Absolute proton affinities of some substituted toluenes: the additivity rule of thumb for ipso attack was written by Eckert-Maksic, Mirjana;Knezevic, Andrea;Maksic, Zvonimir B.. And the article was included in Journal of Physical Organic Chemistry in 1998.Reference of 15777-70-5 This article mentions the following:
The problem of the ipso protonation of toluene and its predominantly disubstituted derivatives was considered by the MP2(fc)/6-31G**//HF/6-31G*+ZPE(HF/6-31G*) theor. model. The substituents involved covered a wide range of different donor-acceptor capabilities. It is shown that the calculated MP2 ipso proton affinities of substituted toluenes follow mutatis mutandis the same additivity rule which was found earlier to be operative in polysubstituted benzenes, naphthalenes and biphenylenes. The additivity equation is both intuitively appealing and useful, being able to offer quant. estimates of the proton affinity by very simple calculation It is based on the concept of the increment, which in turn describes the influence of a single substituent on the proton affinity. Any substituent behaves as a rule as if the other were non-existent, thus giving rise to the independent substituent approximation (ISA). The performance of the additivity rule of thumb is very good, as evidenced by the average absolute deviation of 1 kcal mol-1. Larger deviations are possible, but they rarely occur, being indicative of a difference in interactions between substituents in the initial neutral base and in the final cationic conjugate acid. Finally, it follows as a corollary of the present anal. that protonation ipso to the CH3 group is never thermodynamically the most favorable site of proton attack in the benzene ring, provided that there is a single unsubstituted carbon atom within the aromatic moiety. The relevance of ipso protonation in persubstituted benzenes is briefly discussed. In the experiment, the researchers used many compounds, for example, 4-Hydroxy-3-methylbenzonitrile (cas: 15777-70-5Reference of 15777-70-5).
4-Hydroxy-3-methylbenzonitrile (cas: 15777-70-5) belongs to alcohols. Under appropriate conditions, inorganic acids also react with alcohols to form esters. To form these esters, a wide variety of specialized reagents and conditions can be used. Converting an alcohol to an alkene requires removal of the hydroxyl group and a hydrogen atom on the neighbouring carbon atom. Dehydrations are most commonly carried out by warming the alcohol in the presence of a strong dehydrating acid, such as concentrated sulfuric acid.Reference of 15777-70-5
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