The olefins C4Fa-1, C4Fs-2 (mixture of cis and trans isomers) and i-C1Fs have been prepared by pyrolytic reactions and a Perfluoroisobutene differs markedly in its physical and chemical i-CdF8 reacts with alcohols and bromine at much number of physical and chemical properties determined. properties from the other isomers, which are quite similar to one another. different rates than does C4Fa-1 or C1Fs-2; an attempt has been made to explain these differences.

The electrochemical process for the production of fluorocarbons has been shown to function satisfactorily with a large range of oxygen containing organic compounds. With acids a spread of fluorocarbon products is obtained with the number of carbon atoms both less than and greater than the number of carbon atoms in the hydrocarbon radical of the acid. The most significant percentage, however, is in the fraction having this number of carbon atoms. A number of fluorocarbon hydrides have been isolated from the products. Alcohols and ethers also satisfactorily gave fluorocarbon products.

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The replacement of chlorine by fluorine in a molecule is usually accomplished with the aid of metallic fluorides as reagents or catalysts.' If, however, the chlorine is sufficiently 'labile, the use of anhydrous hydrogen fluoride alone is possible. Because of side reactions induced by the metals, yields in the absence of catalysts are generally better, and the purification of the products is simplified. Chlorine attached to silicon enters readily into reactions such as hydrolysis or ammonolysis. We have found the corresponding reaction with hydrogen fluoride to proceed a t room temperature or below, producing the fluorides in good yield.The previous literature on fluorosilanes is limited, with one exception, to the trisubstituted monofluoro compounds. Triethylmonofluorosilane was made from the reaction of ammonium fluoride on a sulfuric acid solution of di-triethylsilyl ether.3 The addition of SiF4 to an ether solution of a suitable Grignard reagent resulted in the formation of the corresponding trialkyl and triaryl fluorosilane~.~J The preparation of the di-and tri-fluorosilanes of ethyl and phenyl from the action of zinc fluoride on the corresponding chlorides and by a modification of the procedure used by Flood3 employing the hydrolyzed polymer is reported in a recent paper.6In the present work the reaction of hydrogen fluoride on the chlorosilanes proceeded rapidly without the addition of any metallic catalyst. Neither silicon tetrafluoride nor hydrocarbons were detected in the reaction products, indicating the complete stability of the carbonsilicon bond to hydrogen fluoride at room temperature.The chlorosilanes were prepared by the usual procedure' from 'the diethyl ether solution of the appropriate Grignard reagent and silicon tetrachloride. In most cases the mixed chlorosilanes were distilled to obtain the individual chlorides. The methyl compounds, whose boiling points are too similar for convenient separation, and the phenyl compounds, whose boiling points are high, were converted before separation. In all cases the final products were purified by careful fractional distillation.Since the procedure for conversion was essen-(1) For a recent review see