Synthesis and characterization of new multi-site phase transfer catalyst and its catalytic efficiency in dichlorocarbene addition to (R)-Carvone

• We synthesized new multi-site phase transfer catalyst having 4, 8, 12-active sites per molecule.
• Catalytic efficiency of these MPTCs is studied by dichlorocarbene addition to (R)-carvone.
• Catalytic efficiencies are compared with commercially available soluble PTCs such as TBAB and TBAC.
• Based on the results we reported the extraction mechanism for the dichlorocarbene addition to (R)-carvone.

A new multi-site phase transfer catalyst (MPTC) was synthesized from 1,4-dibromo-2,3,5,6-tetramethylbenzene that contain 12 active sites per molecule. The MPTC was thoroughly characterized by different spectral techniques, viz., FT-IR, NMR, MALDI-TOF Mass spectroscopic techniques and elemental analysis. The catalytic efficiency was demonstrated by dichlorocarbene addition to (R)-carvone. The MPTC's catalytic efficiency was compared with the commercially available, single site, phase transfer catalysts (PTCs) by monitoring the disappearance of (R)-carvone using gas chromatography. Among these PTCs the newly synthesized MPTC shows higher activity than the four-site, six-site, and commercially available single site PTCs. Further, new MPTC catalyst was selected for thorough kinetic study for the dichlorocarbene addition to (R)-carvone. Furthermore, the experimental parameters such as concentrations of substrate, catalyst, NaOH, stirring speed, and temperature has been found to play a significant role in the reaction rate. Based on the obtained results suitable mechanism was proposed.

We synthesized a new multi-site phase transfer catalyst having different active sites per molecule. The catalytic efficiency of these MPTCs is studied and proved by bis-dichlorocarbene addition to (R)-carvone under mild reaction conditions. Figure optionsDownload as PowerPoint slide