ISSN:
0941-1216
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
2,6-Dimethoxy-(4a), 2,6-bis(dimethylamino)-(4b), 2,6-dichloro- (4c) and 2,6-dimethoxycarbonyl-9,10-dihydroanthracene (4d) were prepared by conventional methods and used as hydrogen transfer donors to α-methylstyrene (5) between 290-350 °C. The mechanism followed second order kinetics and the rate constants were only slightly influenced by the solvent polarity and the type of substituents introduced. The activation parameters are also closely similar in the series with ΔS≠ values between -21 and -28 cal/mol K. These results, together with the observation of a large isotope effect (kH/kD = 1.4-2.0 at 310-350 °C), suggest that the mechanism involves a primary kinetic H-atom-transfer from the donors to α-methylstyrene (5) in the rate determining step. The compounds 4a-4d constitute a new probe for investigating polar effects on H-transfer reactions.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19983400708
