Лако-красочные материалы — производство

NMR spectroscopy is commonly used for the identification of isomeric tetrazolium salts. There are significant differences in the chemical shifts of C-methyl and ^-methyl protons as shown in Table 4 for compounds 128

CH3 СНзСОСН^® ^CH3 N N I I N-=-N (128)

Compound О ffi N-CH3 C-CH3 128 6.00 4.44 2.92 129 6.12 4.37 2.86

Table 5. ‘H-NMR Chemical Shifts (5) of Methyl-Substituted Tetrazoliums 130-135 Compound 1-CH3 3-CH3 4-CH3 5-CH3 130 4.31 4.58 — — 131 4.33 — 4.60 — 132 — — 4.35 — 133 — — 4.72 — 134 — — 4.30 2.90 135 — 4.62 — 2.78

Table 7. ‘H-NMR Chemical Shifts (5) of N-Phenyl Tetrazoliums 138 and 139

(141)

and 129,187 Table 5 for 130—135,219 and in Table 6 for 136 and 137.180-215 The 5-ring proton chemical shifts in 5-unsubstituted tetrazolium as well as the ortho proton in phenyl substituents at the 5-position are sensitive to N-substituents and substitution patterns as shown in Table 7 for 138 and 139 and in Table 8 for 140 and 141.181-218

Carbon-13 NMR has been used in the study of thiolate and disub — stituted tetrazolium derivatives.217-219 The chemical shifts of both the substituent and ring carbons show strong sensitivity to substitutents as shown in Table 9 for 130—135.219 Tetrazolium salts have also been studied by nitrogen-15 NMR (Table 10).220’221