Hydroquinone, manufacture

Hydroquinone Manufacture without Sulfuric Acid An alternative route to hydroquinone has been developed independently by Snamprogetti, Enichem, and National Chemical Lab Phenol can be directly hydroxylated to hydroxyquinone and catechol with... 

The polymeric products can be made to vary widely in physical properties through controlled variation in the ratios of monomers employed in thek preparation, cross-linking, and control of molecular weight. They share common quaHties of high resistance to chemical and environmental attack, excellent clarity, and attractive strength properties (see Acrylic ester polymers). In addition to acryHc acid itself, methyl, ethyl, butyl, isobutyl, and 2-ethylhexyl acrylates are manufactured on a large scale and are available in better than 98—99% purity (4). They usually contain 10—200 ppm of hydroquinone monomethyl ether as polymerization inhibitor. 

Another commercial appHcation of nucleophilic reactions of nitro-free duoroaromatics is the manufacture of polyetheretherketone (PEEK) high performance polymers from 4,4 -diduoroben2ophenone [345-92-6], and hydroquinone [121-31-9] (131) (see PoLYETHERS, AROMATIC). 

Hydroperoxidation of m- or />Diisopropylbenzene. This is an important industrial route to resorcinol and hydroquinone. The process in principle is identical to the cumene process for the manufacturing of phenol (qv). 

Hydroquinone and catechol are important industrial intermediates, and there has been significant research and development of processes for manufacturing their derivatives. 

Hydroquinone is available in photographic, inhibitor, and technical grade. Manufacturer s specifications are given in Table 3. Table 3. Manufacturer s Specifications for Hydroquinone ... 

Stabilizers. Hydroquinone [123-31 -9] (4) is widely used in commercial resins to provide stabiHty during the dissolution of the hot polyester resin in styrene during the manufacturing process. Aeration of the styrene with oxygen (air) is required to activate the stabilizer, which is converted to an equiHbrium mixture of quinone and the quinhydrone (5) (11). At levels of 150 ppm, a shelf life of over 6 months can be expected at ambient temperatures. 

The N,]S -dialkyl-/)-PDAs are manufactured by reductively alkylating -PDA with ketones. Alternatively, these compounds can be prepared from the ketone and -lutroaruline with catalytic hydrogenation. The /V-alkyl-/V-aryl- -PDAs are made by reductively alkylating -nitro-, -nitroso-, or /)-aminodipheny1 amine with ketones. The AijAT-dialkyl- PDAs are made by condensing various anilines with hydroquinone in the presence of an acid catalyst (see Amines-aromatic,phenylenediamines). 

It is also used to manufacture chlorarule, [118-75-2] a coloring agent, but a new process to synthesize this product has gready reduced this market. This new process, with hydroquinone as raw material (64—67), has the advantage of giving a product of much higher quaUty than can be obtained with 2,4,6-ttichlorophenol. 

In the case of mechanism (6) there are materials available which completely prevent chain growth by reacting preferentially with free radicals formed to produce a stable product. These materials are known as inhibitors and include quinone, hydroquinone and tertiary butylcatechol. These materials are of particular value in preventing the premature polymerisation of monomer whilst in storage, or even during manufacture. 

In the organic chemicals industry, H2O2 is used in the production of epoxides, propylene oxide, and caprolactones for PVC stabilizers and polyurethanes, in the manufacture of organic peroxy compounds for use as polymerization initiators and curing agents, and in the synthesis of fine chemicals such as hydroquinone, pharmaceuticals (e.g. cephalosporin) and food products (e.g. tartaric acid). 

Antioxidants are not important only to the health conscious food manufacturers also rely on these chemicals to maintain the shelf life of their products. Synthetic antioxidants such as butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate and tert-butyl hydroquinone were widely used in food processing to control oxidation and maintain food quality. However, as these synthetic antioxidants are suspected to be carcinogenic they now have restricted use in food (Madahavi and Salunkhe, 1995). Therefore, natural antioxidant sources, especially of plant origin, are of great interest to the food industry. 

Aniline is an aromatic amine used in the manufacture of dyes, dye intermediates, rubber accelerators, and antioxidants. It has also been used as a solvent, in printing inks, and as an intermediate in the manufacture of pharmaceuticals, photographic developers, plastics, isocyanates, hydroquinones, herbicides, fungicides, and ion-exchange resins. It is produced commercially by catalytic vapor phase hydrogenation of nitrobenzene (Benya and Cornish 1994 HSDB 1996). Production of aniline oil was listed at approximately 1 billion pounds in 1993 (U.S. ITC 1994). Chemical and physical properties are listed in Table 1-2. 

Kroll process, 13 84-85 15 337 17 140 in titanium manufacture, 24 851-853 Kroll zirconium reduction process, 26 631 KRW gasifier, 6 797-798, 828 Krypton (Kr), 17 344 commercial, 17 368t complex salts of, 17 333-334 doubly ionized, 14 685 hydroquinone clathrate of, 14 183 in light sources, 17 371-372 from nuclear power plants, 17 362 physical properties of, 17 350 Krypton-85, 17 375, 376 Krypton compounds, 17 333-334 Krypton derivatives, 17 334 Krypton difluoride, 17 333, 336 uses for, 17 336... 

Pifer JW, Hearne FT, Swanson FA et al Mortality study of employees engaged in the manufacture and use of hydroquinone. Int Arch Occup Environ Health 67(4) 267-80, 1995... 

Uses. As an oxidizing agent in photography tanning hides intermediate in the manufacturing of dyes, fungicides, and hydroquinone... 

Benzoquinone was first produced commercially in 1919, and has since been manufactured in several European countries, Japan and the United States. Its major use is in hydroquinone production, but it is also used as a polymerization inhibitor and as an intermediate in the production of a variety of substances, including rubber accelerators and oxidizing agents (lARC, 1977). 

In a modification of the process the sensitized layers are arranged as before but nonwandering couplers are incorporated into the respective layers during manufacture of the film. This means that, after the hydroquinone development has been carried out, the differently coloured images can be formed in one common developer solution. Silver and silver halide are removed as previously. 

The TS-l catalyzed hydroxylation of phenol to a 1 1 mixture of catechol and hydroquinone has already been commercialized by Enichem. Another reaction of considerable commercial importance is the above mentioned ammoximation of cyclohexanone to cyclohexanone oxime66, an intermediate in the manufacture of caprolactam. It could form an attractive alternative to the established process that involves a circuitous route via oxidation of ammonia to nitric acid followed by reduction of the latter to hydroxylamine (figure 4). 

Phenolic wastes are one of the most prevalent forms of chemical pollutants in industry today. The major sources of phenolic waste are insulation fiberglass manufacturing, petroleum refineries, textile mills, steel making, plywood, hardboard production, manufacture of organic chemicals, paint stripping, and wood preservatives. Eisenhauer (1964) first studied oxidation of phenolic wastes with Fenton s reagent. It has been demonstrated that the oxidation of phenol involves the intermediate formation of catechol and hydroquinone (Merz and Waters, 1949 Stein and Weiss, 1951 Wieland and... 

All of the above developing agents have unique characteristics, and some have a special purpose. The shortening of the list of modern developing agents has more to do with ease of manufacture, storage, and shipping than it does with their usefulness. The superadditive effects of hydroquinone, metol, Phenidone, and ascorbic acid (see discussion of superadditivity later in this chapter) has also added to their popularity with manufacturers. 

Developing agents for film can be used for paper and vice versa. In practical terms, some developing agents are more advantageous to use in one process than another. For example, ppd is better suited for film development than for paper development, while chlorhydroquinone is better suited for paper than film. Hydroquinone, metol, ascorbic acid, and Phenidone are well suited for either film or paper. This is an additional reason they are preferred by manufacturers. It is worthwhile to familiarize yourself with the brief description of each developing agent in Appendix 3 Pharmacopoeia. 

Notes A derivative of hydroquinone, chlorhydroquinone was once a mainstay for warm-tone prints. Unfortunately, it is becoming increasingly hard to find, not because it is not useful as a warm-tone developing agent, but because it is both expensive and dangerous to manufacture. 

Uses Aniline is an oily liquid used in the manufacture of dyestuffs, intermediates for dyestuffs, and manufacture of rubber accelerators and antioxidant substances. Aniline has been extensively used as an intermediate in the manufacture of plastics, pharmaceuticals, pesticides, isocyanates, and hydroquinones. Occupational exposure to aniline is extensive and as diverse as its industrial uses. Workers associated with the manufacturing of acetanalide bromide, coal tar, colors and dyes, leather, disinfectants, nitraniline, perfumes, rubber, and photographic materials become victims of adverse effects from aniline. 

New synthetic processes for the preparation of established products were also industrially developed in Japan the manufacture of methyl methacrylate from C4 olefins, by Sumitomo and Nippon Shokubai in France, the simultaneous production of hydroquinone and pyro-catechin through hydrogen peroxide oxidation of phenol by Rhone-Poulenc in the United States the production of propylene oxide through direct oxidation of propylene operating jointly with styrene production, developed by Ralph Landau and used in the Oxirane subsidiary with Arco, which the latter fully took over in 1980 in Germany and Switzerland, the synthesis of vitamin A from terpenes, used by BASF and Hoffmann-La Roche. 

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