Thermochemistry of organic and heteroorganic species. Part XIII. Interrelationship for νCH values in RH molecules and enthalpy of formation of R free radicals in aliphatic compounds
✍ Scribed by A.V. Golovin; V.V. Takhistov
- Publisher
- Elsevier Science
- Year
- 2005
- Tongue
- English
- Weight
- 354 KB
- Volume
- 734
- Category
- Article
- ISSN
- 0022-2860
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✦ Synopsis
Using IR frequencies for gaseous molecules' R-H bonds, some known values of the enthalpies of formation for carbon-centered R % free radicals, and the series of isodesmic reactions, the enthalpies of formation for more than 25 free radicals were found. The variable Dn CH values equivalent for 1 kcal in DBDE (bond dissociation energy) R-H/R 0 -H was applied: 9 cm K1 in alkanes, 11 cm K1 in alkenes RCHaCH-H (RCHaCH 2 ), 12 cm K1 in alkynes RCbC-H, and 14 cm K1 in RCHaO molecules. It was found that in halogenated methanes and some other molecules (CH 3 SH, CH 3 PH 2 , CH 3 NO 2 , CH 3 ONO 2 ) the registered n CH value is much higher than it is expected from BDEs bC-H. The expected n CH frequencies were calculated for about 25 molecules.