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Rate determining acyl halides

Kinetic studies of the acylation of imidazoles with benzoyl halides and sulfonyl halides have been carried out. In acetonitrile, benzoyl fluoride reacts with imidazole in a mixed third- and fourth-order reaction i.e., the rate-determining transition state contains the acid fluoride and two or three molecules of imidazole. With benzoyl chloride in benzene a second-order equation is followed similar to the aroylation of anilines ... [Pg.289]

A new decarboxylative route to free radicals, which has proved particularly successful in preparative work, embodies the thermal (or photochemical) decomposition reaction of 1-hy-droxypyridine-2(l/f)-thione esters 23 with tributyltin hydride, /er/-butanethiol, or a similar hydrogen donor.These esters can be easily prepared from acyl halides and the sodium salt of l-hydroxypyridine-2(l//)-thione, or from the carboxylic acid, dicyclohexylcarbodiimide and l-hydroxypyridine-2(l/f)-thione. The intermediate radicals were readily reduced to the corresponding hydrocarbons 24 in efficient chain reactions with organotin hydrides or thiols as reaction partners, and the proportion of rearranged to unrearranged products could be controlled by the choice of hydrogen donor, its concentration and the temperature. This system was sufficiently quantitative and well behaved for use in kinetic studies, and the rate constants of the (S-scission reactions of the listed cyclopropylmethyl species were determined. [Pg.2501]

The findings are supplemented by acylation and alkylation studies 3-hydroxyisothiazole is very rapidly acylated in non-polar solvents by acyl halides in the presence of tertiary bases the ratio of the products depends on the relative rates of reaction of the two tautomers rather than on their relative proportions. The size of the acyl group and the steric requirements of the catalyst are the critical factors in determining the site of acylation. ... [Pg.566]


See other pages where Rate determining acyl halides is mentioned: [Pg.181]    [Pg.18]    [Pg.110]    [Pg.392]    [Pg.392]    [Pg.439]    [Pg.439]    [Pg.522]    [Pg.330]    [Pg.100]    [Pg.439]    [Pg.228]    [Pg.267]    [Pg.30]    [Pg.16]    [Pg.2]    [Pg.172]    [Pg.155]   
See also in sourсe #XX -- [ Pg.238 ]




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