Azines hydroxy

Table 11 summarizes the main results on the tautomerism of mono-hydroxy-, -mercapto-, -amino- and -methyl-azines and their benzo derivatives, in water. At first sight the equilibrium between 2-hydroxypyridine (71) and pyridin-2-one (72) is one between a benzenoid and a non-benzenoid molecule respectively (71a 72a). However, the pyridinone evidently... 

Hydroxy-pyridines (8) and -azines are both weak acids (cf. phe-... 

Although early investigators considered that 4-hydroxy-l-methyl-phthalazine existed as such in neutral solution, they refer to basicity data which, in the light of present knowledge, would lead to assignment of the l-methylphthalazin-4-one structure (84, R = Me) to the predominant tautomer. The correctness of the oxo structure for phthal-azin-l-one (84, R — H) has been demonstrated using infrared spectroscopy. ... 

Ratio of Zwittbrion Form to Hydroxy Form (pXr) fob Pyridines and Azines in Which a Benzo Ring Carries a Hydroxyl Group... 

Bromo-6-phenyl-s-tetrazine (334) gives the 3-hydroxy analog in quantitative yield after a few minutes at 95° in ethanolic potassium hydroxide or ethanolic ethoxide. As with other highly activated alkoxy-azines (cf. Section III,B,4,c and reference 582), the latter... 

However, in some cases azines can be converted to hydrazones by treatment with excess hydrazine and NaOH. Arylhydrazines, especially phenyl, p-nitrophenyl, and 2,4-dinitrophenyl, are used much more often and give the corresponding hydrazones with most aldehydes and ketones.Since these are usually solids, they make excellent derivatives and are commonly employed for this purpose. Cyclic hydrazones are also known, ° as are conjugated hydrazones. a-Hydroxy aldehydes and ketones and ot-dicarbonyl compounds give osazones, in which two adjacent carbons have carbon-nitrogen double bonds ... 

Pelizzetti et al. (1990) investigated the photocatalytic degradation of atrazine in solution in the presence of suspended titanium dioxide as a catalyst under simulated sunlight. Degradation was rapid but mineralization did not occur. Intermediate compounds included 6-hydroxy-A/-ethyl-/V -(l-methylethyl)-5 triazine-2,4-diamine, 2,4-diamino-6-chloro-A/-(l-methylethyl)-5-triazine, 2,4-di-amino-6-chloro-/V-ethyl-5-triazine, 2,4-diamino-6-chloro-5-triazine, 2,4-diamino-6-hydroxy-5-tri-azine, 2-amino-4,6-dihydroxy-5-triazine, 2-amino-4-hydroxy-6-chloro-5-triazine, 2,4-dihydroxy-6-chloro-s-triazine, 6-chloro-/V-acetyl-/V -(l-methylethyl)-5-triazine-2,4-diamine, and cyanuric acid as the final product. 

ChemicaPPhysical. In aqueous solutions, propazine is converted exclusively to hydroxylprop-azine (2-hydroxy-4,6-bisisopropylamino)-5 triazine by UV light (7, = 253.7 nm) (Pape and Zabik, 1970). In acidic aqueous soil-free systems, propazine hydrolysis is pH dependent and follows first-order kinetics. At 23.5 °C, the estimated hydrolysis half-lives at pH 2.0, 3.0, 4.0, and 5.0 were 9, 36, 141, and 550 d, respectively. The rate of hydrolysis also increased and decreased in the presence of organic matter and calcium salts, respectively (Nearpass, 1972). 

Table 11 summarizes the main results on the tautomerism of mono-hydroxy-, -mercapto-, -amino- and -methyl-azines and their benzo derivatives, in water. At first sight the equilibrium between 2-hydroxypyridine (71) and pyridin-2-one (72) is one between a benzenoid and a non-benzenoid molecule respectively (71a 72a). However, the pyridinone evidently has a continuous cyclic p- orbital system, containing six it- electrons, the usual aromatic count, if the carbonyl group contributes none. This assumption implies the formula (72b), from which by redistribution of electrons we arrive at (72c), which has the same benzenoid system as (71a). Further canonical forms (71b, 71c) can be drawn of (71) which correspond to the non-benzenoid forms of (72). The elusive property of aromaticity is therefore possessed by both tautomers, although not necessarily by both equally. When the carbonyl oxygen of (72) is replaced by less electronegative atoms, as in the imine tautomers of amino heterocycles, or the methylene tautomers of methyl derivatives, the tendency towards polarization in forms corresponding to (72b) and (72c) is considerably less, and the amino and methyl tautomers are therefore favoured in most instances. 

Azin of 2,4,6-trinitro-3-hydroxy-benzaldehyde, also called 2,4,6,2, 4, 6 -Hexanitro-3,3 -dihy-droxybenzadazin (also called Azin des 2,4,6-Trinitrobenzaldehyds in Ger). [H0C6H(N02)3CH N-] 2 mw 510.28, N 21.96%, OB -53.0% in the form of bright yellow needles that are sol in ale or 50% HAc, but insol in benz. Prepd by treating1 2,4,6-Trinitro-3-hydroxybenzaldehyde in hot aq NaOH with hydrazine sulfate Refs 1) Beil 8, [63] 2) H.H. Hodgson ... 

The pyrazole 12 and its 4,4-diethyl analog have been prepared by deoxygenation of the corresponding Af-oxides with phosphorus trichloride in chloroform.52 Treatment of the azine 30 (Ar = 4-MeC6H4, Scheme 11) with hydrogen over palladium gives, as a minor byproduct (4%), the hydroxy-pyrazole 31. A radical mechanism was proposed.16... 

Amino-7-hydroxy-a-vic-triazolo-[d]-pyrimi-dine 5-Amino- 1H- 1,2,3-tri ozolo-[d]-pyrimj-din-7-ol or 5-Amino-7-hydrox y- lH-lf2,3-tri-azolo-[d]-4,6-di azine, N=C(OH)-C—NH-N,... 

Tribenzo-l,4,7-triazacycl[3,3,3]azine ( tricycloquinazoline ) (59) has been shown to be carcinogenic for mouse skin.81 It was synthesized in a number of ways starting with anthranilic acid derivatives82,83 or with anthranil.84 Hydroxy derivatives and [,4C]tricycloquinazoline were... 

Hydrogenation of 9-benzyloxy-3,4-dihydro-l /T,8/T-pyrido[l, 2-aJpyr-azine-l,8-diones over Pd/C catalyst (10%) in MeOH gave 9-hydroxy derivatives (06WOP2006/066414). Transfer hydrogenation of 2-(4-nitrophenyl)perhydropyrido[l,2-fl]pyrazine over Pd/C catalyst with H2NNH2 H20 in EtOH yielded the respective 2-(4-aminophenyl) derivative (06JMC6351). 

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