Manufacture and Uses

The following sections briefly mention the one or two processes used to make the chemical on a large scale. Then the chemical s uses are given with approximate percentages. A close study of this chemistry uncovers many interesting relationships among all 100 top chemicals in the U.S. The section numbers below correspond to the ranking of chemicals from 51-100 in Table 13.1. 

Phosgene is manufactured by reacting chlorine gas and carbon monoxide in the presence of activated carbon. Much of the market is captive. The merchant market is small. 

Uses of phosgene include the manufacture of toluene diisocyanate (45%), methylene diphenyl diisocyanate and polymer diisocyanates (38%), and polycarbonate resins (12%). 

Acetic anhydride may be produced by three different methods. The first procedure involves the in situ production from acetaldehyde of peracetic acid, which in turn reacts with more acetaldehyde to yield the anhydride. In the preferred process, acetic acid (or acetone) is pyrolyzed to ketene, which reacts with acetic acid to form acetic anhydride. A new process to make acetic anhydride involves CO insertion into methyl acetate. This may be the process of the future. 

Approximately 86% of acetic anhydride is used as a raw material in the manufacture of cellulose acetate. 

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J. A. Hathaway and C. R. Buck, "Report of Absence of Health Ha2ards Associated with RDX Manufacture and Use in Shell Loading Plants," in Minutes of 17th Explosives Safety Seminar, Dept, of Defense Explosives Safety Board, Washington, D.C., 1976, p. 683. 

T. W. Lapp, The Manufacture and Use of Selected Aryl and Alkyl Aryl Phosphate Esters, Report NTIS PB-251678, Midwest Research Institute, Feb. 1976. 

A. J. Rudge, The Manufacture and Use ofEluorine and Its Compounds, Oxford University Press, Inc., New York, 1962. 

A number of continuous processes for the manufacture and use of Grignard reagents have been proposed (40), but are of no current commercial significance. 

Although a few simple hydrides were known before the twentieth century, the field of hydride chemistry did not become active until around the time of World War II. Commerce in hydrides began in 1937 when Metal Hydrides Inc. used calcium hydride [7789-78-8J, CaH2, to produce transition-metal powders. After World War II, lithium aluminum hydride [16853-85-3] LiAlH, and sodium borohydride [16940-66-2] NaBH, gained rapid acceptance in organic synthesis. Commercial appHcations of hydrides have continued to grow, such that hydrides have become important industrial chemicals manufactured and used on a large scale. 

S. A. Miller, Mcetykne—Its Properties, Manufacture and Uses, Vol. 2, Academic Press Inc., New York, 1966. 

Manufacture and Uses. Acetoacetic esters are generally made from diketene and the corresponding alcohol as a solvent ia the presence of a catalyst. In the case of Hquid alcohols, manufacturiag is carried out by continuous reaction ia a tubular reactor with carefully adjusted feeds of diketene, alcohol, and catalyst, or alcohol—catalyst blend followed by continuous purification (Fig. 3). For soHd alcohols, an iaert solvent is used. Catalysts used iaclude strong acids, tertiary amines, salts such as sodium acetate [127-09-3], organophosphoms compounds, and organometaHic compounds (5). 

Magnesium nitrate is prepared by dissolving magnesium oxide, hydroxide, or carbonate in nitric acid, followed by evaporation and crystallization at room temperature. Impurities such as calcium, iron, and aluminum are precipitated by pretreatment of the solution with slight excess of magnesium oxide, followed by filtration. Most magnesium nitrate is manufactured and used on site in other processes. 

Maleic Anhydride. The ACGIH threshold limit value in air for maleic anhydride is 0.25 ppm and the OSHA permissible exposure level (PEL) is also 0.25 ppm (181). Maleic anhydride is a corrosive irritant to eyes, skin, and mucous membranes. Pulmonary edema (collection of fluid in the lungs) can result from airborne exposure. Skin contact should be avoided by the use of mbber gloves. Dust respirators should be used when maleic anhydride dust is present. Maleic anhydride is combustible when exposed to heat or flame and can react vigorously on contact with oxidizers. The material reacts exothermically with water or steam. Violent decompositions of maleic anhydride can be catalyzed at high temperature by strong bases (sodium hydroxide, potassium hydroxide, calcium hydroxide, alkaU metals, and amines). Precaution should be taken during the manufacture and use of maleic anhydride to minimize the presence of basic materials. 

The toxicity of chloronaphthalenes requires that special attention and caution be used during their manufacture and use acne is the most common result of excessive skin exposure to them and the most frequendy affected areas are the face and neck (16). Liver damage has occurred in workers who have been exposed repeatedly to vapors, particulady to those of penta- and hexachloronaphthalene [1335-87-1] (17,18). Uses for the chlorinated naphthalenes include solvents, gauge and instmment duids, capacitor impregnants, components in electric insulating compounds, and electroplating stop-off compounds. 

C using a dehydration catalyst consisting of alurninosihcate, Al O, or siUca gel (45). 1-Naphthaleneamine is also toxic (LD q (dogs) = 400 mg/kg) and a suspected human carcinogen, which conditions mandate that appropriate precautions be followed in manufacture and use. 

Polyolefins are manufactured and used in much greater quantity than any other class of plastics. The principal polyolefins are polyethylenes of various densities (LDPE, LLDPE, HDPE) and polypropylene (PP) (see Olefin polymers). 

Clean Air Act and its amendments ia 1970, 1977, and 1990 1967 Air Quahty Standards and National Air Pollution Acts and 1970 National Environmental PoHcy Act) (2) better waste disposal practices (1965 SoHd Waste Disposal Act 1976 Resource Conservation and Recovery Act) (see Wastes, industrial Waste treatment, hazardous wastes) (i) reduced noise levels (1972 Noise Control Act) (4) improved control of the manufacture and use of toxic materials (1976 Toxic Substances Control Act) and (5) assignment of responsibiUty to manufacturers for product safety (1972 Consumer Product Safety Act) (15,16). 

Phenylenediamines can be dia2oti2ed and tetra2oti2ed (20), giving intermediates for various a2o dyes (qv). Their dia2onium salts are commercially manufactured and used in photography. 

In addition to the two main reactions, ie, methylolation and condensation, there are a number of other reactions important for the manufacture and uses of amino resins. For example, two methylo1 groups may combine to produce a dimethylene ether linkage and Hberate a molecule of water ... 

A troublesome side reaction encountered ia the manufacture and use of amino resias is the conversion of formaldehyde to formic acid. Often the reaction mixture of amino compound and formaldehyde must be heated under alkaline conditions. This favors a Canni22aro reaction ia which two molecules of formaldehyde iateract to yield one molecule of methanol and one of formic acid. 

TSCA also addresses the problem of polychlorinated biphenyls (PCBs) and chlorinated fluorocarbons (CECs). EPA has developed regulations on the cleanup, handling, and disposal of PCBs. The manufacture and use of CECs has been banned for all but essential uses, in accordance with the Montreal Agreement, an international treaty on worldwide use of CECs. 

One of the butadiene dimeri2ation products, COD, is commercially manufactured and used as an intermediate in a process called FEAST to produce linear a,C0-dienes (153). COD or cyclooctene [931-87-3], obtained from partial hydrogenation, is metathesi2ed with ethylene to produce 1,5-hexadiene [592-42-7] or 1,9-decadiene [1647-16-1], respectively. Many variations to make other diolefins have been demonstrated. Huls AG also metathesi2ed cyclooctene with itself to produce an elastomer useful in mbber blending (154). The cycHc cis,trans,trans-tn.en.e described above can be hydrogenated and oxidi2ed to manufacture dodecanedioic acid [693-23-2]. The product was used in the past for the production of the specialty nylon-6,12, Qiana (155,156). 

D. W. K. Hardie, A.cetykne, Manufacture and Uses, Oxford University Press, London, UK, 1965. 

Starch Ethers. A large number of starch ethers have been prepared and patented only a few are manufactured and used commercially. Commercially available starch ethers are the hydroxyalkyl ethers, hydroxyethylstarch [9005-27-0] and hydroxypropylstarch [9049-76-7] and cationic starches. 

Starch Esters. As with the starch ethers, a large number of starch esters have been prepared and patented, but only a few are manufactured and used commercially. Both inorganic and organic acid esters can, and have been, made. The latter are prepared by the same general procedure used to make starch ethers. 

Occurrence. Carbon monoxide is a product of incomplete combustion and is not likely to result where a flame bums in an abundant air supply, yet may result when a flame touches a cooler surface than the ignition temperature of the gas. Gas or coal heaters in the home and gas space heaters in industry have been frequent sources of carbon monoxide poisoning when not provided with effective vents. Gas heaters, though properly adjusted when installed, may become hazardous sources of carbon monoxide if maintained improperly. Automobile exhaust gas is perhaps the most familiar source of carbon monoxide exposure. The manufacture and use of synthesis gas, calcium carbide manufacture, distillation of coal or wood, combustion operations, heat treatment of metals, fire fighting, mining, and cigarette smoking represent additional sources of carbon monoxide exposure (105—107). 

Alternative processes for polymer isolation have involved direct dmm drying of latex (84), extmsion isolation of coagulated cmmb (85), and precipitation/drying or spray-drying of the mbber as a powder (86). The powder can be processed directly in continuous compounding equipment (87). The manufacture and use of powdered CR has been reviewed (88). 

The manufacture and uses of oxiranes are reviewed in (B-80MI50500, B-80MI50501). The industrially most important oxiranes are oxirane itself (ethylene oxide), which is made by catalyzed air-oxidation of ethylene (cf. Section 5.05.4.2.2(f)), and methyloxirane (propylene oxide), which is made by /3-elimination of hydrogen chloride from propene-derived 1-chloro-2-propanol (cf. Section 5.05.4.2.1) and by epoxidation of propene with 1-phenylethyl hydroperoxide cf. Section 5.05.4.2.2(f)) (79MI50501). 

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