GB2203152A - Surface active silicone compound - Google Patents

Abstract

Surface active silicone compounds which have an improved stability at a pH above 8 or below 4, have the general formula <IMAGE> wherein R' when present is H or hydrocarbon, a is 2 or 3 and Z represents a hydrophilic substituent, e.g. a sulphonate or polyoxyalkylene containing group. A typical compound is (Me3Si)3C. CH2.CH.2.O. CO.CH (SO3Na)-CH2.COONa. The compounds are obtained a lithiated silylated methane and a compound with a Z group.

Description

SURFACE ACTIVE SILICONE COMPOUND This invention relates to surface active silicone compounds and to a method for making these compounds.

Surface active silicone compounds have been known for some time and include such materials as organopolysiloxane polyoxyalkylene copolymers and sulphonate functional polysiloxanes. G.B. Patent Specification No. 1 198 096 for example, describes a polysiloxane having 0.1 to 100 mole percent of units of the formula M[O3SRSi(R' a 03-a1x wherein 2 M is a cation, R' is a certain monovalent group and R is a certain hydroxy-substituted divalent group where the hydroxy substituent is bonded to a carbon atom vicinal to which the -O3S- group is bonded, a is 0, 1 or 2 and x is 1, 2, 3 or 4 and is equal to the valency of said cation, and 0.0 to 99.9 mole percent of units of the formula R"bSiO4 b 7 wherein R" is hydrogen or a monovalent group as for R', and b is 1, 2 or 3.These polysiloxanes are stated to be useful for example in the production of emulsions for use in making polishes, of treating baths of increased wetting properties and of media having increased surface activity.

In G.B. Patent Specification No. 1 143 206 there are described organopolysiloxane polyoxyalkylene copolymers having the general formula Me3SiO(Me2SiO) q [H(0C2H4) ( OC3H6)yO(CH2)SiOMe]pSiMe3 in which q has a value from 3 to 25, x has a value from 1 to 25, z has a value from 0 to 15, z is 2 or 3, g has a value from 1 to 10, at least 25 percent by weight of the oxyalkylene groups being oxyethylene.

Silicone compounds of the types described above are, however, not suitable for use under acidic and basic conditions. The present invention is concerned with certain silicone compounds which show surface activity and are suitable for use in acidic and basic conditions.

The invention provides in one of its aspects silicone compounds represented by the general formula

wherein each R independently represents an alkyl or aryl group having up to 8 carbon atoms, each R' represents a hydrogen atom or a monovalent hydrocarbon group, Z represents a hydrophilic substituent and a has a value of 2 or 3.

In the general formula of the silicone compounds of the invention R may be for example methyl, ethyl, isopropyl, isobutyl or phenyl. R', if present, may be hydrogen or any monovalent hydrocarbon group. Preferably a has a value of 3, and no R' group is present in the compound of the invention. Z may be any group which has hydrophilic character. Such groups include for example sulphonate containing groups, polyoxyalkylene containing groups, phosphate containing groups, betaine groups and sulphate containing groups. The preferred Z groups are those that contain a sulphonate or a polyoxyalkylene group.

These functional groups may be linked directly or indirectly to the carbon atom having the tri-substituted silyl substituents. Preferably the Z group has the general formula R"Q, wherein R" denotes a divalent group, consisting of H, C and optionally N or Si, and Q is the functional unit, which may be for example a sulphonate group with a cation or a polyoxyalkylene group. Examples of the R" group include n-butylene, o-xylylene, ethyl-propyldimethylammonium and -Si(Me)2(CH2)3-. Examples of Q groups are -SO3Na+ and -(0C2H4)7OH.

The silicone compounds of the invention may be prepared according to a process which comprises (1) the reaction of (R3Si) CH(R3-a with an alkyl lithium compound to form a compound having the general formula (R3Si) C (R')3 Li , and and (2) the direct or indirect reaction of the product of step (1) with a hydrophilic group containing compound, R, R' and a having the denotation mentioned above.

The silicon-containing starting material for step (1) of the method of the invention may be obtained by reacting a silane of the general formula R3SiX, with a lithium compound and a halomethane of the formula XaCHR' wherein R, R' and a are as denoted above and X is a halogen atom.

This halomethane is preferably trichloromethane. In step (1) of the method the compound (R3Si)aCH(R')3 a is reacted with alkyllithium in an appropriate solvent. This step is preferably carried out in a mixture of solvents comprising the solvent in which the alkyllithium compound is supplied.

Such mixtures may include tetrahydrofuran or diethylether.

The reagents used in step (2) will be determined by the type of surface active material one wants to obtain. These reagants may be among others sulphonate group containing compounds, for example 1,3 propane sultone or 1,4 butane sultone or polyoxyalkylene group containing compounds for example allylheptaoxyethylene glycol.By indirect reaction in step (2) is meant that the reaction may also be carried out in several stages, for example, in a first stage the reaction product of step (1) may be reacted with 1,4 dichloromethyl benzene, followed in a second stage by the reaction with sodium sulphite; or in a first stage the product of step (1) may be reacted with dimethyl chloropropylamine, followed in a second stage by the reaction with 1,3 propane sultone; in yet another example the reaction product of step (1) of the method of the invention is reacted with a dialkylchlorosilane in a first stage and is then further reacted in a second stage with a hydrophilic group containing compound having a terminal olefinic unsaturation, for example, allylheptaoxy ethylene glycol.

Surface active agents of the invention have good surface activity. They are also stable in conditions where the pH rises above 8 or falls below 4, where the more conventional surface active material based on silicone compounds break down.

There now follows a number of examples in which all parts and percentages are expressed by weight and Me denotes a methyl group, which illustrate the invention.

Example 1 Preparation of Sulphosuccinate Functional Trisyl Methane A 250ml three neck flask fitted with a stirrer, condenser, dropping funnel and nitrogen inlet was charged with 50ml of dry tetrahydrofuran (THF), 6.96g (0.03 mole) of trisyi methane [(Me3Si)3CH] and 21ml of a 1.4M solution of methyl lithium in Et2O. The ingredients were mixed and heated. The diethyl ether was distilled off after 4 hours, leaving the resulting trisyl methane lithium salt [(Me3Si)3C Li+3 in THF. To this solution, cooled to OOC, 1.5g (0.033 mole) of ethylene oxide were slowly added.

Work up with water and crystallisation from methanol gave the trisylpropanol [(Me3Si) 3CCH2CH2OH] in quantitative yield.

A 100ml three neck flask equipped with a condenser, stirrer and nitrogen inlet was charged with 2.76g (0.01 mole) of trisyl propanol, 20g of toluene and 0.98g (0.01 mole) of maleic anhydride. The mixture was slowly heated to 1100C for 30 minutes then stripped under reduced pressure, yielding the maleate monoester (Me3Si)3CCH2CH2-O-CO-CH=CH-COOH as a yellow oil.

To the maleate ester, 5ml of methanol and a solution of N sodium hydroxide in water were added adjusting the pH to between 7 and 8. The solution was then heated to reflux and 0.95g (0.005 mole) of sodium metabisulphite was added.

The mixture was ref fluxed for 4 hours and cooled to ambient temperature. Precipitation with acetone yielded the corresponding sulphosuccinate functional trisyl methane

Example 2 Preparation of Thiosulphate Functional Trisyl Methane A solution of trisyl methane lithium prepared as described in Example 1 from 17.4g (0.075 mole) of trisyl methane was cooled to OOC. 9.9g (0.082 mole) of allyl bromide were slowly added. After complete addition the mixture was brought to ambient temperature for 20 minutes.

A work up with water and crystallisation from methanol yielded allyl trisyl methane [(Me3Si)3CCH2CH=CH2] in quantitative yield.

A 100ml flask equipped with a stirrer, condenser and nitrogen inlet was charged with 5.44g of the allyl trisyl methane (0.02 mole), 3.2g of mercaptoethane sulphonate (0.02 mole), 10g of H2O and 20g of isopropanol. The mixture was heated to reflux and 0.1% azobutyronitrile was added. The reaction was maintained at reflux for 2 hours.

Stripping off the volatiles at reduced pressure yielded a white solid of the formula (Me3Si)3C-(CH2)3-S-(CH2)2-SO3 Na+ Example 3 A solution of trisyl methane lithium prepared as described in Example 1 from 17.4g (0.075 mole) of trisyl methane, was cooled to 0 C. 0.082 mole of dimethyl hexenyl chlorosilane was slowly added. After complete addition the mixture was brought to ambient temperature for 20 minutes.

A work up with water and crystallisation from methanol yielded hexenyl dimethyl silyl trisyl methane [(Me3Si)3C-Si-(Me2)2-(CH2)4-CH=CH2] .

A 100ml flask equipped with a stirrer, condenser and nitrogen inlet was charged with 3.72g of hexenyl dimethyl silyl trisyl methane (0.01 mole), 1.64g of mercaptoethane sulphonate (0.01 mole), 7g of H2O and 15g of isopropanol.

The mixture was heated to reflux and 0.1% azobutyronitrile was added. The reaction was maintained at reflux for 2 hours. Stripping off the volatiles at reduced pressure yielded a white solid of the formula (Me3Si)3C-Si(Me)2-(CH2)6-S-(CH2)2-SO3 Na+.

Claims (7)

1. A silicone compound represented by the general formula (R3Si) aC1(R') 3-a wherein each R independently represents an alkyl z or aryl group having up to 8 carbon atoms, each R' represents a hydrogen atom or a monovalent hydrocarbon group, Z represents a hydrophilic substituent and a has a value of 2 or 3.

2. A silicone compound according to Claim 1 where a has a value of 3.

3. A silicone compound according to either one of the preceding claims wherein Z contains a sulphonate or a polyoxyalkylene group.

4. A method for preparing a silicone compound represented by the general formula

wherein each R independently represents an alkyl or aryl group having up to 8 carbon atoms, each R' represents a hydrogen atom or a monovalent hydrocarbon group, Z represents a hydrophilic substituent and a has a value of 2 or 3, which comprises (1) the reaction of (R3Si) aCH(R')3a with an alkyl lithium compound to form a compound having the general formula (R3Si)aC (R')3 aLi+, and (2) the direct or indirect reaction of the product of step (1) with a hydrophilic group containing compound, R, R' and a having the denotation mentioned above.

5. A method according to Claim 4 wherein step (1) is carried out in the presence of a solvent which comprises tetrahydrofuran or diethylether.

6. A method according to either of Claims 5 or 6 wherein step (2) is an indirect reaction.

7. A method substantially as hereinbefore described with reference to any one of Examples 1, 2 and 3.