Ammonolysis of chlorobenzene

Ammonolysis. Reactions involving ammonia. Ammonolysis of esters, acyl chlorides, and anhydrides give amides aniline is produced by ammonolysis of chlorobenzene. The reaction is analogous to hydrolysis, with ammonia substituted for water. 

Amination (formerly often called ammonolysis) of chlorobenzene with aqueous ammonia, at 210 °C and 60-70 atmospheres, with a cuprous salt as catalyst, was employed in the manufacture of aniline until around 1970. Recently, a number of novel catalysts with potential for industrial application have been reported (see Section XXII.D). 

Fio. 8-18. Ammonolysis of chlorobenzene effect of temperature ffreeboard 21 per cent). Time 4 hr 0.2 mole CuiO NHi (33 per cent) ratio 5. 

The ammonolysis of chlorobenzene previously operated by Dow in the USA, analogous to the synthesis of phenol from chlorobenzene, has had no commercial importance for some years. Table 5.8 summarizes the production capacities of the major aniline producer countries it is striking that aniline production is limited to a small number of countries. 

An alternative way to produce aniline is through ammonolysis of either chlorobenzene or phenol. The reaction of chlorobenzene with aqueous ammonia occurs over a copper salt catalyst at approximately 210°C and 65 atmospheres. The yield of aniline from this route is also about 96% ... 

Ammonolysis of aryl halides has been performed under PTC conditions.125 The reaction of 2,4-dinitro-chlorobenzene with NH3 (g) in toluene at ambient temperature and pressure gave, in the presence of 10% TBAB and after 3 h, 2,4-dinitroaniline in 16% yield (0.6% in the absence of TBAB). The reaction was complete after 24 h but the product final yield was not reported.125... 

Derivation By (1) catalytic vapor-phase reduction of nitrobenzene with hydrogen (2) reduction of nitrobenzene with iron filings using hydrochloric acid as catalyst (3) catalytic reaction of chlorobenzene and aqueous ammonia (4) ammonolysis of phenol (Japan). 

Heterogeneous liquid phase, involving two or more immiscible liquids. Examples of this are in the nitration of toluene, hydrolysis of chlorobenzene to phenol, and ammonolysis of ethylene dichloride. 

When a catalyst is essential, copper, its oxides, and salts are preferred, and these are almost always used in the ammonolysis of compounds wherein the halogen is attached to an aromatic nucleus not containing negative substituents (e.g., chlorobenzene, chlorobiphenyl (chloroxenene), and chloronaphthalene). In the treatment of alkylene, nitrophenyl, and anthraquinone halides, copper catalysts are not essential but may be used to accelerate the reaction. In the typical reactions of Class 1, presented... 

Mechanical a tation, which is usually dearable, is necessary when the reactants are immiscible. For example, in the ammonolysis of p-nitro-chlorobenzene u ng aqueous ammonia, the denser molten aromatic compound setti to the bottom if no agitation is provided. Agitation is frequently accomplished by means of high-speed propellers or vaned discs. Less intense a tation is provided by-gate, anchor, and paddle types of a tators. In laboratory shaker tubes, the agitation is accomplished by shaking the entire vessel. 

The aminolysis of chlorobenzene with methylamine occurs under approximately the same conditions as ammonolysis to give N-methylaniline. Hughes et al. have found the optimum conditions to be (1) cuprous chlo-... 

Chlorobenzene was one of the first basic organic chemicals produced on a large scale it was already manufactured in 1909 by United Alkali Co, Wipnes/USA. The importance of chlorobenzene rose dramatically during World War I, since it was needed as an intermediate in the production of phenol for the manufacture of picric acid. Other uses, now principally of historic importance, are the production of DDT (l,l,l-trichloro-2,2-di(4-chlorophenyl)ethane) from chlorobenzene and chloral in the presence of sulfuric add, first synthesized in 1874 by Othmar Zeid-ler, and the ammonolysis to produce aniline. 

Amination is also achieved by the use of ammonia (NH3), in a process referred to as ammonolysis. An example is the production of aniline (C6H5NH2) from chlorobenzene (C6H5C1) with ammonia (NH3). The reaction proceeds only under high pressure. 

The replacement of a nuclear substituent such as hydroxyl (-OH), chloro, (-C1), or sulfonic acid (-S03H) with amino (-NH2) by the use of ammonia (ammonolysis) has been practiced for some time with feedstocks that have reaction-inducing groups present thereby making replacement easier. For example, l,4-dichloro-2-nitrobenzene can be changed readily to 4-chloro-2-nitroaniline by treatment with aqueous ammonia. Other molecules offer more processing difficulty, and pressure vessels are required for the production of aniline from chlorobenzene or from phenol (Fig. 3). 

This process permits conversion of half or more of the chlorobenzene in each pass through the reaction vessel with formation of aniline in yields of 95 per cent or higher, based on the consumed chlorobenzene. It also permits carrying out of the ammonolysis reaction and most of the liquor-handling steps in a closed system. It is less laborious and involves less possibility of workmen becoming exposed to the toxic reaction mixture or its vapor than the older batch method of carrying out the reaction. 

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