Evidence of an inversion mechanism for the thermal cis–trans isomerization of push–pull azobenzenes. A volumetric study

1985 ◽  
pp. 903-904 ◽  
Author(s):  
Norio Nishimura ◽  
Tohru Tanaka ◽  
Yoshimi Sueishi
Keyword(s):  
Trans Isomerization ◽  
Volumetric Study ◽  
Inversion Mechanism

Die Lösungsmittelabhängigkeit der thermischen cis-trans-Isomerisierung von N-Benzylidenanilinen mit Donator/Akzeptor-Substituenten.

1976 ◽  
Vol 31 (7) ◽  
pp. 953-959 ◽  
Author(s):  
U. Berns ◽  
G. Heinrich ◽  
H. Gusten
Keyword(s):  
Ground State ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Solvent Polarity ◽  
Linear Functions ◽  
Aryl Group ◽  
Trans Isomerization ◽  
Solvatochromic Shifts ◽  
Z Value ◽  
Inversion Mechanism

Thermal cis →-trans isomerization of eight N-benzylideneanilines with donor and/or acceptor substituents in the para, para'-positions was studied in different solvents by observing the rapid relaxation to the thermodynamic stable trans isomer following flash photolysis. With the push-pull effect of the substituents in the direction of the N-aryl group the rate constant at 25°C is by three powers of 10 faster compared to the N–benzylideneaniline with opposite arrangement of substituents. The rate constants are independent of the nature of the substituents in the para-position of the benzylidene group. The rate constants of N-(4-nitrobenzylidene)-p-anisidine are linear functions of the solvent polarity scale based on solvatochromic shifts (Kosowers Z-value or Dimroths ET-value). With increasing push-pull effect of the substituents in the direction of the N-aryl group the rate constants do no longer depend on the polarity of the solvent. The observed solvent effects on the rates and the activation energies for thermal cis→ trans isomerization suggest that the transition state of the reaction is less polar than the ground state of the sterically hindered cis-N-benzylideneaniline, thus favouring an inversion mechanism to become operative with respect to the N-benzylideneanilines.

Temperature and pressure dependences of thermal cis-to-trans isomerization of azobenzenes which evidence an inversion mechanism

1981 ◽  
Vol 103 (17) ◽  
pp. 5161-5165 ◽  
Author(s):  
Tsutomu Asano ◽  
Toshio Okada ◽  
Seiji Shinkai ◽  
Kazuyoshi Shigematsu ◽  
Yumiko Kusano ◽  
...  
Keyword(s):  
Trans Isomerization ◽  
Temperature And Pressure ◽  
Inversion Mechanism

The Natural History of Petroclival Meningioma: A Volumetric Study

2016 ◽  
Vol 77 (S 02) ◽  
Author(s):  
Matthew Carlson ◽  
Jacob Hunter ◽  
Robert Yawn ◽  
Ray Wang ◽  
Brendan O'Connell ◽  
...  
Keyword(s):  
Natural History ◽  
Petroclival Meningioma ◽  
Volumetric Study ◽  
History Of
Sign in / Sign up

Export Citation Format

Share Document