NMR Spectra of Cyclic Formals Formed during the Early Stage of the Copolymerization of Trioxane and Ethylene Oxide

Abstract

During the early stage of the copolymerization of trioxane and ethylene oxide, we found the formation of three novel cyclic compounds: 1,3,5,7-tetraoxacyclononane (TOCN), 1,3,5,7,10-pentaoxacyclododecane (POCD), and 1,3,5,7,10,13-hexaoxacyclopentadecane (HOCP). These novel cyclic compounds were new direct reaction products of 1 mole of trioxane and 1 mole of ethylene oxide, 1 mole of trioxane and 2 moles of ethylene oxide, and 1 mole of trioxane and 3 moles of ethylene oxide, respectively. We compared the 1H-NMR and 13C-NMR spectra of each cyclic compound and precisely assigned the signals of each spectrum using NOESY (nuclear Overhauser enhancement spectroscopy) and HETCOR (heteronuclear correlated spectroscopy). We also compared the 1H-NMR spectra of POCD and HOCP with the corresponding cyclic formals with one oxymethylene unit, diethylene glycol formal (DEGF) and triethylene glycol formal (TEGF). Interestingly, we found that DEGF and TEGF, which have only one oxymethylene unit, showed no proton splitting of the oxyethylene units, while POCD and HOCP, which have three consecutive oxymethylene units, have split signals for the oxyethylene units.