density, blinding of the filter medium, or addition of large amounts of a cosolvent.
Additionally, this invention is an improvement over the practice of filtering or centrifuging at high temperatures of above 150° C., where these higher temperatures result in less complete separation of the phenyl ester salt from the solvent due to the increased solubility at that temperature. This loss of product often leads to the recycling of the filtrate or centrate with concomitant loss of efficiency, loss of product, and loss of product quality.
In a particularly preferred embodiment, this invention is used to isolate sodium 4-sulfophenyl 6-[(1-oxynonyl)-amino]hexanoate, sodium 4-(nonanoyloxy) benzenesulfonate, or sodium benzoyloxy benzenesulphonate, which are phenyl ester salts used as bleach activators.
Additional objects and advantages of the invention are discussed in the detailed description that follows, and will be obvious from that description, or may be learned by practice of the invention. It is to be understood that both this summary and the following detailed description are exemplary and explanatory only and are not intended to restrict the invention.
DETAILED DESCRIPTION
This invention relates to a process for the isolation of a phenyl ester salt from a mixture comprising sulfolane (tetrahydrothiophene-1,1-dioxide), such as a crude reaction mixture in which a phenyl ester salt is synthesized.
Phenyl ester salts are used as bleach activators in laundry detergents and other cleaning formulations. As shown in the reaction scheme below, the phenyl ester salt is hydrolyzed upon nucleophilic attack by a perhydroxide anion to yield a peroxy acid that acts as a bleaching agent, and a substituted phenolic anion.
To be effective as a bleach activator, the phenyl ester salt must readily react with a perhydroxide anion to produce (activate) the corresponding peroxyacid within the length of time and at the temperature of a typical wash cycle. Employing the process of the invention improves the perh
Attride David C.
Fontenot Kevin J.
Terhune Keith B.
Blake Michael J.
Carr Deborah D.
Eastman Chemical Company
Graves Bernard J.
LandOfFree
Isolation of phenyl ester salts from mixtures comprising... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Isolation of phenyl ester salts from mixtures comprising..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Isolation of phenyl ester salts from mixtures comprising... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2981815