Acetylene glyoxal production

Acetaldehyde, first used extensively during World War I as a starting material for making acetone [67-64-1] from acetic acid [64-19-7] is currendy an important intermediate in the production of acetic acid, acetic anhydride [108-24-7] ethyl acetate [141-78-6] peracetic acid [79-21 -0] pentaerythritol [115-77-5] chloral [302-17-0], glyoxal [107-22-2], aLkylamines, and pyridines. Commercial processes for acetaldehyde production include the oxidation or dehydrogenation of ethanol, the addition of water to acetylene, the partial oxidation of hydrocarbons, and the direct oxidation of ethylene [74-85-1]. In 1989, it was estimated that 28 companies having more than 98% of the wodd s 2.5 megaton per year plant capacity used the Wacker-Hoechst processes for the direct oxidation of ethylene. 

The primary products of the oxidation and hydrolysis of acetylene may be assumed to be respectively glyoxal aud acetaldehyde ... 

The wholly homogeneous character of the oxidation of acetylene has recently been demonstrated and evidence accumulated to support a chain type of reaction.90 The reaction thus appears to be similar to that of ethylene oxidation in regard to kinetics.96 At temperatures of 250° to 315° C. the oxidation proceeded through the stages of glyoxal, formaldehyde, formic acid, carbon dioxide and water. All of the reaction products were isolated and a mechanism, similar to that shown here was postulated ... 

In the presence of nitrogen oxides the reaction between acetylene and oxygen proceeds as a homogeneous reaction catalyzed by NO,.103 Trimeric glyoxal was found to be the major product of the reaction. Formaldehyde, formic acid, carbon oxides, hydrogen, and water constituted the remainder of the product. Under the conditions of the experiments and at temperatures below 260° C. acetylene does not react with NO. 

The action of ozone on acetylene is very violent and explosions result when the reaction is conducted in the vapor phase. However, it is possible to study the mechanism of the reaction by carrying out the ozonization in solution. The ozonide formed in this way is too unstable to be isolated and only by allowing a very slow decomposition to occur by slow evaporation of the solvent is it possible to isolate reaction products. In this way, it has been found that the material remaining after evaporation of the solvent consists of a large proportion of glyoxal (SI per cent) and a small amount of formic acid (5.6 per cent).1,12 The decomposition of the ozonide of acetylene differs from that of ethylene in that the linkage of carbon to carbon is not destroyed. The direct oxidation of acetylene with ozone, however, results in die formation oi formic acid and carbon dioxide.188... 

The destruction of acetylene in the atmosphere occurs only by reaction with OH radicals (Siese and Zetzsch 1995). Typical products are HO2, glyoxal (CHO—CHO), but SOA formation (Volkamer et al. 2009) is also found under laboratory conditions. The polymerization of C2H2 after radiolysis has long been known. 

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