Effective Darzen's condensation of 4-nonanolide with 1,6-dibromohexan-2-one using new bead-shaped insoluble multi-site (six-site) phase transfer catalyst and low concentration of aqueous NaOH

New bead-shaped insoluble polymer-supported multi-site (six-site) phase transfer catalyst (BSIMPTC) was synthesized from mesitylene as a starting material and its catalytic efficiency was studied with the kinetics of Darzen's condensation of 4-nonanolide with 1,6-dibromohexan-2-one. The presence of six active-sites in the newly synthesized BSIMPTC, viz., 2,4,6-tris[(4-(2,2′-bis(N-triethylammoniummethylene chloride) eth-1-ene) phenoxy)benzene was characterized through FT-IR, solid 1H NMR, 13C NMR, SEM and [chloride ion] analyses and found that the BSIMPTC contains ≈6 active-site centers. The Darzen's condensation reaction of 4-nonanolide was performed at lower temperature (40 °C) under pseudo-first order rate conditions by taking lower concentration of aqueous NaOH (15%, w/v, 3.75 M) and excess of 1,6-dibromohexan-2-one. The disappearance of 4-nonanolide was quantitatively monitored by a gas chromatograph for the calculation of the pseudo-first order rate constant. The presence of more number of active-sites in BSIMPTC was further confirmed from the comparative study of pseudo-first order rate constant with the rate constants of single-site polymer-supported phase transfer catalyst. The comparative rate constant results reveal that the BSIMPTC is highly active-than the corresponding soluble six-active-site and almost ≈4 times higher active-than with insoluble/soluble single-site PTCs. The effect of various experimental parameters such as [substrate], [catalyst], [NaOH], stirring speed, and temperature on the rate of the reaction have also been studied and found that each variables are influenced the rate of reaction. Based on the obtained kinetic results, a suitable mechanism is proposed.

A new bead-shaped insoluble polymer-supported multi-site phase transfer catalyst (BSIMPTC), viz., 2,4,6-tris[(4-(2,2′-bis(N-triethylammoniummethylene chloride) eth-1-ene) phenoxy]benzene has been synthesized and were characterized through spectroscopic and microscopic techniques. The catalytic efficiency of BSIMPTC was examined by Darzen's condensation of 4-nonanolide with 1,6-dibromohexan-2-one reaction under pseudo-first order conditions.Figure optionsDownload as PowerPoint slide