Patent GB-684268-A (GB)
Title: Improvements in or relating to organosilicon carboxy acids
IPC: C07F7/08
Filed: 1950-06-02
Abstract: Diorganopolysiloxane emulsions are prepared by adding the siloxane, e.g. dimethylpolysiloxane, to an aqueous solution of an alkali metal or quaternary ammonium salt of an organo-silicon carboxylic acid of the general formula R3SiCnH2nCOOH, wherein each R represents an alkyl, monocyclic aryl or siliconeopentyl (Me3SiCH2-) radical and n is from 2 to 18 inclusive.ALSO:The invention comprises organo-silicon carboxy acids of the formula R3SiCnH2nCOOH, wherein each R is an alkyl, monocyclic aryl or silico-neopentyl ((CH3)3SiCH -) radical and n has a value from 2 to 18 inclusive, and a process for the preparation of the above compounds by reacting an alkali-metal salt of diethylmalonate of the general formula R1CH(COOC2 H5)2, where R1 is hydrogen or an alkyl radical, with compounds of the general formula R3SiCmH2mX, wherein R has the above significance, m has a value of 1 to 17 and X is a halogen atom, saponifying the reaction product R3SiCmH2mCR1(COOC2H5)2 with an alkali-metal hydroxide solution and then hydrolysing and decarboxylating the saponified material by acidifying.  In the above process it is preferred that the halogenated alkyl radical is a chloromethyl radical, and the radical may contain at least three carbon atoms with the halogen further removed from the silicon than the beta-position.  The acetoacetic ester type of synthesis may also be employed to prepare the above acids by reacting the sodium salt of the ethyl ester of acetoacetic acid with the required iodoalkyl substituted silane, the resulting ester is then converted to the acid and the aceto group is cleaved by conventional means.  The alkali metal and quaternary ammonium salts and esters derived from aliphatic alcohols of the above organo-silicon carboxy acids are also referred to.  In the examples: (1) the reaction of chloromethyltrimethylsilane and the sodium salt of diethyl malonate yield the compounds Me3Si(CH2)2COOC2H5 and Me3SiCH2CH (COOC2H5)2 which on hydrolysis and hydrolysis and decarboxylation respectively give Me3Sf (CH2)2COOH; (2) the malonic ester type oi reaction gives the compound PhMe2SiCH2 CH(COOC2H5)2, which on hydrolysis and decarboxylation gives PhMe2Si(CH2)2COOH; (3) (4) and (5) similarly the compounds Me3SiCH2 Si(Me)2CH2CH(COOC2H5)2 and Me3SiCH2Si (Me)2CH2CH2COOH, Me3Si(CH2)3CH(COOC2 H5)2 and Me3Si(CH2)4COOH, and Me3SiCH2 C(Me)(COOC2H5)2 and Me3SiCH2-CH(Me) COOH are prepared; (6) the aceto-acetic ester type of synthesis is used to prepare the compounds Me3SiCH2CH(OCCH3) (COOC2H5), Me3Si (CH2)2COOC2H5 and Me3Si(CH3)3COOH; (7) Me3Si(CH2)3COOH is prepared from the reaction of carbon dioxide and the Grignard reagent prepared from gamma-bromopropyltrimethyl-silane; (8) Me3Si(CH2)5COOH is similarly prepared from the Grignard reagent derived from omega - bromo - n - amyltrimethylsilane.  Specification 684,310 is referred to. Trimethyl- and dimethylphenyl-silylmethyl substituted barbituric acid are prepared by refluxing diethyl trimethylsilylmethylmalonate and diethyl phenyldimethylsilylmethylmalonate, respectively, sodium ethoxide, ethanol and urea and adding conc. hydrochloric acid. Trimethylsilylmethyldimethylsilylmethyl substituted barbituric acid is prepared by a similar method.ALSO:Emulsifying agents for diorganopolysiloxane oils, e.g dimethylpolysiloxane, comprise aqueous solutions of the alkali metal or quaternary ammonium salts of organo-silicon carboxy acids of the general formula R3SiCnH2nCOOH, wherein each R represents an alkyl, monocyclic aryl or silico-neopentyl (Me3SiCH2) radical and n is from 2 to 18 inclusive.