Electrophilic Aromatic Substitution. 4. A Kinetic Study of the Friedel-Crafts Benzylation Reaction in Excess Aromatic

Article abstract of DOI:10.1021/jo00195a014

Kinetic studies have been made of the titanium tetrachloride catalyzed reactions between benzyl chloride and benzene or toluene in an excess of the aromatic hydrocarbon at 30 deg C.The reaction follows first-order dependence upon benzyl chloride and is second order with respect to catalyst.The results depend strongly on the amount of moisture present.Where moisture is minimized using new vacuum line procedures, the results obtained k_T/k_B = 20 (+/-12) and isomer product distribution 41 (+/-3)percent ortho, 6 (+/-2)percent meta, and 53 (+/-3)percent para methyldiphenylmethane, are in good agreement with Brown's selectivity relationship.The reaction mechanism is discussed in terms of attack by a benzyl cation or an ion pair +Ti2Cl9^-> on the aromatic.