Neutral Trichloroacetylations of Alcohols by Hexachloroacetone
The addition of simple alcohols in hexachloroacetone (HCA) in the presence of strong hydrogen bond acceptors (e.g., dimethylformamide) results in a high yield of the corresponding trichloroacetate (via a haloform reaction scheme).The trichloroacetylation reactions are carried out under neutral conditions, and the resultant ester can easily be separated from the reaction mixture via extraction/distillation procedures.Kinetic evidence demonstrates that the trichloroacetylation of alcohols by HCA is a stereoselective process, and further studies suggest that the catalytic role of the acceptors is of a hydrogen bonding nature.
Freedlander, Richard S.,Bryson, Thomas A.,Dunlap, R. Bruce,Schulman, E. M.,Lewis, Charles A.
IR SPECTRA, METHYLENE CHAIN VIBRATIONS AND ROTATIONAL ISOMERISM OF n-ALKYL TRICHLOROACETATES
IR spectra of ten n-alkyl trichloroacetates CCl3COO(CH2)nCH3 (R'-TCA) in the crystalline state (R'-TCAs with n=4, 5 in the glassy state) have been studied.End-group (CCl3COO-) vibrations have been assigned by referring to the previous results for methyl and ethyl analogs and four methylene band progressions have been analyzed.Interaction between methylene and end-group vibrations is discussed.It is suggested that in the crystalline state the nP-TCA (n=2) molecule takes a gauche conformation only in O-CH2-CH2CH3 group and the other R'-TCA molecules adopt the all-trans extended form relative to skeletal rotational axes.
Mido, Yoshiyuki,Komatsu, Nobuhiro,Morcillo, Jesus,Garcia, M. Victoria