Organic thermochemistry

As has been the approach for most of the author s other reviews on organic thermochemistry, the current chapter will be primarily devoted to the relatively restricted scope of enthalpy of formation (more commonly and colloquially called heat of formation) and write this quantity as A//f, instead of the increasingly more commonly used and also proper A//f° and AfHm No discussion will be made in this chapter on other thermochemical properties such as Gibbs energy, entropy, heat capacity and excess enthalpy. Additionally (following thermochemical convention), the temperature and pressure are tacitly assumed to be 25 °C ( 298 K ) and 1 atmosphere (taken as either 101,325 or 100,000 Pa) respectively3 and the energy units are chosen to be kJmol-1 instead of kcalmol-1 (where 4.184 kJ = 1 kcal, 1 kJ = 0.2390 kcal). 

Organic thermochemistry of hydroxylamines, oximes, and hydroxamic acids 55... 

Organic thermochemistry of hydroxylamines, oximes, and hydroxamic acids 69 TABLE 3. Enthalpies of formation for dioximes (kJ mol )... 

Bond dissociation energies (BDEs) are at the heart of organic thermochemistry and many mechanistic considerations, so it is imperative to be able to compute and predict these quantities accurately. The problem is that, upon lengthening a bond in the early stages of cleaving... 

The enthalpy of formation of all three aminophenol isomers have been measured twice. Two well-respected contemporary organic thermochemistry groups have studied these species76,77. Although disparate, they are closer than some other pairs of competing values cited in this text. Which set, if either, do we choose We prefer those of Reference 76. From the archival enthalpy of formation of gaseous phenol of —96.4 0.9 kJmol-1 and equation 2, the enthalpy of formation of any of the isomers is ca —92 kJmol-1 in the... 

I began to collect experimental and theoretical values for BDEs in 1990. Four years later. Dr. S. E. Stein of the National Institute of Standards and Technology (NIST) encouraged me to continue in this task that is essential for chemical kinetics, free radical chemistry, organic thermochemistry, and physical organic chemistry. 

Organic thermochemistry usually deals with molecules in the gaseous state in order to study their intrinsic stabilities in the absence of a crystal lattice, intermolecular bindings in the liquid state, or solvation forces. Therefore the determination of the enthalpy of vaporization or the enfrialpy of sublimation is an essential step in obtaining the enthalpy of formation in die gas phase. The enthalpy of sublimation can be obtained by combination of the enthalpy of vaporization and the enthalpy of fusion (equation (12)). The entibialpy of sion is easily and reliably obtained by DSC. 

Organic thermochemistry at high ab initio levels. 1. A G2(MP2) and G2 study of cyclic saturated and unsaturated hydrocarbons (including aromatics) " ... 

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