The levelling effect of the p-anisyl group on solvolysis reactions

Gassman, Paul G.; Zeller, James R.; Lumb, J. T.

doi:10.1039/c19680000069

Cited by 12 publications

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“…65 The absence of participation may be due to the high nucleophilicity of the solvent and to the a-activating anisyl group which may dump participation from substituents in further away positions. 66 Solvent Effects. The solvolysis rate of 1-C1 and 1-Br increases with the solvent polarity, but the Grunwald-Winstein m values are lower than expected for an SnI reaction (0.7-1.0).67 A value such as for 1-Br is usu- ally associated with Sn2 reactions67 while that for 1-C1 is in an intermediate region.…”

Section: Discussionmentioning

confidence: 99%

Vinylic cations form solvolysis. I. Trianisylvinyl halide system

Rappoport¹,

Gal²

1969

J. Am. Chem. Soc.

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phonium salts which can undergo further decomposition to tetracovalent phosphorus compounds. Experimental SectionMaterials. The starting phosphines were prepared by standard techniques or purchased when possible. Their 1H and 31P nmr spectra agreed with literature values.Reactions. Equimolar quantities (ca. 5 X mol of the phosphine and diethyl peroxide) were allowed to react in methylene chloride. Usually the reactants were cooled to at least 0" before mixing. The reactions were monitored by 1H and 31P nmr spectroscopy. In those studies in which other solvents were used the methylene chloride was evaporated at room temperature in cucuo and the residue was dissolved in the appropriate solvent. Benzoic acid was added to each reaction mixture and the formation of ethyl benzoate was demonstrated by glpc.formed by exchange. Once again the compound 19 is quite unstable and it decomposes readily to tetracovalent phosphorus compounds.The relative instability of the compounds with amino nitrogen bonded to phosphorus is not unexpected. Amino nitrogen can stabilize a positive charge on phosphorus and therefore enhance dissociation to phos-Abstract: Solvolysis of trianisylvinyl chloride (1-CI) and bromide (1-Br) and of l-anisyl-2,2-diphenylvinyl bromide (7) in 80% ethanol follows a first-order course in the substrate, is independent of the concentration of added sodium hydroxide, and is only slightly dependent on that of added p-toluenethiolate ion. The solvolysis of 1-Br is 1.75 times faster than that of a-bromo-p-methoxystyrene, excluding the addition-elimination mechanism. The similar rates for 1-Br and 7 point to the absence of P-aryl participation. The Grunwald-Winstein nz values of 0.34-0.53 and the kl-B,/kl.CI value of 58 at 120" are discussed in terms of intermediate vinylic cations in the solvolysis. The reactivity difference between a-bromostyrene and a-phenylethyl bromide is entirely due to activation energy difference. Vinylic and saturated cations are compared.inylic cations were studied very little until recent V years. Lately, they were suggested as intermediates in electrophilic additions to allenes and acetylenes (eq l),* in the deamination of vinylamine~,~ or in the reaction of 2-oxazolidones in basic solution4 or vinyltriazenes in acidic solution5 (eq 2). Ions with contributing vinylic cation structures were observed by nmr,6 and solvolysis products of acetylenic sulfonates ( I ) Presented in part at

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Section: Discussionmentioning

confidence: 99%

Vinylic cations form solvolysis. I. Trianisylvinyl halide system

Rappoport¹,

Gal²

1969

J. Am. Chem. Soc.

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“…The accelerating effect is not activated in the presence of a directly attached cation‐stabilizing group. For example, the p ‐anisyl group at C7 (Figure ) can stabilize the developing carbonium ion center to the extent where the difference in reactivity between the two classes of compounds almost disappears (a factor of 3) along with the stereospecificity of substitution …”

Section: Spectroscopic Signatures Of Hyperconjugationmentioning

confidence: 99%

Hyperconjugation

Alabugin

Gomes

Abdo

2018

WIREs Comput Mol Sci

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This review outlines the role of hyperconjugative interactions in the structure and reactivity of organic molecules. After defining the common hyperconjugative patterns, we discuss the main factors controlling the magnitude of hyperconjugative effects, including orbital symmetry, energy gap, electronegativity, and polarizability. The danger of underestimating the contribution of hyperconjugative interactions are illustrated by a number of spectroscopic, conformational, and structural effects. The stereoelectronic nature of hyperconjugation offers useful ways for control of molecular stability and reactivity. New manifestations of hyperconjugative effects continue to be uncovered by theory and experiments. This article is categorized under: Structure and Mechanism > Molecular Structures Software > Molecular Modeling Structure and Mechanism > Reaction Mechanisms and Catalysis

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“…9 The present work stemmed from our observation that nearly all reported examples of this rearrangement with 2alkylpyridine N-oxides (1) involved structures with an amethylene group. 9 The present work stemmed from our observation that nearly all reported examples of this rearrangement with 2alkylpyridine N-oxides (1) involved structures with an amethylene group.…”

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confidence: 95%

“…Kinetic runs were carried out in 3-ml quartz uv cells (Pyrocell Manufacturing Company) which had a 1-cm path length. The cells (9) The synthesis of the alcohol precursors of 10b and 9b was modeled after undeuterated analogs. See the Experimental Section.…”

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confidence: 99%

Bicyclo[3.2.0]hept-6-en-2-yl carbonium ion. 2-Methyl substituent effects

Yano¹

1975

J. Org. Chem.

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The rearrangement of diphenyl-2-pyridylmethane A-oxide (8) with acetic anhydride in acetonitrile was investigated. The product was identified as diphenyl-2-pyridylmethyl acetate (10). An intramolecular pathway was elucidated by a combination of oxygen-18 labeling studies and the conversion of l-acetoxy-2-benzhydrylpyridinium perchlorate ( 14) to product by a base (Dabco) other than added acetate ion.

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The levelling effect of the p-anisyl group on solvolysis reactions

Cited by 12 publications

References 0 publications

Vinylic cations form solvolysis. I. Trianisylvinyl halide system

Vinylic cations form solvolysis. I. Trianisylvinyl halide system

Hyperconjugation

Bicyclo[3.2.0]hept-6-en-2-yl carbonium ion. 2-Methyl substituent effects

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