Chromatographic behaviour (GC and HPLC) of 1,n-bis(alkylthio)alkanes

Summary

The retention behaviour of 1,n-bis(alkylthio)alkanes (39 compounds, R¹-S-(CH₂)_n-S-R²) was characterized by gas chromatography on a SE 54 capillary column and by high pressure liquid chromatography on a ODS phase. Generally, the retention times depend both on the number of methylene groups (n) between the two sulphur atoms and on the alkyl groups R¹ and R². Substitution of n-alkyl groups R by e.g.,i-propyl ort-butyl leads to a decrease in the retention times. This can be explained by the weaker attachement of bulky alkyl groups to the ODS phase (HPLC) and lower boiling points (GC), respectively. A linear correlation was found between boiling points and retention data (Kovats indices) in GC. In HPLC the retention increments of the methylene groups — (CH₂)_n — between the two sulphur atoms are lower in the case ofn=2–4 than forn>4, which can be related to a sulphur-sulphur interaction.