Chlorobenzenes production

Recent studies have shown that the reaction, as described by Eq. (11), also requires Pt(II) as a necessary catalyst (29, 84). A range of substituted benzenes has been examined, and by studying concurrent hydrogen-deuterium exchange, it was concluded that the two reactions had common intermediates (29). In this work aqueous acetic acid was used as the solvent, and reactions were followed by measuring the concentration of the chlorobenzene product. Of the several possible mechanisms for the oxidation that have been given (29), only one will be considered here this is the one that has received substantial support from the most recent work (84). In this study, the loss of reactant benzene, the formation of product chlorobenzene, and the formation of platinum(II) were monitored as the reaction proceeded. Also aqueous trifluoroacetic acid was used as the solvent, as it is known that acetic acid is oxidized to chloroacetic acid by platinum(IV) (18). 

Starting from 2-thienylacrylic acid (244), thionyl chloride and pyridine, the chlorinated thieno[3,2-6]thiophene derivative (245) was formed along with the more highly chlorinated product (246), which was isolated as its methyl ester (247 Scheme 83). In refluxing toluene or chlorobenzene, product (245) was not observed and only the ring-chlorinated acid chloride (246) was isolated in 13% yield. A number of analogs were prepared via this reaction <76AHC(19)123). 

Production of chlorobenzene in the United States has declined by nearly 60%, from the peak production volume of 274,000 kkg in 1960 to 112,000 kkg in 1987. This decline is attributed primarily to the replacement of chlorobenzene by cumene in phenol production and the cessation of DDT production in the United States. In addition, pesticide production using chlorobenzene as an intermediate has declined and no major new uses have been found for chlorobenzene in recent years. Therefore, the decline in chlorobenzene production is expected to continue (EPA 1980c, 1985 Hughes etal. 1983 USITC 1988). 

Production, Use, Release, and Disposal. Data indicate that chlorobenzene production has declined dramatically over the past two decades, but current quantitative data on use (especially solvent uses) and disposal practices would be helpful in evaluating the effect of current industrial practices on environmental levels of chlorobenzene. 

Chlorobenzene production has been declining since its peak in 1969, and is likely to continue declining due to the substitution of more environmentally acceptable chemicals. Chlorobenzene is produced by chlorination of benzene in the presence of a catalyst, and is produced as an end product in the reductive chlorination of di- and trichlorobenzenes. 

Performance curves for this gas-liquid CSTR, based on the preceding system of equations and parameters, are illustrated in Figure 24-1. A reasonable design corresponds to 10 < r/X < 10, where the total outlet flow rate of chlorobenzene is between 60 and 93% of the inlet flow rate of liquid benzene, and 45% of the total chlorobenzene product exits the CSTR as a liquid. 

Chlorobenzene and dichlorobenzenes are obtained by direct catalytic chlorination of benzene with chlorine. In the production process, gaseous chlorine is bubbled through a solution of the iron(III) catalyst FeCla in benzene. All chlorination reactions at the aromatic core are highly exothermic (e.g., AH= —131.5 kj mol for chlorobenzene formation from benzene and AH = —124.4 kJ mol for dichlorobenzene formation from chlorobenzene) and therefore appropriate reactor cooling (e.g., by internal coohng coils in the reactor) is required. Keeping the reaction temperature at a certain value is important to adjust the product distribution obtained from the process. For a high selectivity to monochlorobenzene the reaction temperature should be adjusted between 40 and 50 °C. Temperatures below 40 °C are unsuitable due to unfavorably low reaction rates. Temperatures above 50 °C, however, favor the formation of di- and even trichlorobenzenes. To maximize mono-chlorobenzene production it is, moreover, important to work with excess benzene such that the benzene conversion is limited to 65% at the desired full chlorine conversion. 

Hexachlorobenzene is found in the heavies fractions of many chlorination processes, in addition to chlorobenzenes production, from which it may be isolated if necessary. 

Equip a 1 Utre three-necked flask or a 1 litre bolt- head flask with a reflux condenser and a mercury-sealed stirrer. Dissolve 50-5 g. of commercial 2 4-dinitro-l-chlorobenzene in 250 ml. of rectified spirit in the flask, add the hydrazine solution, and reflux the mixture with stirring for an hour. Most of the condensation product separates during the first 10 minutes. Cool, filter with suction, and wash with 50 ml. of warm (60°) rectified spirit to remove unchanged dinitrochlorobenzene, and then with 50 ml. of hot water. The resulting 2 4-dinitrophenylhydrazine (30 g.) melts at 191-192° (decomp.), and is pure enough for most purposes. Distil oflF half the alcohol from the filtrate and thus obtain a less pure second crop (about 12 g.) recrystallise this from n-butyl alcohol (30 ml. per gram). If pure 2 4-dinitrophenylhydrazine is required, recrystallise the total yield from n-butyl alcohol or from dioxan (10 ml. per gram) this melts at 200° (decomp.). 

In a 1 htre round bottomed flask equipped with a reflux condenser place a solution of 62 -5 g. of anhydroas sodium carbonate in 500 ml. of water and add 50 g. of commercial 2 4-dinitro-l-chlorobenzene. Reflux the mixture for 24 hours or until the oil passes into solution. Acidify the yellow solution with hj drochloric acid and, when cold, filter the crystaUine dinitrophenol which has separated. Dry the product upon filter paper in the air. The yield is 46 g. If the m.p, differs appreciably from 114°, recrystallisc from alcohol or from water. 

The commercial product, m.p. 53-55°, may be used. Alternatively the methyl -naphthyl ketone may be prepared from naphthalene as described in Section IV,136. The Friedel - Crafts reaction in nitrobenzene solution yields about 90 per cent, of the p-ketone and 10 per cent, of the a-ketone in carbon disulphide solution at — 15°, the proportions ore 65 per cent, of the a- and 35 per cent, of the p-isomer. With chlorobenzene ns the reaction medium, a high proportion of the a-ketone is also formed. Separation of the liquid a-isomer from the solid p-isomer in Such mixtures (which remain liquid at the ordinary temp>erature) is readily effected through the picrates the picrate of the liquid a-aceto compound is less soluble and the higher melting. 

Ethylbenzene. Prepare a suspension of phenyl-sodium from 23 g. of sodium wire, 200 ml. of light petroleum (b.p. 40-60°) and 56 3 g. (50 9 ml.) of chlorobenzene as described above for p-Toluic acid. Add 43 -5 g. (30 ml.) of ethyl bromide during 30-45 minutes at 30° and stir the mixture for a further hour. Add water slowly to decompose the excess of sodium and work up the product as detailed for n-Butylbenzene. The yield of ethylbenzene, b.p. 135-136°, is 23 g. 

Chlorides are inert. However, the reaction ofp-chlorobenzophenone (9) with a styrene derivative proceeds satisfactorily at 150 C by u.sing dippb [l,4-bis(-diisopropylphosphino)butane] as a ligand to give the stilbene derivative 10. However, dippp [l,3-bis(diisopropylphosphino)propane] is an ineffective ligand[13]. On the other hand, the coupling of chlorobenzene with styrene proceeds in the presence of Zn under base-free conditions to afford the cis-stilbene 11 as a main product with evolution of H . As the ligand, dippp is... 

Reaction of chlorobenzene with p chlorobenzyl chloride and aluminum chloride gave a mixture of two products in good yield (76%) What were these two products ... 

Predict the products formed when each of the following isotopically substituted denvatives of chlorobenzene is treated with sodium amide in liquid ammonia Estimate as quantitatively as possible the composition of the product mixture The astensk ( ) in part (a) designates C and D in part (b) is... 

Polysulfone. Polysulfone is a commercial polymer that is a product of bisphenol A and 1,1 -sulfonylbis (4-chlorobenzene) (see Polymers... 

Other sources of by-product HCl include allyl chloride, chlorobenzenes, chlorinated paraffins, linear alkylbenzene, siHcone fluids and elastomers, magnesium, fluoropolymers, chlorotoluenes, benzyl chloride, potassium sulfate, and agricultural chemicals. 

The most widely used process for the production of phenol is the cumene process developed and Hcensed in the United States by AHiedSignal (formerly AHied Chemical Corp.). Benzene is alkylated with propylene to produce cumene (isopropylbenzene), which is oxidized by air over a catalyst to produce cumene hydroperoxide (CHP). With acid catalysis, CHP undergoes controUed decomposition to produce phenol and acetone a-methylstyrene and acetophenone are the by-products (12) (see Cumene Phenol). Other commercial processes for making phenol include the Raschig process, using chlorobenzene as the starting material, and the toluene process, via a benzoic acid intermediate. In the United States, 35-40% of the phenol produced is used for phenoHc resins. 

Nucleophilic Substitutions of Benzene Derivatives. Benzene itself does not normally react with nucleophiles such as haUde ions, cyanide, hydroxide, or alkoxides (7). However, aromatic rings containing one or more electron-withdrawing groups, usually halogen, react with nucleophiles to give substitution products. An example of this type of reaction is the industrial conversion of chlorobenzene to phenol with sodium hydroxide at 400°C (8). 

Chlorine or bromine react with benzene in the presence of carriers, such as ferric halides, aluminum halides, or transition metal halides, to give substitution products such as chlorobenzene or bromobenzene [108-86-17, C H Br occasionally para-disubstitution products are formed. Chlorobenzene [108-90-7] ... 

Chlorine and bromine add to benzene in the absence of oxygen and presence of light to yield hexachloro- [27154-44-5] and hexabromocyclohexane [30105-41-0] CgHgBr. Technical benzene hexachloride is produced by either batch or continuous methods at 15—25°C in glass reactors. Five stereoisomers are produced in the reaction and these are separated by fractional crystallization. The gamma isomer (BHC), which composes 12—14% of the reaction product, was formerly used as an insecticide. Benzene hexachloride [608-73-17, C HgCl, is converted into hexachlorobenzene [118-74-17, C Clg, upon reaction with ferric chloride in chlorobenzene solution. 

Ortho- and/ i ra-phenylphenols are commercially significant biphenyl derivatives that do not involve biphenyl as a starting material. Both are produced as by-products from the hydrolysis of chlorobenzene [108-90-7] with aqueous sodium hydroxide (68). o-Phenylphenol, ie, l,l-biphenyl-2-ol [90-43-7], particularly as its sodium salt, is widely used as a germicide or fungicide. Pi ra-phenylphenol [92-69-3] with formaldehyde forms a resin used in surface coatings. 

The chlorination of benzene can theoretically produce 12 different chlorobenzenes. With the exception of 1,3-dichlorobenzene, 1,3,5-trichlorobenzene, and 1,2,3,5-tetrachlorobenzene, all of the compounds are produced readily by chlorinating benzene in the presence of a Friedel-Crafts catalyst (see Friedel-CRAFTS reactions). The usual catalyst is ferric chloride either as such or generated in situ by exposing a large surface of iron to the Hquid being chlorinated. With the exception of hexachlorobenzene, each compound can be further chlorinated therefore, the finished product is always a mixture of chlorobenzenes. Refined products are obtained by distillation and crystallization. 

Chlorobenzenes were first synthesized around the middle of the nineteenth century the first direct chlorination of benzene was reported in 1905 (1). Commercial production was begun in 1909 by the former United Alkali Co. in England (2). In 1915, the Hooker Electrochemical Co. at Niagara EaUs, New York, brought on stream its first chlorobenzenes plant in the United States with a capacity of about 8200 metric tons per year. 

The Dow Chemical Company started production of chlorobenzenes in 1915 (3). Chlorobenzene was the first and remained the dominant commercial product for over 50 years with large quantities being used during World War I to produce the military explosive picric acid [88-89-1]. 

The Dow Chemical Company in the mid-1920s developed two processes which consumed large quantities of chlorobenzene. In one process, chlorobenzene was hydrolyzed with ammonium hydroxide in the presence of a copper catalyst to produce aniline [62-53-3J. This process was used for more than 30 years. The other process hydrolyzed chlorobenzene with sodium hydroxide under high temperature and pressure conditions (4,5) to product phenol [108-95-2]. The LG. Earbenwerke in Germany independentiy developed an equivalent process and plants were built in several European countries after World War II. The ICI plant in England operated until its dosing in 1965. 

Although Dow s phenol process utilized hydrolysis of the chlorobenzene, a reaction studied extensively (9,10), phenol production from cumene (qv) became the dominant process, and the chlorobenzene hydrolysis processes were discontinued. 

With the discontinuation of some herbicides, eg, 2,4,5-trichlorophenol [39399-44-5] based on the higher chlorinated benzenes, and DDT, based on monochlorobenzene, both for ecological reasons, the production of chlorinated benzenes has been reduced to just three with large-volume appHcations of (mono)chlorobenzene, o-dichlorobenzene, and -dichlorobenzene. Monochlorobenzene remains a large-volume product, considerably larger than the other chlorobenzenes, in spite of the reduction demanded by the discontinuation of DDT. 

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