Thermochemistry of organic and heteroorganic species. Part XI. A new estimation scheme of the enthalpies of formation for RCH2 free radicals (original) (raw)

2002, Journal of Molecular Structure

tive for systematic gaining of unknown so far values of the enthalpies of formation of free radicals. The following new or corrected values of the free radicals' enthalpies of formation were obtained (kcal mol 21 ): 2bicyclo[2.2.2]octyl z (18), PhCH 2 CH 2 z (54.5), BrCH 2 CH 2 z (33.5), ICH 2 CH 2 z (46.5), CH 2 yCHOCH 2 z (17), z CH 2 O-COCH 3 (254), z CH 2 CH 2 COOEt (263), z CH 2 OCOPh (224.5), z CH 2 OPh (26), H 2 NNHCH 2 z (65), NCCH 2 CH 2 z (60.5), O 2 NCH 2 CH 2 z (24.5), F 2 NCH 2 CH 2 z (19), 3-cyanocyclobutyl z (83) HSCH 2 CH 2 z (36), EtS(O)CH 2 CH 2 z (21.5), EtSO 2 CH 2 CH 2 z (254), z CH 2 PH 2 (41.2), z CH 2 At (68), H 3 ECH 2 z (39.5, 57.5, 77.5, 97) (E Si, Ge, Sn, Pb, respectively). The DH f 0 values for z CH 2 SH and Me 3 CCH 2 z free radicals 42 and 5 kcal mol 21 , respectively, were derived by using all three procedures as compared with earlier found values of 36.3 and 8.7 kcal mol 21 , respectively. From the known enthalpic shift DDH f 0 7.2 kcal mol 21 for RCHyCH 2 ! RPh replacement and the regularity in thermochemistry of RCH 2 z /RCHyCH 2 species, the new or corrected values of the molecules' enthalpies of formation were found (kcal mol 21 ): BrCHyCH 2