Chlorotoluenes, hydrolysis

This method is capable of producing p- or m-cresol from the corresponding cymene (isopropyltoluene). Alkaline chlorotoluene hydrolysis is used to formulate a cresol mixture with a high m-cresol content. However, information pertaining to domestic use of this process was unavailable (Fiege and Bayer 1987). 

The hydrolysis of p bromotoluene with aqueous sodium hydroxide at 300°C yields m methylphenol and p methylphenol in a 5 4 ratio What is the meta—para ratio for the same reac tion carried out on p chlorotoluene" ... 

Halogen Reactions. Hydrolysis of chlorotoluenes to cresols has been effected by aqueous sodium hydroxide. Both displacement and benzyne formation are involved (27,28). o-Chlorotoluene reacts with sodium in Hquid ammonia to afford a mixture of 67% of o-toluidine [95-53-4] and 33% of yW-toluidine [108-44-1], C H CIN, as shown in equation 3 (29). 

The side-chain chlorine contents of benzyl chloride, benzal chloride, and benzotrichlorides are determined by hydrolysis with methanolic sodium hydroxide followed by titration with silver nitrate. Total chlorine determination, including ring chlorine, is made by standard combustion methods (55). Several procedures for the gas chromatographic analysis of chlorotoluene mixtures have been described (56,57). Proton and nuclear magnetic resonance shifts, characteristic iafrared absorption bands, and principal mass spectral peaks have been summarized including sources of reference spectra (58). Procedures for measuring trace benzyl chloride ia air (59) and ia water (60) have been described. 

The results for the hydrolysis of chlorobenzene, o-chlorotoluene and p-chloroanisole in presence of cuprous oxide at different temperatures (Fig. 14) show a good selectivity for the reaction of the chlorobenzene. But, the p-chloroanisole is also transformed by a secondary demethylation reaction into the corresponding p-chlorophenolate. 

The first step involves hydrolysis, with concentrated sulfuric acid, of p-toluene-sulfonyl chloride, which is quite cheap. The resulting sulfonic acid is chlorinated smoothly in the position ortho to the —CHs group, the reaction being carried out in sulfuric acid solution using iron as a catalyst. Finally, the sulfo group is split out with steam, yielding the desired o-chlorotoluene in excellent yield. This process is less satisfactory for use in the laboratory, but gives the best results in industrial operations. 

Generally, the reaction rates of aryl halides follow the order iodides > bromides > chlorides > fluorides. This fact can be used for the selective substimtion in polyhalogenated systems. For instance, 2-bromo -chlorotoluene gives 76% of 5-chloro-2-methylphenol by treatment with sodium hydroxide at 200 °C. Nevertheless, polyhalogenated systems which contain fluorides have a variable behaviour depending on the reaction temperature. At lower temperatures preferential hydrolysis of the fluoride takes place and at >200 °C the usual reactivity order iodides > bromides > chlorides > fluorides is observed. For instance, l,2-dibromo-3,4,5,6-tetrafluorobenzene affords 2,3-dibromo-4,5,6-trifluorophenol in 87% yield by treatment with potassium hydroxide at 85 °C. Under the same conditions, 1,4-dibromo-2,3,5,6-tetrafluorobenzene produces a 78% yield of 2,5-dibromo-3,4,6-trifluorophenol. However, 4-fluorobromobenzene with NaOH at 200 °C gives 4-fluorophenol in 70-79% yield. ... 

Vapor phase hydrolysis of chlorotoluenes appears to be accompanied by a much smaller degree of isomerization than liquid phase hydrolysis, and accordingly, the Hooker-Raschig process is considered more attractive than the original Dow process. The process, however, is much less attractive than the sulfonation and alkylation processes. The chemistry of the process is as follows ... 

Azoic Diazo Component 32, produced by nitration of >-chlorotoluene followed by reduction of the resulting 4-chloro-2-nitrotoluene and Azoic Diazo Component 34, produced by nitration of o-benzenesulfonotoluidide followed by hydrolysis. Va.ria.mine Blue B the half sulfate [6254-98 4] of (90), ie, Azoic Diazo Component 35 used for dark blue or green shades is marketed as the free base or half sulfate. It is produced by condensation of anisidine with 2-chloro-5-nitrobenzenesulfonic acid, reduction, and desulfonation of the resulting 5-amino-2- anisidinobenzenesulfonic acid. 

In the commercial synthesis of cresols, the most common processes are alkaline hydrolysis of chlorotoluene, the cleavage of cymene hydroperoxide and the alkylation of phenol in the gas phase with methanol. Alkali fusion of toluenesulfonic acids has largely lost its earlier significance, because of the inorganic salts which are co-produced. 

For the manufacture of cresols by alkaline hydrolysis of chlorotoluene, toluene firstly reacts with chlorine, e.g. at 30 °C using FeCl3/S2Cl2 as a catalyst, to yield a chlorotoluene mixture (o/p-ratio 1 1). 

If the separation of the isomers is carried out at the chlorotoluene stage (distilla-tion/crystallization), an o-/m-cresol mixture arises during hydrolysis of o-chloro-toluene in the ratio 1 1, from which pure m-cresol can be produced, whereas the hydrolysis of p-chlorotoluene gives a m-/p-cresol mixture. 

For the production of the necessary chrysanthemum acid substituent , 4-chlorotoluene is chlorinated photochemically and the 4-chlorobenzyl chloride converted into the nitrile with sodium cyanide. Base-catalysed introduction of the isopropyl group and subsequent hydrolysis of the nitrile, followed by chlorination, yields 2-isopropyl-(4-chlorophenyl)-acetyl chloride as an intermediate component for the production of fenvalerate. 

Chlorotoluene, which is manufactured in Western Europe in quantities of ca. 20,000 tpa, is used mainly in the production of cresols (see Chapter 5.3.43) by hydrolysis. In addition, it is used, via the intermediate 2-chlorobenzal chloride, as a raw material for the manufacture of optical brighteners, such as benzaldehyde-2-sulfonic acid. 

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