Naphthalene, alkyl affinities

Affinities toward other alkyl radicals have also been measured by Szwarc and his co-workers using techniques similar to those described above, It is interesting to compare the affinities of naphthalene with those of quinoline toward methyl, ethyl, and n-propyl radicals (Table X). 

Early studies of the affinity of acid dyes for wool revealed noteworthy correlations with dye structure. For example, in four pairs of monoazo dyes differing only by replacement of a benzene by a naphthalene nucleus, the affinity increase in each pair was consistently within the range -4-6 to -6.3 kj/mol. In three related pairs of dyes, an additional sulpho group reduced the affinity by about -4 kj/mol. In a series of alkylsulphuric acids (ethyl, octyl, dodecyl) and in two series of monoazo dyes containing alkyl chains of increasing length, the increment per methylene group was consistently about -1.66 kj/mol. A close correlation between affinity and Mr was also obtained for a series of substituted phenylazo-l-naphthol-4- sulphonic acid dyes [115]. 

The first reaction was found by Levy and Szwarc to be predominant when methyl radicals attacked isooctane. The second reaction is predominant, however, for aromatic hydrocarbons. The free radicals formed in the above two reactions will react with each other, with other free radicals, or with impurities. The affinity of the methyl radical to attack an aromatic increases in the following order benzene, diphenyl ether, pyridine, diphenyl, benzophenone, naphthalene, quinoline, phenanthrene, pyrene, and anthracene. The ability of free alkyl radicals to interact with isopropylbenzene and cyclohexene decreases in the following order methyl, ethyl, propyl, butyl, isopropyl, sec-butyl, and tertiary butyl. 

CyD dimers and trimers have been developed to improve the binding ability for specific applications. Although the dimer linked with a short alkyl chain 1 showed higher affinity for ditopic guest molecules like p-toluidino-6-naphthalene sulfonate... 

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