Chlorobenzene, manufacture

Dinitrochlorobenzene can be manufactured by either dinitration of chlorobenzene in filming sulfuric acid or nitration ofy -nitrochlorobenzene with mixed acids. Further substitution on the aromatic ring is difficult because of the deactivating effect of the chlorine atom, but the chlorine is very reactive and is displaced even more readily than in the mononitrochlorobenzenes. 

With the exception of use in the manufacture of polymers, markets for chlorobenzenes are mature, and demand is expected to show Htde if any growth in the next few years. 

The chlorobenzene operations in the United States were developed primarily for the manufacture of phenol, aniline, and DDT. However, with the process changes in the production of phenol and aniline, the phase-out of DDT production, and changes in the herbicide and solvent markets, the U.S. production of chlorinated benzenes has shmnk by more than 50% since the total production peaked in 1969. U.S. production of monochlorobenzene peaked in the 1960s and decreased to a low of 101 million kg in 1986 with an 11% and 9% increase, respectively, in 1988 and 1989. 

Other Chlorobenzenes. The market for the higher chlorobenzenes (higher than di) is small in comparison to the combined mono- and dichlorobenzenes. Trichlorobenzenes are used in some pesticides, as a dye carrier, in dielectric fluids, as an organic intermediate and a chemical manufacturing solvent, in lubricants, and as a heat-transfer medium. These are small and decreasing markets. 

The major aromatics (organics having at least one ring structure with six carbon atoms) manufactured include benzene, toluene, xylene, and naphthalene. Other aromatics manufactured include phenol, chlorobenzene, styrene, phthalic and maleic anhydride, nitrobenzene, and aniline. Benzene is generally recovered from cracker streams at petrochemical plants and is used for the manufacture of phenol, styrene, aniline, nitrobenzene, sulfonated detergents, pesticides such as hexachlorobenzene, cyclohexane (an important intermediate in synthetic fiber manufacture), and caprolactam, used in the manufacture of nylon. Benzene is also used as a general purpose solvent. 

Phenol was manufactured for many years by the Dow process, in which chlorobenzene reacts with NaOH at high temperature and pressure (Section 16.S). Now, however, an alternative synthesis from isopropylbenzene, commonly called... 

Chlorobenzene is manufactured by the reaction between benzene and chlorine. A number of secondary reactions occur to form undesired by products. 

The research department has developed a new process for producing chlorobenzene and wants to pursue it further. The company has never produced chlorobenzene, but feels that if the price is right it would be willing to build a plant for its production. Before doing this, not only must it estimate what the proposed plant will cost but it must determine what costs the current manufacturers have. The proposed process will be dropped unless it has an economic advantage over the present process. 

Chlorobenzene(s), 3 602 6 211-225 24 275 Antoine constants, 6 215t from benzene, 3 619t, 620 chlorocarbon/chlorohydrocarbon of industrial importance, 6 227t diffusion coefficient in air at 0° C, l 70t economic aspects, 6 219-222 health and safety factors, 6 218-219 manufacture, 6 213-217 physical and thermodynamic properties, 6 214t... 

We know that nuclear halogens can be replaced by amine groups but with difficulty. Yet aniline has been manufactured from chlorobenzene by heating it with excess aqueous ammonia in presence of Cu20 at about 250° under pressure. 

Since mtro-groups in the o- and p-positions increase the mobility of halogens directly attached to the aromatic ring (p. 106), nitrophenols can also be obtained from chloronitrobenzenes. Thus p-chloronitro-benzene can be decomposed by alkalis in the autoclave, and 2 4-dinitrophenol, an important intermediate product for the manufacture of sulphur dyes, is produced from the corresponding chlorobenzene by an even milder treatment. 

Tyl RW, Neeper-Bradley TL. 1989. Paradichlorobenzene Two generation reproductive study of inhaled paradichlorobenzene in Sprague-Dawley (CD) rats. Laboratory Project 86-81-90605. Washington, DC Chemical Manufacturers Association, Chlorobenzene Producers Association. 

Tetrachlorodibenzo-p-dioxin (TCDD) is believed to be a byproduct in chemical processing generated by a halophenol or chlorobenzene starting material. An intermediate reaction will occur at an elevated temperature (equal to or greater than 160°C), an alkaline condition, or in the presence of a free halogen. The end reaction results in either direct dioxin, intermediate dioxin, or predioxin formation that will ultimately form dibenzo-p-dioxins [10]. TCDD is suspected in wastewaters from pesticide manufacture that uses such raw materials as 2,4,5-trichlorophenol (2,4,5-T) and 1,2,4,5-tetra-chlorobenzene, which are characteristic of TCDD precursors. A TCDD level as high as 111 mg/L has been found in drums of waste from the production of the pesticide 2,4,5-T. 

Another development is due to the interest in polychlorodibenzofurans, spurred by their occurrence as environmental contaminants. Polychloro-phenols are manufactured in large amounts (150,000 tons per annum) and find a wide range of uses. The usual method of manufacture involves the hydrolysis of chlorobenzenes, and side reactions, favored by high temperature, can lead to the production of polychlorodibenzofurans and poly-chlorodibenzo-p-dioxins. The Seveso incident is well known." Polychloro-biphenyls are also widely used industrial chemicals, particularly in heat exchange systems, and their pyrolysis leads to the formation of polychloro-dibenzofurans. Polychlorodibenzofurans have also been detected in the fly ash and flue gases of incinerators and industrial heating plants. The most toxic of the polychlorodibenzofurans are 2,3,7,8-tetra-, 1,2,3,7,8-penta-, and 2,3,4,7,8-pentachlorodibenzofuran, and an extensive literature exists on the environmental pollution and the results of human exposure to these substances. A particularly tragic example of the latter occurred in 1968 in the Fukuoka prefecture of Japan after consumption of rice oil contaminated with a commercial polychlorobiphenyl. 

Chlorobenzene. Chlorobenzene is an important solvent and intermediate in the production of chemicals and dyes. Its use in phenol manufacture, however, was superseded by the introduction of the cumene process. 

To manufacture aniline from chlorobenzene and ammonia, cuprous oxide or diamino cuprous chloride has been used as the catalyst and the reaction is usually carried out in the liquid phase under pressure (7). There are few reports on the reaction in gas phase. Jones (8) found that CuX was active for aniline formation while ZnX led to the formation of dichlorobenzenes. The reaction of benzaldehyde with ammonia over zeolite has never been reported. 

These solvents include tetrahydrofuran (THF), 1,4-dioxane, chloroform, dichloromethane, and chlorobenzene. The relatively broad solubility characteristics of PSF have been key in the development of solution-based hollow-fiber spinning processes in the manufacture of polysulfone asymmetric membranes (see Hollow-fibermembranes). The solvent list for PES and PPSF is short because of the propensity of these polymers to undergo solvent-induced crystallization in many solvents. When the PES structure contains a small proportion of a second bisphenol comonomer, as in the case of RADEL A (Amoco Corp.) polyethersulfone, solution stability is much improved over that of PES homopolymer. 

Diphenyl ether itself is a byproduct in the manufacture of phenol from chlorobenzene and aqueous caustic at elevated temperatures (29,30, 31, 32, 33) and by proper control of conditions can be made the major product of the reaction. 

Chlorobenzene is a colorless liquid with an almond-like odor. The compound does not occur widely in nature, but is manufactured for use as a solvent (a substance used to dissolve other substances) and is used in the production of other chemicals. Chlorobenzene persists in soil (several months), in air (3.5 days), and water (less than 1 day). Additional information can be found in Chapters 3, 4, and 5. 

The current primary uses of chlorobenzene are as a solvent for pesticide formulations, diisocyanate manufacture, degreasing automobile parts, and for the production of nitrochlorobenzene. Solvent uses accounted for about 37% of chlorobenzene consumption in the United States in 1981, nitrochlorobenzene production for 33%, and diphenyl oxide and phenylphenol production for 16% of consumption. Chlorobenzene is also used in silicone resin production and as an intermediate in the synthesis of other halogenated organics. The past major use of chlorobenzene was as an intermediate in phenol and DDT production (Hughes et al. 1983). 

The principal source of chlorobenzene in water is release from chemical manufacturing facilities. Dow Chemical Company estimated that 0.1% of its annual production enters waters (EPA 1980a). Perry et al. (1979) found chlorobenzene in 6/63 industrial effluent in concentrations up to 100 pg/L. Based on 1,338 samples collected from about 1980 to 1983, the medium concentration of chlorobenzene in waste effluent was < 3 ppb and was detected in 54 samples. The total amount released to the environment was not reported (Staples et al. 1985). Chlorobenzene has been detected in both surface and groundwater samples at hazardous waste sites. Data from the Contract Laboratory Program (CLP) Statistical Database indicate that chlorobenzene occurred in surface water at 13 sites at a geometric mean concentration of 17 ppb in positive samples and in... 

PCDD/Fs can be formed during the manufacture of chlorophenols, chlorobenzenes, and chlorobiphenyls, and the production and use of them could be important sources. Some researchers believe that the manufacture of halogenated organic chemicals is the largest contributor of PCDD/Fs in China (Huang et al., 2001). While some specified sources have been closed in developed countries, the release of PCDD/Fs from chemical manufacturing is still a problem in China due to the use of dated processes or technologies, despite their limited use. These chemical manufactures are described below. 

By-product hydrochloric acid. Hydrogen chloride is a by-product of the commercial production of many organic chemicals. Thus, in the manufacture of chlorobenzene, hydrogen chloride is liberated ... 

Benzene is a volatile, colorless, highly flammable liquid that is consumed as a raw material for the manufacture of phenolic and polyester resins, polystyrene plastics, alkylbenzene surfactants, chlorobenzenes, insecticides, and dyes. It is hazardous both for its ignitability and toxicity (exposure to benzene causes blood abnormalities that may develop into leukemia). Naphthalene is the simplest member of a large number of multicychc aromatic hydrocarbons having two or more fused rings. It is a volatile white crystalline solid with a characteristic odor and has been used to make mothballs. The most important of the many chemical derivatives made from naphthalene is phthalic anhydride, from which phthalate ester plasticizers are synthesized. 

Diphenyl ether (diphenyl oxide) is obtained as a by-product in the manufacture of phenol from chlorobenzene and caustic soda. 

Chlorobenzene is used as a solvent and for the manufacture of nitrochlorobenzenes. It is manufactured by passing dry chlorine through benzene, using ferric chloride (FeCl3) as a catalyst ... 

The more efficient route via cumene has superceded the fusion of benzene sulfonic acid with caustic soda for the manufacture of phenol, and the hydrolysis of chlorobenzene to phenol requires far more drastic conditions and is no longer competitive. Ethylene chlorohydrin can be hydrolyzed to glycol with aqueous sodium carbonate. 

NaCI) and is typical of the poor atom economy associated with fine chemical manufacturing. Recent industrial advances [25] use HF in place of the fluoroboric acid, however, stoichiometric amounts of NaF and NH4F salts are produced as waste with the fluorobenzene. Other approaches using HF exchange of chlorobenzene also generate HCI as a waste [7],... 

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