抄録
The chemical shifts of iodomethylbenzenes have not been systematically measured by PMR, as the Diehl's additive principle1) does not hold in these molecules. Here, the iodomethylbenzenes such as six monoiodoxylene isomers, iodomesitylene, 4-iodo-1, 2, 3-trimethylbenzene, 4-iodo-1, 2, 5-trimethylbenzene, three monoiodotetramethylbenzene isomers, 2, 5-diiodo-p-xylene, and 4, 5-diiodo-ο-xylene, were synthesized, and the applicability of the extended Diehl's additive principle (Reed's equation2) were taken as the samples and the chemical shifts were measured in 10% CCl4 solutions in which a small amount of TMS was added, using a HITACHI R-24 NMR spectrometer (60 MHz). The chemical shifts of iodomethylbenzenes were calculated by the Reed's equation with the same precision as in the methylbenzenes, and, it was found that the result obtained by calculation based on the additivity law does not fit well to the observed values this may suggest by the additivity law that the parameters for methyl group are not sufficiently free from the effects of the iodo group.
