86428-68-4Relevant articles and documents
COMPARISON OF SYN DEHYDROHALOGENATIONS FROM TANS-1-BROMO-2-CHLOROCYCLOALKENES PROMOTED BY COMPLEX BASE AND BY POTASSIUM TERT-BUTOXIDE
Croft, Alan P.,Bartsch, Richard A.
, p. 2737 - 2740 (1983)
Compared with t-BuOK-t-BuOH, syn eliminations from trans-1-bromo-2-chlorocycloalkanes (C4-C8) induced by NaNH2-NaO-t-Bu in THF are rapid, exhibit greater propensity for dehydrochlorination and show little sensitivity to ring size of the dihalocycloalkane.
ALKENE EPOXIDATIONS CATALYSED BY CHEMICALLY ROBUST Mn(III) PORPHYRINS AND PROMOTED BY HOCl UNDER AQUEOUS-ORGANIC TWO-PHASE CONDITIONS IN THE ABSENCE OF AXIAL LIGAND AND PHASE-TRANSFER CATALYST: REACTION MECHANISM AND LARGE-SCALE PREPARATIVE APPLICATIONS
Banfi, Stefano,Dragoni, Massimo,Montanari, Fernando,Pozzi, Gianluca,Quici, Silvio
, p. 431 - 436 (2007/10/02)
Under CH2Cl2/H2O two-phase conditions alkene epoxidations, catalysed by Mn(III)-porphyrins and promoted by aqueous NaOCl adjusted at pH 10.0 with NaHCO3, proceed in the absence of a phase-transfer catalyst and, for electron-rich olefins, also in the absence of axial ligands.Under these conditions, reliable kinetic measurements on cyclooctene epoxidation can be obtained by using the chemically robust Mn(III)-tetra(2,6-dichlorophenyl)porphyrin chloride, as the side reactions associated with the oxidative demoliton of the axial ligand and of the quaternary onium salts donot occur.The results indicate that reactions follow Michaelis-Menten saturation kinetics which are confirmed by the oxidation rates of different substrates in competitive epoxidations.The absence of strong axial ligands, like pyridine or imidazole bases, highlights the autocatalytic behaviour of the reactions, probably because the produced epoxides act as weak axial ligands.Indeed, reactions are noticeably accelerated by initial addition of consistent amounts of epoxides.Under the conditions reported here electron-rich olefins can be oxidised on a large scale, the overall catalyst turnovers being in the range 30,000-100,000 in 20-24 h at 20 deg C.
