Abstract Several 1-X-sabstitirted-3-methoxy-4-trideuteromethoxybenzens were synthesized and their electron impact ionization mass spectra were measured with an ionizing energy of 20 eV. From the peak intensity ratio of [M [BOND] CD 3] and [M [BOND] CH 3] the fragmentation-directing ability of the substituent X was evaluated. The most powerful group was found to be NH 2, which expelled a methoxy methyl group only from its para position. ...
