Acetylene manufacturing methods

Newer coal-based methods of acetylene manufacture under development include the AVCO process, based on the reaction of coal in a hydrogen plasma. Finely divided coal is passed through a hydrogen plasma arc generating temperature gradients of up to 15,000 K. About 67% of the coal is consumed, yielding char and acetylene in concentrations up to 16%. An energy requirement of 9.5 kW h/kg acetylene has been reported (33). 

The central intermediate for all manufacturing methods of Vitamin A and j -carotene is ) -ionone, for which the production process has already been discussed in connection with the fragrances of violets (c/ section 3.2.3). To briefly recapitulate the essentials of the different strategies The starting material used hy Hoffmann-La Roche was acetylene, while BASF used isobutylene, and... 

In the United States and Canada, calcium carbide is the principal raw material for acetylene manufacture. Calcium carbide and water may be made to react by several methods to produce acetylene, with calcium hydroxide as a coproduct. Acetylene is also manufactured by the thermal or arc cracking of hydrocarbons, and by a process employing the partial combustion of methane with oxygen. 

Until World War 1 acetone was manufactured commercially by the dry distillation of calcium acetate from lime and pyroligneous acid (wood distillate) (9). During the war processes for acetic acid from acetylene and by fermentation supplanted the pyroligneous acid (10). In turn these methods were displaced by the process developed for the bacterial fermentation of carbohydrates (cornstarch and molasses) to acetone and alcohols (11). At one time Pubhcker Industries, Commercial Solvents, and National Distillers had combined biofermentation capacity of 22,700 metric tons of acetone per year. Biofermentation became noncompetitive around 1960 because of the economics of scale of the isopropyl alcohol dehydrogenation and cumene hydroperoxide processes. 

In the 1980s cost and availabiUty of acetylene have made it an unattractive raw material for acrylate manufacture as compared to propylene, which has been readily available at attractive cost (see Acetylene-DERIVED chemicals). As a consequence, essentially all commercial units based on acetylene, with the exception of BASF s plant at Ludwigshafen, have been shut down. AH new capacity recendy brought on stream or announced for constmction uses the propylene route. Rohm and Haas Co. has developed an alternative method based on aLkoxycarbonylation of ethylene, but has not commercialized it because of the more favorable economics of the propylene route. 

The hydroformylation of acrolein cyclic acetals has received considerable attention in the recent patent literature as a route to 1,4-butanediol (76-52). This diol is a comonomer for the production of polybutylene terephthalate, an engineering thermoplastic. The standard method for its manufacture has been from acetylene and formaldehyde, as shown in Eqs. (37) and (38) ... 

Dibromoethane is a halogenated aliphatic hydrocarbon produced when gaseous ethylene comes in contact with bromine. The mixing of ethylene and bromine is accomplished in a variety of ways. One of the more common manufacturing processes involves a liquid-phase bromination of ethylene at 35°-85°C. After the bromination of ethylene, the mixture is neutralized to free acid and then purified by distillation. Other methods of 1,2-dibromoethane formation include the hydrobromination of acetylene and a reaction of 1,2-dibromoethane with water (Fishbein 1980 HSDB 1989). 

Pyridine and its derivatives are technically-important fine chemicals. Their isolation from coal tar is decreasing, whereas their manufacture by synthetic methods has increased rapidly. The classical pathways to pyridine have been discussed by Abramovitch (74HC14-1-4). Many of them rely on the reaction of aldehydes or ketones with ammonia in the vapor phase. However, the condensation processes used suffer from unsatisfactory selectivity. Using soluble organocobalt catalysts of the type [YCoL] allows pyridine and a wide range of 2-substituted derivatives to be prepared selectively and in one step from acetylene and the appropriate cyano compound [Eq.(l)]. 

In 1969, 90% of vinyl acetate was manufactured by this process. By 1975 only 10% was made from acetylene, and in 1980 it was obsolete. Instead, a newer method based on ethylene replaced this old acetylene chemistry. A Wacker catalyst is used in this process similar to that for acetic acid. Since the acetic acid can also be made from ethylene, the basic raw material is solely ethylene, in recent years very economically advantageous as compared to acetylene chemistry. An older liquid-phase process has been replaced by a vapor-phase reaction run at 70-140 psi and 175-200°C. Catalysts may be (1) C—PdCb—CuCb, (2) PdClj—AI2O3, or (3) Pd—C, KOAc. The product is distilled water, acetaldehyde, and some polymer are... 

Uses In addition to the extensive use of acetylene in oxyacetylene welding it is used as a starting material for the manuf of inorg and org acetylides as well as many other compds. Some of them such as acetone, acetaldehyde, acetic acid, acetic anhydride, etc are indispensible in the manuf and testingof expls and ammo. Acetylene was also used to manufacture tetranitromethane by the method described in PATR 2510 (1958), p Ger 195, under Tetan... 

MacKie and Orton [71] found that tetranitromethane could be obtained by reacting anhydrous nitric acid with acetylene in the presence of mercuric nitrate. During World War II the Germans manufactured tetranitromethane by this method on a semi-commercial scale, after they had developed the industrial process (Schim-melschmidt [72]). 

A primary method for the manufacture of acetylene is to react calcium carbide, the principal raw material, with water to produce acetylene with calcium hydroxide as a byproduct ... 

In addition, when compounds containing a multiple bond such as acetylene are used as raw materials, the consumption of F2 can be reduced and the heat of reaction is also lowered. Because this method prevents the cleavage of C—C bond, it is particularly suitable for the manufacture of C2F6. In our experiment, C2F6 can be obtained at a yield as high as 90% or more [20]. 

The method of making lewisite was suggested by the analogous method of mustard-gas manufacture used by the Allies. Thus, mustard is formed by the action of ethylene on sulfur monochloride, while lewisite is produced by action of acetylene on araeme trichloride in the pieaenct of aluminum trichloride acting as a catalyst. The dark brown viscid liquid a hich results from this latter reaction is decomposed by treatment with hydrochloric acid at O C. (32 F.), and an oil is obtained which < an be fractionated by distillation in vacuo into three chlor inyl derivatives of arsenic trichloride. These derivatives, which differ from each other only by the successive addition to the arsenic trichloride of one, two, or three molecules of acetylene, are as follows (see Chart Xlll) ... 

In contrast to acetaldehyde, where a choice exists between several well-established manufacturing processes, vinyl acetate has been produced until recently by two principal methods—i.e., by the catalytic vapor-phase acylation of acetylene and by the acetalization of acetaldehyde. The new procedure for vinyl acetate manufacture consists of oxidizing ethylene in acetic acid—a process closely related to the Wacker acetaldehyde process. All three manufacturing approaches are outlined in Table XII. 

Method of manufacture all industrial processes for preparing carotenoids are based on P-ionone. This material can be obtained by total synthesis from acetone and acetylene via dehydrolinalol. The commercially available material is usually extended on a matrix such as acacia or maltodex-trin. These extended forms of beta-carotene are dispersible in aqueous systems. Beta-carotene is also available as micronized crystals suspended in an edible oil such as peanut oil. 

The method of manufacture of nitroform from acetylene found as early as 1900 by Baschieri (Voi. I, p. 587) was described by Orton and McKie [141]. It became possible to convert one of the carbons of acetylene to nitroform through a mercury catalysed oxidation-nitration process with nitric acid. Nitroform is an intermediate product of nitration and yields tetranitromethane under the action of excess nitric acid (Vol. I, p. S94). The method was developed during World War II by Schultheiss I42] and Schimmelschmidt 143 on a large laboratory scale with the atm of producing tetranitromethane. l ater the industrial scale method for the manufacture of nitroform was created by Wctter-holm [I44 (and is described below). 

Acetaldehyde. The manufacture of acetaldehyde in Germany by hydration of acetylene is described by Alexander (2) and by Brundrit, Taylor, and Ellis (25). Acetaldehyde preparation by hydrolysis of lower vinyl ethers is brieffy indicated in the latter reference as well as by Reaper and Direnga (55). For complete coverage of the literature on these methods, see references (27,44, 2, 4, 4)-... 

Prior to 1916, acetaldehyde was manufactured by the oxidation of alcohol in the liquid phase with bichromate and sulfuric add.1 Since that time it has been ade quite largely by the hydration of acetylene in sulfuric acid solutions activated with mercury salts. However, the relatively low price of ethanol in America has made the formation of acetaldehyde by vapor phase dehydrogenation or limited oxidation of the alcohol attractive commercially. To this end several methods have been proposed for conducting the transformation industrially. Developments of processes employing vapor phase oxidation reactions have all been based largely on the prindples disclosed by the early work, a considerable portion of which had been undertaken purely for the purpose of research and not industrialization. 

Vinyl monomers are well-known for their very-high chemical reactivity and their specific ability to form polymers. Since the most direct and easiest synthesis method involved the addition of an acid to acetylene, this compound provided the ideal raw material for a tong rime. However, acetylene is an expensive raw material, so that, although it is still employed today to manufacture a number of vinyl monomers, a significant part of recent advances in petrochemicals manufacture has consisted m its replacement by ethylene and propylene ... 

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