TY - JOUR
T1 - Catalytic post-modification of alkene polymers. Chemistry and kinetics of dehydrogenation of alkene polymers and oligomers with pincer Ir complexes
AU - Ray, Amlan
AU - Kissin, Yury V.
AU - Zhu, Keming
AU - Goldman, Alan S.
AU - Cherian, Anna E.
AU - Coates, Geoffrey W.
N1 - Funding Information:
We thank the Division of Chemical Sciences, Office of Basic Energy Sciences, Office of Energy Research, US Department of Energy for support of this research, grant DE-FG02-93ER14353.
PY - 2006/8/18
Y1 - 2006/8/18
N2 - The paper presents details of catalytic dehydrogenation reactions of two high molecular weight, highly branched hydrocarbons, a polymer of 1-hexene and an oligomer of 1-butene, and describes kinetic analysis of these reactions. The dehydrogenation reactions were catalyzed with two pincer Ir complexes, [4-methoxy-2,6-C6H3(CH2P-tert-Bu2)2]IrH2 and [4-methoxy-2,6-C6H2(CH2P-iso-Pr2)2]IrH2, and were carried out at 150 °C in p-xylene solutions with norbornene as a hydrogen acceptor. The structure of all dehydrogenation reaction products and the Ir species was determined by 1H and 31P NMR. Mechanistically, these reactions are similar to dehydrogenation reactions of low molecular weight alkanes. Kinetic analysis of the reactions yielded the values of effective rate constants for all major reaction steps in the catalytic cycle. The results show that catalytic dehydrogenation of branched polymers in the presence of an alkene hydrogen acceptor is feasible at increased temperatures and represents a viable route to post-synthetic modification of branched polyolefins.
AB - The paper presents details of catalytic dehydrogenation reactions of two high molecular weight, highly branched hydrocarbons, a polymer of 1-hexene and an oligomer of 1-butene, and describes kinetic analysis of these reactions. The dehydrogenation reactions were catalyzed with two pincer Ir complexes, [4-methoxy-2,6-C6H3(CH2P-tert-Bu2)2]IrH2 and [4-methoxy-2,6-C6H2(CH2P-iso-Pr2)2]IrH2, and were carried out at 150 °C in p-xylene solutions with norbornene as a hydrogen acceptor. The structure of all dehydrogenation reaction products and the Ir species was determined by 1H and 31P NMR. Mechanistically, these reactions are similar to dehydrogenation reactions of low molecular weight alkanes. Kinetic analysis of the reactions yielded the values of effective rate constants for all major reaction steps in the catalytic cycle. The results show that catalytic dehydrogenation of branched polymers in the presence of an alkene hydrogen acceptor is feasible at increased temperatures and represents a viable route to post-synthetic modification of branched polyolefins.
KW - Dehydrogenation
KW - Kinetics of dehydrogenation
KW - Oligomers
KW - Pincer Ir complexes
KW - Polyolefins
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U2 - 10.1016/j.molcata.2006.04.017
DO - 10.1016/j.molcata.2006.04.017
M3 - Article
AN - SCOPUS:33747376690
VL - 256
SP - 200
EP - 207
JO - Journal of Molecular Catalysis A: Chemical
JF - Journal of Molecular Catalysis A: Chemical
SN - 1381-1169
IS - 1-2
ER -