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2-Methylpyrazine 1,4-dioxide

Side chain reactivity is also enhanced and is typified by the difference in reactivity of 2-methylpyrazine and 2-methylpyrazine 1,4-dioxide towards anion formation and subsequent condensation reactions. 2-Methylpyrazine undergoes condensation with benzal-dehyde at 180 °C, with zinc chloride catalysis, to yield the styrylpyrazine (58), whereas the corresponding reaction of 2-methylpyrazine 1,4-dioxide proceeds at 25 °C under base catalysis (67KGS419). [Pg.173]

Forexample, good yields of 2-chloropyrazine 4-oxide,391,392 2-carbox-amidopyrazine 4-oxide,392 and 2-methylpyrazine 1,4-dioxide,391 have been obtained by oxidation of the appropriate pyrazine. In general, the preferred product from oxidation of monosubstituted pyrazines at lower temperatures is the monooxide formed by oxidation on the nitrogen remote from the substituent, whereas 1,4-dioxides are obtained by prolonged heating at higher temperatures.155 Pertrifluoro-acetic acid oxidation of 2,5-dichloro-3,6-dimethylpyrazine furnishes the di-iV-oxide, whereas permaleic acid gives only the mono-iV-oxide.393... [Pg.193]

Methylpyrazine 1,4-dioxide and 2,3-dimethylpyrazine 1,4-dioxide condense with aromatic aldehydes under mild conditions to give styryl derivatives,418 and treatment of the di-V-oxides with pyridine and iodine gives pyrazinyl methylpyridinium iodides (Scheme 48).419... [Pg.200]

Methylpyrazine 1,4-dioxide (297) gave 2-[2-(pyridin-2-yl)vinyl]pyrazine 1,4-dioxide (298) [2-pyridinecarbaldehyde, NaOH, MeOH—H20, N2, 80°C, 5 min 96%] isomers and analogues likewise.81... [Pg.124]

Methylpyrazine 1,4-dioxide with phosphoryl chloride gives a mixture of... [Pg.89]

Methylpyrazine 1,4-dioxide 2-Acetoxymethylpyrazine, 3-Acetoxymethylpyrazine 1-oxide, 2-methy ipyrazine 1-oxide 738... [Pg.91]

Methyl- and 2,3-dimethylpyrazine 1,4-dioxide when heated with pyridine and iodine undergo King s reaction from 2-methylpyrazine 1,4-dioxide the quaternary salt, 2-pyridiniomethyIpyrazine 1,4-dioxide iodide (41, R = H) was obtained, and this with p-nitrosodimethylaniline in alkaline medium gave the nitrone (42, R = H) (763). [Pg.93]

Bromination of 23-diniethylpyrazine 1,4-dioxide in dioxane in the presence of benzoyl peroxide gave 2-(bromomethyl)-3-methyl- and 2,3-bis(bromomethyl)-pyrazine 1,4-dioxide (739), and 2-methylpyrazine 1,4-dioxide gave 2-bromo-... [Pg.116]

Pyrazinecarboxylic acid has been obtained by selenious acid oxidation in pyridine of methylpyrazine or aqueous permanganate oxidation of ethylpyrazine, in yields of 64 and 48%, respectively.171,218 It has also been obtained in 70% yield by partial decarboxylation of pyrazine-2,3-dicarboxylic acid on heating in vacuo at 210°.219 Aqueous permanganate oxidation of 2,5-distyrylpyrazine gives the 2,5-dicarboxylic acid.220 Pyrazine-2,5-dicarboxylic acid has also been prepared in 45% yield by direct carboxylation of pyrazine with carbon dioxide at 50 atm pressure at 250° for 3 hours in the presence of a potassium carbonate and calcium fluoride catalyst.221 Pyrazine-tricarboxylic acid (57), obtainable in only very poor yields by oxidation of 2,5-dimethyl-3-ethylpyrazine, is prepared in 87% yield by alkaline permanganate oxidation of 2-(D-arabo)tetrahydroxybutyl-quinoxaline (56).222 Decarboxylation of the tricarboxylic acid by... [Pg.141]

Only methyl groups seem to cause little steric hindrance, and hence 2-methylpyrazine was converted by peracetic acid into a 3 2 mixture of 1- and 4-oxides (78JOC3367), the preponderance of the former arising from the +1, + M effects of methyl. The 2,6-dimethyl compound has been variously reported to form a 1 1 mixture of monoxides, with a small amount of dioxide (59JA5160), or a 1 2 mixture of 1- and 4-oxides (83JHC311). Both the 2,3-(82JHC465) (32 R = Me) and 2,5-dimethyl isomers (58JOC1603), and... [Pg.156]

Acetoxymethyl-6-methylpyrazine 2-Acetoxymethyl-5-methylpyrazine 1,4-dioxide 2-Acetoxymethyl-5-methylpyrazine 1-oxide 2-Acetoxymethyl-5-methylpyrazine 4-oxide 2- Acetoxymethyl-5-phenylpyrazine 2-Acetoxymethyl-6-phenylpyrazine... [Pg.353]

Bromo-5-methyl-2-pyrazinamine 3-Bromo-5-methyl-2-pyrazinamine 4-oxide 2-Bromo-3-methylpyrazine 2-Bromomethylpyrazine 1,4-dioxide... [Pg.378]

Guanidinopropyl)-3-isopropyl-2(l//)-pyrazinone 3,6,AA V,X-Hexamethyl-2,5-pyrazinedicarboxamide 2-Hexylamino-3,6-dimethylpyrazine 2-Hexylamino-3,6-dimethylpyrazine 4-oxide 2-Hexylaminopyrazine 2-Hexylaminopyrazine 4-oxide 2- Hexyl- 3,6-dimethylpyrazine 2- Hexyl- 5,6- dimethy lpy razi ne 2- Hexyl -3,6- dimethy lpy razi ne 1,4- dioxide 2-Hexyl-3-methoxypyrazine 2- Hexyl- 3-methylpyrazine... [Pg.425]

Other oxidations include that of methylpyrazine with selenious acid in pyridine to give 64% of 2-carboxypyrazine (669) and 2,5-dimethylpyrazine with selenium dioxide to 2,5-dicarboxypyrazine (676) a patent (677) claims oxidation of methylpyrazine with sodium dichromate and aqueous phosphoric acid in an autoclave at 225-350° to give 74% 2-carboxypyrazine. likewise, 2,5-dimethylpyrazine gives 67% 2,5-dicarboxypyrazine, and 2,6-dimethylpyrazine gives 59%... [Pg.79]

The strong base-weakening effect of an A-oxide substituent upon a para-situated sp nitrogen atom is exemplified by a comparison of the of pyrazine [0.65 (122)] with that of pyrazine A-oxide [0.05 (745)]. The pKg of 3-methylpyrazine 1-oxide is 0.46 (745). Pyrazine A-oxides form salts thus 2,5-dimethylpyrazine A-oxide forms 1 1 addition products with hydrogen chloride, methyl iodide, and benzyl chloride (625). Thermodynamic parameters for the second protonation of tetramethylpyrazine 1,4-dioxide have been determined from measurements at 25, 40,60,80, and 90° (746). [Pg.86]

Pyrazine 1-oxide and 1,4-dioxide could not be cyanated at the a-position with potassium cyanide and potassium ferricyanide in protic solvents, even at 130° (755). Attempts to nitrate 2,5-dimethylpyrazine 1,4-dioxide (625) and 3-methylpyrazine 1-oxide (626) were unsuccessful. [Pg.88]

Matsuura and co-workers (756) have reexamined the reactions of the A -oxides of 2,5-dimethylpyrazine and found that 2,5-dimethylpyrazine di-A -oxide (29) when heated with phosphoryl chloride at 160° gave 2,5-dichloro-3,6-dimethylpyrazine (6%) (30), 3-chloro-2,5-dimethylpyrazine 1-oxide (5%) (31), and 5-chloromethyl-2-methylpyrazine 1 -oxide (9%) (32). In addition small amounts of other chlorinated products, 3-chloro-2-chloromethyl-5-methylpyrazine (33) and 2,5-bischloromethyl-pyrazine (34), were identified. These authors also examined the action of p-tosyl chloride, methane sulfonyl chloride, and mixtures of phosphoryl chloride and concentrated sulfuric acid, but state that these did not give good results. Pyrazine 1-oxide and phosphoryl chloride have been shown to give 2reaction conditions it gave 2-chloropyrazine 1-oxide (757). Pyrazine 1,4-dioxide and benzenesulfonyl chloride also gave a low yield of 2-chloropyrazine 1-oxide (758). [Pg.89]

Dimethylpyrazine 1,4-dioxide 2-Acetoxymethyl-6-methylpyrazine and 2,6-dimethylpyrazine 4-oxide 760... [Pg.91]

Methylpyrazine 1-oxides react with benzaldehyde to give styrylpyrazine 1-oxides. Thus tetramethylpyrazine 1,4-dioxide, p-dimethylaminobenzaldehyde, and 37% hydrochloric acid at 140° for 15 hours gave 2,3,5,6-tetra(p-dimethyIaminostyryl)-pyrazine 1,4-dioxide (713) 2,5-dimethylpyrazine 1,4-dioxide, benzaldehyde, and sodium hydroxide gave 2,5-distyrylpyrazine 1,4-dioxide, and 2,5-dimethylpyrazine... [Pg.92]

Dichloro-3,6-dimethylpyrazine 1,4-dioxide with phosphoryl chloride at 170° gave 2,5-dichloro-3,6-bis(chloromethyl)pyrazine and 2,5-dichloro-3-chloromethyl-6-methylpyrazine 1-oxide and 2,5-dichloro-3,6-dimethylpyrazine 1-oxide gave 2,5-dichloro-3-chloromethyl-6-methylpyrazine (756). [Pg.115]

Peroxyacetic acid oxidation of 2-acetoxymethyl-5-methylpyrazine gave the 1,4-dioxide which hydrolyzed in 0.1% sulfuric acid to 2-hydroxymethyl-5-methyl-pyrazine 1,4-dioxide (625) and 2,3-di(acetoxymethyl)pyrazine 1,4-dioxide was subjected to transesterification with lower alcohols in the presence of a catalytic amount of alkali to give 2,3-di(hydroxymethyl)pyrazine 1,4-dioxide (739). [Pg.187]

Amino-3-cyano-5-methylpyrazine 1,4-dioxide (91) refluxed for several minutes with acetic anhydride formed 3-acetamido-2-cyano-5-hydroxy-6-methylpyrazine 1-oxide (92) (24%) (532) and 2-acetoxymethyl-5-methylpyrazine 1,4-dioxide refluxed with acetic anhydride afforded a mixture of2,5-di(acetoxymethyl)pyrazine 1-oxide, with some 2,5-diacetoxymethylpyrazine and a monoxide of 2-acetoxy-methyl-5-methylpyrazine (625). 2-Formylpyrazine hydrate 1,4-dioxide with aqueous sodium hydroxide or bicarbonate at < 37° in an unusual reaction gave 3-carboxy-pyrazine 1-oxide mixed with 5 [Pg.188]

Amino-3with sodium methoxide overnight has been shown to give 3-amino-2-cyano-5-methoxy-6-methylpyrazine 1-oxide (532). [Pg.190]

The Vilsmeier reaction on 2-methylpyrazine has been described in Section IV.2C(7) (717), and King s reaction on 2-methyl(and 23-dimethyl)pyrazine 1,4-dioxide has been described in Section IV.3C(7) (763). Pyrazine with A, jV-dimethyl-acetamide, ammonium peroxydisulfate, and ferrous sulfate gave 2-(A -acetyl-iV-methylaminomethyl)pyrazine (1188). [Pg.213]

Alkylpyrazines with other substituents have been oxidized to carboxylic acids as follows 2-acetamido-6-methylpyrazine was oxidized in aqueous magnesium sulfate with potassium permanganate to 2-acetamido-6aqueous potassium permanganate at room temperature to 2-carboxy-3-chloropyrazine, which was also obtained by oxidation of 2-chloro-3-methylpyrazine with selenium dioxide in boiling aqueous pyridine (947). Oxidations of 2-methoxy-3-methyl-... [Pg.250]


See other pages where 2-Methylpyrazine 1,4-dioxide is mentioned: [Pg.450]    [Pg.450]    [Pg.90]    [Pg.275]    [Pg.276]    [Pg.228]    [Pg.230]    [Pg.354]    [Pg.378]    [Pg.429]    [Pg.436]    [Pg.450]    [Pg.90]    [Pg.90]    [Pg.91]    [Pg.115]    [Pg.119]    [Pg.152]    [Pg.208]    [Pg.241]    [Pg.243]    [Pg.243]   
See also in sourсe #XX -- [ Pg.87 ]




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2-Methylpyrazine

2-Methylpyrazine 1,4-dioxide with phosphoryl chloride

Methylpyrazines

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