Propanone, decomposition product

In an intramolecular version of ketocarbenoid a-C/H insertion, copper-promoted decomposition of l-diazo-3-(pyrrol-l-yl)-2-propanone (258a) or l-diazo-4-(pyrrol-l-yl)-2-butanone (258b) resulted in quantitative formation of the respective cycli-zation product 259 242 >. The cyclization 260 -> 261, on the other hand, is a low-yield reaction which is accompanied by olefin formation. The product ratio was found to vary with the copper catalyst used, but the total yield never exceeded 35 % 243>. 

The decomposition of lignin into aromatic repeat units is a long practiced art that reached its zenith around 1800 a.d. Production of chemicals by wood pyrolysis was extensively practiced until, between 1750 and 1850 a.d., coal slowly displaced wood as the major chemical source available to man. Wood is usually pyrolyzed at 260-4 lO C and lignin at 300-440 C to produce 50 wt % charcoal, 10-15% tar, and lesser amounts of 2-propanone, ethanoic acid, and methanol [16-181. The tar is often called wood creosote and is a complex mixture of substituted phenols and aromatics. It contains phenol, 2- and 4-methylphenol, 2,4-dimethylphenol, 2-methoxyphenol, 4-methyl-2-methoxyphenol, and 4-ethyl-2-methoxyphenol [19]. 

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