Toluene chlorine derivatives

The ring-chlorinated derivatives of toluene form a group of stable, industrially important compounds. Many chlorotoluene isomers can be prepared by direct chlorination. Other chlorotoluenes are prepared by indirect routes involving the replacement of amino, hydroxyl, chlorosulfonyl, and nitro groups by chlorine and the use of substituents, such as nitro, amino, and sulfonic acid, to orient substitution followed by their removal from the ring. 

Ring-Substituted Derivatives The ring-chlorinated derivatives of benzyl chloride, benzal chloride, and benzotrichloride are produced by the direct side-chain chlorination of the corresponding chlorinated toluenes or by one of several indirect routes if the required chlorotoluene is not readily available. Physical constants of the main ring-chlorinated derivatives of benzyl chloride, benzal chloride, and benzotrichloride are given in Table 4. 

When the two groups in disubstituted benzenes are different, the same three isomers are possible that are possible when the substituents are the same. Compounds with two different substituents are usually named as positional derivatives of a monosubstituted (parent) compound. Above, the common (and commercial) name for methylbenzene is toluene, and the chlorinated derivatives are named as shown above. However, the same two chlorinated derivatives can also be properly named 2-chloromethylbenzene and 4-chloromethylbenzene. In this case, for naming, the parent compound is methylbenzene and it is understood that the methyl group is in the 1-position. The terms ortho- (1,2-), meta- (1,3-), and para- (1,4-) are also sometimes used for example, 2-chlorotoluene can be called ortho-c Aoioio -uene. This can be very confusing, but in the chemical industry, outside of the research labs, the common names for the parent compounds are almost always used. 

In some cases this reaction takes place with water alone but usually some other substance is present e.g., calcium hydroxide or carbonate, potassium hydroxide, metallic iron or iron salts which actsasacatalizer. The mono-chlorine derivative of toluene and other benzene homologues may also be used for preparing the aldehydes. In this case the reaction is in two steps, first, reaction with water yielding the alcohol, and second. 

Brominations are, in most cases, carried out by methods similar to those for the preparation of chlorine derivatives. Sampey (127) gives a history of the photobromination of benzene and toluene. Davis (123) made a thorough examination of the relative rates of bromination of the olefins, concentrating particularly on ethylene. An unusual method for producing bromine compounds is by the use of bromosuccinimide or related compounds. This method is called the Wohl-Ziegler reaction and causes allylic bromination. It has been the subject of a couple of reviews (124,1 0). 

The foUowing activity coefficients and interaction parameters determined by GLC for solute-statistical copolymers may be found in the literature (a) forty three non-polar and polar solutes on ethylene-vinyl acetate copolymer with 29% weight of vinyl acetate at 150.6 and 160.5°C [105] chloroform, carbon tetrachloride, butyl alcohol, butyl chloride, cyclohexanol, cyclohexane, phenol, chlorobenzene and pentanone-2 on the same copolymer with 18% weight vinyl acetate at 135°0 [102], normal xdkanes (C5, Oj, Og, Ojo), oct-l-ene, chlorinated derivatives, n-butanol, toluene, benzene, methyl-propyl-ketone and n-butyl-cyclohexane on the copolymer mentioned with 40% weight vinyl acetate at 65, 75 and 85°0 [68, 106] (b) n-nonane, benzene, chloroform, methyl-ethyl-ketone and ethanol in methyl methacrylate-butyl methacrylate copolymer with 10% butyl methacrylate [32] (c) hydrocarbons in styrene-alkyl methacrylates copolymers at 140°C [101] (d) the solutes in (b) on butadiene-acrylonitrile copolymer with 34% weight acrylonitrile [68]. 

As solvents, aromatic hydrocarbons (benzene, toluene), and chlorinated derivatives of aliphatic or aromatic hydrocarbons can be used. Reference 3 includes some technological details and the factors that influence the development of the synthesis process. 

Methylphenol. y -Cresol is produced synthetically from toluene. Toluene is chlorinated and the resulting chlorotoluene is hydrolyzed to a mixture of methylphenols. Purification by distillation gives a mixture of 3-methylphenol and 4-methylphenol since they have nearly identical boiling points. Reaction of this mixture with isobutylene under acid catalysis forms 2,6-di-/ f2 -butyl-4-methylphenol and 2,4-di-/ f2 -butyl-5-methylphenol, which can then be separated by fractional distillation and debutylated to give the corresponding 3- and 4-methylphenols. A mixture of 3- and 4-methylphenols is also derived from petroleum cmde and coal tars. 

Of greater versatility is an extension of Albert and Royer s acridine synthesis. The first successful use of this in the quinazoline series was for the removal of the chlorine atom in 2-chloro-4-phenylquin-azoline, although it had been used previously to prepare 8-nitro-6-methoxyquinazoline in very poor yield. The 4-chloroquinazoline is converted to its 4-(A -toluene-p-sulfonylhydrazino) quinazoline hydrochloride derivative which is decomposed with alkali in aqueous ethylene glycol at lOO C (Scheme 13). The yields are high (60-70%) when R is Me, Cl, OMe but low when R is NO2, and in the latter case it is preferable to use dilute sodium carbonate as the base. This reaction is unsatisfactory if the unsubstituted pyrimidine ring is unstable towards alkali, as in 1,3,8-triazanaphthalene where the pyrimi-... 

The ratio of the chloride mixture mainly derives from the toluene/chlo-rine ratio and the contact time. Benzyl chloride is produced hy passing dry chlorine into hoiling toluene (110°C) until reaching a density of 1.283. At this density, the concentration of henzyl chloride reaches the maximum. Light can initiate the reaction. 

With trisubstitution by the same or different substituents, the three positional isomers shown above are possible. When the substituent groups are the same, the positional numbers are given followed by the suffix tri-. For example, if the three groups are chlorine, the first isomer above is named 1,2,3-trichlorobenzene. The compound above with different substituents is named as a derivative of the parent compound toluene (methylbenzene) where it is understood that the methyl group is in the 1-position. 

Bakke et al. (1982) have shown how montmorillonite catalyses chlorination and nitration of toluene nitration leads to 56 % para and 41 % ortho derivative compared to approximately 40 % para and 60 % ortho derivatives in the absence of the catalyst. Montmorillonite clays have an acidity comparable to nitric acid / sulphuric acid mixtures and the use of iron-exchanged material (Clayfen) gives a remarkable improvement in the para, ortho ratio in the nitration of phenols. The nitration of estrones, which is relevant in making various estrogenic drugs, can be improved in a remarkable way by using molecular engineered layer structures (MELS), while a reduction in the cost by a factor of six has been indicated. With a Clayfen type catalyst, it seems possible to manipulate the para, ortho ratio drastically for a variety of substrates and this should be useful in the manufacture of fine chemicals. In principle, such catalysts may approach biomimetic chemistry our ability to predict selectivity is very limited. 

Such xenobiotics as aliphatic hydrocarbons and derivatives, chlorinated ahphatic compounds (methyl, ethyl, methylene, and ethylene chlorides), aromatic hydrocarbons and derivatives (benzene, toluene, phthalate, ethylbenzene, xylenes, and phenol), polycyclic aromatic hydrocarbons, halogenated aromatic compounds (chlorophenols, polychlorinated biphenyls, dioxins and relatives, DDT and relatives), AZO dyes, compounds with nitrogroups (explosive-contaminated waste and herbicides), and organophosphate wastes can be treated effectively by aerobic microorganisms. 

Benzene and its derivatives are used widely throughout the chemical industry as solvents and raw materials. Mono-, di-, and trichlorobenzenes are used directly as pesticides for their insecticidal and fungicidal properties. Benzene, toluene, and chlorobenzene are used as raw materials in the synthesis of at least 15 pesticides, although their main use is as a carrier solvent in 76 processes. Additional priority pollutant aromatics and chlorinated aromatics exist as impurities or as reaction byproducts because of the reactions of the basic raw materials and solvent compounds. 

Thus hydrochloric acid is a derivative of chlorine. About 93% of it is made by various reactions including the cracking of ethylene dichloride and tetrachloroethane, the chlorination of toluene, fluorocarbons, and methane, and the production of linear alkylbenzenes. It is also a by-product of the reaction of phosgene and amines to form isocyanates. 

The polar effect was at first invoked to explain various directive effects observed in aliphatic systems. Methyl radicals attack propionic acid preferentially at the a-position, ka/kp = 7.8 (per hydrogen), whereas chlorine " prefers to attack at the /3-position, ka/kp = 0.03 (per hydrogen). In an investigation of f-butyl derivatives, a semiquanti-tative relationship was observed between the relative reactivity and the polar effect of the substituents, as evidenced by the pK, of the corresponding acid. In the case of meta- and / ara-substituted toluenes, it has been observed that a very small directive effect exists for some atoms or radicals. When treated by the Hammett relation it is observed that p = —0.1 for H , CeHs , P-CH3C6H4 and CHs . On the contrary, numerous radicals with an appreciable electron affinity show a pronounced polar effect in the reaction with the toluenes. Compilation of Hammett reaction constants and the type of substituent... 

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