Reactions and products revealed by NMR spectra of deuterated dimethylsulfoxide with iodomethane in neutral and basic media

Abstract

<div><p>Reactions occurring within each one of two mixtures, a mixture of deuterated dimethylsulfoxide, DMSO-<i>d</i>₆, with CH₃I (system I) and another mixture of DMSO-<i>d</i>₆ with CH₃I, NaOH and water (system II), were monitored by 1D and 2D nuclear magnetic resonance (¹H, ¹³C, heteronuclear multiple quantum correlation, heteronuclear multiple bond correlation and diffusion-ordered NMR spectroscopy). The analysis of the spectra as a function of reaction time revealed the formation of methoxy-bis(trideuteromethyl)sulfonium iodide, <b>3</b>; the precipitation of hexadeuterated trimethyloxosulfonium, <b>2a</b>; a methyl exchange between DMSO-<i>d</i>₆ and <b>2a</b> to produce trideuterated dimethylsulfoxide, DMSO-<i>d</i>₃, <b>4</b>, and nona-deuterated trimethyloxosulfonium iodide, <b>2b</b>; and the production of small quantities of methanol, <b>5</b>, trideuterated dimethylsulfide, <b>6</b>, and dimethyl ether, <b>7</b>, in both systems. Only system II precipitated deuterated [Na₄(DMSO-<i>d</i>_x)₁₅][(I₃)₃I], <b>1a</b>, a green solid with metallic shine that corresponds to an isotopomer of <b>1</b>, which is produced by the self-assembly of DMSO and CH₃I in the presence of NaOH and water.</p></div