Chloroquinolines, methoxydechlorination

In the same series of compounds,i.e. the 4-chloroquinolines, rates of methoxydechlorination are treated in a similar manner, yielding a further set of 6-1 (epi-) and 7-1 (cata-) substituent constants, which are listed in Table VII. The necessary p-value was obtained by plotting the rate data against the pA data and using the slope of the... 

Illuminati et al. have also investigated the methoxydechlorination of 4-substituted-2- and 2-substituted-4-chloroquinolines. The relation between the reaction site, the 2- or 4-position, and the substituent in the 4- or 2-position, respectively, is always meta. The authors found the two reaction series well correlated with one another, but diverging quite seriously from the Hammett correlation. They concluded that mesomerically electron-donating substituents, because of the importance of resonance structures like 12 and 13, are more deactivating than expected, while electron-withdrawing substituents, and even the methyl group, seem to follow normal a correlation. 

Illuminati et al. have also investigated the methoxydechlorination of a series of 2-chloroquinoxahnes. Since p-values for the 2- and 4-chloroquinolines differ and since no p-values for 3-chloro compounds are available, direct calculation of bicyclic values obtained from the methoxydechlorination of the 2-chloroquinolines (cf. Table VII), which is seen to be excellently linear, with a p-value of 4.55, somewhere between the values for the 2-and 4-chloroquinoline series. From this p-value, [Pg.251]

Table 19. Relative rates in homolytic t-butylation of 3-(a)- and 4-(b)-X-substituted pjrridines, in nucleophilic methoxydechlorination of 4-(c)-X-substituted-2-chloroquinoline and amination of l-Cl-2-N02-4-(d)- and 5-(e)-X-benzenes with piperidine...

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