 BackShort Report ScienceAsia 24 (1998): 065-071 |doi: 10.2306/scienceasia1513-1874.1998.24.065 VIBRATIONAL FREQUENCIES AND STRUCTURE OF ESTRAGOLE USING SEMIEMPIRICAL CALCULATIONSORAWAN SIRICHOTE, KANIDTHA HANSONGNERN AND PRAVIT SUDKEAWABSTRACT: The vibrational spectrum of liquid estragole (4-methoxy-1-allylbenzene) was obtained from FT-IR spectroscopy. Comparison among experimental fundamental vibrational frequencies and fundamental vibrations calculated using five semiempirical methods (CNDO, INDO, MNDO, AM1 and PM3) indicate PM3 method gives the best agreement of vibrational description. Ab initio calculations using 3-21G, 3-21G* and 6-31G* basis sets were performed for comparison. It was found that 6-31G* gave the best frequency results but it was only 1 % more reliable than PM3 method. Since estragole is one of the significant attractants for the American western corn rootworm (WCR), Diabrotica virgifera virgifera Leconte, the study of molecular structure of estragole from PM3 method was then used to probe for some information about the WCR active site. Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkla 90112, Thailand. Received February 4, 1998
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