Some investigations of fusing and dissolving samples

When both Si-H and Si-vinyl are present, the sum of these groups can be determined bromometrically. For Si-H a gasvolumetric method is applied and Si-vinyl results from the difference. The bromometric determination is carried out by dissolving the sample in a mixture of carbon tetrachloride/acetic acid, addition of excess solution of bromine in acetic acid and back-titration of the unconsumed bromine. Mercuric chloride serves as a catalyst for the bromine addition. The Si-H determination is carried out by measuring the hydrogen gas evolved after hydrolysis of the sample in wet n-butanol in the presence of sodium n-butanolate. The bromometric method proved to be also useful for the rapid and sensitive determination of either Si-vinyl or Si-H. The time required is 45 min, the lower limit is 0.02 mmole per g.