Ethanetetracarboxylate perhydrates

Abstract

Ethane tetracarboxylate perhydrates represented by the formula ##EQU1## wherein M is alkali metal or ammonium are useful as complexing agents and as sources of hydrogen peroxide. The compounds are particularly useful as ingredients of detergent formulations wherein they provide detergency building, bleaching, and disinfectant functionality.

Description

BACKGROUND OF THE INVENTION

This invention relates to novel ethane tetracarboxylate perhydrates useful as complexing agents for various metal and alkaline earth metal ions (particularly ions such as calcium and magnesium which contribute to "hardness" of water) and which serve as sources of hydrogen peroxide to provide oxidizing, bleaching and disinfectant functionality.

The utility of compounds characterized by the ability to complex ions in aqueous media which contribute to hardness thereof e.g., calcium and magnesium and/or provide in combination with various detergent surfactants, detergent formulations of enhanced cleansing ability is well recognized by those skilled in the art. Such compounds are used in water treating applications to "soften" water and/or inhibit scale formation and/or as detergency builders.

Further, the utility of hydrogen peroxide and compounds serving as a source of this material which exhibit bleaching and disinfectant functionality is well understood.

In detergent formulations both detergency building and bleaching and disinfectant functionality are often desired. Since detergency building and bleaching functionality are not generally found in a single compound having acceptable stability, the preparation of a formulation having both functionalities normally requires the use of a plurality of components with attendant problems related to chemical compatibility, the formulation of uniform mixtures, etc.

It is apparent, therefore, that a single stable compound possessing both detergency builder and bleaching function would constitute a substantial advance in the detergent art as well as being useful in those applications in which the independent functionalities are desired.

SUMMARY OF THE INVENTION

It is an object of this invention to provide novel compounds useful as complexing agents and/or detergency builders and which also serve as sources of hydrogen peroxide to provide the recognized functionality associated with this material.

The compounds of this invention are ethane tetracarboxylate perhydrates whose structure, synthesis, and use will be understood from the following description of the preferred embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The compounds of the present invention are represented by the formula ##EQU2## wherein M is alkali metal or ammonium. The compound wherein M is sodium is particularly preferred.

The compounds of the present invention are conveniently prepared by reacting tetra alkali metal or ammonium ethane tetracarboxylate with aqueous hydrogen peroxide. Reaction conditions such as concentration, temperature, pressure, etc. do not appear to be critical. For example, the reaction can conveniently be conducted using anhydrous or hydrated ethane tetracarboxylate and 30-50% by weight aqueous hydrogen peroxide at ambient temperature (about 25.degree.C.) and atmospheric pressure. Product is isolated by drying the mixture (preferably at ambient temperature).

The ethane tetracarboxylate employed in the synthesis of the compound of the present invention is a well known material whose preparation is described in the literature.

The ethane tetracarboxylate perhydrates of this invention are useful as agents for complexing metal and/or alkaline earth metal ions in aqueous media. The amount of tetracarboxylate required to effectively complex the ions in a given system will depend, to some extent, on the particular polycarboxylate salt being used and the particular metal or alkaline earth metal ions in the aqueous media. Generally, complexing is more effective in basic solution. Optimum conditions and amounts of complexing agent can readily be determined by routine experimentation.

As sources of hydrogen peroxide, the compounds of this invention are utilized in substantially the same manner as sodium perborate. Since the ethane carboxylate moiety associated with the hydrogen peroxide provides building functionality, the compound offers particular advantages as contrasted to perborates wherein the boron moiety is relatively inert with regard to detergency functionality.

The ethane tetracarboxylate perhydrates are particularly useful as bleaching agents and as builders in detergent formulations. Generally, the use of the alkali metal salts, particularly the sodium salt, is preferred.

The detergent formulations will contain at least 1% by weight and preferably at least 5% by weight of the ethane tetracarboxylate perhydrate of this invention. In order to obtain the maximum advantages, the use of from 5 to 75% is particularly preferred. If the detergent formulation contains nitrogen containing compounds capable of forming N.fwdarw.O adducts it may be desirable to limit the amount of perhydrate present in order to inhibit the formation of such adducts. Suitable quantities can be determined by routine testing. The ethane tetracarboxylate perhydrate compound can be the sole detergency builder of the formulation or can be utilized in combination with other detergency builders which may constitute from 0 to 95% by weight of the total builders in the formulation. By way of example, builders which can be employed in combination with the novel compounds of this invention include water soluble inorganic builder salts such as alkali metal polyphosphates, i.e., the tripolyphosphates and pyrophosphates, alkali metal carbonates, borates, bicarbonates and silicates and water soluble organic builders including amino polycarboxylic acids and salts such as alkali metal nitrilotriacetates, cycloalkane polycarboxylic acids and salts, ether polycarboxylates, alkyl polycarboxylates, epoxy polycarboxylates, tetrahydrofuran polycarboxylates such as 1,2,3,4 or 2,2,5,5 tetrahydrofuran tetracarboxylates, benzene polycarboxylates, oxidized starches, amino (trimethylene phosphonic acid) and its salts, diphosphonic acids and salts (e.g., methylene diphosphonic acid; 1-hydroxy ethylidene diphosphonic acid) and the like.

The detergent formulations will generally contain from 5 to 95% by weight total builder (although greater or lesser quantities may be employed if desired) which, as indicated above, may be solely the ethane tetracarboxylate perhydrate compounds of this invention or mixtures of such compounds with other builders. The total amount of builder employed will be dependent on the intended use of the detergent formulation, other ingredients of the formulation, pH conditions and the like. For example, general laundry powder formulations will usually contain 20 to 60% builder; liquid dishwashing formulations 11 to 12% builder; machine dishwashing formulations 60 to 90% builder. Optimum levels of builder content as well as optimum mixtures of builders of this invention with other builders for various uses can be determined by routine tests in accordance with conventional detergent formulation practice.

The detergent formulations will also contain a water soluble detergent surfactant. Any water soluble anionic, nonionic, zwitterionic or amphoteric surfactant can be employed.

Examples of suitable anionic surfactants include soaps such as the salts of fatty acids containing about 9 to 20 carbon atoms, e.g., salts of fatty acids derived from coconut oil and tallow; alkyl benzene sulfonates--particularly linear alkyl benzene sulfonates in which the alkyl group contains from 10 to 16 carbon atoms; alcohol sulfates; ethoxylates alcohol sulfates; hydroxy alkyl sulfonates; alkyl sulfates and sulfonates monoglyceride sulfates; acid condensates of fatty acid chlorides with hydroxy alkyl sulfonates and the like.

Examples of suitable nonionic surfactants include alkylene oxide (e.g., ethylene oxide) condensates of mono and polyhydroxy alcohols, alkyl phenols, fatty acid amides, and fatty amines; amine oxides; sugar derivatives such as sucrose monopalmitate; long chain tertiary phosphine oxides; dialkyl sulfoxides; fatty acid amides, (e.g., mono or diethanol amides of fatty acids containing 10 to 18 carbon atoms), and the like.

Examples of suitable zwitterionic surfactants include derivatives of aliphatic quaternary ammonium compounds such as 3-(N,N-dimethyl-N-hexadecylammonio) propane-1-sulfonate and 3-(N,N-dimethyl-N-hexadecylammonio)-2-hydroxy propane-1-sulfonate.

Examples of suitable amphoteric surfactants include betains, sulfobetains and fatty acid imidazole carboxylates and sulfonates.

It will be understood that the above examples of surfactants are by no means comprehensive and that numerous other surfactants are known to those skilled in the art. It will be further understood that the choice and use of surfactants will be in accordance with well understood practices of detergent formulation. For example, anionic surfactants, particularly linear alkyl benzene sulfonate are preferred for use in general laundry formulations, whereas low foaming nonionic surfactants are preferred for use in machine dishwashing formulations.

The quantity of surfactant employed in the detergent formulations will depend on the surfactant chosen and the end use of the formulation. In general, the formulations will contain from 5 to 50% surfactant by weight, although as much as 95% or more surfactant may be employed if desired. For example, general laundry powder formulations normally contain 5 to 50%, preferably 15 to 25% surfactant; machine dishwashing formulations 0.5 to 5%; liquid dishwashing formulations 20 to 45%. The weight ratio of surfactant to builder will generally be in the range of from 1:12 to 2:1.

In addition to builder and surfactant components, detergent formulations may contain fillers such as sodium sulfate and minor amounts of dyes, optical brighteners, soil anti-redeposition agents, perfumes and the like.

If desired, the formulation may contain other bleaching agents to supplement the ethane tetracarboxylate perhydrate.

Bleach activators such as tetraacetylethylenediamine, sodium p-acetoxybenzene sulfonate, or tetraacetylglycouril may be advantageously employed to promote release of hydrogen peroxide by ethane tetracarboxylate.

The invention is further illustrated by the following examples (all parts and percentages are by weight unless otherwise indicated):

EXAMPLE I

Ten grams anhydrous tetrasodium-1,1,2,2-ethane tetracarboxylate are dissolved in 15 ml. of 50% aqueous hydrogen peroxide. The mixture is evaporated to yield a solid which is further dried over a desiccant at a temperature of about 25.degree.C. The resulting tetrasodium ethane-1,1,2,2-tetracarboxylate perhydrate ##EQU3## is a crystalline material exhibiting the following Cu K-.alpha. X-ray diffraction pattern.

______________________________________ 2.THETA. d-spacing relative intensity ______________________________________ 15.65 2.8553 100 14.28 3.1227 100 18.30 2.4531 90 14.05 3.1728 50 11.55 3.8470 40 16.85 2.6572 40 16.38 2.7313 35 22.60 2.0043 35 ______________________________________

EXAMPLE II

Detergent formulations are prepared containing about 17 parts linear sodium alkylbenzene sulfonate having an average molecular weight of about 230; 8.5 parts silicate having a 1:2 ratio of Na.sub.2 O:SiO.sub.2 ; 24.5 parts sodium sulfate and 50 parts tetra sodium ethane-1,1,2,2-tetracarboxylate perhydrate. This composition is compared in cleaning effectiveness on polyester/cotton and cotton fabrics with an otherwise identical composition containing no tetra sodium ethane-1,1,2,2-tetracarboxylate perhydrate. Detergency performance of the formulations containing the builder as determined by measurement of the difference in reflectance of washed and unwashed samples averages twice that of the formulation containing no tetra sodium ethane-1,1,2,2-tetracarboxylate perhydrate. Similar results are obtained with formulations containing 25 parts and 38 parts tetra sodium ethane-1,1,2,2-tetracarboxylate perhydrate. The formulations are also found to provide effective bleaching of the fabrics at wash temperatures above 90.degree.C. in absence of bleach activators and at lower temperatures (50.degree.-60.degree.C.) if activators such as these previously referred to are employed.

Claims

What is claimed is:

1. A compound represented by the formula ##EQU4## wherein M is alkali metal or ammonium.

2. A compound of claim 1 wherein M is sodium.