TY - JOUR
T1 - Autocatalysis and surface catalysis in the reduction of imines by SmI 2
AU - Rao, Chintada Nageswara
AU - Hoz, Shmaryahu
PY - 2011/9/21
Y1 - 2011/9/21
N2 - The reduction of the three imines, N-benzylidene aniline (BAI), N-benzylidenemethylamine (BMI), and benzophenone imine (BPI), with SmI 2 gives the reduced as well as coupled products. The reactions were found to be autocatalytic due to the formation of the trivalent samarium in the course of the reaction. When preprepared SmI3 was added to the reaction mixture, the reaction rate increased significantly. However, the kinetics were found to be of zero order in SmI2. This type of behavior is typical of surface catalysis with saturation of the catalytic sites. Although no solids are visible to the naked eye, the existence of microcrystals was proven by light microscopy as well as by dynamic light scattering analysis. Although HRTEM shows the existence of quantum dots in the solid, we were unable to make a direct connection between the existence of the quantum dots and the catalytic phenomenon. In the uncatalyzed reaction, the order of reactivity is BPI > BMI > BAI. This order does not conform to the electron affinity order of the substrates but rather to the nitrogen lone pair accessibility for complexation. This conclusion was further supported by using HMPA as a diagnostic probe for the existence of an inner sphere electron transfer reaction.
AB - The reduction of the three imines, N-benzylidene aniline (BAI), N-benzylidenemethylamine (BMI), and benzophenone imine (BPI), with SmI 2 gives the reduced as well as coupled products. The reactions were found to be autocatalytic due to the formation of the trivalent samarium in the course of the reaction. When preprepared SmI3 was added to the reaction mixture, the reaction rate increased significantly. However, the kinetics were found to be of zero order in SmI2. This type of behavior is typical of surface catalysis with saturation of the catalytic sites. Although no solids are visible to the naked eye, the existence of microcrystals was proven by light microscopy as well as by dynamic light scattering analysis. Although HRTEM shows the existence of quantum dots in the solid, we were unable to make a direct connection between the existence of the quantum dots and the catalytic phenomenon. In the uncatalyzed reaction, the order of reactivity is BPI > BMI > BAI. This order does not conform to the electron affinity order of the substrates but rather to the nitrogen lone pair accessibility for complexation. This conclusion was further supported by using HMPA as a diagnostic probe for the existence of an inner sphere electron transfer reaction.
UR - http://www.scopus.com/inward/record.url?scp=80052793461&partnerID=8YFLogxK
U2 - 10.1021/ja205885q
DO - 10.1021/ja205885q
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AN - SCOPUS:80052793461
SN - 0002-7863
VL - 133
SP - 14795
EP - 14803
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 37
ER -