109890-33-7Relevant academic research and scientific papers
Energy Barrier for 1,2-Chlorine Migration in α-Methyl-α-chlorobenzyl(chloro)carbene
Liu, Michael T. H.,Murray, Shawn K.,Zhu, Jianhuan
, p. 1650 - 1652 (1990)
An activation energy of 3.4 kcal mol-1 (1 cal = 4.184 J) was obtained for the 1,2-chlorine migration in α-methyl-α-chlorobenzyl(chloro)carbene.
Laser flash photolysis study of substituent effects on the rate of 1,2-H migration in a series of benzylchlorocarbenes
Liu, Michael T. H.,Bonneau, Roland
, p. 3604 - 3607 (2007/10/02)
Laser flash photolysis of para-substituted 3-chloro-3-benzyldiazirines in isooctane produces the corresponding carbenes, which react with pyridine to form ylides or undergo 1,2-H migration to form the (Z)- and (E)-β-chlorostyrenes. The rate for the 1,2-H migration is determined by plotting the pseudo-first-order rate constants for the growth of the ylide vs [pyridine] and extrapolating to zero pyridine concentration. In the case of (p-chlorobenzyl)chlorocarbene, the carbene decay can be monitored directly at 310 nm, whereas in [p-(trifluoromethyl)benzyl]chlorocarbene, the 285-nm trace may be analyzed as the sum of the absorption of the carbene and of the product β-chlorostyrenes. A Hammett plot of the logarithms of the rate constants for 1,2-H migration vs σp values gave a ρ value of -1.0, consistent with a hydride-like 1,2-H shift to the carbene center. The rate constants for the cyclopropanation of carbenes with tetramethylethylene (TME) were determined. In particular, the cyclopropanation of (p-chlorobenzyl)chlorocarbene with TME gave a negative activation energy of -4.7 kcal mol-1.
Thermolysis and Photolysis of 3-Chloro-3-benzyldiazirines in Alkenes: Evidence for a Carbene-Alkene Complex
Liu, Michael T. H.,Soundararajan, N.,Paike, N.,Subramanian, R.
, p. 4223 - 4227 (2007/10/02)
Photolysis and thermolysis of substituted 3-chloro-3-benzyldiazirines in alkenes yielded cyclopropanes and chlorostyrenes as products.The results suggest that the cyclopropanation of benzylchlorocarbenes is independent of substituents.However, 1,2-hydrogen migration is accelerated by OCH3 or CH3 substituents, and is decelerated by a Cl substituent on the phenyl ring.These results support the existence of an energy barrier to 1,2-H migration.Evidence is provided for carbene-alkene complexation.
