Phenol from chlorobenzene

Write chemical reaction for the preparation of phenol from chlorobenzene. 

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. 

Steam and silica gel to produce phenol from chlorobenzene, the Dow process with steam and a copper salt catalyst, etc. 

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

Hydrolysis of chlorobenzene and the influence of silica gel catalysts on this reaction have been studied by Freidlin and co-workers (109). Pure silica gel gave up to 45% phenol from chlorobenzene at 600°C. When the silica gel was promoted with 2% cupric chloride, up to 75% phenol was obtained (381). A number of other salts were tested by Freidlin and co-workers as promoters, but they exerted an adverse effect on the activity or selectivity of the catalyst. With 0.2% cupric chloride and 6% metallic copper, the activity of silica-gel was doubled (389). At 500° under the above conditions, the halides were hydrolyzed at rates decreasing in the following order chloride, bromide, iodide, fluoride (110). The specific activation of aryl halides by cupric chloride was demonstrated by conversion of chlorobenzene to benzene and of naphthyl chloride to naphthalene when this catalyst was supported on oxides of titanium or tin (111). The silica promoted with cupric chloride was also found to be suitable for hydrolysis of chlorophenols and dichlorobenzenes however, side reactions were too prominent in these cases (112). 

Nucleophilic substitution of aryl halogen atoms requires significant energy input. Thus, in the Dow process for the synthesis of phenol from chlorobenzene, the chlorine atom is only successfully hydrolysed by aqueous sodium hydroxide at 300 °C under pressure. Displacement by ammonia is achieved at 200 °C over copper(I) oxide and conversion to benzonitrile occurs using copper(I) cyanide in boiling dimethylfor-mamide, HCONMe. ... 

Unpublished experimente by Lloyd show that in a vapor-phase reaction the rate of formation of phenol from chlorobenzene and steam in the presence of silica gel is negligible at 350 C but exceedingly rapid at 575 C. 

Fio. 13-1. B lation between the temperature and the time neoesaaiy to secure a 92 per cent yield of phenol from chlorobenzene and aqueous caustic. 

Phenol from Chlorobenzene, Dow Process. The Dow phenol processes base on the hydrolysis of chlorobenzene in caustic soda solution at temperatures of about 360°C and pressures of about 4,000 psi. Although the basic reaction was discovered in 1914 by Meyer and Bei us, the jdevelop-ment of the commercial application of the reaction had to await the introduction of satisfactoiy materials of construction and the solution of a number of chemical and chemical engineering problems. 

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 apparent exception to the generalization about the lack of reactivity of aryl halides to nucleophilic substitution is an early industrial process for the synthesis of phenol from chlorobenzene. When heated at 300°C under high pressure with aqueous NaOH, chlorobenzene is converted to sodium phenoxide. Neutralization of this salt with aqueous acid gives phenol. 

Outline a reasonable synthesis of 4 nitrophenyl phenyl ether from chlorobenzene and phenol... 

Benzene Chlorination. In this process, benzene is chlorinated at 38—60°C in the presence of ferric chloride catalyst. The chlorobenzene is hydrolyzed with caustic soda at 400°C and 2.56 kPa (260 atm) to form sodium phenate. The impure sodium phenate reacts with hydrochloric acid to release the phenol from the sodium salt. The yield of phenol is about 82 mol % to that of the theoretical value based on benzene. Plants employing this technology have been shut down for environmental and economic reasons. 

Residual traces of these impurities must thus be removed by some technique such as recrystallisation from chlorobenzene or acqueous alcohol. The melting point is a useful measure of purity and for polycarbonate resins the melting point should be in the range 154-157°C compared with values of 140-150°C for epoxy resin grade bis-phenol A. 

Phenol is also produced from chlorobenzene and from toluene via a benzoic acid intermediate (see Reactions and Chemicals from Toluene ). 

Phenol can also be produced from chlorobenzene and from cumene, the major route for this commodity. 

Chlorobenzene, electrostatic potential map of, 565 13C NMR absorptions of, 536 phenol from, 575 p-Chlorobenzoic acid, pKa of, 760... 

Phenol has been obtained by distillation from petroleum and synthesis by oxidation of cumene or toluene, and by vapor-phase hydrolysis of chlorobenzene (USITC 1987). In 1995, 95% of U.S. phenol production was based on oxidation of cumene except at one company that used toluene oxidation and a few companies that distilled phenol from petroleum (CMR 1996). In 1995 the total annual capacity of phenol production approached 4.5 billion pounds (CMR 1996). 

Precursor Theory PCDD/Fs are formed from chemically related compounds as precursors. Chemically related products of PCDD/Fs are chloro-phenols and chlorobenzenes. Both classes of compounds are present in the... 

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). 

Figure 20 Schematic diagram of the flow reactor working in recycled mode for the hydroxylation of chlorobenzene and phenol. (From Ref. 137.)...

Production of monochlorobenzenes peaked in the 1960s with production volume at about 600 million lb. It was down to 152 million lb in 1998. The most significant cause for the decline is the replacement of monochlorobenzene by cumene as the preferred raw material for phenol manufacture. Other reasons include the elimination of the herbicide DDT, the change of diphenyl oxide process from chlorobenzene to phenol and a significant drop in solvent use. The production volume for ODCB and PDCB were 50 and 91 million lb, respectively, in 1998. 

This compound (1 g) was added to melted phenol (8 g) with KOH (0.26 g) at 60°C. The mixture was stirred at 165-170°C for 3 h. The cooled solution was diluted by methanol, filtered, and washed by methanol and hot water. Yield 1.07 g (95%) mp 258-260°C. After crystallization from chlorobenzene, orange crystals, were obtained 272-273°C. 

Partial condensers, 24, 341 Partial reduction, 79, 113 Patent blues, 301 Permanent red 2G, 267 Phenanthrene, 1 Phenol, 51, 86 from chlorobenzene, 76, 88 technical observations, Phenolphthalein paper, 395 Phenols, separation, 30 Phend-o-svdfonic acid, 51 Phenol-m-sulfonic acid, 144,145... 

Chlorobenzene, commercially produced by the Raschig process (see p. 108), is resistant to nucleophilic substitution under normal conditions, but in the Dow process, treatment with sodium hydroxide at 300 °C under high pressure is effective. Phenol may also be prepared from chlorobenzene by reaction with steam at 450 °C over a catalyst. 

A certain amount of phenol, as well as the cresols, is obtained from coal tar (Sec. 12.4). Most of it (probably over 90%) is synthesized. One of the synthetic processes used is the fusion of sodium benzenesulfonate with alkali (Sec. 30.12) another is the Dow process, in which chlorobenzene is allowed to react with aqueous sodium hydroxide at a temperature of about 360°. Like the synthesis of aniline from chlorobenzene (Sec. 22.7), this second reaction involves nucleophilic substitution under conditions that are not generally employed in the laboratory (Sec. 25.4). 

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