Journal of the American Chemical Society p. 6089 - 6096 (1985)
Update date:2022-08-29
Topics:
Lias, Sharon G.
Karpas, Zeev
Liebman, Joel F.
New values for the heats of formation of CF2, CCl2, CClF, CFH, and CClH have been derived from estimations of the thermochemistry of the reaction(s) CXYH+ + B -> CXY + BH+ where X and Y are F and/or Cl and B is a molecule for which an absolute value of the gas-phase basicity (or proton affinity) is available.The experiments, carried out in an ion cyclotron resonance spectrometer, lead to the following values for the heats of formation (in kcal/mol) of the ground-state singlet carbenes: CF2, -49 +/- 3; CCl2, 39 +/- 3; CFCl, -2 +/- 7; CFH, 26 +/-3; CClH, 71 +/-5.The value for CF2 is lower by about 5 kcal/mol than the previously accepted value, but in good agreement with values derived from previous "bracketing" results and also in agreement with values derived from the observed threshold energies for ionic dissociation processes.The value for CCl2 is significantly lower than the 1976 value of 47 +/-3 kcal/mol recommended by S.W.Benson, but in good agreement with an earlier value (40 +/- 5 kcal/mol) recommended by this author with more recent experimental results on the onset energy of formation of Cl2- from CCl4.The values for CFH, CClH, and CFCl are all approximately equal to the averages of the heats of formation of the corresponding CX2 and CY2 species, in agreement with assumptions made in previous estimates of these quantities.Values for the C-X bond energies in the halomethylenes, the heats of formation of the corresponding CXY+ ions, and the ionization potentials of the CXY species are derived from the results.From the most recent calculations of the energy differences between the ground-state singlet halomethylenes and the first triplet state, values for the heats of formation of the triplet halomethylenes are obtained; an analysis of trends in these values indicates that 3CF2 is substantially destabilized.
View MoreSichuan Highlight Fine Chemicals Co., Ltd.
Contact:+86-28-8525 1605
Address:A5-102 Airport base,388 West Airport Huang He Zhong Lu,2 Section
Contact:+0086-21-61984905-1
Address:Building 60,Zimian Park, LongYang industrial Area, 1515Nong,Yuandong Road Fengxian District, Shanghai ,China
Jiangsu Haian Petro chemical Plant
Contact:+86-513-88902723
Address:99, Changjiang West Road, Haian County, Jiangsu
Beijing Tianjia Chemical Science & Technology Co.,Ltd
Contact:86-0550-2392698
Address:No.388, Shiliang Road (East),
Weifang Dongxing Chitosan Factory
website:http://dxchitosan.lookchem.com/
Contact:13475651157
Address:Weifang city ,shandong province
Doi:10.1016/0022-328X(85)87115-1
(1985)Doi:10.1039/c3ra45042b
(2014)Doi:10.1039/c7ob01785e
(2017)Doi:10.1016/j.bmc.2006.06.026
(2006)Doi:10.1016/j.tet.2011.09.076
(2011)Doi:10.1039/c39930000323
(1993)