Extent of hydration of dimethyl sulfoxide in aqueous solution

✍ Scribed by Hans Schott

• Publisher: John Wiley and Sons
• Year: 1969
• Tongue: English
• Weight: 282 KB
• Volume: 58
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.2600580807

✦ Synopsis

The maximum hydration of dimethyl sulfoxide (DMSO) in aqueous solution at 25" was investigated by the deviation of experimental values of fluidity, dielectric constant, refractive index, density, and molar refraction from values calculated by linear interpolation between the values of the two pure liquids as a function of mole fraction. The maximum deviation in fluidity and dielectric constant occurred at the ratio of three water molecules per DMSO molecule; this is the maximum hydration. The magnitude of the maximum deviation was 203x for fluidity and 4% for dielectric constant. The maximum deviation in refractive index and molar refraction occurred at water-DMSO molar ratios of 2: 1 and 1 : 1 . These two values are shown to be low.

Keyphrases 0 Dimethyl sulfoxide hydration-aqueous solution 0

Viscosity-dimethyl sulfoxide-water mixtures 0 Density-dimethyl sulfoxide-water mixtures 0 Refractive indexes-dimethyl sulfoxide-water mixtures Dimethyl sulfoxide (DMSO) is a powerful solvent for inorganic (1, 2) and organic compounds including high polymers (3), and is therefore often used as a medium for conducting reactions (2-4). In the pharmaceutical field, DMSO is unique as a skin penetrant and greatly improves the percutaneous absorption of many drugs (5). During a study of solutions of organic compounds in DMSO-water mixtures, it became necessary to know the extent of hydration of DMSO, i.e., the maximum number of water molecules associated with a DMSO molecule at room temperature. A review of the physicochemical literature on the DMSO-water system revealed the need for additional data. Pertinent old and new data and their interpretation are presented here.