The thermal isomerization of bicyclic oxazines into epoxyepimines. A preliminary theoretical study

1990 ◽  
Vol 68 (9) ◽  
pp. 1625-1628 ◽  
Author(s):  
Michel Sana ◽  
Georges Leroy ◽  
Jean-Luc Vaerman ◽  
Heinz Gunter Viehe
Keyword(s):  
Substituent Effect ◽  
Theoretical Study ◽  
Thermal Isomerization ◽  
Model Systems ◽  
Rate Determining Step ◽  
Bond Homolysis

The thermal isomerization of bicyclic oxazines 1 to epoxyepimines 2 depends on the N-substituent. BDE calculations on model systems agree with the mechanistic picture. The rate-determining step in N—O bond homolysis is facilitated by N-vinyl substituents. Keywords: oxazines, BDE, NO bond, substituent effect.

Substituent effect on N–H bond dissociation enthalpies of carbamates: a theoretical study

2015 ◽  
Vol 93 (3) ◽  
pp. 279-288 ◽  
Author(s):  
Rupinder preet Kaur ◽  
Damanjit Kaur ◽  
Ritika Sharma
Keyword(s):  
Substituent Effect ◽  
Density Functional ◽  
Theoretical Study ◽  
Natural Bond Orbital ◽  
Stabilization Energy ◽  
Isodesmic Reactions ◽  
Bond Dissociation ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Orbital Analysis

The present investigation deals with the study of the N–H bond dissociation enthalpies (BDEs) of the Y-substituted (NH2-C(=X)Y-R) and N-substituted ((R)(H)NC(=X)YH) carbamates (X, Y = O, S, Se; R = H, CH3, F, Cl, NH2), which have been evaluated using ab initio and density functional methods. The variations in N−H BDEs of these Y-substituted and N-substituted carbamates as the effect of substituent have been understood in terms of molecule stabilization energy (ME) and radical stabilization energy (RE), which have been calculated using the isodesmic reactions. The natural bond orbital analysis indicated that the electrodelocalization of the lone pairs of heteroatoms in the molecules and radicals affect the ME and RE values depending upon the type and site of substitution (whether N- or Y-). The variations in N−H BDEs depend upon the combined effect of molecule stabilization and radical stabilization by the various substituents.

pH-Sensitive C–ON Bond Homolysis of Alkoxyamines of Imidazoline Series: A Theoretical Study

2014 ◽  
Vol 118 (20) ◽  
pp. 5542-5550 ◽  
Author(s):  
Dmitriy A. Parkhomenko ◽  
Mariya V. Edeleva ◽  
Vitaly G. Kiselev ◽  
Elena G. Bagryanskaya
Keyword(s):  
Theoretical Study ◽  
Ph Sensitive ◽  
Bond Homolysis

Theoretical study of spiropyran–merocyanine thermal isomerization

2004 ◽  
Vol 388 (1-3) ◽  
pp. 218-222 ◽  
Author(s):  
Grazia Cottone ◽  
Rosina Noto ◽  
Gianfranco La Manna
Keyword(s):  
Theoretical Study ◽  
Thermal Isomerization
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