Ketone, alicyclic large ring

Ketocarbenes of type (21) obtained from acyclic and medium to large ring alicyclic a-diazo ketones (20) are prone to react by way of an intramolecular [1,2] H-shift, especially under catalytic conditions, to afford a, 3-unsaturated ketones (22). °4 -60 Pranzen has shown that the Wolff rearrangement of diazo ketones (20) is favored if temperatures in excess of 100 °C are used in the photochemical or Ag20-pro-moted decompositions. Related [1,2] methyl shifts can also occur, and this pathway is the principal decomposition route of 4-diazo-2,2,5,5-tetramethyl-3-hexanone. ... 

Formation of large ring alicyclic ketones from dicarboxylic acids by thermal decomposition of salts with metals of the second and fourth groups of the periodic table (Ca, Th, Ce) ... 

The enthalpy of fomation of two such species has been measured, namely the cyclopropane and cycloheptane derivatives. The difference between the values for these two species, both as solids, is 238.1 kJmol . Is this difference plausible Consider the difference between the enthalpies of formation of the parent cycloalkanes as solids, 194 kJ mol . The ca 44 kJ mol discrepancy between these two differences seems rather large. However, there are idiosyncracies associated with the enthalpies of formation of compounds with three-membered rings and almost nothing is known at all about the thermochemistry of compounds with seven-membered rings. Rather, we merely note that a seemingly well-defined synthesis of cycloheptyl methyl ketone was shown later to result in a mixture of methyl methylcyclohexyl ketones, and superelectrophilic carbonylation of cycloheptane resulted in the same products as methylcyclohexane, namely esters of 1-methylcyclohexanecarboxylic acid. The difference between the enthalpies of formation of the unsubstituted alicyclic hydrocarbons cycloheptane and methylcyclohexane as solids is 33 kJmol . This alternative structural assignment hereby corrects for most of the above 44 kJ mol discrepancy in the enthalpies of formation of the two oximes. More thermochemical measurements are needed, of oximes and cycloheptanes alike. 

Thorough kinetics studies of the chlorination of aliphatic, alicyclic, and arylalkyl ketones with CBT were carried out by Indian workers (82PIA921). Kinetic measurements were performed using aqueous acetic acid and the addition of HC104 and NaCl. In the presence of mineral acid the reaction is first order in ketone and acid and zero order in CBT. A large kinetic isotopic effect was observed (for acetone kHlkD = 6.6). Addition of chloride ion causes some changes in the reaction order they become first order in CBT, 0.6 in ketone, and 0.2 in chloride ion. The rate constant for chlorination of substituted acetophenones correlate with a constants for substituents in the aryl ring (p is -0.57). On the basis of these data the mechanism in the absence and in the presence of chloride ion was developed. 

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