The effect of alkene structure upon the rates and product composition of addition of 4-chlorobenzenesulfenyl chloride

Sçhmid, George H.; Dean, Coleen L.; Garratt, Dennis G.

doi:10.1139/v76-177

Cited by 27 publications

(9 citation statements)

References 12 publications

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“…Such a correlation was, however, unsuccessful. In accord with previous studies [16][17][18][19][20], satisfactory correlations with both simple and extended Taft equations could be obtained only by selectively excluding members of the 62 compounds, in particular, those compounds containing a sterically bulky group such as tert-butyl. The utility of such.…”

Section: Resultssupporting

confidence: 85%

Electrophilic Additions to Allenes. VIII. The Kinetics and Mechanism of the Addition of Benzenesulphenyl Chloride to Allenes

Beaulieu

Morrisset

Garratt

1985

Israel Journal of Chemistry

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The rates of addition of benzenefulphenyl chloride to 62 alkyl substituted allenes have been determined in methylene chloride solution at 24.5°C. The rates of addition span a range of 3.4 × 103 in reactivity. No correlation with the extended Taft equation or variations thereof was found when the rates of all 62 compounds were considered. Partitioned rate constants, wherein each term reflects the relative propensity for attack upon a given π orbital‐lobe of the allenic system, allows one to demonstrate the specific effect of placing an alkyl group in each of three stereochemically distinct positions. Of note is the observation that while the magnitude of the polar effect of an alkyl group changes with the stereochemical location, this magnitude is a constant for methyl, ethyl and isopropyl. The rates reported herein are interpreted in terms of rate‐limiting formation of alkylidenethiiranium ions.

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Section: Resultssupporting

confidence: 85%

Electrophilic Additions to Allenes. VIII. The Kinetics and Mechanism of the Addition of Benzenesulphenyl Chloride to Allenes

Beaulieu

Morrisset

Garratt

1985

Israel Journal of Chemistry

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“…Protonation is the best example of a reaction which proceeds with attack on one carbon of a double bond to form an open carbonium ion, and we have thoroughly examined the effects of structure upon reactivity in this case (40). The most clear-cut example of an electrophilic addition proceeding through rate-determining formation of a bridged three-center ion is sulfenyl halide addition to alkenes, and the structural effects on this reaction have also been well documented (45). Therefore the effect of structure on the rate of oxymercuration may be compared to these two reactions as a suitable guide to the mechanism of this reaction.…”

Section: Discussionmentioning

confidence: 99%

Structural effects on reactivity in the oxymercuration reaction

Ambidge¹,

Dwight²,

Rynard³

et al. 1977

Can. J. Chem.

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. 55,3086 (1977). The kinetics of the reaction of mercuric acetate with alkenes in methanol can be measured directly by observing the ultraviolet absorbance of the solution at 265 nrn. For more reactive alkenes stopped flow techniques are required, but for less reactive substrates conventional spectrophotorneters are adequate. The measured rates are in satisfactory agreement with values obtained by other methods. The rates of several cyclopropylalkenes were measured in this way, and relative reactivities of some of the same substrates were obtained by the competition method. Rates obtained by both methods are in qualitative agreement, and show very high reactivity for the cyclopropylalkenes. These rates are analyzed by comparison with model reactions involving open ions (acid-catalyzed hydration) and bridged ions (sulfenyl halide addition). The comparisons suggest that the oxyrnercuration of alkenes not substituted with strongly resonance electron-donating substituents, for example ethylene, proceeds through bridged rate-determining transition states that put very little positive charge on carbon, but that when strongly resonance electron-donating substituents such as cyclopropyls are present, the rate-determining transition state resembles an open carboniurn ion.Chern. 55,3086 (1977).On peut rnesure la cinetique de la reaction de I'acetate mercurique avec les alcenes dans le methanol d'une manitre directe en observant l'absorption dans I'ultraviolet d'une solution a 265 nrn. Pour les alcenes reactifs, on doit faire appel aux techniques de flux stoppes mais pour des substrats moins reactifs, des rnethodes spectrophotornCtriques conventionnelles sont adequates. Les vitesses mesurtes sont en bon accord avec les valeurs obtenues par d'autres rnethodes. De cette rnaniere on a rnesure les vitesses de reaction de plusieurs cyclopropylalkenes et des reactivitks relatives de quelques uns des mCrnes substrats ont pu Ctre obtenues par des methodes cornpktitives. Les vitesses obtenues par les deux methodes sont en bon accord qualitatif et indiquent une tres grande reactivite pour les cyclopropylalkenes. On a analyse ces vitesses par cornparaison avec des reactions rnodkles impliquant des ions ouverts (I'hydratation acido-catalyske) et des ions pontes (addition de l'halogenure de sulfenyle). Ces comparaisons suggerent que l'oxyrnercuration des alcenes non-substitues par des substituants agissant comrne electro-donneurs puissants par resonance, par exernple l'kthylene, procede par des Ctats de transition dkterrninant la vitesse de la reaction qui sont pontes et qui induisent trts peu de charge positive au niveau du carbone; toutefois lorsque des substituants agissant forternent cornrne des Clectro-donneurs a cause de la resonance tel que le cyclopropyle, sont presents, I'Ctat de transition determinant la vitesse ressernble a un ion en forme ouverte.[Traduit par le journal]The oxymercuration reaction has been exten- mercury species is unknown in most cases. For It has been established that the rate of oxy-reactions in 0.01 M ...

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“…[3][4][5] For ethylene, we have chosen an efficient electrophilic addition reaction of arenesulfenyl chloride to an alkene. [19] This approach can provide hyperpolarization of nuclear spins leading to NMR signal enhancements of about 10 4 and more. Therefore, even the enrichments of approximately 0.1 % should be detectable, and the enrichments for the catalytic system used here are expected to be on the order of 1 %.…”

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confidence: 99%

Nuclear Spin Isomers of Ethylene: Enrichment by Chemical Synthesis and Application for NMR Signal Enhancement

et al. 2013

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Taking CH2CH2 for a spin: Enrichment of the nuclear spin isomers of ethylene was achieved by a catalytic reaction of acetylene with parahydrogen (see scheme). The spin isomers were used for NMR signal enhancement, both with and without subjecting them to a chemical reaction. The interconversion times of the nuclear spin isomers were evaluated at ambient pressure, thus revealing extremely long‐lived spin states with lifetimes of (1000±400) s.

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The effect of alkene structure upon the rates and product composition of addition of 4-chlorobenzenesulfenyl chloride

Cited by 27 publications

References 12 publications

Electrophilic Additions to Allenes. VIII. The Kinetics and Mechanism of the Addition of Benzenesulphenyl Chloride to Allenes

Electrophilic Additions to Allenes. VIII. The Kinetics and Mechanism of the Addition of Benzenesulphenyl Chloride to Allenes

Structural effects on reactivity in the oxymercuration reaction

Nuclear Spin Isomers of Ethylene: Enrichment by Chemical Synthesis and Application for NMR Signal Enhancement

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