3091.     SCHMAHL, N. G.  [Hydrolysis of Carbides.]  Ztschr. Elektrochem., vol. 40, 1934, p. 68-70; Brennstoff-Chem., vol. 15, 1934, p. 154; Chem. Abs., vol. 28, 1934, p. 2288.

        It is known that in the hydrolysis of various carbides, hydrocarbons are produced.  Thus, in the decomposition of (Ca, Sr, Ba, Mg, Be) C2, of (Li, Na, K, Rb, Cs)2 C2 and Al2(C2)3 with H2O, C2H2 is formed, while with Al4C3 and Be3C, CH4 and with Mg2C3 propyne is obtained.  The reason for the formation of specific hydrocarbons is that in the decomposition at every point of the carbide lattice through oxide formation and the splitting of the lattice, determined amounts of H2 and energy are available, which are divided among the hydrocarbon atoms present.  Thus, in the decomposition of BeC2, only C2H2, and in that of Be2C only CH4 can be produced according to the equations:  BeC2+H2O=BeO+C2H2 and Be2C+2H2O=2BeO+CH4.  The relations are not quite so clear when mixtures of various hydrocarbons are produced.  With the carbides of the rare earths besides other hydrocarbons, C2H2 and CH4 are formed, in the ratio of 3:1, according to the equation:  4XC2+6H2O=2X2O3 (hydrate) +3C2H2+CH4+CH2.  The CH2 radical may form various hydrocarbons depending on the energy relations.  If the heat effect of oxide formation is strictly positive, then hydrocarbons with great energy demands (for example C2H4) are formed.  With acid decomposition of Fe carbides, not only gaseous and liquid hydrocarbons are produced but also solid hydrocarbons and carbon.  This makes the clarification of the reaction mechanism difficult.  One must assume the presence of a carbide richer in C (for example FeC2).  There is considerable known of its existence, although there is yet no sure proof of it.  The operating technique of catalysts appears to agree with the points discussed.

        SCHMERLING, L.  See abs. 1579a.