Chemical manufacturing, chemicals used toluene

Your company receives toluene, a listed toxic chemical, from another facility, reacts the toluene with air to form benzoic acid, and further reacts the benzoic acid with a cadmium catalyst to form terephthallc acid. Cadmium compounds and terephthallc acid are also listed toxic chemicals. Your company processes toluene, and otherwise uses (not processes) the cadmium catalyst (see the definition of "otherwise use" below). Your company manufactures benzoic acid and terephthallc acid. Benzoic acid, however, is not a listed chemical and thus does not trigger reporting requirements. 

From the chemical manufacturing industry, catalytic cracking and catalytic hydrogenation, gas absorption or scrubbing processes in which desired or waste products are removed from a waste stream, the nitration of benzene and toluene where the reactants have limited mutual solubility, and carbonylation processes using carbon monoxide. 

Uses Toluene is a clear, colorless, flammable, and sweet- pungent-smelling liquid. It is extensively used as a solvent in different industries, (e.g., rubber chemical manufacture, drugs and pharmaceuticals, thinner for inks, paints dyes, perfume manufacture). 

There are over 8000 chemicals that exhibit commercially significant optical properties. Some of these are natural products such as indigo, chlorophyll, and cochineal, but the majority are synthesized in a series of steps involving dye intermediates (any of the 3000 or more organic and inorganic chemicals used as raw material precursors to manufactured dyes, the most important of which are benzene and naphthalene). Coal tar dyes refers to the dyestuffs originating from the complex mix of hydrocarbons (benzene, toluene, xylene, pyrene, naphthalene, anthracene, etc.) present in coal tar (8007-45-2). Petroleum has succeeded coal as the dominant source of dye intermediates. Dyes, pigments, and dye intermediates include... 

Many organic chemicals may be manufactured by several alternative processes using different chemical feedstocks. For example, toluene diisocyanate can be produced by hydrogenation of phosgene or by nitration and phosgenation of toluene, and propylene can be made by dehydrogenating propane or by pyrolyz-ing butane, naphtha, or propane (63). 

Cross-sensitivity may be a problem since other chemicals will sometimes interfere with a stain tube reaction. For example, the presence of xylene will interfere with stain tubes calibrated for toluene. Manufacturer s handbooks give information on the known crosssensitivities of their products. This point emphasises the need to consider the whole range of chemicals used in a process rather than just the major ones. 

In order to illustrate the impact on future processes we are pleased to give herewith the following comparison to produce valuable product widely used namely Para Toluene Sulphonic Acid (PTSA). The current process for manufacturing this chemical is sulphonation of toluene at high temperatures in a glass lined reactors using 98 % Sulphuric acid. 

Although the bulk of the toluene never is isolated from the gasoline pool, approximately 5.5 billion lb of high-purity (98-100%) toluene was produced for nonfuel consumption in the United States in 1988. Approximately 50 percent of this toluene was dealkylated to benzene. The second largest end-use was as a solvent for coatings, paints, and lacquers. Also of importance was the use of toluene as an intermediate in the manufacture of other chemicals, mainly toluene diisocyanate and benzoic acid. 

Cyclic Hydrocarbons. The cyclic hydrocarbon intermediates are derived principally from petroleum and natural gas, though small amounts are derived from coal. Most cycHc intermediates are used in the manufacture of more advanced synthetic organic chemicals and finished products such as dyes, medicinal chemicals, elastomers, pesticides, and plastics and resins. Table 6 details the production and sales of cycHc intermediates in 1991. Benzene (qv) is the largest volume aromatic compound used in the chemical industry. It is extracted from catalytic reformates in refineries, and is produced by the dealkylation of toluene (qv) (see also BTX Processing). 

Tables 16 and 17 Hst tke analytical test methods for different properties of interest. The Manufacturing Chemists Association, Inc. (MCA) has pubUshed the Chemical Safety Data Sheet SD 63, which describes in detail procedures for safe handling of use of toluene (46). The Interstate Commerce Commission classifies toluene as a flammable Hquid. Accordingly, it must be packaged in authorized containers, and shipping must comply with ICC regulations. Properties related to safe handling are autoignition temperature, 536°C explosive limits, 1.27—7.0 vol % in air and flash point 4.4°C, closed cup.

Benzoic Acid. Ben2oic acid is manufactured from toluene by oxidation in the liquid phase using air and a cobalt catalyst. Typical conditions are 308—790 kPa (30—100 psi) and 130—160°C. The cmde product is purified by distillation, crystallization, or both. Yields are generally >90 mol%, and product purity is generally >99%. Kalama Chemical Company, the largest producer, converts about half of its production to phenol, but most producers consider the most economic process for phenol to be peroxidation of cumene. Other uses of benzoic acid are for the manufacture of benzoyl chloride, of plasticizers such as butyl benzoate, and of sodium benzoate for use in preservatives. In Italy, Snia Viscosa uses benzoic acid as raw material for the production of caprolactam, and subsequendy nylon-6, by the sequence shown below. 

Vinyltoluene. Viayltoluene is produced by Dow Chemical Company and is used as a resia modifier ia unsaturated polyester resias. Its manufacture is similar to that of styrene toluene is alkylated with ethylene, and the resulting ethyltoluene is dehydrogenated to yield vinyltoluene. Annual production is ia the range of 18,000—23,000 t/yr requiring 20,000—25,000 t (6-7.5 x 10 gal) of toluene. 

In the United States all other processes have been completely phased out and virtually all benzoic acid is manufactured by the continuous hquid-phase air oxidation of toluene. In the late 1950s and the early 1960s both Dow Chemical and Snia Viscosa constmcted faciUties for Hquid-phase toluene oxidation because of large requirements for benzoic acid in the production of phenol and caprolactam. Benzoic acid, its salts, and esters are very useful and find appHcation in medicinals, food and industrial preservatives, cosmetics, resins, plasticizers, dyestuffs, and fibers. 

Ben2oic acid is almost exclusively manufactured by the cobalt cataly2ed Hquid-phase air oxidation of toluene [108-88-3]. Large-scale plants have been built for ben2oic acid to be used as an intermediate in the production of phenol (by Dow Chemical) and in the production of caprolactam (by Snia Viscosa) (6-11). 

AH commercial processes for the manufacture of caprolactam ate based on either toluene or benzene, each of which occurs in refinery BTX-extract streams (see BTX processing). Alkylation of benzene with propylene yields cumene (qv), which is a source of phenol and acetone ca 10% of U.S. phenol is converted to caprolactam. Purified benzene can be hydrogenated over platinum catalyst to cyclohexane nearly aH of the latter is used in the manufacture of nylon-6 and nylon-6,6 chemical intermediates. A block diagram of the five main process routes to caprolactam from basic taw materials, eg, hydrogen (which is usuaHy prepared from natural gas) and sulfur, is given in Eigute 2. 

Mono- and dichlorotoluenes ate used chiefly as chemical iatermediates ia the manufacture of pesticides, dyestuffs, pharmaceuticals, and peroxides, and as solvents. Total annual production was limited prior to 1960 but has expanded greatly siace that time. Chlorinated toluenes ate produced ia the United States, Germany, Japan, and Italy. Siace the number of manufacturers is small and much of the production is utilised captively, statistics covering production quantities ate not available. Worldwide annual production of o- and -chlorotoluene is estimated at several tens of thousands of metric tons. Yearly productions of polychlorotoluene ate ia the range of 100—1000 tons. 

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