在晶 (固 )态下 ,化合物邻苯二甲酸 L-( +) -2 ,3 -O-亚异丙基苏力糖酯存在两种不同的构象形式 ,利用螺旋片段判定规则及ω值 ,结合 X射线衍射数据及扭转角数据 ,对这两种构象形式的所有螺旋片段进行了分析 ,尽管两种构象形式的净值螺旋性相反 ,但仍然得出总净值螺旋性与旋光方向一致的结论 In the crystalline (solid) state, there are two different conformational forms of the compound L- (+) -2, 3-O-isopropylidene sibutyl phthalate. By using the rule of helical segment determination and the value of ω , We combine the X-ray diffraction data and the torsion angle data to analyze all the helical segments of these two conformational forms. Although the net helicity of the two conformational forms is opposite, the conclusion that the total net helicity is consistent with the optical rotation is obtained