BDE

The energy required for homolytic bond cleavage is called the bond dissociation energy (BDE) A list of some bond dissociation energies is given m Table 4 3... 

The BDE theory does not explain all observed experimental results. Addition reactions are not adequately handled at all, mosdy owing to steric and electronic effects in the transition state. Thus it is important to consider both the reactivities of the radical and the intended coreactant or environment in any attempt to predict the course of a radical reaction (18). AppHcation of frontier molecular orbital theory may be more appropriate to explain certain reactions (19). 

However, because of the high temperature nature of this class of peroxides (10-h half-life temperatures of 133—172°C) and their extreme sensitivities to radical-induced decompositions and transition-metal activation, hydroperoxides have very limited utiUty as thermal initiators. The oxygen—hydrogen bond in hydroperoxides is weak (368-377 kJ/mol (88.0-90.1 kcal/mol) BDE) andis susceptible to attack by higher energy radicals ... 

Bond dissociation energies (BDEs) for the oxygen—oxygen and oxygen— hydrogen bonds are 167—184 kj/mol (40.0—44.0 kcal/mol) and 375 kj/mol (89.6 kcal/mol), respectively (10,45). Heats of formation, entropies, andheat capacities of hydroperoxides have been summarized (9). Hydroperoxides exist as hydrogen-bonded dimers in nonpolar solvents and readily form hydrogen-bonded associations with ethers, alcohols, amines, ketones, sulfoxides, and carboxyhc acids (46). Other physical properties of hydroperoxides have been reported (46). 

Bde salts, cholesterol, phosphoHpids, and other minor components are secreted by the Hver. Bile salts serve three significant physiological functions. The hydrophilic carboxylate group, which is attached via an alkyl chain to the hydrophobic steroid skeleton, allows the bile salts to form water-soluble micelles with cholesterol and phosphoHpids in the bile. These micelles assist in the solvation of cholesterol. By solvating cholesterol, bile salts contribute to the homeostatic regulation of the amount of cholesterol in the whole body. Bile salts are also necessary for the intestinal absorption of dietary fats and fat-soluble vitamins (24—26). 

These data can be combined with ionization potential (IP) data according to the scheme below to determine bond dissociation energies (BDE). 

Falk, H Lhe Cheinutrji of Luieaa Ghgo yaaote. find Bde fhgineiu Springer, New York-VAen,... 

O.D., abbrev. (optisches Drehungavermogen) optical rotatory power, od. dgL, abbrev. (oder dergleichen) or the like, bde, a. waste, deserted. 

Estimated from S — O BDE, except as noted. b From Table 4. 

JIn the cyclic compound thiirane 1-oxide. See text for meaning of BDE in this case. 

Radical 3-value Hyperfine splittings0 (gauss) Rotational barrier (kcal mol-1) 2kt(M s ) at 173 K BDE[X—SO] (kcal mol-1)... 

Table 2. Singlet-triplet energy separations (AEsx) in M-H monomers, M—M bond dissociation energies (BDEs), SCF calculated bond lengths for the hypothetical, linear dimers HMMH (M = B, Al, Ga, In, or Tl) ...

Carlsson, G., Kulkami, P, and Larsson, P. et al. (2007). Distribution of BDE-99 and effects on metamorphosis of BDE-99 and-47 after oral exposure in Xenopus tropicalis. Aquatic Toxicology 84, 71-79. 

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