From Taft plots given below in figures 3 and 4, it may be assumed that the ortho-substituent effects originate from 1H-tautomer again with the deviation of NH2 group (blue square, figure ). The deviation is due to the fact that the 1H tautomer having larger dipole moment than 2H tautomer becomes more favorable for solvation by solvent water as shown in scheme 4B below. In the solvation process of 1H tautomer of 5-aminotetrazole in the formation of hydrogen bonds, both the hetero ring and the amino group are involved (scheme 4B). Also it is noteworthy to see the correlation is improved without the bulky groups like CF3, I and NO2 (figure ) is yet an additional evidence to say that position 5 of tetrazole is an orthocarbon to N1-H.