Thermolabile Kohlenwasserstoffe, 30 Thermische Stabilität und Bildungsenthalpie von 1,1,2,2‐ und 1,1,1,2‐Tetraphenylethan. – Die Stabilisierungsenergien von Benzhydryl‐ und Triphenylmethyl‐Radikalen

Beckhaus, Hans‐Dieter; Dogan, Barbara; Schaetzer, Jürgen; Hellmann, S.; Rüchardt, Christoph

doi:10.1002/cber.19901230126

Cited by 27 publications

(2 citation statements)

References 44 publications

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“…The same procedure based on force-field calculations, had been used to calculate the temperature dependance of A~b H~ of several alkylated benzenes successfully [22]. The summary of experimental results with the standard enthalpies of formation AfH~ derived from our measurements is given in Table V.…”

Section: Resultsmentioning

confidence: 99%

Thermochemical study of aliphatic and phenyl-substituted geminal diacetates

et al. 1996

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The standard enthalpies of combustion AeH ~ of aliphatic diacetates 1 and aromatic diacetates 2 were measured calorimetrically. The enthalpies of vaporization Av~pH ~ or sublimation A~uhH ~ of 1 and 2 were obtained from the temperature function of the vapor pressure measured in a flow system. From AfH~ of 1 and 2 new values of group increments for the estimation of standard enthalpies of formation of these classes of compounds were derived. The geminal interaction energy between the geminal acyloxy groups shows no anomeric stabilization.KEY WORDS: Enthalpy of combustion; enthalpy of formation; enthalpy of vaporization; geminal interaction of substituents.

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Section: Resultsmentioning

confidence: 99%

Thermochemical study of aliphatic and phenyl-substituted geminal diacetates

et al. 1996

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“…Triphenylmethyl phenyl oxide PhOCPh 3 was synthesized by coupling of Ph 3 CCl with PhONa in dry ether under reflux for 4 h . Triphenylmethyl phenyl amine PhNHCPh 3 was prepared as described by Siskos et al Synthesis of N -methyl- N -triphenylmethyl aniline PhN(Me)CPh 3 followed the method introduced by Behloul et al Preparation of 1,1,1,2-tetraphenylethane PhCH 2 CPh 3 was made by coupling of Ph 3 CLi and PhCH 2 Br in absolute THF at low temperature …”

Section: Methodsmentioning

confidence: 99%

Kinetic and Energetic Analysis of the Free Electron Transfer

Baidak¹,

Naumov²,

Brede³

2008

J. Phys. Chem. A

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In this paper, the bimolecular free (unhindered) electron transfer (FET) from various trityl-containing compounds to the solvent radical cations of n-BuCl is described. In good agreement with the previously studied cases, the FET involving trityl-derived compounds results in the formation of two different types of the radical cation, which undergo the subsequent fragmentation via two alternative reaction channels. This unusual effect is caused by the intramolecular rotational motion in the ground-state molecules around the arrow-marked bond Ar-//-X-CPh 3 (Ar = aromatic moiety; X = S, O, NH, CH 2), since such oscillations are directly connected with the electron distribution within the molecule. An unhindered electron jump from the donor trityl compound to the solvent radical cation, taking place in the subfemtosecond time range, generates the solute radical cation with the inherited geometry and the electron distribution of its precursor. Among the whole variety of produced radical cations, two extreme conformer states can be distinguished, namely, a planar and a twisted state. The planar type represents the structures with minimum energy, whereas the twisted type is destabilized by the increased value of the rotational barrier in the ionized state. The difference in the energetic profiles between planar and twisted radical cations plays a crucial role in their subsequent fragmentation. The planar radical cation follows the thermodynamically favored pathway generating ArX (*) and Ph 3C (+). A distinct part of the twisted radical cation dissociates faster than it relaxes into the more preferable planar conformation and, therefore, produces a thermodynamically unfavorable couple of products: ArX (+) and Ph 3C (*). This fragmentation channel is exclusively caused by FET. The undertaken quantum chemical calculations enable the judgment of the energetics of the different dissociation channels of the radical cations of the trityl derivatives.

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Thermochemistry of Dienes and PolyenesThis study is dedicated to the memory of Prof. Thomas L. Jacobs who first introduced the author to cyclic acetylenes, dienes and cumulenes on an examination in 1963

Liebman

2009

Patai's Chemistry of Functional Groups

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Introduction: Scope and Definitions Nonconjugated Dienes and Polyenes Cumulated Or Allenic Dienes and Polyenes (Cumulenes) Conjugated Acyclic Dienes Cyclic Dienes Conjugated Polyenes Conjugated Species With Exo ‐Methylene Groups: Fulvenes, Isotoluenes, Xylylenes and Related Species Annulenes: Aromaticity and Antiaromaticity Acknowledgments

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Thermolabile Kohlenwasserstoffe, 30 Thermische Stabilität und Bildungsenthalpie von 1,1,2,2‐ und 1,1,1,2‐Tetraphenylethan. – Die Stabilisierungsenergien von Benzhydryl‐ und Triphenylmethyl‐Radikalen

Abstract: Standardabweichungen in Klammern.b, Siehe Tab. 2, FuBnote 'I. -Fehler berechnet aus den Standardabweichungen von AH;(c) und AH:uhT.dl H, = AH$'(g) -AH," berechnet aus: CH2 = -5.13, CH = -2.16, C = -0.30, CllH = 3.28 und C,, = 5.6216).

Cited by 27 publications

References 44 publications

Thermochemical study of aliphatic and phenyl-substituted geminal diacetates

Thermochemical study of aliphatic and phenyl-substituted geminal diacetates

Kinetic and Energetic Analysis of the Free Electron Transfer

Thermochemistry of Dienes and PolyenesThis study is dedicated to the memory of Prof. Thomas L. Jacobs who first introduced the author to cyclic acetylenes, dienes and cumulenes on an examination in 1963

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