75524-53-7Relevant academic research and scientific papers
Theoretical and experimental studies on the Baeyer-Villiger oxidation of ketones and the effect of α-halo substituents
Grein, Friedrich,Chen, Austin C.,Edwards, David,Crudden, Cathleen M.
, p. 861 - 872 (2007/10/03)
The Baeyer-Villiger reactions of acetone and 3-pentanone, including their fluorinated and chlorinated derivatives, with performic acid have been studied by ab initio and DFT calculations. Results are compared with experimental findings for the Baeyer-Villiger oxidation of aliphatic fluoro and chloroketones. According to theoretical results, the first transition state is rate-determining for all substrates even in the presence of acid catalyst. Although the introduction of acid into the reaction pathway leads to a dramatic decrease in the activation energy for the first transition state (TS), once entropy is included in the calculations, the enthalpic gain is lost. Of all substrates examined, pentanone reacts with performic acid via the lowest energy transition state. The second transition state is also lowest for pentanone, illustrating the accelerating effect of the additional alkyl group. Interestingly, there is only a small energetic difference in the transition states leading to migration of the fluorinated substituent versus the alkyl substituent in fluoropentanone and fluoroacetone. These differences match remarkably well with the experimentally obtained ratios of oxidation at the fluorinated and nonfluorinated carbons in a series of aliphatic ketones (calculated, 0.3 kcal/mol, observed, 0.5 kcal/mol), which are reported herein. The migration of the chlorinated substituent is significantly more difficult than that of the alkyl, with a difference in the second transition state of approximately 2.6 kcal/mol.
Hard Acid and Soft Nucleophile Systems. Part 11. Har-Soft Affinity Inversion: Dehalogenation of α-Halogeno Ketones with Aluminium Chloride and a Thiol
Fuji, Kaoru,Node, Manabu,Kawabata, Takeo,Fujimoto, Mayumi
, p. 1043 - 1048 (2007/10/02)
α-Halogeno ketones have been dehalogenated with a combination of aluminium chloride and ethanethiol.The mechanism involved in deiodination and debromination differs from that of dechlorination and defluorination.A hard-hard interaction between carbonyl oxygen and aluminium chloride and a soft-soft interaction between iodine or bromine and thiol are the dominant factors for direct deiodination and debromination.In dechlorination and defluorination there is initial formation of the corresponding dithioacetal, whereby hard carbonyl oxygen is replaced by the soft sulphur atom. α-Chloro- and α-fluoro-dithioacetals then undergo dehalogenation to afford vinyl sulphide as a result both of a favourable soft-soft interaction between the sulphur atoms in the dithioacetal entity and thiol, and also a favourable hard-hard interaction between the nucleopilic chlorine or fluorine and aluminium chloride. α-Chloro- and α-fluoro-benzyl benzyl ketones afforded the dehalogenated product with concomitant 1,2-transposition of the carbonyl group.This suggests that there is an indirect path which operates competitively via a 1,2-dithio-olefin from α=halogenodithioacetals to vinyl sulphide.Addition of thiol to vinyl sulphide leads to the final product.A concept of hard-soft affinity inversion is proposed.
TAMING ELEMENTAL FLUORINE: INDIRECT USE OF FLUORINE FOR THE SYNTHESIS OF α-FLUOROKETONES
Rozen Shlomo,Menahem, Ynon
, p. 19 - 32 (2007/10/02)
Fluorine and sodium trifloroacetate react at -75 deg to produce a variety of fluoroxy-compounds.Although it is possible to direct the reaction towards the formation of CF3COOF or CF3CF2O, mixtures may be used when only the electrophilic fluorine has to be
