Butanone, decomposition product

The simple stoichiometry, the first-order kinetics as well as the absence of inhibition all indicate that the decompositions of methyl cyclobutyl ketone and cyclo-butanone proceed according to a simple unimolecular mechanism. However, the experimental results do not rule out the intermediateformation of biradicals. The presence of trace amounts of cyclopropane, detected among the decomposition products of cyclobutanone, could be considered as evidence for this, although, due to analytical difficulties, the presence of cyclopropane cannot be regarded as unequivocally established. 

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>. 

Intermolecular cyclopropanation of diazoketones is an effective method in organic synthesis. Wenkert and coworkers have applied this methodology to the synthesis of a substantial number of cyclopropane adducts 2868, 2969 and 307° which are synthetic intermediates in the preparation of natural products (equations 41—43). Copper catalysts were chosen for these transformations. Another interesting application of intermolecular cyclopropanation is to be found in Daniewski s total synthesis of an aromatic steroid. Palladium(II) acetate catalysed decomposition of 4-bromo-l-diazo-2-butanone in the presence of m-methoxystyrene was used to give the cyclopropyl ketone 31 which was a key intermediate in the total synthesis (equation 44)71. 

The important concentration-time profiles include those for 1,2- and 2,3-epoxybutane, 2-methyloxetan, tetrahydrofuran, butyraldehyde and 2-butanone, the relative concentrations of these products being determined by the relative rates of 1- and 2-butylperoxy radical isomerization and decomposition. The kinetic data used to represent these reactions were the parameters recommended by Walker [229] in 1961. The formation of butyraldehyde and 2-butanone require internal isomerizations of the form... 

Diazirines can be formed by photoisomerization of diazo compounds. Irradiation of perfluoro-3-diazo-2-butanone (272) at wavelengths >320 nm either at RT in carbon tetrachloride solution or at 77K in an argon matrix yielded perfluoroacetyhnethyl-diazirine (273), together with products resulting from decomposition of the diazo compound to a carbene. ... 

The 24 hour photolysis of chlorendic anhydride (III) in acetone in the presence of diethoxyacetophene (IV) yielded at least twelve measurable products as observed by the GC/MS procedure (Table I). Some of the products observed, i.e. 4-methyl-4-hydroxy-2-pentanone, biacetal, 4-methyl-3-pentene-2-one, ethyl acetate, 3-methyl-3-hy-droxy-2-butanone, 4-methyl-2-pentanone, and 2,4-pentane-dlone, are clearly derived from the photochemically induced decomposition of acetone and/or dlethoxyacetophe-none. 

The total quantum yield of decomposition of 3-methyl-2-butanone as estimated by Lissi et al. (1973/1974) from an extrapolation of the product yields to zero absorbed light intensity gave 0.75. This is in good agreement with that derived from co = 0.78 estimated by Zahra and Noyes (1965) in photolysis at 127°C. 

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