Acetaldehyde from acetylene

Substances having triple linkages when dissolved in sulphuric acid take up the elements of water, particularly if mercuric salts are present. The simplest example of this reaction is the preparation of acetaldehyde from acetylene itself in the manner described above. 

Small amounts of acetaldehyde (from acetylene) are converted industrially into alcohol by catalytic hydrogenation, and large amounts are transformed into acetic acid by catalysed autoxidation (with oxides of manganese). 

Ref la). It is miscible with w, ale and eth (See also Ref 7). Various methods of prepn are given in Refs 1.3 9 In Ref 2 is described the catalytic production of acetaldehyde from acetylene and steam over activated carbon and promoted by phosphoric acid. 

Developments in the production of acetaldehyde from acetylene have focussed attention on this reaction. Alcohols may also be formed from olefines. Sulphuric acid (20—4 5%), phosphoric acid 30—35%), or acetic acid (96%), in presence of a mercury salt may be employed. Selenium dioxide has been used for a similar purpose. (J. C. S., 1932, 2342.) See also, A. C. R 1934,123. 

This method finds commercial application in the production of acetaldehyde from acetylene. Mercuric salts in the presence of dilute sulfuric acid act as the catalyst. The reaction has been extended to higher alkylacetylenes, which are obtained in about 60% yield from sodium acetylide and alkyl halides. These compounds are readily hydrated in aqueous solutions of acetone, methanol, or acetic acid to give 80-90% yields of the corresponding methyl ketones, fot example, methyl butyl, methyl amyl, and methyl hexyl ketones. Hydration has been accomplished by passing the acetylenic hydrocarbon and steam over a phosphoric acid catalyst at 150-204° and atmospheric pressure. ... 

Derivation By-product in the production of acetaldehyde from acetylene. 

Acyclic aldehydes from acetylene—e.g., acetaldehyde from acetylene... 

This reaction was first reported by Fittig and Schrohe in 1875 and subsequently extended by Kutscheroff in 1881. It is an acid-catalyzed hydration of alkynes into ketones. In this reaction, dilute sulfuric acid and mercuric salt are used as catalysts, and mercuric chloride can form a complex with acetylene in aqueous solution. This reaction has been used to prepare ketones from higher alkynes, such as propyne, and vinylacetylene as well as in commercial production of acetaldehyde from acetylene. ... 

Since 1960, the Hquid-phase oxidation of ethylene has been the process of choice for the manufacture of acetaldehyde. There is, however, stiU some commercial production by the partial oxidation of ethyl alcohol and hydration of acetylene. The economics of the various processes are strongly dependent on the prices of the feedstocks. Acetaldehyde is also formed as a coproduct in the high temperature oxidation of butane. A more recently developed rhodium catalyzed process produces acetaldehyde from synthesis gas as a coproduct with ethyl alcohol and acetic acid (83—94). 

From Acetylene. Although acetaldehyde has been produced commercially by the hydration of acetylene since 1916, this procedure has been almost completely replaced by the direct oxidation of ethylene. In the hydration process, high purity acetylene under a pressure of 103.4 kPa (15 psi) is passed into a vertical reactor containing a mercury catalyst dissolved in 18—25% sulfuric acid at 70—90°C (see Acetylene-DERIVED chemicals). 

In the United States butadiene was prepared initially from ethanol and later by cracking four-carbon hydrocarbon streams (see Butadiene). In Germany butadiene was prepared from acetylene via the following steps acetylene — acetaldehyde — 3-hydroxybutyraldehyde — 1,3-butanediol — ... 

Chemical Uses. In Europe, products such as ethylene, acetaldehyde, acetic acid, acetone, butadiene, and isoprene have been manufactured from acetylene at one time. Wartime shortages or raw material restrictions were the basis for the choice of process. Coking coal was readily available in Europe and acetylene was easily accessible via calcium carbide. 

Most of the vinyl acetate produced in the United States is made by the vapor-phase ethylene process. In this process, a vapor-phase mixture of ethylene, acetic acid, and oxygen is passed at elevated temperature and pressures over a fixed-bed catalyst consisting of supported palladium (85). Less than 70% oxygen, acetic acid, and ethylene conversion is realized per pass. Therefore, these components have to be recovered and returned to the reaction zone. The vinyl acetate yield using this process is typically in the 91—95% range (86). Vinyl acetate can be manufactured also from acetylene, acetaldehyde, and the hquid-phase ethylene process (see Vinyl polymers). 

Hydrogenation of Acetaldehyde. Acetaldehyde made from acetylene can be hydrogenated to ethanol with the aid of a supported nickel catalyst at 150°C (156). A large excess of hydrogen containing 0.3% of oxygen is recommended to reduce the formation of ethyl ether. Anhydrous ethanol has also been made by hydrogenating acetaldehyde over a copper-on-pumice catalyst (157). 

Ethylene is produced in quantity using acetylene or propylene as feedstock to make a large number of products (Figure 7.2-3) such as acetaldehyde, acrylonitrile, acetic acid, and acetic anhydride. These are made generally from acetylene which is made from calcium carbide. 

North American producers of, 7 129t physical properties of, 7.T15-117 5 29t production from acetaldehyde, 7 102, 111 production from acetylene, 7 219 production from carbon monoxide, 5 4-5 production of, 76 299 24 265... 

S)-(-)-CITRONELLOL from geraniol. An asymmetrically catalyzed Diels-Alder reaction is used to prepare (1 R)-1,3,4-TRIMETHYL-3-C YCLOHEXENE-1 -CARBOXALDEHYDE with an (acyloxy)borane complex derived from L-(+)-tartaric acid as the catalyst. A high-yield procedure for the rearrangement of epoxides to carbonyl compounds catalyzed by METHYLALUMINUM BIS(4-BROMO-2,6-DI-tert-BUTYLPHENOXIDE) is demonstrated with a preparation of DIPHENYL-ACETALDEHYDE from stilbene oxide. A palladium/copper catalyst system is used to prepare (Z)-2-BROMO-5-(TRIMETHYLSILYL)-2-PENTEN-4-YNOIC ACID ETHYL ESTER. The coupling of vinyl and aryl halides with acetylenes is a powerful carbon-carbon bond-forming reaction, particularly valuable for the construction of such enyne systems. 

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... 

Acetic acid is one of the oldest known chemicals. Dilute acetic acid, vinegar, has been made by aerobic bacterial oxidation of ethanol. It has also been reclaimed by extraction or extractive distillation from pyroligneous acid, which was obtained from the extractive distillation of wood (J ). In the early nineteen hundreds, oxidation of acetaldehyde became the main source of acetic acid. The acetaldehyde has been obtained from acetylene ( ). ethylene (3) or ethanol as indicated below. 

A number of routes are available for the synthesis of 2,2 -bipyridines where one of the pyridine rings is built up from simpler entities. For example, condensation of 2-(aminomethyl)pyridine (31) with acetaldehyde or acetylene over a silicon-alumina catalyst at 450°C gives 2,2 -bipyridine, ° whereas 2-cyanopyridine reacts with acetylene at 120°C in the presence of a cobalt catalyst to afford 2,2 -bipyridine in 95% yield.2-Acetylpyridine with acrolein and ammonia gives 2,2 -bipyridine in the presence of dehydrating and dehydrogenating catalysts, and related condensations afford substituted 2,2 -bipyridines. ° In a similar vein, condensation of benzaldehyde with 2 mol of 2-acetylpyridine in the presence of ammonia at 250°C affords 2,6-di(2-pyridyl)-4-phenylpyridine, ° and related syntheses of substituted 2,2 6, 2"-terpyridines have been described. Likewise, formaldehyde with two moles of ethyl picolinoylacetate and ammonia, followed by oxidation of the product and hydrolysis and decarboxylation, affords a good... 

In the mid-l O s, it was found that acetic acid itself could be catalytically dehydrated to ketene, which when absorbed in fresh acid gave the anhydride. Soon after this process became commercially established, the older processes of making the anhydride were discontinued. By this time synthetic acetic acid was being made from acetylene via acetaldehyde oxidation, from synthetic ethyl alcohol also via acetaldehyde, and by the direct oxidation of fermentation ethyl alcohol. The ketene route to acetic anhydride, in addition to starting from acetic acid, later employed acetone as raw material. 

Catalysts used to convert ethylene to vinyl acetate are closely related to those used to produce acetaldehyde from ethylene. Acetaldehyde was first produced industrially by the hydration of acetylene, but novel catalytic systems developed cooperatively by Farbwerke Hoechst and Wacker-Chemie have been used successfully to oxidize ethylene to acetaldehyde, and this process is now well established (7). However, since the largest use for acetaldehyde is as an intermediate in the production of acetic acid, the recent announcement of new processes for producing acetic acid from methanol and carbon monoxide leads one to speculate as to whether ethylene will continue to be the preferred raw material for acetaldehyde (and acetic acid). 

Acetaldehyde is a useful huilding block for acetic aod, acetic anhydride. and chloral Ills currently produced from ethylene, ethanol, propane, and butane Production from acetylene appear to be outdated... 

The principle of this method has been utilised on the industrial scale, and with success for the preparation of acetone. The acetic acid may be prepared from acetylene via acetaldehyde (see p. 433), thus providing a commercial synthesis of acetone from coke. 

In about 2 hours the beads adhere together somewhat then paracet-aldehyde begins to collect at the bottom of the bottle. Water is added, 2—3 c.cs. at a time, at intervals during the formation. The yield is good, and there is practically no escape of acetylene or acetaldehyde from the apparatus. The action consists in the formation of a mercuric sulphate acetylene compound and its subsequent decomposition giving paracet-aldehyde. The passage of acetylene should be continued for about 2 days. The contents of the bottle are finally shaken up with ether, the ethereal solution separated, dried over anhydrous sodium sulphate, and distilled. Paracetaldehyde passes over as a colourless liquid, boiling point 124°. 

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