Silicon chloride reaction with, phosgene

Sulphonic acids and their salts are analysed by GC after esterification with diazomethane or after chlorination with thionyl chloride or phosgene [119]. Reaction with thionyl chloride proceeds according to Scheme 5.14. A 0.5-g sample of sulphonic acid or its salt is placed into a round-bottomed flask fitted with a magnetic stirrer and a reflux condenser, 0.5 ml of dimethylformamide and 20 ml of thionyl chloride are added and the mixture is refluxed for several minutes up to 2 h (according to the character of the sample) until the evolution of gas from the reaction mixture ceases (detection with the aid of a bubbler filled with chlorobenzene). If a salt is chlorinated, solid chloride produced in the reaction mixture must be removed by dilution with dichloromethane and by careful filtration through a fine glass filter. Excess of thionyl chloride and solvent is evaporated carefully under decreased pressure. The residue is dissolved in a suitable solvent (CCU) and analysed by GC (silicone stationary phase, temperature 160°C). 

Phosphates and silicates of metals often react with phosgene at elevated temperatures and yield the metal chloride and phosphorus oxychloride or silicon dioxide. The reaction with ferric phosphate at 300-350°C has been proposed as a synthetic method for phosphorus oxychloride, POCI3. 

Trimethylsilyl-, triethoxysilyl- and trigermyl-triazoles are noted for the intermolecular exchange of such functions (74JOM(70)347). Reactions of l-trimethyIsiIyl-l,2,4-triazole with acetyl chloride, ethyl chloroformate or phosgene affords acyltriazoles (60CB2804). Trimethyl-stannyl compounds (62RTC202) are usually less reactive than the corresponding silicon derivatives. 

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