STEREOSELECTIVE ISOMERIZATION OF EUGENOL TO TRANS-ISOEUGENOL CATALYZED BY IN SITU GENERATED NICKEL(0) PHOSPHINES

• Main Author: Saputra, Leo
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/71440
• Institution: Institut Teknologi Bandung

Double bond isomerization of eugenol to only trans-isoeugenol was successfully catalyzed by in situ generated Ni(0) phosphine from inexpensive Ni(II) sources (NiCl2(PPh3)2, NiCl2?6H2O, Ni(NO3)2?6H2O, or Ni(OAc)2?4H2O), phosphine ligands (PPh3, P(Ph-pOMe)3, or P(Ph-pMe)3), and reducing agent Zn. High eugenol conversion >99%, selectivity to trans-isoeugenol >97%, and TOF >1,116 h-1 could be achieved using 0.167 mol% of NiCl2(PPh3)2 relative to eugenol at room temperature (27 °C) in 30 minutes of reaction. Mol ratio of Ni(II):PPh3:Zn 1:1:1 gave high catalytic activities. The catalytic activities were significantly increased by addition 5 ?L of acetonitrile or 4-chlorobutyronitrile (mol ratio of Ni(II):4- chlorobutyronitrile 1:1). Kinetic studies showed that the reaction was pseudo first order with the values of kobs 0.252 min-1 (80 °C), ?S‡ -93 J/mol?K (-22 e.u.), and Ea 61 kJ/mol. Computational studies showed that trans-isoeugenol was thermodynamically and kinetically more favorable than cis-isoeugenol for the reaction catalyzed by Ni(0) phosphine. Dissociation of phosphine ligand was predicted as a possible way for eugenol coordinated to Ni(0) phosphine. The competition of nitrile ligand as a destabilizing agent for the intermediates or as a stabilizing agent for transition state will be studied in more detailed.