Oxidative halogen moieties

Antimony trioxide (SbaOj). It is produced from stibnite (antimony sulphide). Some typical properties are density 5.2-5.67 g/cm- pH of water suspension 2-6.5 particle size 0.2-3 p,m specific surface area 2-13 m-/g. Antimony trioxide has been the oxide universally employed as flame retardant, but recently antimony pentoxide (SbaOs) has also been used. Antimony oxides require the presence of a halogen compound to exert their fire-retardant effect. The flame-retarding action is produced in the vapour phase above the burning surface. The halogen and the antimony oxide in a vapour phase (above 315 C) react to form halides and oxyhalides which act as extinguishing moieties. Combination with zinc borate, zinc stannate and ammonium octamolybdate enhances the flame-retarding properties of antimony trioxide. 

The known chemistry of the bisftrifluoromethyOnitroxyl [3i, 34] includes additions to both olefins [75, 36 37] and fluoroolefins [iaddition products with chlorotnfluoroethene or tetrafluoroethene [39] The nitroso denvative, (Cp3)3NONO, reacts with a liimted set of halogenated olefins to add the (CF3)2NO and NO moieties [40]... 

The effect of a substituent may be substantially modified by fast, concurrent, reversible addition of the nucleophile to an electrophilic center in the substituent. Ortho- and para-CS.0 and pam-CN groups have been found by Miller and co-workers to have a much reduced activating effect on the displacement of halogen in 2-nitrohaloben-zenes with methoxide ion [reversible formation of hemiacetal (143) and imido ester anions (144)] than with azide ion (less interaction) or thiocyanate (little, if any, interaction). Formation of 0-acyl derivatives of 0x0 derivatives or of A-oxides, hydrogen bonding to these moieties, and ionization of substituents are other examples of reversible and often relatively complete modifications under reaction conditions. If the interaction is irreversible, such as hydrolysis of a... 

In /r-bridged dimers, two phthalocyanine moieties are linked by one or more bridging atoms such as oxygen or halogens. Niobium(V) oxide tribromide (NbOBr,) when treated with phthalonitrile in 1-chloronaphthalene at 230CC for 3 hours produces /r-bromo-/t-dioxobis[nio-bium(V) phthalocyanine] tribromide in 52%.232... 

Nucleophilic halogenations tend to favor the pyridine moiety. The Meisenheimer reaction of thieno[3,2-6]pyridine N-oxide (125) gave only a 24% yield of a 1.4 1 mixture of the 5- and 7-chloro derivatives. Nucleophilic displacement of a 7-nitro group provided a more satisfactory route to the 7-chloro (73%) and 7-bromo (39%) derivatives (85JHC1249). 

Dibromo-l,4-xylene or its 2,5-dichloro derivative is obtained by bromination or, correspondingly, chlorination of 1,4-xylene. It is oxidized to form 2,5-dibro-moterephthalic acid or its dichloro derivative 59. Subsequent reaction with aryl-amine, for instance in the presence of copper acetate, affords 2,5-diarylamino-terephthalic acid 60. It is also possible to replace the halogen atoms stepwise by arylamino moieties [11]. Cyclization to form linear trans-quinacridones, as in the above-mentioned method, is achieved by using acidic condensation agents ... 

Studies of Equilibria and Shift Reagents.—N.m.r. studies of the exchange of halogen in boron trihalide adducts of trimethylphosphine, its oxide, and sulphide,49 and exchange of chloro- and methoxy-groups between methylphosphino and methyl-silyl or -germyl moieties,80 have been reported. The rates of ionization of phosphoranes... 

Accordingly, many reactions can be performed on the sidewalls of the CNTs, such as halogenation, hydrogenation, radical, electrophilic and nucleophilic additions, and so on [25, 37, 39, 42-44]. Exhaustively explored examples are the nitrene cycloaddition, the 1,3-dipolar cycloaddition reaction (with azomethinylides), radical additions using diazonium salts or radical addition of aromatic/phenyl primary amines. The aryl diazonium reduction can be performed by electrochemical means by forming a phenyl radical (by the extrusion of N2) that couples to a double bond [44]. Similarly, electrochemical oxidation of aromatic or aliphatic primary amines yields an amine radical that can be added to the double bond on the carbon surface. The direct covalent attachment of functional moieties to the sidewalls strongly enhances the solubility of the nanotubes in solvents and can also be tailored for different... 

The oxidative degradations of binuclear azaarenes (quinoline, isoquinoline, and benzodrazines) by hydroxyl and sulfate radicals and halogen radicals have been studied under both photochemical and dark-reaction conditions. A shift from oxidation of the benzene moiety to the pyridine moiety was observed in the quinoline and isoquinoline systems upon changing the reaction from the dark to photochemical conditions. The results were interpreted using frontier-orbital calculations. The reaction of OH with the dye 3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-(l,8)(2//,5//)-acridinedione has been studied, and the transient absorption bands assigned in neutral solution.The redox potential (and also the pA a of the transient species) was determined. Hydroxyl radicals have been found to react with thioanisole via both electron transfer to give radical cations (73%) and OH-adduct formation (23%). The bimolec-ular rate constant was determined (3.5 x lO lmoU s ). " ... 

Organotellurium tri- and dihaUdes undergo a-elimination by oxidative, photolytic or thermal routes, giving the corresponding halides with a selective transference of the halogen at the position where the tellurium moiety was originally attached (/pxo-substitution). 

Synthesis was directed towards metabolic stability and this was found in the bis-triazole series of compounds. Metabolic stability is achieved by the relative resistance of the triazole moiety to oxidative attack, the presence of halogen functions on the phenyl grouping, another site of possible oxidative attack, and steric hindrance of the hydroxy function, a site for possible conjugation. 

A textured metallocene polyethylene foam sheet suitable for use in a floor covering is made using a highly coactivated azodicarbonamide package which blows the metallocene polyethylene effectively. The preferred coactivators are zinc oxide and urea. The textured surface of metallocene polyethylene foam is formed by a chemical embossing process which utilises a liquid triazole having an alkyl moiety as a foam-expansion inhibitor. The triazole is dissolved in a non-polar solvent to form the foam inhibitor. The preferred inhibitor is a hydrocarbon which may be halogenated. 

Solubilized lignin solutions are easily oxidized and the presence of the aromatic units containing electron-withdrawing ether and alcohol moieties makes it available for electrophilic substitution reactions, such as nitration, halogenation, hydroxylation, etc. 

In order to activate the 21 position to halogenation, it is hrst converted to an oxalate. Condensation of the triketone with ethyl oxalate in the presence of alkoxide proceeds preferentially at the 21 position to give (12-2) due to the well-known enhanced reactivity of methyl ketones. Reaction of the crude sodium enolate with bromine leads to the dibromide (12-3), the oxalate moiety being cleaved under the reaction conditions. The Favorskii rearrangement is then used to, in effect, oxidize the 17 position so as to provide a site for the future hydroxyl group. Thus, treatment of (12-3) with an excess of sodium methoxide hrst provides an anion at the 17 position (12-4). This then cyclizes to the transient cyclopropanone (12-5)... 

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