Quinoxaline sulfones,

Six-inembered heterocyclic fused sulfones produced by annulation of dihydrothiophenes include the quinoxaline sulfone 40 derived from 3-bromo-4-oxotetrahydrothiophene dioxide and 1,2-diaminobenzene <94TI0721>. The difficulty in extrusion of SO2 from this sulfone has already been discussed. We found similar problems in attempts to generate the quinoline... 

The formation of quinoxaline quaternary salts is often difficult. However, reaction of quinoxaline with ethyl iodide in boiling acetonitrile gives ethyl quinoxalinium iodide in 76% yield, and treatment of the parent base with methyl toluene-p-sulfonate at room temperature gives methyl quinoxalinium toluene-p-sulfonate in quantitative yield. ... 

Methylthioquinoxaline (47) gave a separable mixture of 2-methylsulfinyl- (48) and 2-methylsulfonylquinoxaline (49) (NaBr02, AcOH, H2O, <20°C, 2 h 69% and 8%, respectively) or only the sulfone (49) (KMnOa, AcOH, H2O, 20°C 76%) analogs, like 2-phenylsulfinyl- (70%) and 2-phenylsulfonyl-quinoxaline (88%), were made similarly. ... 

The second class of benzo-fused heterocycles accessible from benzofuroxans are benzimidazole oxides. In this case only one carbon from the co-reactant is incorporated in the product. With primary nitroalkanes 2-substituted l-hydroxybenzimidazole-3-oxides (46) are formed via displacement of nitrite, and / -sulfones behave similarly. The nitrile group of a-cyanoacetamides is likewise eliminated to alford 2-amide derivatives (46 R = CONRjX and the corresponding esters are formed in addition to the expected quinoxaline dioxides from acetoacetate esters. Under similar conditions secondary nitroalkyl compounds afford 2,2-disubstituted 2//-benzimidazole-1,3-dioxides (47). Benzimidazoles can also result from reaction of benzofuroxans with phosphorus ylides <86T3631>, nitrones (85H(23)1625>, and diazo compounds <75TL3577>. 

The second synthetic route to PAE containing quinoxaline units involved the reaction of an aromatic dihydroxy quinoxaline or aromatic bis(hydroxy-quinoxaline) with activated aromatic difluoro compounds (Eq. (3)) [15]. The dihydroxy quinoxaline and bis(hydroxyquinoxaline) monomers were readily prepared from the condensation of 1,2-diaminobenzene with 4,4 -dihydroxyben-zil and aromatic bis(o-diamines) with 4-hydroxybenzil, respectively. The Tgs of a series of PAE containing quinoxaline units are presented in Tables 3 and 4. For these polymers, the trend for the Tg is sulfone > carbonyl > terephthaloyl-> isophthaloyl. This trend holds for most polymer families when polymers of similar molecular weights are compared. Several polyphenylquinoxalines of the same chemical structure as those in Table 3 were also prepared by the poly-... 

NBQX (6-Nitro-2,3-dioxo-1,2,3,4-tetrahydro-benzo[f]quinoxaline-7-sulfonic acid amide)... 

The preparation of quinoxaline derivatives carrying a substituent in the benzene ring requires suitably substituted o-phenylenediamines. These have been prepared by reductive cleavage (SnCl2) of appropriately substituted 2,1,3-benzoselenadiazoles (I9).21 Benzo-selenadiazoles, readily prepared from 1,2-diaminobenzenes and selenium dioxide, undergo halogenation at positions 4 and 7 and sulfonation at C-4. 5,6-Dichloro- 2,3-diphenylquinoxaline has been synthesized from benzil and l,2-diamino-3,4-dichlorobenzene, the diamine in turn was obtained from 4,5-dichloro-2,l,3-benzoselenadiazole.22... 

Sulfonation of quinoxaline-2,3-dione (58) with fuming sulfuric acid yields the 6-sulfonic acid (59).69 Similarly, if quinoxaline-2,3-dione is... 

Oxidation of 2-methyl-3-(methylthio)quinoxaline 1,4-dioxide with 1 equivalent of m-chloroperbenzoic acid yields the corresponding sulfoxide, and 2 equivalents of oxidizing agent gives the sulfone, both products being isolated in good yield. Treatment of the substituted sulfoxide- or sulfone-quinoxaline dioxides with aqueous halogen acids leads to nucleophilic displacement and the formation of 2-haloquinoxaline 1,4-dioxides.199... 

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... 

Although the most commonly used reactive systems involve the halotriazine and sulfa-toethyl sulfone (vinyl sulfone) groups, halo-genated pyrimidines, phthalazines, and quinoxalines are also available (Fig. 13.14). For all of these systems, alkali is used to facilitate dye-fiber fixation, and fixation occurs either by nucleophilic substitution or addition (Figs. 13.15-13.16). 

Figure 38 Synthesis of PAEKs incorporating various types of functional groups. Types of X groups incorporated imide, amide, sulfone, ester, azo, quinoxaline, aliphatic, fluoroaliphatic, fluoroaromatic. (From Ref. 164.)...

The quinoxaline resin was provided by F. Arnold of Materials Laboratory. The synthesis of this resin has been described elsewhere (5). The sulfone resin was synthesized by Gulf Research and Development Co. (9). This batch of resin is labelled as ATS-6. 

The decomposition by the iron(II) salt of hydroxylamine-O-sulfonic acid in the presence of formamide, alkylformamides, or A -alkylacetamides provides the amino radical cation +NH3 which, by hydrogen abstraction, generates carbamoyl and a-Wamidoalkyl radicals. Both kinds of radicals selectively attack protonated quinoxaline. 

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