Determination of the heat of formation of trimethylindium and calculation of the mean In—CH3 bond dissociation energy

1968 ◽  
Vol 46 (10) ◽  
pp. 1633-1634 ◽  
Author(s):  
W. D. Clark ◽  
S. J. W. Price
Keyword(s):  
Bond Dissociation Energy ◽  
Dissociation Energy ◽  
Chloroform Solution ◽  
Kinetic Studies ◽  
Heat Of Formation ◽  
Enthalpy Of Reaction ◽  
Kcal Mole ◽  
Bond Dissociation ◽  
The Mean

The enthalpy of reaction of In(CH3)3,c with a chloroform solution of bromine is −162.5 kcal mole−1. With this value ΔHf0298[In(CH3)3,c] = 29.5 kcal mole−1 and ΔHf0298[In(CH3)3,g] = 41.1 kcal mole−1. Combining the latter with ΔHf0298[CH3,g] = 33.2 kcal mole−1 and ΔHf0298[In,g] = 58.2 kcal mole−1 then gives E(In—CH3) = 38.9 kcal mole−1. From previous kinetic studies D[(CH3)2In—CH3] + D[In—CH3] = 87.9 kcal mole−1. Hence D[CH3In—CH3] = 28.8 kcal mole−1.

The CH 2 : CH.CH 2 —CH 3 bond dissociation energy and the heat of formation of the allyl radical

1950 ◽  
Vol 202 (1069) ◽  
pp. 263-276 ◽  
Keyword(s):  
Bond Dissociation Energy ◽  
Dissociation Energy ◽  
Heat Of Formation ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Allyl Radical ◽  
First Order ◽  
Bond Dissociation ◽  
Benzyl Radicals ◽  
Thermal Stability Of

The pyrolysis of butene-1 was investigated by a flow technique, toluene being used as a carrier gas. It was found that butene-1 decomposed into allyl and methyl radicals according to the equation CH 2 : CH.CH 2 — CH 3 → CH 2 : CH.CH 2 + CH 3 . Methyl radicals were removed by reaction with toluene giving methane and benzyl radicals. The rate of the initial decomposition was measured by the rate of formation of methane. The decomposition was found to be a homogeneous first order gas reaction. The activation energy was calculated at 61.5 kcal./mole and it was identified with the CH 2 : CH.CH 2 — CH 3 bond dissociation energy. Taking D (CH 2 : CH.CH 2 —CH 3 ) at 61.5 kcal./mole we calculated from thermochemical data D (CH 2 : CH.CH 2 —H) at 76.5 kcal./mole and the heat of formation of allyl radical at + 30 kcal./mole. The fate of allyl radicals is discussed and the thermal stability of these is compared with that of benzyl radicals.

The C—Br bond dissociation energy in halogenated bromomethanes

1951 ◽  
Vol 209 (1096) ◽  
pp. 110-131 ◽  
Keyword(s):  
Bond Dissociation Energy ◽  
Dissociation Energy ◽  
Methyl Bromide ◽  
Frequency Factor ◽  
Unimolecular Dissociation ◽  
Bond Dissociation Energies ◽  
Kcal Mole ◽  
Fast Reaction ◽  
Bond Dissociation ◽  
Dissociation Energies

The pyrolyses of methyl bromide and of the halogenated bromomethanes, CH 2 CI. Br, CH 2 Br 2 , CHCl 2 .Br, CHBr 3 , CF 3 Br, CCI 3 . Br and CBr 4 , have been investigated by the ‘toluene-carrier' technique. It has been shown that all these decompositions were initiated by the unimolecular process R Br → R + Br. (1) Since all these decompositions were carried out in the presence of an excess of toluene, the bromine atoms produced in process (1) were readily removed by the fast reaction C 6 H 5 .CH 3 + Br → C 6 H 5 . CH 2 • + HBr. Hence, the rate of the unimolecular process (1) has been measured by the rate of formation of HBr. The C—Br bond dissociation energies were assumed to be equal to the activation energies of the relevant unimolecular dissociation processes. These were calculated by using the expression k ═ 2 x 10 13 exp (- D/RT ). The reason for choosing this particular value of 2 x 10 13 sec. -1 for the frequency factor of these reactions is discussed. The values obtained for the C—Br bond dissociation energies in the investigated bromomethanes are: D (C—Br) D (C—Br) compound (kcal./mole) compound (kcal./mole) CH 3 Br (67.5) CHBr 3 55.5 CH 2 CIBr 61.0 CF 3 Br 64.5 CH 2 Br 2 62.5 CCI 3 Br 49.0 CHCl 2 Br 53.5 CBr 4 49.0 The possible factors responsible for the variation of the C—Br bond dissociation energy in these compounds have been pointed out.

The mean bond dissociation energy of the carbonmagnesium bond in bis(2,2-dimethylpropyl)magnesium

2010 ◽  
Vol 102 (2) ◽  
pp. 109-113 ◽  
Author(s):  
O. S. Akkerman ◽  
G. Schat ◽  
E. A. I. M. Evers ◽  
F. Bickelhaupt
Keyword(s):  
Bond Dissociation Energy ◽  
Dissociation Energy ◽  
Bond Dissociation ◽  
The Mean
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