The role of base ion-pairing in bimolecular elimination: the effect on the syn-anti dichotomy

Svoboda, Martin; Hapala, J.; Závada, Jiřı́

doi:10.1016/s0040-4039(01)84297-0

Cited by 18 publications

(3 citation statements)

References 10 publications

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“…Under an argon atmosphere, to 1.14 g (8 mmol) of boron trifluoride etherate (freshly distilled from calcium hydride) and acenaphthylene (13.7 g, 24 mmol) in 60 ml of ether was slowly added 0.25 g (6 mmol) of lithium aluminum deuteride. The reaction was stirred at ambient temperature for 12 hr and then worked up by adding saturated sodium sulfate and extracting with ether.…”

Section: Methodsmentioning

confidence: 99%

Elcb Reaction of 1-methoxyacenaphthene. II. Elimination step

Hunter¹,

Shearing²

1973

J. Am. Chem. Soc.

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16 mm)) with >85% recovery. The ether fractions were distilled (at 0.05 mm) with >75% recovery.The olefin was analyzed for deuterium content by both proton nmr and mass spectrometry at low electron energy. The composition of the ether mixture was determined by a combination of nmr and mass spectrometric techniques. Nmr analysis of 10-15°wt % solutions in carbon tetrachloride allowed determination of the ratios of cis (3.14 ppm) and trans (3.36 ppm) protons ß to the trideuteriomethoxy group. Mass spectrometric analysis at low electron energy allowed determination of the relative amounts of ma-terial containing zero, one, or two hydrogens. These two types of data allowed extraction of the percentages of the four ethers.Acknowledgment. The authors wish to thank the National Research Council of Canada for their financial support and the Agricultural Research Institute for use of their nmr facilities. We also wish to thank J. B. Stothers and E. W. Warnhoff for their valuable assistance.

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Section: Methodsmentioning

confidence: 99%

Elcb Reaction of 1-methoxyacenaphthene. II. Elimination step

Hunter¹,

Shearing²

1973

J. Am. Chem. Soc.

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“…In these reactions the crown ethers pro-I as an additional tool for the elucidation of the duced various effects, in Some Cases increasing the character of the transition states of these reactions second-order rate constant and in other cases (1)(2)(3)(4)(5)(6)(7)(8). Recently Alunni et (1) concluded, from decreasing it.…”

Section: Introductionmentioning

confidence: 99%

The influence of crown ethers on the kinetics of E1cB and E2 β-elimination reactions of di(4-nitrophenyl)fluoroethanes with sodium methoxide in methanol

Leffek¹,

Schroeder²

1982

Can. J. Chem.

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. Can. J. Chem. 60, 3077 (1982). The addition of crown ethers 1,4,7,10,13-pentaoxacyclopentadecane ( 1 5 0 ) and 1,4,7,10,13,16-hexaoxacyclooctadecane (18C6) in quantities equimolar to the base, to p-elimination reactions of l,l,l-trifluoro-2,2-di(4-nitropheny1)ethane and 1-fluoro-2,2-di(4-nitropheny1)ethane promoted by sodium methoxide in methanol, has been investigated. In the E2 reaction of the monofluoro compound, the crown ethers caused no change in the kinetic order and only small changes in the second-order rate constants and activation parameters. The primary deuterium isotope effect was also unaltered by the presence of crown ethers.For the (ElcB), reaction of the trifluoro compound, no change in kinetic order was found, but slightly larger rate constant changes and an increase in the isotope effect from k,lkD = 1.0 to 1.25 at 25°C was observed. This is interpreted a s an alteration in mechanism from (ElcB), towards (ElcB),.

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“…The range of synthetic application of ionic reagents is thereby extended, and this has been particularly apparent in the development of two phase reactions (19-23) in which ion transfer is catalyzed by crown ethers. The influence of crown ethers on reactions believed to involve metal cationanion pairs has also been profitably explored (24)(25)(26) and interpretation of the dependence of reaction rate, stereochemistry, or specificity has, in several cases, clarified aspects of reaction mechanism (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38).…”

mentioning

confidence: 99%