Toluene methyl side chain

Benzaldehyde.—The aldehydes of the aromatic seiies may also be obtained by the oxidation of a methyl side-chain with chromium oxychloride. The solid brown product, C,H,.CH.)(CrO,CL)2, formed by adding C1O2CIJ to toluene, dissolved in carbon bisulphide, is decomposed with water, and benzaldehyde sepaiates out (Etard). Other methods for pie-paring aromatic aldehydes are (i) the Fiiedel-Crafts reaction, in which a mixture of carbon monoxide and hydrogen chloride aie passed into the hydrocaibon in presence of aluminium chloride and a little cuprous chloride,... 

The initiation step in the high-temperature oxidation of toluene is the pyrolytic cleavage of a hydrogen atom from the methyl side chain, and at lower temperatures it is 02 abstraction of an H from the side chain, namely... 

The H2—02 radical pool that then develops begins the reactions that cause the fuel concentration to decay. The most effective attackers of the methyl side chain of toluene are OH and H. OH does not add to the ring, but rather abstracts a H from the methyl side chain. This side-chain H is called a benzylic H. The attacking H has been found not only to abstract the benzylic H, but also to displace the methyl group to form benzene and a methyl radical [69], The reactions are then... 

Aromatic hydrocarbons which have methyl side chains mainly behave like toluene and form aldehydes, while combustion is stimulated and selective oxidation of the nucleus is repressed. The oxidation of methyl-naphthalene, for example, exhibits a low selectivity with respect to phtha-lic anhydride formation, combustion and maleic acid formation being the dominating reactions. Durene is a special case because it resembles o-xy-lene. The oxidation of durene over a V—W—O catalyst at 420° C is reported to produce pyromellitic dianhydride, phthalic and maleic anhydride, although combustion dominates (Geiman et al. [122]). 1,2,4-Trimethyl-benzene yields dimethylbenzene and trimellitic acid if oxidized on a Sn— V—O catalyst. Kinetic data have been measured by Balsubramanian and Viswanath [37]. 

The structure and numbering system for pyridine are given in Section 11.21, where we are also told that pyridine is aromatic. Oxidation of 3-methylpyridine is analogous to oxidation of toluene. The methyl side chain is oxidized to a carboxylic acid. 

Toluene undergoes catalyzed chlorination or bromination in the same manner as benzene, with equal quantities of 0- and p-chlorotoluenes being produced. When, however, the catalyst is omitted and the hydrocarbon is treated with either halogen at the reflux temperature, preferably with exposure to hght, the chlorine or bromine atoms enter the methyl side chain rather than the nucleus, with formation in succession of the mono-, di-, and trihalo derivatives. 

Benzene itself is quite toxic to humans and can cause severe liver damage toluene, although not harmless. Is much less toxic. How can such different behavior of two very similar compounds be possible To eliminate benzene from the body, the aromatic ring must be oxidized, but intermediates in this oxidation are damaging. However, the methyl side chain of toluene can be oxidized to give benzoic acid, which can be excreted. None of the intermediates in this process causes health problems. Conversely, nitro-substituted PAHs, especially of benzo[a]pyrene, are often about 1 0 times more carcinogenic than their unsubstituted analogues, and studies are currently underway to understand this effect. 

A benzylic radical is generated if a compound like toluene reacts with bromine or chlorine atoms. Hydrogen abstraction occurs from the side-chain methyl, producing a resonance-stabilized radical. The... 

The course of the reaction of methyl-substituted benzene derivatives with cesium fluoroxysulfate in acetonitrile at 35-40 C strongly depends on the structure of the molecule. Toluene (16, R1 = R2 = H) and other alkyl-substituted benzenes 16 and 17 are mainly functionalized on the side chain, while 1,3.5-trimethylbenzene (18) gives mainly ring-substituted products 24 however. 1.2.4,5-tetramethylbenzene (19) and hexamethylbenzene again give mainly or exclusively side-chain products.25... 

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