Organic chemistry for advanced students (Volume 2)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1918 Excerpt: ...a much lower temperature. Dehydration. Whilst metallic catalysts are chiefly effective in adding or removing hydrogen, the metallic oxides, such as anhydrous alumina, thoria, the blue oxide of tungsten (W2Os), and, as Ipatiew has shown, aluminium phosphate and silicate, possess a dehydrating action.1 At temperatures of 300 to 350 the alcohols (with the exception of methyl alcohol, which gives methyl ether) are converted into the corresponding olefines. Ethyl alcohol forms ethylene, and borneol gives menthene, &c. Two catalysts, such as copper and alumina or thoria, may thus produce essentially different reactions, for, with the metal, the alcohol loses hydrogen and yields aldehyde; but with the oxide it loses water and gives the olefine. According to Sabatier,1 both reactions are determined by a labile union of the catalyst with the compound, which differ, however, in the nature of the products. The action of a dehydrating and a reducing catalyst may sometimes be combined, so that the olefine is first formed and then converted into the saturated hydrocarbon.3 Carvomenthol has been converted in this way into menthane (Part III, p. 230). The dehydrating action of metallic oxides can also be accompanied by the addition of other groups, and Sabatier and Mailhe have succeeded in preparing primary and secondary amines by passing a mixture of alcohol and ammonia over heated thoria at temperatures 1 Ipatiew, Ber., 1901, 37, 2956; Sabatier and Mailho, Ann. Chem. Phys., 1910, 20, 341. 2 Sabatier and Murat, Cumpt. rind., 1912, 153, 385; Ipatiew, Ber., 1912, 45, 3205; Ber., 1911. 44, 2000. 3 Comp. rend., 1911, 153, 100. between 250 and 350. Thus, propyl alcohol and ammonia give a mixture of propylamine and dipropylamine, C3H7OH + NH3 = C3H,NH2 + H2O C H,OH + C3H7NH...