Methane from acetaldehyde

OaN)aCH-CH(CHs>NH2. Yel crysts, mp decompca 120°. Can be prepd from acetaldehyde-ammonia, CHsCH(OH)NMa and dinitro-methane... 

In the reaction of peracetic acid with acetaldehyde (in the absence of oxygen) the majority of the methyl radicals abstract hydrogen, preferentially from acetaldehyde, to form methane ... 

From Acetaldehyde and Malonic Acid.—Another synthesis proves the constitution of crotonic acid as A2-butenoic acid. A di-basic acid known as malonic acid has the constitution of di-carhoxy methane HOOC—CH2—COOH. When this acid is heated with acetaldehyde (paraldehyde) and glacial acetic acid condensation occurs as in the synthesis of crotonic aldehyde and in the Perkin-Fittig synthesis (p. 172). A dibasic acid is obtained which loses carbon dioxide and yields a mono-basic acid which is crotonic acid. 

Ozonide (5ab) prepared from acetaldehyde containing 21.05% oxygen-18 was treated with excess methyllithium in an apparatus which allowed collection of evolved gases. In every case, at least 1 mole of methane was collected (small traces of water accounted for some of the methane). Analysis of the product mixture by GPC revealed isopropyl alcohol (9) and 3-methyl-2-butanol (10) in approximately equimolar amounts and in high yield (ca. 60%, by GPC). 

Because hydrogen can easily be removed from a reaction stream, many dehydrogenations have been studied. These include dehydrogenation of methane to carbon,326 ethane to ethene,327,328 propane to propene,329 n-butane to butenes,330 isobutane to isobutene,331,332 cyclohexane to benzene,332-334 meth-ylcyclohexane to toluene 335 n-heptane to toluene,336 methanol to formaldehyde,330 and ethanol to acetaldehyde.337... 

Extensive experimental and theoretical studies on hydrogen production from SRE have been reported. In the thermodynamic studies carried out by Vasudeva et al. [190], it was reported that in all ranges of conditions considered, there is nearly complete conversion of ethanol and only traces of acetaldehyde and ethylene are present in the reaction equilibrium mixture. Methane formation is inhibited at high water-to-ethanol ratios or at high temperatures [191]. 

The distribution of by-products originating from the methyl group in acetaldehyde oxidation is significantly different for each catalyst. Typical results are presented in Table II. Methane is the predominant by-product with cobalt acetate, while methane and carbon dioxide and methyl esters and carbon dioxide predominate with manganese and copper acetates, respectively. 

Reaction 22a is important only with cobalt acetate catalyst and accounts for the fast rate of methane formation during the reaction of peracetic with acetaldehyde. It can also explain how methane is produced only from the methyl group of peracetic acid. This reaction path is more important with cobalt probably because of the higher oxidation potential of the cobalt (III)-cobalt (II) couple relative to that of the manganese (III) -manganese (II) couple. 

Two isomers are described in the literature 2-Methyl-l,2,3-propanetriol or f3-Methylgylcerol, CH2(OH).C(CH3XOH).CH2.OH, col vis liq, bp 115-20° at 1.6mm. d 1.186 at 20°, nD 1.4730 at 20°, can best be prepd by hydration of /S-methyl-glycidol(2,3-epoxy- 2-metiiyl-l-propanol), and can be prepd directly from either dichloro-tert-butyl alcohol or /3-methylglycerol monochlorohydrin(Ref 2). See also Refs 1,4 5) and 2-(Hydroxymetby[)-l,3-propanediol or Trimethylol Methane, CH2(OH).CH(CH2OH)2 was prepd by Fujii(Ref 3) from a mixt of acetaldehyde formaldehyde(10 25 mol) heated with Ca(OH)2 and the product reduced with H in the presence of Ni... 

In contrast, the newly-generated CO in Equations 10.25 and 10.26 removes extra energy from the discharge reactions, such that the CO molecules will be in an excited state and react easily with methane to generate acetaldehyde [88] ... 

Further Reduction to a Hydrocarbon. In the reduction of benzo-phenone with aluminum ethoxide the formation of 7% of diphenyl-methane was observed. When benzohydrol was treated with aluminum ethoxide under the same conditions, 28% reduction to diphenylmethane occurred.12 In these reactions acetic acid, rather than acetaldehyde,-was formed from the ethoxide. Aluminum isopropoxide does not give this type of undesirable reaction with this reagent, pure benzohydrol is easily obtained in 100% yield from benzophenone.6 37 However, one case of reduction of a ketone to the hydrocarbon has been observed with aluminum isopropoxide.17 When 9, 9-dimethylanthrone-10 (XU) was reduced in xylene solution, rather than in isopropyl alcohol, to avoid formation of the ether (see p. 190), the hydrocarbon XUII was formed in 65% yield. The reduction in either xylene or isopropyl alcohol was very slow, requiring two days for completion. 

This is probably because 0 atoms produced in primary process (45) react much more rapidly with C2H6 than with N20. Several products are formed including ethylene, butane, carbon monoxide, hydrogen, methane, and probably ethanol and acetaldehyde. More ethylene is formed than one would expect from the amount of butane. It was found that 0 atoms react rapidly with ethylene, which is one of the photolytic products. The reaction-rate constant of O atoms with ethylene is estimated to be about 330 times as rapid as that with ethane.82 Complete elucidation of the mechanism of O-atom reaction with ethane is complicated because of the rapid reaction of O atoms with one or more of the products. 

It also can be produced directly from natural gas, methane, and other aliphatic hydrocarbons, but this process yields mixtures of various oxygenated materials. Because both gaseous and liquid formaldehyde readily polymerize at room temperature, formaldehyde is not available in pure form. It is sold instead as a 37 percent solution in water, or in the polymeric form as paraformaldehyde [HO(CH20)nH], where n is between 8 and 50, or as trioxane (CH20)3. The greatest end use for formaldehyde is in the field of synthetic resins, either as a homopolymer or as a copolymer with phenol, urea, or melamine. It also is reacted with acetaldehyde to produce pentaerythritol [C(CH2OH)4], which finds use in polyester resins. Two smaller-volume uses are in urea-formaldehyde fertilizers and in hexamethylenetetramine, the latter being formed by condensation with ammonia. 

The direct observation of the acetyl radical from the reaction of hydrogen atoms with acetaldehyde is particularly important because recent studies of the reaction in the gas phase have led to conflicting conclusions. McKnight et al. (1967) concluded that the acetyl radical is formed, whereas Lambert e< a . (1967) suggested that the initial reaction yielded the formyl radical and methane. Clearly the low-temperature result supports the former interpretation. 

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