1,721,048 research outputs found
Anion nucleophilicity in ionic liquids: a comparison with traditional molecular solvents of different polarity
No full textThe nucleophilic reactivity of a homogeneous series of anions (halides, pseudohalides and organic anions) in the ionic liquids [hexmim] [ClO4] and [hexmim] [PF6] has been measured in their reaction with n-alkyl methanesulfonates, and compared with that found in traditional molecular solvents of different polarity, that is, chlorobenzene, DMSO, and MeOH. (c) 2005 Elsevier Ltd. All rights reserved
Ricerca del mezzo di reazione eco-compatibile per processi innovativi della chimica fine
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TETRABUTYLAMMONIUM FLUORIDE - A POWERFUL CATALYST FOR THE REGIOSELECTIVE OPENING OF EPOXIDES WITH THIOLS
No full textTetrabutylammonium fluoride (1) catalyses under mild conditions the opening of epoxides 2a-k with thiols 3-6 to produce the corresponding beta-hydroxy thioethers 7-11 in excellent yields (88-100%) and with high regioselectivity. Furthermore, O-protected glycidols react without any loss of the protective group
REGIOSELECTIVE CONVERSION OF O-PROTECTED GLYCIDOLS TO FLUOROHYDRINS CATALYZED BY TETRABUTYLAMMONIUM DIHYDROGENTRIFLUORIDE UNDER SOLID-LIQUID PTC CONDITIONS
No full textA number of O-protected glycidols are regioselectively converted into the corresponding fluorohydrins FCH2CH(OH)CH2OX by reaction with catalytic amounts of Bu4N+H2F3- and a molar excess of KHF2. Most of the protective groups (X) examined are stable under the above conditions, moreover stereogenic carbons are not affected
REDUCTION OF ALLYLIC NITRO-COMPOUNDS TO OXIMES WITH CARBON-DISULFIDE UNDER SOLID LIQUID PHASE-TRANSFER CATALYSIS CONDITIONS
No full textSYNTHESIS OF PENTACOORDINATED TETRAALKYLAMMONIUM AND TETRAALKYLPHOSPHONIUM DIFLUOROSILICATES
No full textSeveral quaternary onium difluorosilicates 3, R(2)(1)R(2)SiF(2)(-) Q(+) (Q = R(3)(3)R(4)N(+), R(3)(3)R(4)P(+)), have been prepared by reaction of a trisubstitued silane I, R(2)(1)R(2)SiH, and an onium hydrogendifluoride 2, Q(+) HF2-, in benzene. The products 3 are isolated in very good yields (92-98%) and purity (> 99%)
TCT-catalyzed Beckmann rearrangement of ketoximes in biodegradable ionic liquids
No full textImidazolium-based ionic liquids (ILs) containing ester moieties in the side chain were successfully used as an alternative to traditional ILs in the Beckmann rearrangement of ketoximes catalyzed by 2,4,6-trichloro[1,3,5]triazine. The procedure is mild and suitable for both aromatic and cycloaliphatic substratesaffording the rearrangement products in good to quantitative yields. The process is eco-sustainable since these ILs are biodegradable and in addition they can be recovered and reused
Regioselective opening of epoxides to beta-amido alcohols under solid-liquid PTC conditions
No full textA study on the ring opening of a number of epoxides 1 with trifluoroacetamide (2) under solid-liquid phase transfer catalysis (SL-PTC) conditions has been performed. The reaction is completely regioselective affording beta-amido alcohols 3 deriving from the attack of the nucleophile to the less substituted carbon atom of the oxirane ring. (C) 1997 Elsevier Science Ltd
Novel concise synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines by ring opening of glycidols under solid-liquid phase transfer catalysis conditions
No full textThe ring opening of glycidols with N-(2-fluorophenyl)toluene-p-sulfonamide under SL-PTC conditions, followed by ring closure with (BuOK)-O-t, provides a novel high yielding synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines
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