2- Phenyl-3 quinoxaline

Catalytic reduction of 2-acetyl-3-methylquinoxaline (29) in ethanol with 1 mole of hydrogen, gives a deep crimson solution, from which red-brown needles of 2-acetyl-l,4-dihydro-3-methylquinoxaline (30) are obtained. Ethanolic solutions of (30) reoxidize on exposure to air to 2-acetyl-3-methylquinoxaline, but the solid dye is stable in air for several days. Similar results are obtained with 2-acetyl-3-phenyl-quinoxaline (31), from the reduction of which a purple-red dye (32) is obtained. ... 

Note Both direct and indirect alkanelyses are illustrated in these examples. 2,3-Bis(p-bromophenyl)quinoxaline (91) with phenylacetylene (2 equiv) gave 2,3-bis[p-(phenylethynyl)phenyl]quinoxaline (92) (PhsP, Cul, EtsN, AcN Me2, 20°C, A, 15 min then (Ph3P)2PdCl2 i, SOX, 10 h 20%). ... 

Benzyl-3-phenylquinoxahne 1,4-dioxide afforded 2-(a-bromobenzyl)-3-phenyl-quinoxaline 1,4-dioxide (162) (Bf2, AcOEt, reflux, 4h 70%). " ... 

Methoxy-5-nitro-3-phenylquinoxaline gave only 6-methoxy-5-nitro-3-phenyl-quinoxaline 1-oxide (232) (AcOH, 30% H2O2, 80°C, 3 h 81%) 1,3-dimethyl-2(17/)-quinoxalinone 4-oxide (233) was made similarly but in only... 

Benzoxadiazole 1-oxide (462) and styrene (463 R = Ph) gave 2-phenyl-quinoxaline 1,4-dioxide (464, R = Ph) (CHCI3, reflux, >30 h 43%) 2-p-methoxyphenylquinoxaline 1,4-dioxide (464, R CfiFTtOMe-p) (58%), 2-(pyridin-4-yl)quinoxaline 1,4-dioxide (464, R pyridin-4-yl) (35%), and other such quinoxalines were made similarly.1035... 

Dimethylaminophenyl)-3,4-dihydroquinoxaline gave 2-(p-dimethylamino-phenyl)quinoxaline (tetrachlorobenzoquinone, PhH, reflux, 1 h 76%).780... 

Corresponding electron-transport materials have been made by replacing the amino substituents in the first shell by oxadiazole groups (29) [70, 61] or phenyl-quinoxalines (30) [60]. As in the case of the amines, dendrimer-shaped structures are obtained by repeating the substitution pattern in a second shell (31) [76], The Tg was increased from 142°C in 29 to 222° C in 31. 

Fig. 15. Dynamic mechanical thermal behavior of poly(imide-co-phenyl ether phenyl quinoxaline)...

Cyclodehydration of m-phenylglyoxal-2-phenylhydrazone with anhydrous AlCl3-NaCl, at 150°-160° yields some 2-phenyl-quinoxaline, together with 4-phenylcinnoline.38 The same workers prepared 2-(o-hydroxyphenyl)quinoxaline (34) from o-hydroxyphenyl-glyoxal-2-phenylhydrazone (33) under similar conditions. Quinoxaline formation is thought to proceed through a diazetine intermediate as shown.39... 

Cyclization of cr-aryl-o-nitroacetanilides 56 to quinoxaline A-oxides has been reported independently by three groups.66-68 Thus treatment with ethanolic sodium ethoxide of 56 (R=R =H R2=Ph), synthesized from o-nitroaniline and PhCH2COCl, gives l,2-dihydro-2-oxo-3-phenyl-quinoxaline 4-oxide (57 R=R =H, R =Ph). 

Peracetic acid oxidation of 2-carbamoylquinoxaline (94) at 20°-25° gives the monoxides 95 and 96, and at higher temperatures the 1,4-dioxide (97) is isolated in 50% yield, together with a small amount of the 1,4-dioxide of 2-amino-3-quinoxalinone.m However, Hayashi and co-workers report the isolation of only 96 from 94 using monoperphthalic acid in ether <10°.109 In their attempt to correlate the nature of 2-substitution with the formation of 1- versus 4-oxides, they examined the behavior of some 2-alkyl substituted quinoxalines 113,114 2-ethylquin-oxaline gives the 1- and 4-oxides and the 1,4-dioxide, 2-isopropylquin-oxaline yields the 4-oxide and the 1,4-dioxide however, 2-f-butylquin-oxaline only furnishes the 4-oxide because of steric hindrance.114 The N-oxidation of 2-phenyl- and 2-alkyl-3-phenyl-quinoxalines with monoperphthalic acid furnishes the products shown in Table 1.114... 

Quinoxaline 1-oxide (209) reacts with phenyl isocyanate to give 2-anilinoquinoxaline (210) together with 1,3-diphenyl-l-(2-quinoxalinyl)-urea (211) and cyclized oxidation product of the urea 212.215 2-Quinoxalinone 4-oxide (205) and its 1-methyl derivative undergo addition reactions, e.g., with phenyl isocyanate and benzyne to give compounds 214 and 216, respectively.216 These reactions are formulated as proceeding via the intermediate cycloadducts 213 and 215. Compound 216 has also been obtained by photolysis of 3-(o-hydroxy-phenyl)quinoxaline 1-oxide.51 1,3-Dipolar cycloaddition of quinoxaline... 

Migration accompanying the cleavage of an oxaziridine is also involved in the rearrangement in high yield of 2-benzoyl-3-phenyl-quinoxaline 1,4-dioxide (183) to the benzimidazolone (184) on photolysis in methanol.167... 

PB PBI PBMA PBO PBT(H) PBTP PC PCHMA PCTFE PDAP PDMS PE PEHD PELD PEMD PEC PEEK PEG PEI PEK PEN PEO PES PET PF PI PIB PMA PMMA PMI PMP POB POM PP PPE PPP PPPE PPQ PPS PPSU PS PSU PTFE PTMT PU PUR Poly(n.butylene) Poly(benzimidazole) Poly(n.butyl methacrylate) Poly(benzoxazole) Poly(benzthiazole) Poly(butylene glycol terephthalate) Polycarbonate Poly(cyclohexyl methacrylate) Poly(chloro-trifluoro ethylene) Poly(diallyl phthalate) Poly(dimethyl siloxane) Polyethylene High density polyethylene Low density polyethylene Medium density polyethylene Chlorinated polyethylene Poly-ether-ether ketone poly(ethylene glycol) Poly-ether-imide Poly-ether ketone Poly(ethylene-2,6-naphthalene dicarboxylate) Poly(ethylene oxide) Poly-ether sulfone Poly(ethylene terephthalate) Phenol formaldehyde resin Polyimide Polyisobutylene Poly(methyl acrylate) Poly(methyl methacrylate) Poly(methacryl imide) Poly(methylpentene) Poly(hydroxy-benzoate) Polyoxymethylene = polyacetal = polyformaldehyde Polypropylene Poly (2,6-dimethyl-l,4-phenylene ether) = Poly(phenylene oxide) Polyp araphenylene Poly(2,6-diphenyl-l,4-phenylene ether) Poly(phenyl quinoxaline) Polyphenylene sulfide, polysulfide Polyphenylene sulfone Polystyrene Polysulfone Poly(tetrafluoroethylene) Poly(tetramethylene terephthalate) Polyurethane Polyurethane rubber... 

Upon photolysis, 3-phenylquinoxalin-2(l//)-one 4-oxide rearranges to 3-(2-hydroxy-phenyl)quinoxalin-2(l )-one in 20% yield. 

Catalytic reduction of 2-acetyl-3-methyl(or 3-phenyl)quinoxaline with 5% palladium on activated charcoal in ethanol gives 2-acetyl-3-methyl(or 3-phenyl)-l,4-dihydroquinoxaline. °... 

Dipolar cycloaddition of iV-imines, derived from the mono-7V-amino salt of 2-phenyl-quinoxaline, with dimethyl acetylenedicarboxylate results in formation of a tricyclic heterocyclic ring system with bridgehead nitrogen. 

A family of acetylene-terminated phenyl quinoxalines have been synthesized by the Polymer Branch of the Materials Laboratory. ( 1) These phenyl quinoxalines are remarkable for their thermooxidative stability and resistance to moisture. These materials have potential for structural applications as adhesives or composite matrix resins.(2) The feature of moisture resistance makes the materials especially attractive for bonding aluminum. However, problems arise from the fact that aircraft aluminum alloys (and their surface oxiges) are altered by exposures to temperatures above 177 C (350 F) and this is much lower than the polymerization temperatures of the acetylene-terminated oligomers. 

Physical and mechanical characteristics have been measured and catalogued for the phenyl quinoxaline family in a related internal research project. From these data, 3,3 -Bis(4-[3-ethynyl phenoxy] phenyl)-2,2 -diphenyl-6,6 biquinoxaline (or BA-DAB-BA for short) was selected. Bis-(triphenyl phosphine) nickel II chloride was chosen as the initiator. 

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