Phenyldimethylcarbinol and its o-, m-and ^-monoalkvl (methyl, ethyl, isopropyl and Z-butyl) derivatives were synthesized. With one exception, these carbinols were converted readily to the corresponding tertiary chlorides by treatment with hydrogen chloride. The failure of o-Z-butylphenyldimethylcarbinol to yield the expected tertiary chloride is attributed to the large strains to be expected in this molecule, a homomorph of the unknown y-di-Z-butylbenzene. The rates of hydrolysis of the various tertiary chlorides in 90% aqueous acetone were measured at several temperatures. The small increase in rate (25°) observed in the meta alkyl derivatives ( , 1.00; m-Me, 2.00; w-Et, 1.94; m-i-Pr, 1.87; m-Z-Bu, 1.85) is attributed primarily to the inductive effect of the substituent. The minor decrease in effect with increased branching is attributed to a small hyperconjugative contribution transmitted to the ortho position of the aromatic ring and relayed to the reaction center by induction. The much larger effect of the para alkyl groups (p-Me, 26.0; p-Et, 22.0; p-i-Pr, 18.8; p-t-Bu., 14.4) is attributed to hyperconjugation stabilization of the electron deficient center by the alkyl group. From the observation that both in the meta and para positions methyl and Z-butyl groups have similar effects, it is concluded that carbon-to-carbon hyperconjugation must be nearly as important as carbon-to-hydrogen hyperconjugation. A methyl group in the ortho position (o-Me, 3.63) is far less important than a methyl group in the ^-position (p-Me, 26.0). This is attributed to steric hindrance of resonance in the transition state. With increasing bulk of the ortho substituent, the effect increases (c-Et, 2.07; o-i'-Pr, 0.847). The rate data obey the empirical relationship, log p¡ = c log (pi!mi), previously developed for the substitution reactions of toluene.
It is proposed that molecules having the same or closely similar molecular dimensions be termed "homomorphs." By consideration of the strains present in representative molecular addition compounds, an estimate is reached of the strains present in related homomorphic molecules. It is concluded that strains of 5.4 kcal./mole are present in homomorphs of di-Z-butylmethane, strains of 17 kcal./mole in homomorphs of 2,6-dimethyl-Z-butylbenzene, and strains of at least 25 kcal./mole in homomorphs of o-di-Z-butylbenzene. The strains in homomorphs of hemimellitene (1-2 kcal.) and o-Z-butyltoluene (4-6 kcal.) are somewhat smaller. In all of these cases it is possible to follow the effect of the strain upon the chemical properties of a wide variety of homomorphic derivatives. The concept of homomorphs permits a useful correlation between the chemical properties of molecules of widely different functions, but of similar sizes and shapes. o
This paper is the first of a series in which will be reported the results of an extensive study of the reactions of cyanogen with organic compounds. On the basis of its inorganic reactions cyanogen has repeatedly been compared to the halogens (1,2). Some early work even indicated that a similar comparison could be made in the field of organic chemistry. Merz (3), for example, reported that a mixture of benzene vapor and cyanogen passed through a red hot tube gave benzonitrile, terephthalic acid nitrile, and hydrogen cyanide. Desgrez (4) studied the effect of aluminum chloride and cyanogen on boiling benzene. Decomposition of the reaction products with concentrated hydrochloric acid yielded benzonitrile, benzoyl cyanide, benzil, and unidentified compounds. Vorlander (5) claimed that toluene, diphenyl, ethylbenzene, and phenetole behaved in a similar manner.However, Machek's report (6) that catechol in aqueous solution reacted with cyanogen to give a 52% yield of 2,3-dihydroxybenzonitrile did not stand up on reexamination, and Hahn and Leopold (7) concluded later that the reaction consisted of condensation between the phenolic and cyano groups and that no nuclear substitution had taken place. Even aniline, which brominates with such extreme ease, produced symmetrical N , N-diphenyloxamidine (8) instead of aminocyanobenzene.Brief investigation of alcohols, aldehydes, phenylhydrazine, semicarbazide, diphenylguanidine, and benzylamine (9) also showed that comparison with halogens was a poor premise on which to base predictions regarding cyanogen chemistry.The behavior of each of the amino compounds above could be described as an aminolysis of cyanogen. Under such circumstances the absence from the literature of reactions between cyanogen and aliphatic amines was particularly intriguing. A series of preliminary experiments, consisting in the saturation of a large number of organic liquids and solutions, was, therefore, undertaken and it was quickly indicated that reactions with primary aliphatic amines, secondary aliphatic amines, aliphatic diamines, and mercaptans could be expected once the proper conditions were discovered. The investigation of these reactions has since been actively pursued and the results of one such study are reported in this paper.
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