- DIOLS AS EFFECTIVE COCATALYSTS IN THE PHASE TRANSFER CATALYZED PREPARATION OF 1-ALKYNES FROM 1,2-DIHALIDES
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Bis-tertiary diols accelerate bis-eliminations of HX from 1,2-dihalides in the presence of an onium salt as phase transfer catalyst and potassium hydroxyde as base.PEG 400 catalyzes the same elimination, but isomerizations from 1-alkyne to mixtures with the 2-alkyne and the 1,2-diene occur easily.
- Dehmlow, Eckehard V.,Thieser, Rainer,Sasson, Yoel,Neumann, Ronny
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p. 3569 - 3574
(2007/10/02)
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- Polyfunctionalized N-Tensides. VII. Substitution and Elimination in the Reaction of 1,2-Dihalogenoalkanes with Amines
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1,2-Dichloroalkanes, 1,2-Dibromoalkanes and mixtures of 1-bromo-2-chloroalkanes and 1-chloro-2-bromoalkanes react with primary or secondary amines and give both elimination and substitution products, often in a nearly 1:1 proportion.The elimination products are the cis and trans-1-halo-1-alkenes, the 2-halo-1-alkenes, the 1,3- and 2,4-dienes and the 1-alkenes.The main substitution products are the 1,2-bis-aminoalkanes.Physical dates, 1H-n.m.r.-spectra,surface tension values and CMC-dates are given.
- Beger, J.,Meerbote, E.
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- POLY(STYRYLMETHYLTHIOL) AS AN EFFICIENT DEBROMINATING REAGENT OF 1,2-DIBROMIDES
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Dibromides are readily debrominated by means of poly(styrylmethyl thiolate) with formation of the respective olefins.The polymeric reagent with a high content of sulphhydryl groups can be easily prepared from chloromethylated polystyrene; it extends possibilities of protection-deprotection reactions of the double bond.
- Janout, Vaclav,Cefelin, Pavel
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p. 3913 - 3916
(2007/10/02)
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- Application of Phase Transfer Catalysis, 14.- Preparation of Alkynes from Halides with Solid Potassium tert-Butoxide and Crown Ether
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Preparatively very simple and mild HX eliminations with solid potassium tert-butoxide in petroleum ether in the presence of catalytic amounts of crown-6 are described. 1,2-Dihalides (from alkenes) and 1,1-dihalides (from aldehydes) yield 1-alkynes; internal geminal dihalides (from symmetric ketones) give internal alkynes in excellent yields. 2,2-Dihalides (from methyl ketones) yield homogeneous 1-alkynes only if the 3-position is blocked. (E)-Haloalkenes lead also to alkynes in a syn-elimination process.
- Dehmlow, Eckehard V.,Lissel, Manfred
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