The infra-red absorption spectra of some α-phenylhydrazono-ketones and alcohols

Antimicrobial Evaluation of Novel Metals Complexes of n- Isonicotinamido-2-hydroxy-5-methoxybenzalaldimine

“…In the entire hydrazones, the absorptions such as 1540, 1520 cm −1 have been allocated to absorption of amide-II. The NH stretching absorption in free ligands occurs at ∼3300 and 3220 cm −1 as described in the literature [39]. The other significant band occurs at ∼1585-1600 cm −1 allocated to ν(C=N) (azomethine) mode [35;39].…”

Tetronic acids and derivatives. Part XI . Structure of coupling products of tetronic acids with benzenediazonium sulfate

“…The main features of ir spectra of compounds la-c are: a weak and broad band between 3500 and 2000 cm-', a single band at 1775 cm-' (five-membered lactone), two absorptions of almost equal intensities at 1715 and 1675 cm-' and finally a broad band at 1540 cm-'. Some confusion exists in the literature about the position of the C=N-band in related acyclic systems, either at 1540 cm-' (6) or in the 1630-1670 region (7). We have verified that the absorption at 1675 cm-' cannot be attributed to an azomethine vibration, since both bands at 1715 and 1675 cm-' faded by converting compounds la-c to oximes 2 or phenylhydrazones 3 (3).…”

“…In a very recent communication, the closely related 3-parabromophenylhydrazone of L-dehydroascorbic acid 4 was shown by and 'H nmr to exist in a single configuration, presumably syn (9, accord-ing to a previous X-ray crystallographic analysis (5). This unquestionnable result sharply contrasts with those of coupling products of acyclic 3-ketoesters, usually represented as hydrogen-bonded anti tautomers 5 (6)(7)(8)(9) and with all known examples of tetronic acids bearing at C-3 an exocyclic double bond such as 3-benzylidene tetronic acids 6 (10) or 3-acyl tetronic acids 7 (1,ll) which exist in an almost equal ratio of both syn and anti tautomers. This apparent discrepancy prompted us to examine the spectral parameters of compounds 1 and we were gratified to find the first structural difference between a ;v C CH, CH, 719 tetronic and an ascorbic derivative presumably arising from the somewhat particular sugar residue at C-5 in the latter.…”

Chemistry of carbofunctionally substituted hydrazones

“…On the other hand, IR studies 140 of phenylglyoxalarylhydrazones indicate that the isomeric (Z) and (E) forms of these compounds can be easily distinguished by the position of the carbonyl as well as the NH stretching bands. Tanner 141 found that the carbonyl frequencies of both the (Z) and (E) forms of phenylglyoxal-2-nitrophenylhydrazone were almost the same (1641 and 1640 cm -1 , respectively) and that there was only a little difference in the NH stretching frequencies of these isomers (3128 and 3166, respectively). The NMR of the hydrazone NH of α-oxophenylhydrazones appears at δ 12-14 ppm.…”