Manufacture of aniline

Aromatic amines can be produced by reduction of the corresponding nitro compound, the ammonolysis of an aromatic haUde or phenol, and by direct amination of the aromatic ring. At present, the catalytic reduction of nitrobenzene is the predominant process for manufacture of aniline. To a smaller extent aniline is also produced by ammonolysis of phenol. 

The predominant process for manufacture of aniline is the catalytic reduction of nitroben2ene [98-95-3] ixh. hydrogen. The reduction is carried out in the vapor phase (50—55) or Hquid phase (56—60). A fixed-bed reactor is commonly used for the vapor-phase process and the reactor is operated under pressure. A number of catalysts have been cited and include copper, copper on siHca, copper oxide, sulfides of nickel, molybdenum, tungsten, and palladium—vanadium on alumina or Htbium—aluminum spinels. Catalysts cited for the Hquid-phase processes include nickel, copper or cobalt supported on a suitable inert carrier, and palladium or platinum or their mixtures supported on carbon. 

Table 4 Hsts the manufacturers of aniline in the United States at the end of 1989.

Report of the British Intelligence Objectives Subcommittee on (1) The Manufacture of Nitration Products ofBenyene, Toluene, and Chlorobenyene at Griesheim and Eeverkusen, (2) The Manufacture of Aniline andiron Oxide Pigments at Uerdigen, PB 77729 (also issued as BIOS Report No. 1144) and BIOS Trip Report No. 2526, Sept.-Oct. 1946, pp. 25-32. 

The largest user of phenol in the form of thermosetting resins is the plastics industry. Phenol is also used as a solvent and in the manufacture of intermediates for pesticides, pharmaceuticals, and dyestuffs. Styrene is used in the manufacture of synthetic rubber and polystyrene resins. Phthalic anhydride is used in the manufacture of DMT, alkyd resins, and plasticizers such as phthalates. Maleic anhydride is used in the manufacture of polyesters and, to some extent, for alkyd resins. Minor uses include the manufacture of malathion and soil conditioners. Nitrobenzene is used in the manufacture of aniline, benzidine, and dyestuffs and as a solvent in polishes. Aniline is used in the manufacture of dyes, including azo dyes, and rubber chemicals such as vulcanization accelerators and antioxidants. 

In the manufacture of aniline by the hydrogenation of nitrobenzene, the offgases from the reactor are cooled and the products and unreacted nitrobenzene condensed. The hydrogen and inerts, containing only traces of the condensed materials, are recycled. 

In the manufacture of aniline, the condensed reactor products are separated in a decanter. The decanter separates the feed into an organic phase and an aqueous phase. Most of the aniline in the feed is contained in the organic phase and most of the water in the aqueous phase. Using the data given below, calculate the stream compositions. 

In the manufacture of aniline from nitrobenzene the reactor products are condensed and separated into an aqueous and organic phases in a decanter. The organic phase is fed to a striping column to recover the aniline. Aniline and water form an azeotrope, composition 0.96 mol fraction aniline. For the feed composition given below, make a mass balance round the column and determine the stream compositions and flow-rates. Take as the basis for the balance 100 kg/h feed and a 99.9 percentage recovery of the aniline in the overhead product. Assume that the nitrobenzene leaves with the water stream from the base of the column. 

Note Problems 2.5 to 2.8 can be taken together as an exercise in the calculation of a preliminary material balance for the manufacture of aniline by the process described in detail in Appendix F, Problem F.8. 

In the manufacture of aniline, liquid nitrobenzene at 20 °C is fed to a vaporiser where it is vaporised in a stream of hydrogen. The hydrogen stream is at 30 °C, and the vaporiser operates at 20 bar. For feed-rates of 2500 kg/h nitrobenzene and 366 kg/h hydrogen, estimate the heat input required. The nitrobenzene vapour is not superheated. 

The process used in the manufacture of aniline from nitrobenzene is described in Appendix G, design problem G.8. The process involves six significant stages Vaporisation of the nitrobenzene... 

In the manufacture of aniline by the hydrogenation of nitrobenzene, the off-gases from the reactor are cooled and the products and unreacted nitrobenzene condensed in a shell and tube exchanger. A typical composition of the condensate is, kmol/h aniline 950, cyclo-hexylamine 10, water 1920, nitrobenzene 40. The gases enter the condenser at 230 °C and leave at 50 °C. The cooling water enters the tubes at 20 °C and leaves at 50 °C. Suggest suitable materials of construction for the shell and the tubes. 

Nitroaromatics TNT, nitrobenzene, nitrophenols, atrazine Manufacture of aniline, dyes, drugs (P,D) Explosive industry, military facilities (P, D) Manufacture of pesticides and herbicides (D) C [46]... 

Uses of hydrogen chloride—Hydrogen chloride is sometimes used in the preparation of an ester, for example ethyl benzoate, where it acts as both an acid catalyst and a dehydrating agent. Hydrochloric acid is used primarily to produce chlorides, for example ammonium chloride. It is extensively used in the manufacture of aniline dyes, and for cleaning iron before galvanising and tin-plating. 

Uses Solvent for cellulose ethers modifying esterification of cellulose acetate ingredient of metal polishes and shoe polishes manufacture of aniline, benzidine, quinoline, azobenzene, drugs, photographic chemicals. 

Other metal-acid reducing systems may be used reduction with iron and hydrochloric acid is employed on the technical scale for the manufacture of aniline. 

Nitrobenzene is a pale yellow oily liquid (mp, 5.7°C bp, 211°C) with an odor of bitter almonds or shoe polish. It is produced mainly for the manufacture of aniline. It can enter the body through all routes and has a toxicity rating of five. Its toxic action is much like that of aniline, including the conversion of hemoglobin to methemoglobin, which deprives tissue of oxygen. Cyanosis is a major symptom of nitrobenzene poisoning. 

Monochlorobenzene is a flammable clear liquid (fp, -45"C bp, 132°C) used as a solvent, solvent carrier for methylene diisocyanate, pesticide, heat transfer fluid, and in the manufacture of aniline, nitrobenzene, and phenol. The 1,2- isomer of dichlorobenzene (ortho-dichlorobenzene) has been used as a solvent for degreasing hides and wool and as a raw material for dye manufacture. The 1,4- isomer (para-dichlorobenzene) is also used in dye manufacture and as a moth repellant and germicide. All three isomers have been used as fumigants and insecticides. The 1,2- and 1,3-(meta) isomers are liquids under ambient conditions, whereas the 1,4- isomer is a white sublimable solid. Used as a solvent, lubricant, dielectric fluid, chemical intermediate, and formerly as a termiticide, 1,2,4-trichlorobenzene is a liquid (fp, 17°C bp, 213°C). 

Uses Nitrobenzene is a colorless to pale yellow liquid. It has been used extensively in a variety of industries, (e.g., the manufacture of aniline dyes and soaps, as solvent for paints, for refining lubricating oils, as shoe polish, floor polish, dressings for leather products, the manufacture of explosives). 

The coal tar dye industry received its first stimulus when the manufacture of aniline was started — first in England — and aniline has remained one of its most important products. A considerable amount of aniline is still used today in the production of aniline black on the fiber. Large quantities are ako used in the preparation of dyes of various classes, either direcdy or after conversion into numerous other intermediates. Aniline is also an im rtant starting material in the preparation of pharmaceutical products. Apparently, the largest consumer of aniline derivatives in modem times, however, is the rubber industry, which uses huge quantities of diphenylguanidine, thiocarbanilide, and other sulfur containing aniline derivatives as vulcanization accelerators. 

The commercial dyestuff is the hydrochloride of rosanilinc the acetate, however, is also sometimes met with. The free base is also prepared for the manufacture of aniline blue. 

FIGURE 7. Manufacture of aniline blue by phenylation (arylation) of amino groups in aniline red (magenta, fuchsine), 1860s. Edelstein Collection... 

FIGURE 18. Calco Chemical Division, American Cyanamid Company, Bound Brook, New Jersey, 1938. This facility was a major manufacturer of aniline and other aromatic amines, and in the 1950s pioneered the large-scale production of aniline by continuous fluid-bed, vapor-phase reduction of nitrobenzene (Catan process). Edelstein Collection... 

In 1943, Calco produced around 97% of the US consumption of sulfadiazine (79), and was the sole American producer of sulfaguanidine (78), both supplied to the Army and Navy Munitions Board. The armed forces also demanded sulfathiazole (77), which cured several common diseases caused by streptococcus, staphylococcus, pneumonococcus and gonococcus, as well as preventing and curing wounds and burns115. In Britain, ICI stepped up manufacture of aniline and A,A-dimethylaniline for explosives, as well as for antimalarials and other pharmaceutical products116,117. 

From the 1970s dye-making in the US and Europe went into decline, in part due to tariff reductions in the US (commencing in 1968) and environmental concerns (since many intermediates were toxic). New centers of manufacturers were in Asia, including Japan, Korea, India and China, and Eastern Europe. However, there was considerable expansion in manufacture of anilines in Europe and North America for isocyanates. 

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