Synthesis of novel polymethacrylate bearing an (S)-(+)-1-cyclohexylethyl urea group in the side chain and its chiral recognition ability

Abstract

A new chiral methacrylate, (S)-(+)-1-cyclohexylethyl-(2-methacryloyloxyethyl)urea (CEMOU), was synthesized from 2-methacryloyloxyethyl isocyanate (MOI) and (S)-(+)-cyclohexylethylamine. Radical homopolymerization of CEMOU was performed in several solvents to obtain the corresponding chiral polymers having hydrogen bonds based on urea moieties. Specific optical rotations of poly(CEMOU) were slightly changed by the measurement temperature, which may be attributed in part to a change of conformation caused by hydrophobic interaction between the cyclohexyl groups. From the results of radical copolymerization of CEMOU (M1) with styrene (ST, M2) or methyl methacrylate (MMA, M2), monomer reactivity ratios (r1, r2) and Alfrey–Price Q–e values were determined: r1 = 0.89, r2 = 0.12, Q1 = 2.45, e1 = 0.68 for the CEMOU–ST system; r1 = 0.48, r2 = 0.18, Q1 = 8.39, e1 = 1.97 for the CEMOU–MMA system. The chiroptical property of the poly(CEMOU-co-ST) was slightly influenced by the co-units. Poly(CEMOU)-bonded silica gel as the chiral stationary phase (CSP) was prepared for high-performance liquid chromatography (HPLC). The CSP resolved trans-2-dibenzyl-4,5-di(o-hydroxyphenyl)-1,3-dioxolane in normal phase such as n-hexane/2-propanol by HPLC. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1018–1025, 2003