メチルステリンのガスクロマトグラフィー (第2報)

6-メチル基の導入による保持時間変化

抄録

In the previous paper of this series, the retention characteristics of 4-methyl sterols were investigated with a view for establishing a systematic relationship between the structure of sterols and their gas chromatographic characteristics. The present report deals an extended study on 6-methyl sterols prepared from cholesterol. The retention data for five 6-methyl sterols and for their derivatives at C-3 were expressed in terms of relative retention times (Table-1), methylene unit values (Table-2) and retention factors due to the introduction of 6-methyl group into sterols (Table-3), on SE-30, OV-17 and DEGS phase, respectively. Main results obtained were as follows :
1) The retention times of 6-methyl sterols and their derivatives were generally or mostly found to be larger than those of the corresponding non-methylated sterols and their derivatives. However, 6-methylcholesteryl-trifluoroacetate exhibited a retention time smaller than that of cholesteryl-trifluoroacetate on OV-17 phase. On DEGS phase, the trimethyl-silylether derivatives of 6 α-methylcholestanol and 6-methylcholesterol exhibited almost same retention times as compared with the corresponding non-methylated derivative.
2) The effect of intramolecular interaction between 6-methyl group and a C-3 functional group on the retention time was less marked as compared to the case with 4-methyl group (Fig-1).
3) The saturated compound with 6 α-methyl group was eluted faster than the corresponding 6 β-methyl isomer. On the other hand, the reverse was the case with 6 α-methyl-Δ⁴-cholesten-3-one and 6 β methyl Δ⁴ cholesten-3-one, and the latter eluded before the former.