Ethylene acetaldehyde

The changeover from ROO radicals to HOO radicals and the switch from organic peroxides to HOOH has been shown as temperature is increased in propane VPO (87,141). Tracer experiments have been used to explore product sequences in propane VPO (142—145). Propylene oxide comes exclusively from propylene. Ethylene, acetaldehyde, formaldehyde, methanol, carbon monoxide, and carbon dioxide come from both propane and propylene. Ethanol comes exclusively from propane. 

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. 

Grouping Acetone Ethane Ethyl-acetate Acetylene Ethyl amine Ethylene Acetaldehyde Ethyl glycol Crude oil Ethyl-ether Carbon disulphide Ethyl Nitrite... 

Ethylene can be oxidized to a variety of useful chemicals. The oxidation products depend primarily on the catalyst used and the reaction conditions. Ethylene oxide is the most important oxidation product of ethylene. Acetaldehyde and vinyl acetate are also oxidation products obtained from ethylene under special catalytic conditions. 

With lowering of the temperature, the selectivities for ethylene, acetaldehyde and ethanol were significantly enhanced. The highest selectivity for ethylene in the case of MnMo04 was 28%, while in the other two cases they were 22-25%. The selectivity for acetaldehyde was the highest (8%) on MnM04 (Figure 3). 

Oxidations of other materials Hydrogen Ethylene Acetaldehyde Ethane... 

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). 

The photoreactions of saturated five-membered heterocycles are generally characterized by initial carbon-heteroatom bond homolysis. Tetrahydro-furans150 and 1,3-dioxolans151 behave in this way, and the major photoproducts of 2,2-dimethyl-1,3-dioxolan, for example, are acetone, propyl acetate, ethylene, acetaldehyde, methyl acetate, and oxiran. The vinyltetrahy-drofuran (180) is converted on irradiation in methanol to the ketal (181) and the ketone (182) by way of a Wagner-Meerwein shift in the carbocation... 

Oxidation of organic compounds such as toluene, cumene, o-xylene, ethylene, acetaldehyde, butane, sec-butyl benzene. 

Decomposition/ dehydration of ethanol M ex.- SiOj-R, ( M= Na,K, Li, Cu, La, Tn, Mg. The main products were ether, ethylene, acetaldehyde and hydrogen. (Zn)Si-R gave high selectivity for acetaldehyde. 57... 

The photolysis of dimethyl and diethyl ethers in the gas phase was first studied by Harrison and Lake (172) using a hydrogen discharge lamp. They reported the formation of formaldehyde from dimethyl ether, and ethylene, acetaldehyde, and formaldehyde from diethyl ether. 

The future of the commercial acetaldehyde processes mainly depends on the availability of cheap ethylene. Acetaldehyde has been replaced as a precursor for 2-ethylhexanol ( aldol route ) or acetic acid (via oxidation cf. Sections 2.1.2.1 and 2.4.4). New processes for the manufacture of acetic acid are the Monsanto process (carbonylation of methanol, cf. Section 2.1.2.1), the Showa Denko one-step gas-phase oxidation of ethylene with a Pd-heteropolyacid catalyst [75, 76], and Wacker butene oxidation [77]. Other outlets for acetaldehyde such as pentaerythritol and pyridines cannot fill the large world production capacities. Only the present low price of ethylene keeps the Wacker process still attractive. 

Acetoxylations (oxyacylations) have to be seen in context with olefin oxidation to carbonyl compounds (Wacker process, Section 2.4.1). With the lowest olefin, ethylene, acetaldehyde is formed. In water-free acetic acid no reaction takes place. Only in the presence of alkali acetates - the acetate ion shows higher nu-cleophilicity than acetic acid - ethylene reacts with palladium salts (eq. (1)) to give vinyl acetate, the expected product, as first reported by Moiseev et al. [1]. Stem and Spector [2] independently used [HP04] as base in a mixture of isooctane and acetic acid. This reaction could be exploited for a commercial process to produce vinyl acetate and closed the last gap replacing acetylene by the cheaper ethylene, a petrochemical feed material, for the production of large-tonnage chemical intermediates. 

Many workers consider that ethylene oxide isomerizes to acetaldehyde (18). Twigg suggests that formaldehyde and acetaldehyde are intermediates both in the stepwise and in the direct formation of carbon dioxide. The contribution of aldehydes to oxidation processes may be found out by oxidizing ethylene-acetaldehyde and ethylene-formalde-... 

The most important processes with respect to scale are p-xylene — teiephthalic acid, ethylene — ethylene oxide, ethylene — acetaldehyde, ethylene/HOAc — vinyl acetate, methanol — formaldehyde, acetaldehyde — acetic acid. 

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