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.