Volume 2

Organic chemistry for advanced students / by Julius B. Cohen.

  • Julius B. Cohen
Date:
1907-1913
Catalogue details

Licence: Public Domain Mark

Credit: Organic chemistry for advanced students / by Julius B. Cohen. Source: Wellcome Collection.

    22/448 (page 12)
    nitriles and hydrogen cyanide do not. When hydrogen cyanide is heated it polymerises; but there is no evidence that it undergoes isomeric change ; nitriles, on the other hand, yield isocyanides. The polymeride obtained from hydrogen cyanide forms glycosine on hydrolysis and is therefore aminomalonitrile, NH2.CH(CN)2, indicat¬ ing thereby that the nitrile rather than the isocyanide has undergone polymerisation.1 There are a large number of chemical facts which point in the same direction, such as the preparation of hydrogen cyanide from formamide 2 and formoxime3 by dehydration, a reaction which corresponds to nitrile formation. Its additive compounds with metallic chlorides4 resemble those of the nitriles and its stability towards ethylhypochlorite and chlorine is in marked contrast to the alkyl isocyanides5 (p. 8). Its union with diazomethane to form acetonitrile6 has been discounted as a fact in favour of the nitrile structure since the discovery that isocyanide is also formed.7 Many of the physical constants also indicate a nitrile structure ; its refractivity,8 its high dielectric constant and ionising power correspond to those of the lower nitriles.9 Michael and Hibbert10 take the same view and regard the true hypothetical acid as having the isocyanide structure, but from the absence of salt formation when pure hydrogen cyanide is added to trialkylamines (though the cyanides of these substances can be formed in other ways) they conclude that the actual compound is formonitrile. It is true that the primary and secondary amines do yield unstable salts, but it is contended that the union is accompanied by isomeric change, a form of argument which has an air of special pleading. On the other hand Chattaway and Wadmore11 adopt the isocyanide formula on account of the ease with which hydrogen is exchanged for halogen in hydrogen cyanide and its salts. C : NH, C : NCI, C : NK Cyanogen chloride has the characteristic properties of a nitrogen chloride and consequently the isocyanide formula for hydrogen cyanide explains most satisfactorily its whole chemical behaviour. The weak character of the free acid compared with the effect of 1 Lescoeur and Rigaut, Compt. rend., 1879, 89, 810. 2 Hofmann, Trans. Chem. Soc., 1863, 16, 74. * 8 Dunstan and Bossi, Trans. Chem. Soc., 1898, 73, 360. 4 Klein, Annalen, 1850, 74, 86. 6 Nef, Annalen, 1895, 287, 274. 6 V. Pechmann, Ber., 1895, 28, 857. 7 Peratoner and Palazzo, Atti R. Accad. Lincei, 1907, 10, 432. 8 Briihl, Zeit. physik. Chem., 1895, 10, 512. 9 Schlundt, Zeit. physik. Chem., 1901, 5, 157. 10 Annalen, 1909, 384, 64. 11 Trans. Chem. Soc., 1902, 81, 192.