- On the Solvent Dependence of cis-Diazene Inversion
-
Solvent dependence of nonradical inversion rates of cis-diazenes cannot be due to viscosity variation because these rates are too slow.For cis-azoadamantane, in a variety of aromatic and nonaromatic hydrocarbons, they show a correlation with solvent internal pressure giving an approximate activation volume of +7 cm3/mol.
- Neuman, Robert C.,Gunderson, Howard J.
-
-
Read Online
- cis-Diazenes. Viscosity Effects, One-Bond Scission, and Cis-Trans Isomerization
-
Effects of solvent viscosity on the rates of overall thermal decomposition, deazatization, and iomerization of several symmetric and unsymmetric cis-diazenes (cis-azoalkanes) have been determined in pure alkanes and mixtures of octane and mineral oil.Increasing viscosity decreases the overall decomposition and deazatization rates for all of these cis-diazenes.While isomerization rates also decrease with increasing viscosity for most of the diazenes, that for cis-N-tert-butyl-N'-1-norbornyldiazene (1) increases.These results are interpreted in terms of deazatization via one-bond scission and an intermediate diazenyl radical, isomerization via nonradical inversion, and the possibility of isomerization via a diazenyl radical for 1.
- Neuman, Robert C.,Grow, Richard H.,Binegar, Glen A.,Gunderson, Howard J.
-
p. 2682 - 2688
(2007/10/02)
-
- Decomposition and Isomerization of Bridgehead Cis 1,2-Diazenes (Azoalkanes)
-
Four acyclic cis 1,2-diazenes, azo-1-adamantane (cis-ada), azo-bicyclooctane (cis-), azo-1-bicycloheptane (cis-), and azo-1-bicyclohexane (cis-) have been generated by UV irradiation of the corresponding trans-isomers.These compounds differ greately in stability, cis- easily surviving at 100 deg C and cis-ada not being isolable.Whereas cis- and cis-only isomerize back to trans on heating, the other two compounds undergo competing loss of nitrogen.The observation that the energy of the transition state for isomerization remains at 42 +/- 1 kcal mol-1 regardless of the cis ground state energy is used to argue that thermal isomerization proceeds via semilinearization rather than rotation.A remarkable correlation of cis ground state energy with cis n,?* excitation energy has emerged from this study.
- Chae, Woo-Ki,Baughman, Sharon A.,Engel, Paul S.,Bruch, Manfred,Oezmeral, Cenan,et al.
-
p. 4824 - 4833
(2007/10/02)
-
