Radical Polymerization of Isomeric Methacrylic Monomers:  cis- and trans-(2-Phenyl-1,3-dioxan-5-yl) Methacrylate

Abstract

Two new monomers, cis-(2-phenyl-1,3-dioxan-5-yl) methacrylate (CPDM) and trans-(2-phenyl-1,3-dioxan-5-yl) methacrylate (TPDM), have been synthesized. The stereochemical configuration in both monomers was unequivocally assigned by correlation 1H−13C NMR experiments. The radical polymerization reactions of both monomers were studied by ultraviolet spectroscopy and electron paramagnetic resonance spectroscopy to determine the polymerization rate parameter k p/k t 1/2 and the absolute propagation and termination rate constants (k p and k t) at different temperatures. The values of k p/k t 1/2 lie in the range 0.40−0.55 L1/2/(mol1/2 s1/2) for CPDM and 0.29−0.37 L1/2/(mol1/2 s1/2) for TPDM at temperatures between 45 and 70 °C, showing that the polymerization rate of the cis monomer with the substituents in equatorial−axial positions on the dioxane ring is higher than that of its trans counterpart with the phenyl and ester residue in equatorial positions on the dioxane ring. Using EPR measurements of the polymer radical concentrations, similar values for k p were obtained for both trans and cis monomers, whereas the termination rate constant of the trans monomer was about twice that of the cis monomer at the same temperature.

Reaction kinetics and gel effect on the polymerization of 2‐ethoxyethyl methacrylate and 2(2‐ethoxyethoxy) ethyl methacrylate

“…For UV measurements, the ratio between the initial and instantaneous monomer concentrations is equivalent to ( A 0 − A ∞ )/( A − A ∞ ), where A 0 , A , and A ∞ are the absorbances of the monomer at the wavelength considered at the beginning of the reaction at time t and at total conversion, respectively. Therefore, eq 1 can be transformed into the following expression:24–27 …”

“…To calculate the absolute values of the termination‐rate coefficients, it is necessary to determine the real value of the efficiency factor at different conversions. We believe that its accurate determination is not possible by the conventional EPR method,27 according to which a radical such as TEMPOL reacts quantitatively with the radicals originated by decomposition of the initiator and that theoretically would initiate the monomer polymerization. Consequently, we only determine the relation 〈 k t 〉/ f , whose values are shown in the last column of Table 1 for the polymerization of EEMA and DEMA.…”

Migration Phenomena in Methacrylic Esters and Polymers Derived from Glycerol

“…The characterization of the purified products was made by 1 H and 13 C NMR spectroscopy and confirmed the structure of the polymers: P2,3GM, PCPDM, and PTPDM. [4][5][6][7][8][9][10][11][12] The number average molecular weights of the samples of PCPDM and PTPDM were 9 Â 10 4 and 1.4 Â 10 5 Da, whereas a lower bound for this quantity estimated from kinetic results was 2 Â 10 5 Da for P2,3GM.…”

“…Thus, 1,3GM was prepared by hydrolysis of cis or trans-(2-phenyl-1,3-dioxan-5-yl) methacrylates (CPDM and TPDM), which were obtained by reaction between methacryloyl chloride, glycerol, and benzaldehyde, according to the procedure shown in Scheme 1 and widely described elsewhere. [12] Once the two configurational isomers cis-(2-phenyl-1,3-dioxan-5-yl) methacrylate (CPDM) and trans-(2-phenyl-1,3-dioxan-5-yl) methacrylate (TPDM) were separated and purified, 1,3GM was prepared by hydrolysis of CPDM and/ or TPDM in the same way as indicated above for the hydrolysis of IPMA. In spite of the successful hydrolysis reactions, secondary processes took place from the beginning of the reaction that led to a mixture of 1,3GM and 2,3GM.…”

Fragmentation of Carbohydrate Anomeric Alkoxyl Radicals: New Synthesis of Chiral 1‐Fluoro‐1‐halo‐1‐iodoalditols

“…1,3‐Dioxan‐5‐yl methacrylate, cis ‐ and trans ‐2‐phenyl‐1,3‐dioxan‐5‐yl methacrylate, and cis ‐ and trans ‐2‐cyclohexyl‐1,3‐dioxan‐5‐yl methacrylate were obtained by procedures described elsewhere 15–17. As an example, the synthesis route of the two latter monomers is given in Scheme .…”