ChemInform Abstract: Reaction of Pyrocatechol and Hydroquinone with Bromo‐ and Hydroxyadamantane.

Miryan, N. I.; Yurchenko, A. G.; Kirienko, E. I.

doi:10.1002/chin.199040163

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“…36 The reaction of toluene with 1 bromo adamantane afforded a mixture of the para and meta substituted products: 4 and 3 (1 adamantyl)toluenes in different contents, and no 2 (1 adamantyl)toluene (ortho substituted product) was detected even as traces. 104 No 1 (1 adamantyl)naphthalene (D) was observed in the products (A, В, C) of naphthalene alkylation by 1 ada mantanol or 1 bromoadamantane in the CCl 4 -Lewis acid (ZnCl 2 , FeCl 3 ) medium. The formation of D is prevented by the repulsion of the hydrogen atoms at the C(2) atom of the Ad + cation and at the C(8) atom of the naphthalene ring 105 (Scheme 5).…”

Section: Reactions Of Arene Alkylationmentioning

confidence: 97%

First steps of the reactions of alkanes and arenes with adamantyl cations in sulfuric acid in comparison with other reagents

Rudakov

Volkova

2008

Russ Chem Bull

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Solutions of 1 adamantanol in sulfuric acid at T < 100 °С interact with alkanes (RH, [H 2 SO 4 ] > 85%) and arenes (ArH, [H 2 SO 4 ] > 59%). The data on the kinetics, kinetic isotope effect (KIE), effects of the structure of RH and ArH and acidity of the medium, and the observation of 1,4 cis dimethylcyclohexane isomerization indicate that adamanyl cations (Ad + ) serve as reactive species. In the reactions with alkanes, the Ad + cation abstracts the hydride ion from RH in the rate determining step. Compensation dependences appear between the activa tion parameters for the KIE and "effect 5/6" (ratio of the rate constants for the С-Н bond cleavage in cyclopentane and cyclohexane) in the reactions of cycloalkanes with Ad + and other electrophilic reagents, such as "anthracene" (An 2 )H + and hydroxymethyl (CH 2 OH) + cations and Hg II ions, including the points of the lower selectivity limit (k H /k D ) = 1.4, ("5/6") = 1. In the reactions with the Ad + cation, the bond selectivity 3 0 : 2 0 of alkanes is higher, while 2 0 : 2 0 is lower compared to other reagents. In the first case, the selectivity is probably deter mined predominantly by the energies of the cleaved С-Н bonds, whereas in the second case it is determined by steric hindrances. Judging by the kinetic and selectivity data in the series benzene-toluene-o xylene-m xylene and the absence of the reaction with p xylene, mesity lene, and pseudocumene, it can be concluded that the main contribution to the Ad + + ArH interaction is made by adamantylation to the para and meta positions of the benzene ring, whereas the ortho positions are inaccessible to the attack because of steric hindrances.

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Section: Reactions Of Arene Alkylationmentioning

confidence: 97%