Nitrotoluenes, chlorination

Dichlorobenzyl chloride (l,2-dichloro-4-chloromethylbenzene) containing some 2,3-dichlorobenzyl chloride is produced by the chloromethylation of o-dichlorobenzene ia oleum solution (73). Chlorination of 2-chloro-6-nitrotoluene at 160—185°C gives a mixture of 2,6-disubstituted benzal chloride and 2,6-dichlorobenzyl chloride (74). 

Toxic compounds are frequently rendered less toxic by electrochemical treatment, for instance dehalogenation of chlorinated derivatives such as PCBs or AOX (performed in a divided cell or in the absence of Cl ions in a monocell) odors are eliminated or greatly reduced, i.e. reduction of nitrotoluene which can be a serious odor nuisance biodegradability is improved. Elimination of colloids and surfactants is possible. 

Other high-boiling solvents such as nitrobenzene and 2-nitrotoluene can also be used in the solvent process, but 4-nitrobiphenyl, a listed carcinogen, is produced when nitrobenzene is employed. One way to avoid the formation of substituted biphenyls is to employ a polysubstituted toluene as solvent, the substituents being chlorine or alkyl groups, mainly propyl. These are difficult to prepare but they have been patented by Toyo Inks. 

Side-chain halogenation is illustrated also by the bromination of p-nitrotoluene (Expt 6.28). The radical mechanism with molecular bromine is similar to that of chlorination above N-bromosuccinimide has also found use as a side-chain brominating reagent and its application is described in Expts 6.119 and 6.152. 

Chlorination.1 C120 is particularly useful for side-chain chlorination of deactivated aromatic substrates by a free-radical process involving CIO . Although it cun be used to convert methylarenes to mono- and dichloromethyl derivatives, it is particularly useful for conversion to trichloromethylarenes. Thus it converts p-nitrotoluene into p-nitrobenzotrichloride in 99.8% yield. It is also useful for selective replacement of benzylic hydrogens. 

Peng et a/.[45] reported the nitration of toluene with liquid nitrogen dioxide and oxygen in the presence of a variety of zeolites, and using toluene as reactant and solvent. The reactions were performed at room temperature over 22 h. In the absence of catalyst the reaction was highly unselective giving a mixture of MNTs, dinitrotoluenes, phenylnitromethane and benzaldehyde. In the presence of zeolites, HZSM-5 and HBeta, the selectivity to the p-nitrotoluene was enhanced. In contrast with the results reported by Smith et a/.,[14] HZSM-5 zeolite exhibited better selectivity than Beta zeolite (57 % and 46 %, respectively), which can be attributed to the absence of mediation of the chlorinated solvent molecules, as well as to the higher Si/Al of the HZSM-5 sample (Si/Al =1000). It was found that zeolites... 

Nitrotoluenes and other substituted toluenes are not sufficiently acidic to be chlorinated by CC14 in basic environment, but partially a-chlorinated methylbenzenes do react to yield substituted benzotrichlorides (equation 74)622. 

Analogous Sulfonations. Exactly the same method can be used for sulfonating p-nitrochlorobenzene, p-nitrotoluene, o-m trochlorobenzene, chlorobenzene, and many other compounds. On the other hand, it is usually not possible to sulfonate dinitaro compounds in this way. Dinitrochlorobenzene and dinitrotoluene are decomposed explosively by treatment with fuming sulfuric acid. If dinitrochloro-benzenesulfoitic acid is to be prepared, for example, one starts with p-nitrochloro-benzene/ This is sulfonated, as described previously, and the sulfonic acid is converted to dinitrochlorobenzenesulfonic acid by treatment with mixed acid (50 50 sulfuric and nitric acids) at low temperatures. This product yields, on replacement of the chlorine by —OH and partial reduction, 4-nitro-2-aminophenol-6-sulfonic acid (nitro acid III), which is used in preparing chrome dyes. 

Chlorination of o-nitrotoluene gives about two-thirds of the 2,6 isomer and one-third of the 2,4-nitrochlorotoluene. 2,4-Dichlorobenzaldehyde, obtained from the latter isomer, yields no valuable dyes, and it is desirable, therefore, to separate the isomeric nitrochlorotoluenes. The separation can be accomplished by careful fractional distillation under reduced pressure. 

Chloronitrotoluene and 2,6-chlorotoluidine are technically important in other respects also. The former compound is the starting material for the prepara-oitn of 4,4 -dichloroindigo, which yields, on further chlorination or bromination, the very greenish 4,5,4, 5 -tetrahalogenindigos (e.g., brilliant indigo 4G). 2,6-Chloro-toluidine, as fast scarlet TR base, is used in generating ice colors (naphthol AS). The isomeric 4-chloro-2-toluidine (fast red KB base), prepared by reduction of the by-product 4-chloro-2-nitrotoluene, is used for the same purpose. 

Of the difiFerent isomers which might be formed, according to the above rules, by further substitution into disubstituted derivatives, the unsymmetrical (1,2,4) derivatives are strongly favored. Symmetrical (1,3,5) trisubstitution products are formed only with diflSculty, and vicinal (1,2,3) derivatives are generally formed only as by-products in insignificant amounts. (The chlorination of o-nitrotoluene is an exception, see page 160.)... 

Ortho-nitrobenzyl chloride was prepared in 1883 by Abelli, together with the meta-compound, by the reaction of concentrated nitric acid on benzyl chloride. It may also be obtained, according to Haussermann and Beek, by the action of chlorine at 130° to 140° C. on a mixture of 2 parts of o-nitrotoluene and i part sulphur. 

Reductive oxidation of />-nitrotoluene to -aminobenzaldehyde, 31, 6 Reformatsky reaction, 37, 38 Reissert s compound, 38, 58 Reissert reaction, 38, 58 Replacement, benzenesulfonate groups by bromine atoms, 31, 82 bromine, by a thiol group, 30, 35 by fluorine, 36, 40 chlorine, by an amino group, 31,45 by a thiol group, 32, 101 by iodine, 30, 11 by methoxyl, 32, 79 by nitrile, 36, 50 in an imido-chloride group by an anilino group, 31, 48 chlorine and nitro by ethoxyl radicals, 32,68... 

Air oxidation of a variety of aliphatic and alkyl aromatic compounda air oxidation of p-nitrotoluene sulfuric acid substitution chlorination of a variety of organic compounds reaction between isobutylene and acetic acid oxidation of ethylene to acetaldehyde (Wacker processes) hydrochlorination of olehns absorption of phosphine in an aqueous soluhon of formaldehyde and hydrochloric acid acehc acid from the carbonylation of methanol oxidation of tri-alkyl phosphine dimerization of olefins. 

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