tailieunhanh - Two long chain alkyl alcohols from the leaves of acroton tonkinensis gagnep, euphorbiaceae

In continuation of our reports on the chemical constituents of Croton tonkinensis Gagnep. (Euphorbiaceae) [1] this paper deals with the isolation and structure elucidation of two long chain alkyl alcohols. Two compounds 1 and 2 were isolated by repeated silica gel column chromatography of the n-hexane soluble fraction obtained from the methanol extract of the dried leaves of C. tonkinensis by liquid - liquid fractionation [2]. The long aliphatic chains of both compounds 1 and 2 were characterized by the 1 H and 13 C NMR spectra: H (3H, t, J = Hz), C (q) for the terminal methyl groups; H (m) and - (m), C - (all t) for the chain methylene groups. | Journal of Chemistry Vol. 42 1 P. 132 2004 SHORT COMMUNICATION TWO LONG CHAIN ALKYL ALCOHOLS FROM THE LEAVES OF ACROTON TONKINENSIS GAGNEP. EUPHORBIACEAE Received 18-9-2003 PHAN MINH GIANG PHAN TONG SON Faculty of Chemistry College of Natural Science Vietnam National University In continuation of our reports on the chemical constituents of Croton tonkinensis Gagnep. Euphorbiaceae 1 this paper deals with the isolation and structure elucidation of two long chain alkyl alcohols. Two compounds 1 and 2 were isolated by repeated silica gel column chromatography of the n-hexane soluble fraction obtained from the methanol extract of the dried leaves of C. tonkinensis by liquid - liquid fractionation 2 . The long aliphatic chains of both compounds 1 and 2 were characterized by the 1H and 13C NMR spectra 0H 3H t J Hz ỖC q for the terminal methyl groups ỖH m and - m ỖC - all t for the chain methylene groups. In the 1H and 13C NMR spectra of compound 1 the signals for the second methyl group at ỖH 3H d J Hz ỖC q and for the neighbouring carbinol methine at ỖH 1H sextet J Hz ỖC d were indicative for a secondary alcohol. The molecular ion peak was not visible in the EIMS spectrum of 1 but the peak at m z 406 M-H2O . allowed us to calculate the molecular formula of 1 as C29H60O. Thus the structure of 1 was elucidated as n-nonacosan-2-ol. Differing from alcohol 1 which possesses a secondary structure the primary structure of alcohol 2 was deduced from the NMR signals at ỖH 2H t J Hz ỖC t . Compound 2 was determined as n-triacontan-1-ol on the basis of the EIMS peak at m z 420 M-H2O . C30H62O. n-Nonacosan-2-ol 1 . White powder. EIMS 70 eV m z 406 M-H2O . 1H-NMR 300 MHz CDCl3 Ỗ 3H t J Hz CH3-29 3H d J Hz Ch3-1 m and m 26 CH2 1H sextet J Hz CH-2 13C-NMR 300 MHz CDCl3 Ỗ q C-29 q C-1 all t 25 CH2 t C-3 d C-2 . n-Triacontan-1-ol 2