Bamford and Stevens. 4735 924. T h e Decomposition of Toluene-p-sulphonylhydrazones by Alkali.

High molecuiar-weight poly(dimethylsilmethy1enes) have been prepared by the catalytic polymerisation of 1 ,I ,3,3-tetramethyl-I ,3-drsilacyclobutane ; di-p-chloro-dichlorobis(alkene)diplatinum( I I ) compounds proved to be the most reactive of several catalyst systems studied. The molecular weight of the polymer could be controlled by the addition of small amoumts of alkyl silicon hydrides or carbon tetrabromide, and ihe polysilmethylenes then contained Si-H or Si-Br groups. Poly(dimethylsilme.thylene) gums were converted into a new type of rubber.THE unusual reactivity of silacyclobutaiies and 1,3-disilacyzhbutanes, attributed to the strain energy of the compressed ring systems, has been the subject of several recent Communications.l Disilacyclobutanes polynierise on htating at above 200" or on prolonged reaction with potassium hydroxide,2 but generally the polymers so obtained are of relatively low molecular weight, e.g., 15,00@ after heating at 304)" for 14 hours under pressure., We yenberg and Nelson have recently reported that platinum on charcoal or chloroplatinic acid bring about polymerisation of these monomers at 1100".Independently we have found that many materials function as catalysts for the polymerisation of compounds of type (I), the most effective being alkene platinum chlorides such as di-p-chloro-dichlorobis(cyc1ohexerae)diplatinum(iI), (C,H,,),Pt,Cl,, which causes vigorous polvnierisations at temperatures between 20 and 60". However, the range of catalysts (Table 1) TABLE 1 Relative efficiencies of catalysts in polymerisation of 1,1,3,3-tetraniethyl-l,3-disilacyclobutane Poly,iiet.isa?io>l complete within 5 mi%.

showed that aliphatic diazocompounds do not combine with tertiary amines as they do with phosphines; diphenyldiazomethane when heated with triethylamine undergoes the same decomposition to benzophenone azine as when heated in other solvents. If the first product of decomposition of the diazo-compound is the uncharged diphenylmethylene radical Ph&, it is conceivable that this will co-ordinate, reversibly, with the amine, giving Ph,C-NEt,, although in the end its fate is to combine with unchanged diazo-compound, yielding the azine. A case might then be found in which the dipolar ion would be stable or would undergo irreversible change to a significant product. We failed to effect the combination of diazofluorene with fluorenone methylimine to give the specially stabilised compound (I) ; -+ c but diazofluorene and benzyldimethylamine afforded a considerable amount of 9-benzyl-9dimethylaminofluorene (11). Wittig and Felletschin (Annalen, 1944, 555, 133) obtained the same compound from (111) via the unstable (IV).

Good yields of er-chloroalkylsilanes have been obtained by the addition of n-butyl-lithium to a mixture of a chlorosilane and certain chloroalkanes in tetrahydrofuran at -1 20". It is proposed that the products are formed essentially by an in situ reaction of chloroalkyl-lithium derivatives with the chlorosilane. The reaction has been used to prepare compounds containing Si.CCI,*Si linkages. Ethylmagnesium bromide behaves in a similar way to n-butyllithium in some cases, but gives much lower yields of the a-chloroalkylsilane.WHEN mixtures of a chlorosilane with certain chloroalkanes are treated with an organolithium reagent at about -120", good yields of a-chloroalkylsilanes are obtained. Thus a mixture of chlorotrimethylsilane (I) and 1 ,l-dichloroethane in tetrahydrofuran gives a 59% yield of 1,l-dichloroethyltrimethylsilane when treated with an equivalent amount of n-butyl-lithium in nhexane.

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