Syntheses and Properties of S-thiostearates

Abstract

Most of the S-thiostearates (C17H35COSR') were prepared by heating the appropriate alkyl halides with S-potassium thiostearates in ethanol-ether. The S-thiostearates prepared were as follows : R'=methyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-hexyl, heptyl, octyl and dodecyl. S-sec-butyl, S-heptyl and S-octyl thiostearates thus prepared are believed to be new compounds and they showed the melting points of 24.424.6, 45.045.2 and 44.545.0°C, respectively. S-n-hexyl thiostearate showed the melting point of 37.337.5°C, which was lower than that reported before.Earch of the series of the S-thiostearates shows an alternation of the melting points. Fig.-5 represents the plot of the melting points of S-thiostearates against the number of carbon atoms (R') in the S-thiostearates. The odd members in the S-thiostearates melt at higher temperature than the even members.The ultraviolet absorption spectra of the S-thiostearates were also measured in cyclohexane solution, and the effect of R' on the π→π* band (234mμ) and n-π* band (270300mμ) was studied. The λmax and εmax did not appear which might be affected by the R' (Table-2).Further, the infrared absorption spectra of the S-thiostearates were measured in a KBr disk. The S-thiostearates having straight chain R' give no influence on the νmax of νC=O band and νC_??_S band, but νmax of the νC=O band seems to shift toward small wave numbers (cm-1) according to the branches of R' (Fig.-2).