Studies of 1,2-quinone monooximes and their metal complexes
The chemistry of 1,2-quinone monooximes hi« been reviewed. The synthesis of 5-amlno, 5-alkylamino and 5-acylamino substituted 1,2-benzoquinone monooximes was systematically studied. Thus, It has been found that 5-amino-1,2-benzoquinone-2-oxime (5-AqoH), 5-ethylamino-4-methyl 1-1,2- benzoquinone-2-ox I me (5-Et-4-MeqoH), 5-hexylamino-1,2-benzoquinone-2-oxime (5-HxqoH) and 5-heptylamino-1,2-benzoquinone-2-oxime (5-HptqoH) were best prepared by the reaction of the corresponding phenol with sodium nitrite In the presence of concentrated hydrochloric acid. Under these conditions, N-nitrosation was inhibited and the 1,2-benzoquinone- 2-oxlme hydrochlorides were formed. The 5-acylaminc1,2-benzoqulnone-2- oximes, 5-propionylamino-1,2-benzoquinone-2-oxime (5-PrqoH), 5-butyrylamino-l,2-benzoquinone-2-oxime (5-BuqoH), 5-pentanoylamino-1,2-benzoquinone-2-oxime (5-PeqoH), and 5—heptanoylamino-1,2-benzoquinone-2-oxime (5-HpqoH) were obtained from their metal complexes, since the direct reaction of the phenol with sodium nitrite failed to give the compounds giving the corresponding l,4-benzoquinone-4-oximes,3- proplonylamino-1,4-benzoquinone-4-oxime (3-PrqoH), 3-butyrylamino-1,4- benzoquinone-4-oxlme (3-BuqoH), 3-pentanoylamino-1,4-benzoquinone-4- oxime (3-PeqoH) and 3-heptanoylamino-1,4-benzoquinone-4-oxime (3-HpqoH) instead. Spectroscopic analysis has shown the compounds to exist in the quinone oximic rather than In the nitrosophenollc form. X-ray crystallographic studies of 5-HxqoH, 5-Et-4-MeqoH and 5- Et-4-MeqoH.HCI have shown ail three compounds to have some 1,4-oxime- imino character. The synthesis of nlckel(ll), copper(ll), palladium(ll) and platinum(ll) complexes of the acylamino and alkylamino substituted 1.2- benzoqulnone-2- oximes both by the direct and nitrosation methods was examined. The nitrosation method gave rise to complexes NI(qo)2.nH20, Cu(qo)2.nH20 and Pd(qo)2 but failed to give the corresponding platinum complexes. The latter were only obtained by the direct method. The nickel(ll) and oopper(ll) complexes reacted with pyridine and 2,2-dlpyrldyl to give adducts of the type NI(qo)2(py)2 Cu(qo) (py) and M(qo) (dipy) respectively. The palladium and platinum complexes however failed to react with either of the Lewis bases. Magnetic moment studies showed the hydrated complexes and Lewis base adducts to be magnetically dilute and thus monomeric. Such studies, as well as IR and LSIMS mass spectral analysis of the anhydrous complexes Ni(qo) and Cu(qo) , showed them to be associated both in the solid State and in solution. The reaction of selected 1,2-quinone monooximes (qoH) and metal 1.2- quinone monooximates (M(qo)2; qoH = 1,2-nap ht hoqu I none-1-oxime (1-nqoH), 1,2-naphthoquinone-2-oxime (2-nqoH), 3-butyrylamino-1,2-benzo-quinone-2-oxime, 4-chlora-1,2-benzoquinone-2-oxlme (4-ClqoH), 4-bromo-1,2-benzoquinone-2-oxime (4-BrqoH), 5-acetylamino-1,2-benzoquinone-2-oxime (5-AcqoH), 5-hydroxy-1,2-benzoquinone-2-oxlme (5-HqoH); M = Nl and Cu) with dimethyl acetylenedicarboxylate (DMAD) was systematically examined. The reaction of 1-nqoH and 5-HqoH gave rise to nucleophile addition products cis- and trans-(0-1,2-dicarbomethoxyethenyl)-1,2-naphthoquinone-1 -oxime, trans-(0-dicarbomethoxyethenyI)-5-hydroxy-1,2-benzoquinone-2-oxime. The yields were enhanced by the presence of small amounts of alkali and alkaline earth metal chlorides. With M(1-nqo)2 and M(Buqo)2 (M = Ni, Cu) 1,4-oxazines were the only products formed. However, M(4-Clqo)2 and M(4-Brqo)2 1,4-benzoxazinones and 1,4-benzoxazines were isolated. The reaction of the structurally related 1,2-dloxlmes emd metal 1,2-dioxlmates M(dmgH)2 and M(dagH)2» (dmgH2 = dimethylglyoxime; dagH_ = 1,2-dlaminoethanedlone dIoxIme; M = NI, Cu) with DMAD was also examined. The dimethylglyoxime and its metal complexes failed to afford any adducts while the 1,2-diaminoethanedione dioxIme and its metal complexes gave nucleophilic addition products cis- and trans-bls(0-1,2-dicarboxyethenyl)-1,2-diaminoethanedione dioxime. Mechanisms for the reaction of DMAD with both the quinone monooximes and the 1,2-dioximes have been proposed.
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