Isotope Effects in Carbonium Ion Reactions. III. The Solvolysis of Methyltolylcarbinyl Chloride<sup>1</sup>

Lewis, Edward S.; Johnson, Robert R.; Coppinger, Galvin M.

doi:10.1021/ja01521a056

Cited by 9 publications

(5 citation statements)

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“…Methyl p-tolyl ketone was synthesized by Friedel-Crafts acylation of toluene from acetic anhydride and aluminum chloride. 24 The product has a bp of 74-76 °C (2 mmHg).…”

Section: Methodsmentioning

confidence: 99%

Deuterium isotope effects on the carbon-13 chemical shifts of carbocations

Servis¹,

Shue²

1980

J. Am. Chem. Soc.

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“…Methyl p-tolyl ketone was synthesized by Friedel-Crafts acylation of toluene from acetic anhydride and aluminum chloride. 24 The product has a bp of 74-76 °C (2 mmHg).…”

Section: Methodsmentioning

confidence: 99%

Deuterium isotope effects on the carbon-13 chemical shifts of carbocations

Servis¹,

Shue²

1980

J. Am. Chem. Soc.

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“…As a result, the difference between the zero-point energies of the P-C-D bonds and the P-C-H bollds is less in the transition state than in the initial state, leading to a higher enthalpy of activation for the deuterated con~pound. This argument is well established (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) and was applied in an earlier paper (11) to isopropyl compounds solvolyzing in water. Our present results show that if such an effect is present in the isopropyl case, it must be cancelled by another enthalpy effect of the opposite sign.…”

Section: Zero-point Energy Effectsmentioning

confidence: 91%

“…Secondary P-deuterium isotope effects in solvolytic reactions have been studied by several groups of workers (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). In all cases, replacement of hydrogen on /?-carbon atoms of the alkyl radical by deuterium led to a reduction in the rate of solvolysis.…”

mentioning

confidence: 99%

DEUTERIUM KINETIC ISOTOPE EFFECTS: V TEMPERATURE DEPENDENCE OF Β-Deuterium EFFECTS IN WATER SOLVOLYSIS OF ISOPROPYL COMPOUNDS

Leffek¹,

Robertson²,

Sugamori³

1961

Can. J. Chem.

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The secondary 8-deuterium isotope effect ( k n / k~) has been measured over a range of temperature for the water solvolysis reactions of isopropyl ~nethanesnlphonate, p-toluenesulphonate, and bromide. In these cases the isotope effect is due to a difference in entropies of activation of the isotopic analogues rather than a difference in the enthalpies of activation. I t is suggested that the observed isotope effect is due to internal rotatio~lal effects of the methyl groups in the isopropyl radical, and the lack of an isotope effect on the enthalpy of activation is accounted for by a cancellation of an effect from this source and one from zero-point energy.

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“…Deuterium substitution slightly decreases the rate of solvolysis of p-methylphenyl-l -chloroethane •' kp-cds/ kp ch8 is 1.08 (30 cal/mol per D) in acetic acid at 50°a nd only 1.01 in "80%" acetone at 38°. 29 A greater isotope effect is found in the -methyl substituent, which is under greater electron demand: ka.cnj ka.cd3 = 1.28 in acetic acid at 50°. 29 Deuterium substitution in the a position of para alkyl substituents also reduces solvolysis rates of p-alkylbenzhydryl chloride; e.g., kP"cm/kP-cB,, = 1.06 in "80%" acetone at 0°.80 The basicity of acetophenone is greater than that of its CDs analog, kf^/ksn* = 0.775 (-51 cal/mol per D).S1 Aromatic substitution gives varied effects.…”

Section: Thus the Differential Absorption (H Vs D Compound)mentioning

confidence: 97%

“…29 A greater isotope effect is found in the -methyl substituent, which is under greater electron demand: ka.cnj ka.cd3 = 1.28 in acetic acid at 50°. 29 Deuterium substitution in the a position of para alkyl substituents also reduces solvolysis rates of p-alkylbenzhydryl chloride; e.g., kP"cm/kP-cB,, = 1.06 in "80%" acetone at 0°.80 The basicity of acetophenone is greater than that of its CDs analog, kf^/ksn* = 0.775 (-51 cal/mol per D).S1 Aromatic substitution gives varied effects. Nitration of CD3Ph apparently shows no significant effect;82-34 e.g., ks/kT -1.002 ± 0.002 per tritium.…”

Section: Thus the Differential Absorption (H Vs D Compound)mentioning

confidence: 97%

Deuterium isotope effects in the principal electronic transition of nitrobenzene and aniline and their p-alkyl derivatives

Schubert¹,

Murphy²,

Robins³

1970

J. Org. Chem.

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Deuterium Isotope Effects in Electronic Transition 951 defined charge-transfer band was observed and whenever there was little distortion of the spectrum owing to reaction-product formation. Only absorbance data from the first two increments of donor could be used because significant amounts of reaction product had accumulated by the time the third addition of donor was made. Considering these limitations, the equilibrium constants obtained are questionable. Results for the complexes are given in Table I.Although valid comparisons cannot be made from the equilibrium constants, some qualitative differences are evident from the optical spectra. There certainly appears to be some hindrance to complex formation by methyl substitution in the positions adjacent to the nitrogen atom, and the effect is more pronounced with disubstitution than with monosubstitution. Also, if the assumption is made that all of the complexes have approximately equal extinction coefficients, the amount of complexation may be estimated from the intensity of the charge-transfer band after the initial addition of donor, since the concentrations of reactants were the same for each system. The initial spectrum was used, since only small amounts of reaction products had distorted the spectrum and consumed TONE at this point. The peaks decreased in intensity in the order 3,4-lutidine > 3,5-lutidine > 4-picoline > pyridine. Using this method of analysis, the intensities of the complex bands of the donors which are not sterically hindered parallel closely their basicities. Although comparisons of the steric effect and order of donor strength are not conclusive, these data indicate that the donors act as n-electron donors toward TONE.Esr investigations of the TCNE-pyridine systems showed the nine-line spectrum of the TONE anion radical, but no evidence was found for any other paramagnetic species. The lack of evidence for the presence of the pyridine cation radical implies that the formation of the TONE anion radical may not be due to the dissociation of the charge-transfer complex.The radical anion is formed in good yields by the reaction of TONE with cyanide ion,14 and this method was used to synthesize the potassium salt of the anion radical in this laboratory. Since the formation of both pentacyanopropenide and tricyanoethenolate ions in the donor-TCNE systems liberates cyanide ion, this ion is very likely responsible for the reduction of TONE to the anion radical. This possibility is supported by our finding that the concentration of radical increased slowly over a period of hours.

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Isotope Effects in Carbonium Ion Reactions. III. The Solvolysis of Methyltolylcarbinyl Chloride¹

Cited by 9 publications

References 0 publications

Deuterium isotope effects on the carbon-13 chemical shifts of carbocations

Deuterium isotope effects on the carbon-13 chemical shifts of carbocations

DEUTERIUM KINETIC ISOTOPE EFFECTS: V TEMPERATURE DEPENDENCE OF Β-Deuterium EFFECTS IN WATER SOLVOLYSIS OF ISOPROPYL COMPOUNDS

Deuterium isotope effects in the principal electronic transition of nitrobenzene and aniline and their p-alkyl derivatives

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Isotope Effects in Carbonium Ion Reactions. III. The Solvolysis of Methyltolylcarbinyl Chloride1

Cited by 9 publications

References 0 publications

Deuterium isotope effects on the carbon-13 chemical shifts of carbocations

Deuterium isotope effects on the carbon-13 chemical shifts of carbocations

DEUTERIUM KINETIC ISOTOPE EFFECTS: V TEMPERATURE DEPENDENCE OF Β-Deuterium EFFECTS IN WATER SOLVOLYSIS OF ISOPROPYL COMPOUNDS

Deuterium isotope effects in the principal electronic transition of nitrobenzene and aniline and their p-alkyl derivatives

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Isotope Effects in Carbonium Ion Reactions. III. The Solvolysis of Methyltolylcarbinyl Chloride¹