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Organic Chemistry) P1: FPP 2nd Revised Pages Qu: 00, 00, 00, 00 Encyclopedia of Physical Science and Technology EN002C-64 May 19, 2001 20:39 Table of Contents (Subject Area: Organic Chemistry) Pages in the Article Authors Encyclopedia Acetylene Robert J. Tedeschi Pages 55-89 Armin Guggisberg and Alkaloids Pages 477-493 Manfred Hesse Bioconjugate Claude F. Meares Pages 93-98 Chemistry Carbohydrates Hassan S. El Khadem Pages 369-416 Catalysis, Piet W. N. M. van Leeuwen Pages 457-490 Homogeneous Fuel Chemistry Sarma V. Pisupadti Pages 253-274 Heterocyclic Charles M. Marson Pages 321-343 Chemistry Organic Chemical Josef Michl Pages 435-457 Systems, Theory Organic Chemistry, John Welch Pages 497-515 Synthesis J. Ty Redd, Reed M. Izatt Organic Macrocycles Pages 517-528 and Jerald S. Bradshaw Organometallic Robert H. Crabtree Pages 529-538 Chemistry Pharmaceuticals, Giancarlo Santus and Pages 791-803 Controlled Release of Richard W. Baker Physical Organic Charles L. Perrin Pages 211-243 Chemistry Stereochemistry Ernest L. Eliel Pages 79-93 P1: GLQ Revised Pages Qu: 00, 00, 00, 00 Encyclopedia of Physical Science and Technology EN001F-4 May 25, 2001 16:2 Acetylene Robert J. Tedeschi Tedeschi and Associates, Inc. I. Introduction VIII. Processes for Acetylene Production II. Acetylene and Commodity Chemicals IX. Chemistry of Specialty Products III. Production of Acetylene and Commodity X. Vinyl Ethers Chemicals XI. Flavor and Fragrance Compounds and Vitamins IV. Acetylene-Based Processes for Large-Volume A and E Chemicals XII. Acetylenic Pesticides V. Important Chemical Uses for Acetylene XIII. Acetylenic Reactions with Research and VI. Reppe Products Commercial Potential VII. Specialty Acetylenics and Derivatives XIV. Acetylene Research in Russia GLOSSARY Carbonylation Reaction of acetylene with carbon monoxide and alcohols to form acrylate esters; Reppe Acetylenic Pertaining to organic compounds containing process. a triple bond ( C C ) or acetylene group in the Commodity chemicals Large-volume, multitonnage molecule. chemicals, some of which are derived from acetylene. Adjuvant Acetylenic diol used with pesticides to en- Ethynylation Reaction of acetylene with aldehydes and hance activity, lower the rate of application, and in- ketones to form acetylenic alcohols and diols. crease safety. Grignard Organomagnesium halide used in acetylenic Alkynol Primary, secondary, or tertiary acetylenic alco- and other syntheses. hol with the hydroxyl group generally adjacent or α to Oil-well acidizing Use of acetylenic alcohols (alkynols) the triple bond. as corrosion inhibitors to protect steel pipe during Ammoxidation Acrylonitrile manufactured by oxidation acidizing operations undertaken to free oil from lime- of propylene in the presence of ammonia. stone formations. Aprotic Pertaining to highly polar solvents such as Pesticides Agricultural chemicals including herbicides, dimethyl sulfoxide (DMSO), hexamethylphospho- insecticides, miticides, fungicides, and bacterial con- ramide (HMPA), N-methyl-pyrrolidone (NMP), and trol agents. acetonitrile that can hydrogen bond or complex with Reppe products and technology Pioneered by Dr. acetylene and acetylenic compounds; used to dissolve Walter Reppe of the I. G. Farben; various prod- and activate acetylene. ucts derived from the reaction of acetylene with 55 P1: GLQ Revised Pages Encyclopedia of Physical Science and Technology EN001F-4 May 7, 2001 16:19 56 Acetylene formaldehyde to yield butyne-1,4-diol and propargyl lene burned in the presence of oxygen provided a very hot alcohol. flame, useful in the joining of metals. The welding indus- Surfynols Acetylenic hydroxyl compounds used as high- try today still uses significant amounts of acetylene in spite speed, low-foam wetting–dispersing agents and as of the availability of less expensive fuels such as propane. agricultural adjuvants and formulation aids. Initially, acetylene was handled in industry as the undi- Trofimov reaction Formation of substituted pyrroles luted liquefied gas below its critical temperature of 36◦C and N-vinylpyrroles by reaction of acetylene with at a pressure greater than 600 psig. This appeared to be ketoximes. a safe procedure until a series of industrial explosions Vinylation Reaction of acetylene with alcohols or pyrol- in the early 1900s eliminated the practice. Today acety- lidone to form vinyl ethers and vinylpyrrolidone. lene is shipped in cylinders under pressure that contain a mixture of diatomaceous earth or asbestos, acetone, and stabilizers. Another safe method of transport is via granu- ACETYLENE CHEMISTRY is the chemistry of the lar calcium carbide in sealed containers, free of water. The carbon–carbon triple bond ( C C ). This functionality large-volume use of acetylene for the manufacture of com- defines the unique chemistry of this reactive group, in ad- modity chemicals has led to the building of plants, either dition to its diverse and important applications. The high petrochemical or calcium carbide, “across the fence” from electron density of the triple bond with its circular, sym- acetylene producers. Today the factors leading to acety- metrical π field makes acetylene and its derivatives reac- lene hazards are well understood and have been well doc- tive and useful intermediates for synthesizing a wide va- umented. Acetylene now poses a minimum risk in well- riety of organic compounds. These organic products find operated processes and plants. wide use in the synthesis of flavors and fragrances, vita- mins A, E, and K, β-carotene, pesticides, surfactants, cor- rosion inhibitors, and specially intermediates. This article II. ACETYLENE AND COMMODITY describes the technology and applications of acetylene, CHEMICALS acetylenic compounds, and the chemicals derived from them. From 1965 to 1970 more than 1 billion pounds of acetylene In the mid-1960s more than 1 billion pounds of were used annually to manufacture a variety of chemi- acetylene were used annually for the production of cals. Welding applications constituted ∼10% of this to- large-volume (commodity) chemicals. Since then, acety- tal. After 1970, the use of acetylene for the manufac- lene has been gradually supplanted by less expensive ture of commodity chemicals began to decline markedly, olefin feedstocks. However, acetylene is still used in and by 1979–1983 only 269 million pounds were em- multimillion-pound levels to produce Reppe chemicals ployed. Less expensive petrochemical raw materials such (butynediol, propargyl alcohol, butanediol, butyrolactone, as ethylene, propylene, butadiene, amylenes, and methane N-methylpyrrolidone, polyvinylpyrrolidone, and vinyl were replacing acetylene. Table I summarizes chemicals ether copolymers) and specialty acetylenic chemicals and manufactured mainly from actylene before 1965, types of their derivatives. Large volumes of butanediol are used in processes, and replacement raw materials. The principal the manufacture of engineering plastics such as polybuty- use of the monomers listed in the table was in diverse lene terephthalate. Other significant uses for acetylene in polymer applications spanning plastics, latex emulsions, specialty areas include acetylene black, vitamins A and E, rubbers, and resins. Chlorinated solvents were important flavor–fragrance (F & F) compounds, corrosion inhibitors, in vapor degreasing, but their use in more recent years acetylenic surfactants, and pesticides. Acetylenic chemi- has been gradually limited as a result of toxicity and air cals, polymers, and derivatives of potential value in re- pollution. search and commerce are also discussed. Some special The applications of the polymer products derived from aspects of acetylene chemistry research in Russia are also the above monomers are not within the scope of this article. summarized. III. PRODUCTION OF ACETYLENE AND I. INTRODUCTION COMMODITY CHEMICALS Acetylene has always been an important raw material for The following tabulation shows the gradual decline in U.S. making chemical products. In the early years of its history acetylene production from its high point of 1.23 billion (circa 1890–1900) it was used extensively as an illuminant pounds in 1965 to ∼269 million pounds in 1979. In 1965 for trains and city streets. It was soon realized that acety- bulk acetylene was valued at 7–12c//lb, while ethylene was P1: GLQ Revised Pages Encyclopedia of Physical Science and Technology EN001F-4 May 7, 2001 16:19 Acetylene 57 TABLE I Early Acetylene-Based Chemicals Product C2H2 process Replacement raw material Replacement process Acrylates and acrylic acid Reppe carbonylation (CO + C2H2) Propylene (C3H6) Two-stage oxidation Acrylonitrile C2H2 + HCN C3H6 Ammoxidation (C3H6–O2–NH3) Chloroprene C2H2-Vinylacetylene-HCl Butadiene Chlorination and dehydrochlorination Chlorinated hydrocarbons C2H2 + Cl2 C1–C3 feedstocks; C2H4 Chlorination–dehydrochlorination Vinyl acetate C2H2 + acetic acid Ethylene (C2H4) Oxyacetylation Vinyl chloride C2H2 + HCl Ethylene Oxychlorination C2H2 + HCl C2H2 + C2H4 Balanced ethylene–acetylene 3–4c//lb. By 1983–1984 the cost ratio was approximately tion is a mix from calcium carbide, by-product acetylene the same, with acetylene valued at about 55–75c//lb and from cracking, and partial oxidation processes. ethylene at 23–29c//lb. The nine U.S. acetylene producers, with their capacity in millions of pounds, were AIRCO-BOC, Calvert City, 6 Year C2H2 used (10 lb) KY, and Louisville, KY (75); Dow, Freeport, TX (16); Hoffmann–La Roche, Nutley, NJ (5); Monochem, 1965 1230 Geismar, LA (180); Rohm and Haas, Deer Park, TX (55); 1967 1065
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