Chlorine with nitro compounds

F/>110°C). Hygroscopic. May form unstable and explosive peroxides. A possible polymerization hazard. Contact with strong oxidizers may cause fire and explosions. Contact with mixture of acetic acid -t-dinitrogen trioxide may cause explosion. Incompatible with strong bases, chlorinated hydrocarbons, nitro compounds. On small fires, use foam, dry chemical, water spray, or COj extinguishers. 

Liquid-phase hydrogenation of chlorinated aromatic nitro compounds for example, conversion of />-chloronitrobenzene to />-chloroaniline in a stirred tank with a powder catalyst (Ni/Si02 or Pd on activated carbon). 

Solvents with weak hydrogen bonding (hydrocarbons, chlorinated hydrocarbons, nitro compounds, nitriles)... 

In many cases, the yields of these products are high. However, the use of /V-silylated triazoles as nucleophiles or the use of cyclic nitroso acetals (475) substituted at the C-3 atom leads to a noticeable decrease in the yield of the oximes. Therefore, steric hindrance in nitroso acetals and a decrease in nucleophilicity of A-centered nucleophiles result in an increase in the contribution of side reactions. It should be emphasized that C -nucleophiles, such as anions of nitro compounds, are not involved in coupling reactions with cyclic nitroso acetals (475). However, the products, which formally correspond to the C,C-coupling mechanism, can be prepared by the nucleophilic substitution of chlorine in compound (476 d) by a Sa/2 mechanism (Scheme 3.254, product (483c), the yield was 79%). 

The authors of primary Reference 80 present their own and selected literature values for the R—NO bond enthalpies for the hydrocarbyl cases of Me, Et, t-Bu, allyl and benzyl, as well as mixed fluorinated, chlorinated methyl radicals. We now wish to compare nitroso species with the corresponding amino and nitro compounds. Choosing what we consider the most reliable and relevant nitroso compound data, and accompanying them with the corresponding radical data, we derive enthalpies of formation of gaseous nitrosomethane, 2-methyl-2-nitrosopropane and o -nitrosotoluene81 to be 65 2, —29 4 and 174 7 kJmol-1. (By comparison, the earlier values recommended8 for nitrosomethane and 2-methyl-2-nitrosopropane were 70 and —42 kJmol-1 respectively.)... 

Chemical/Physical. Anticipated products from the reaction of 1,2-dichlorobenzene with ozone or OH radicals in the atmosphere are chlorinated phenols, ring cleavage products, and nitro compounds (Cupitt, 1980). Based on an assumed base-mediated 1% disappearance after 16 d at 85 °C and pH 9.70 (pH 11.26 at 25 °C), the hydrolysis half-life was estimated to be >900 yr (Ellington et al, 1988). 

Chemical/Physical. Anticipated products from the reaction of 1,4-dichlorobenzene with ozone or OH radicals in the atmosphere are chlorinated phenols, ring cleavage products, and nitro compounds (Cupitt, 1980). 

Some reactions of 2,2 -bipyridine /V-oxides have been reported. The l,T-dioxide is nitrated readily to 4,4 -dinitro-2,2 -bipyridine 1,T-dioxide. ° ° °" 2,2 -Bipyridine 1-oxide is also nitrated in the 4 position. The nitro groups in 4,4 -dinitro-2,2 -bipyridine l,T-dioxide are reactive, being replaced by chlorine with concentrated hydrochloric acid," by bromine with acetyl bromide, by hydroxyl with dilute sulfuric acid, and by alkoxy groups with sodium alkoxides. Some of the dialkoxy derivatives are useful catalysts for the oxidation of aromatic compounds. The dinitro dioxide is deoxygenated to 4,4 -dinitro-2,2 -bipyridine with phosphorus trichloride in chloroform, and other substituted l,T-dioxides behave similarly, but with phosphorus trichloride alone, 4,4 -dichloro-2,2 -bipyridine results. The dinitro dioxide is reduced by iron powder in acetic acid to 4,4 -diamino-2,2 -bipyridine, whereas 4,4 -dichloro-2,2 -bipyridine l,T-dioxide is converted to its 4,4 -diamino analogs with amines. Related reactions have been described. ... 

Several reactive chloro compounds have been used to attempt to effect the controlled monochlorination of aromatic amines. One such reagent is N-chlorosuccinimide, with which the chlorination of aniline, for example, can be largely restricted to monosubstitution, although a mixture of isomers (orthopara, 1.9 1) is obtained.24 One approach to the achievement of specific ortho chlorination is illustrated by the synthesis of o-chlorobenzanilide (Expt 6.61), readily hydrolysable to o-chloroaniline. The anilide is formed, by a type of Swi mechanism indicated below, when AT-phenylhydroxylamine is benzoylated and the product is treated with thionyl chloride.25 The reaction has been successfully applied to several substituted JV-phenylhydroxylamines, prepared by the controlled reduction of the corresponding substituted nitro compounds (cf. Expt 6.87). 

Some of the sensitizing (and cytotoxic) effects of the nitro compounds can be attributed to GSH depletion. Activated chlorine maybe replaced by GS" [reaction (89) Wardman 1982 Stratford et al. 1983)], but the reaction is much more general. For example, the 2-nitroimidazoles react with GS by N02 release. These reactions are slow, but are considerably speeded up by glutathione-S-transferase (Wardman et al. 1973). 

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