26708-31-6Relevant academic research and scientific papers
Chlorination of α,β-Unsaturated Ketones and Esters in the Presence of Acid Scavengers
Heasley, Victor L.,Elliott, Stephen L.,Erdman, Paul E.,Figueroa, Daphne E.,Krosley, Kevin W.,et al.
, p. 393 - 399 (2007/10/02)
The chlorination of a series of α,β-unsaturated ketones and esters by Cl2 in CH3OH, with and without acid scavengers such as N-chlorosuccinimide (NCS), pyridine and 2,6-lutidine, is described.Methyl vinyl ketone and cyclohex-2-enone have also been chlorinated in ethanol.Mixtures of Markovnikov(M) and anti-Markovnikov(AM) methoxy chlorides and dichlorides are formed in most cases; phenyl vinyl ketone gives no M products in the absence of pyridine, M methoxy chloride is not formed with (E)-4-chlorobut-3-en-2-one under any conditions, pyridine has no effect on the product ratios and methyl 3-chlorobut-2-enoate forms only dichloride.Chlorination of the ketones in the presence of the pyridines results in a significant increase in the M regioisomer (except for methyl isopropenyl ketone and the ketones mentioned), giving M : AM ratios which are similar to the corresponding esters.Ratios for the esters are not affected significantly by pyridine.We ascribe the effect of the pyridine bases to the elimination of acid and the acid-catalysed mechanism, permitting the chlorination to occur via a carbon-carbon ?-bond (chloronium ion) mechanism.The rate of chlorination of methyl vinyl ketone is retarded by pyridine but is still considerably faster than methyl acrylate.NCS, in contrast to N-bromosuccinimide (NBS) reported previously, has no effect on the M : AM ratio.The chlorination of methyl vinyl ketone with NCS and HCl gives markedly different results from Cl2.
ADDITION OF CHLORINE, BROMINE AND BROMINE CHLORIDE TO SOME α,β-UNSATURATED METHYL ESTERS
Korhonen, Ilpo O. O.,Pitkaenen, Maija,Korvola, Jorma N. J.
, p. 2837 - 2841 (2007/10/02)
The additions of chlorine, bromine and bromine chloride to trans methyl 2-butenoate 1, trans methyl 2-methyl-2-butenoate 2 and methyl 3-methyl-2-butenoate 3 under ionic conditions were studied.Bromine chloride addition always gave as a major regioisomer the 2-bromo-3-chloro compound, almost quantitatively in the case of 3.The mechanism of bromonium ion ring-opening (SN1 or SN2) is discussed with respect to the double bond substitution and regioisomer proportions.The dihalo products were identified by MS, 1H and 13C NMR.
