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人们广泛使用“哈武斯透视式”表示含有吡喃环的糖类的结构。这些结构式没有真实表达出六环糖(即吡喃糖)的分子构型。虽然结构式很容易画出来,然而对于学生来说,缺少一个“把环上碳原子上连的‘—H’和‘—OH’应放在环的上方或下方”的指导原则,要学会就感到吃力。有几种现代的教科书强调吡喃糖环的几何形状。学生们已经碰到了这些书强调的原则,突出的问题是:已醛糖中较大的羟甲基(C—6)应以较有利的平伏健位置(e键)连在环上的碳原子(C—5)上,以减少空间位阻。
The widely used “Houghsian perspective” refers to the structure of sugars containing pyran rings. These structural formulas do not truly convey the molecular configuration of the hexacyclic sugar (ie pyranose). Although the structure is easy to draw, for students it is a lack of a guideline that says “-H” and “-OH” attached to the ring carbon atoms should be placed above or below the ring " Strenuous Several modern textbooks emphasize the pyranose ring geometry. Students have come across the principle emphasized in these books, highlighting the fact that the larger methylol (C-6) in aldose should be bound to the carbon atom on the ring with the more favorable equatorial (e-bond) (C-5) to reduce steric hindrance.