The Reaction of Some Aromatic and Related Hydroaromatic Compounds with Chlorine Acetate in Acetic Acid.

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Elnadi,Abdelrahman Hassan
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University of Khartoum
Rates, relative rates, isomer distribution, and partial rate factors for the chlorination reaction of some alkyl benzenes and related hydro aromatic) compounds by chlorine acetate in three different compositions of aqueous acetic acid in presence and. absence of perchloric acid, as a catalyst have been determined Neutral and positively charged species, of the type: C1OAC ,HOC1, C l OACH, H2OCl and C l are believed to be involved Some linear free energy relationships have been tested, and for alkyl benzenes the agreement observed and calculated partial rate factors in reactions involving different species (neutral and positively charged species) is considered to be good, thus providing some measure of independence of the requirements of the additively principle from the nature of the reagents involved in the substitution process. Comparison of the logarithm of partial rate factors for the 3-and 4- positions in ortho -xylene with the corresponding values for the 2-and 4- positions in toluene indicates the absence of steric hindrance to substitution ortho to a methyl group under the reaction conditions employed Reactivity of an orientation in the hydro aromatic compounds investigated (i.e. indane, tetrahydronaphthalene and 9, 10-dihydroanthracene) have been discussed in the light of the theories recently advanced to account for the Nills Nixon effect. Those theories require regular fall inα- aryl reactivity with increasing strain on the partially hydrogenated ring attached to the aromatic nucleus. Our results confirm the previous findings. In addition to ring-strain the reactivity of 9, 10-dihy droanthracene has been discussed in terms of activation of aryl α - and aryl-β-positions by the benzyl group as required by the activation parameters in the diphenylmethane system. This treatment, although approximate, lends support to the theoretical finding based on the ring-strain effect.
211 Pages
Reaction;Aromatic; Hydroaromatic;Compounds;Chlorine Acetate;Acetic Acid