1.2- Dibromoethane rate constants

Figure 3. Reaction of electrogeneraied anion radicals (solid symbols), OEPFe(I) (open symbols), and EtioPCo(I) (half-open symbols) with 2,3-dibromo-2,3-dimethylbutane ( , , V )i l,2-dibromo-2-ethylbutane ( , H, ), 1,2-dibromooctane ( , , O ). and 1,2-dibromoethane ( A, A, A) (0) represents the reaction of 1,2-dibromoethane with e-(di C4 Ph)2-CT-TPPFe(I). Variation of the rate constant with the standard potential of the electron donor.

Figure 12 Arrhenius plot for the second-order rate constant ( hs-) for the nucleophilic displacement of bromide from 1,2-dibromoethane (EDB) by bisulfide ion (HS ) (after Barbash, 1993).

The natural phosphorescence rate constants suggest again that the Tj transitions are about 10 to 100 times more allowed for ketones than for cis-azoalkanes. It should be noted that the phosphorescence rate of azoalkanes is not accelerated by heavy atoms such as in 1,2-dibromoethane as solvent [50] or thallium in zeolites [147]. This is expected since phosphorescence from a (n,7i) state to the 71 ground state is an El-Sayed rule allowed process [143], which is inherently fast (in comparison to phosphorescence from (7r,7r) states) and is less likely to be much assisted by heavy atoms [153]. 

Table 20.2 Equilibrium constants N autho/N tran,s for the trans/gauche isomerism of 1,2-dibromoethane at 25 °C. Source JE Leffler and E Crunwald, Rates and Equilibria of Organic Reactions, Dover Publications, New York, 1989.

---

See also in sourсe #XX -- [ ]

---