As-Triazines

The synthesis of 9H-benzo[2,l-e]thiazolo-[2,3-c]-as-triazine (401) was achieved by oxydative cyclization of 2-imino-3-(o-aminophenyl)-4-phenyl-4-thiazoline (718, 719). This latter reacts also with paraformaldehyde in hot toluene yielding 3-phenyl-9H.10H-benzo[l,2-/]thiazolo-[2,3-d][l,3,5]triazepine (402) (720). This heterocyclic sytem is also formed when carboxylic acids replace paraformaldehyde (Scheme 230) (721). 

According to systematic triazine nomenclature, 6-azauracil is 3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine (42). The indexes of the Chemical Abstracts describe it as as-triazine-3,5(2H,4H)-dione. In addition ... 

The replacement of a heterocyclic hydroxyl group (generally in the 0X0 form, Section II,E, 2,e) with thioxo or chloro groups by phosphorus pentasulfide or phosphorus oxychloride presumably proceeds through nucleophilic substitution (frequently acid-catalyzed, 21 and 86) of thiophosphoryloxy and dichlorophosphoryloxy intermediates. The 4-position in pyrimidine is more reactive than the 2-position and, at low temperature, this type of thionation of pyrimidine-2,4-diones is specific for the 4-position. In as-triazine... 

Chloro-l-methyl-2-quinoxalinone (215), which cannot anionize, reacts readUy with iV -methylaniline. 6-Bromo-as-triazine-3,5-dione (216) is largely anionized by dimethylamine but not by thiourea... 

Statements in the hterature on the reactivity of the ring-positions in monocyclic azines are conflicting. Reactivity is said to be greater at the position ortho (or alpha) than at the position para (or gamma) to an azine nitrogen 2-> 4-position in pyridine and pyrimidine and 3-> 5-position in as-triazine. By others, the... 

Sodium methyl mercaptide in xylene was reported to react (25°, 2 hr) in a stepwise fashion with 3,5-dichloro-as-triazine to yield the 3-methylthio-5-chloro and then (70°, 2 hr) the 3,5-bis-methylthio derivatives. However, the structure of the former is very likely to be 307. With dimethylamine in benzene (25°, 5 min), ethyleneimine in ether (25°, 3 min), and alcoholic ammonia (25°, few min), this dichloro derivative was assumed to form 3-amino derivatives. The high reactivity of as-triazines is demonstrated by the facile ethoxylation... 

Another nucleophilic substitution demonstrating greater reactivity at the 5-position is nucleophihc thionation (via cationized forms of polythiophosphoryloxy intermediates such as structure 126) of as-triazine-3,5-dione and of its 2-methyP and 6-methyl derivatives to form 312 in 50-100% yields. Thionation at the 3-position... 

The high level of reactivity of as-triazines is also indicated by 5-substitution of 312 with ammonia or amines (110°, 20 hr, 40-65% yield) and with hydroxylamine or hydrazine (65-80°,... 

Chloro-5,6-diphenyl-as-triazine readily undergoes methoxy-de-chlorination at 25° (< 12 hr) with methanolic methoxide and at 65° (4.5 hr) in non-basified methanol. The chloro group is also displaced by hydrazine (80°, 1 hr), ammonia (140°, 6 hr), and phenyl-magnesium bromide (70°, 12 hr), the latter forming the triphenyl compound 315.3-Chloro-6-phenyl-as-triazine is unstable to cold water or alkali and to hot alcohol or aqueous potassium carbonate. ... 

Methylthio and 3-carboxymethylthio substituents are easily hydrolyzed, the latter much more readily (cf. 136 and 237) but only in acid. A 3-sulfonic acid group (cf. 314) is readily displaced, especially in acid solution. Conversion of 3-amino-5,6-diphenyl-as-triazine into the 3-oxo analog with alkali proceeds rather easily (100°, < 4 hr), as it does with other amino-azines. 

Substituents in the 6-position (cf. 267) show appreciable reactivity. 6-Bromo-as-triazine-3,5(2j, 4j )-dione (316) undergoes 6-substitution with secondary amines or hydrazine, with mercaptide anions or thiourea (78°, 16 hr), with molten ammonium acetate (170°, 24 hr, 53% yield), and with chloride ion during phosphorous oxychloride treatment to form 3,5,6-trichloro-as-triazine. The latter was characterized as the chloro analog of 316 by treatment with methanol (20°, heat evolution) and hydrolysis (neutral or acid) to the dioxo compound. The mercapto substituent in 6-mercapto-as-triazine-3,5(2iI,4if)-dione is displaced by secondary... 

Nucleophilic substitution of as-triazines is discussed in relation to hydrogen bonding and the effects of the leaving group and of other nuclear substituents in Sections II,C,D, and E, respectively. 

The 3-amino-8-oxo derivative of 1,2,4,5,7-pentaazanaphthalene (475) is known as well as various 3-substituted derivatives of the 6,8-dioxo compound. The 3-methylthio- and 3-ethylthio-6,8-dioxo derivatives and their 7-methyl and 5,7-dimethyl analogs were prepared by ring-closure. 3-Ethylthiopyrimido[4,5-e]-as-triazine-6,8-dione was 3-substituted with alkali 2N, 100°, > 30 min) or acid 2N, 100°, < 2 hr, 70% yield) and with ammonia, aniline, piperidine, or monoalkylamines (in pyridine, 115°, 4 hr, 75-85% yield). ... 

Chemical Name Sodium salt of (6R,7R)-7-[2-(2-amino-4-thiazolyl)-2-(methoxyimino)ace-tamido] -8-oxo-3-[[(1,4,5,6-tetrahydro-4-methyl-5,6-dioxo-as-triazin-3-yl)thio] methyl] -5-thia-1 -azabicycio [4.2.0] oct-2-ane-2-carboxylic acid... 

A number of substituted triazines are used as herbicides, and their biodegradation has been discussed in Chapter 10, Part 1. Treatment of soil contaminated with atrazine (2-chloro-4-(ethylamino)-6-isopropylamino-l,3,5-triazine) illustrated a number of significant features. Although the soil that was used had the potential for degradation, a laboratory experiment with Pseudomonas sp. strain ADP that had an established potential for atrazine degradation revealed important limitations. There was a substantial decline in the numbers of Pseudomonas sp. strain ADP and only limited mineralization. Supplementation with citrate or succinate increased the survival of the strain, and successful mineralization was dependent on the preservation of a carbon/nitrogen ratio >10 (Silva et al. 2004). The last would apply generally to substrates with a low C/N ratio such as triazines. 

Kakiuehi et al. [84] studied the adsorption properties of two types of nonionic surfactants, sorbitan fatty acid esters and sucrose alkanoate, at the water-nitrobenzene interface. These surfactants lower the interfacial capacity in the range of the applied potential with no sign of desorption. On the other hand, the remarkable adsorption-desorption capacity peak analogous to the adsorption peak seen for organic molecules at the mercury-electrolyte interface can be observed in the presence of ionic surfactants, such as triazine dye ligands for proteins [85]. 

Another type of special diene, the polyaza benzene heterocyclics, such as triazines and tetrazines, is discussed in Section 6.6.2. 

Pesticide levels often exceed the requirements posed by the Ground Water Directive (2006/118/EC), thus constituting a serious threat to ground water quality. This becomes especially relevant in those cases in which groundwater are used as human supply source. Of particular concern is the fact that the commercialisation of formulations containing some of the most commonly found pesticides, such as triazines (atrazine, simazine, etc.), lindane have been aheady banned in Europe. 

Direct oxidation of condensed 1,2,3-triazines to N-oxides has not been studied in detail, and the feasibility of such methods has been rigorously established in only a single instance (see Section II, C, 2). With the exception of the 1,2,3-triazinium betaine N(l)-oxides, which are discussed separately, all the remaining known 1,2,3-triazine N-oxides, which are 3-oxides, have been prepared by diazotization of appropriate precursors. Thus, diazotization of o-aminophenylketoximes (14, R = Me,. Ph) gives the corresponding 4-substituted 1,2,3-benzotriazine 3-oxides (15) directly. " Formulation of these products as triazine N-... 

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