Alditol Acetates의 분자구조 = The Structures of Alditol Acetates

국문 초록 (Abstract)

D-glucitol hexaacetate와 xylitol pentaacetate의 결정구조를 단결정 X-선 회절법으로 연구하였다. D-glucitol hexaacetate는 공간군 P2₁, 단위세포 상수는 a=10.275(2), b=8.363(1), c=12.560(5) Å ; β=95.97(2)°; Z=2이고, xylitol pentaacetate는 공간군이 P2₁/C이고, a=18.126(1), b=11.422(2), c=8.649(1) Å, β=95.03(1)°이며 Z=4이다. 회절세기는 diffractometer로 얻었고, 분자구조는 직접법으로 밝혔으며, 최소자승법으로 정밀화하였다. 두 분자에 걸쳐 결합의 평균길이는 C(sp³)-C(sp³)가 1.514(10), C(sp³)-O : 1.444(6), C(sp²)-O : 1.347(9), C(sp²)=O : 1.197(6), C(sp²)-C(sp³) : 1.479(9)Å이고, 평균 결합각도는 C(sp³-C(sp³)-C(sp³)가 114.6(17), O-C(sp³)-C(sp³) : 109.4(23), C(sp²)-O-C(sp³) : 117.4(6), O=C(sp²)-O : 122.6(6), C(sp³)-C(sp²)-O : 111.8(7), C(sp³ )-C(sp²)=O : 125.5(4)°이다. 두 분자내의 탄소 사슬들은 extended zigzag chain으로 되어있어 D-glucitol과 xylitol 분자들의 conformation과는 다르다. Acetate group들의 각 원자들은 모두 한 평편상에 놓여있다.

다국어 초록 (Multilingual Abstract)

The crystal structures of two alditol acetates, D-glucitol hexaacetate and xylitol pentaacetate, have been determined by diffraction methods with Mo-Ko radiation, using direct methods for phase determinations. The crystal data are : for D-glucitol hexaacetate, P2₁ with a=10.275(2), b=8.363(1), c=12.560(5) Å ; β=95.97(2)°; Z=2 ; for xylitol pentaacetate, P2₁/C with a=18.126(1), b=11.422(2), c=8.649(1) Å, β=95.03(1)°, Z=4. Both molecules have extended zigzag carbon chain conformations which differ from previous studies of the structures of D-glucitol and xylitol and also differ from NMR studies on alditol acetates. The bond lengths and angles are normal, with mean values over both structures of C(sp³)-C(sp³) : 1.514(10), C(sp³)-O : 1.444(6), C(sp²)-O : 1.347(9), C(sp²)=O : 1.197(6), C(sp²)-C(sp³) : 1.479(9)Å, C(sp³)-C(sp³)-C(sp³) : 114.6(17), O-C(sp³)-C(sp³) : 109.4(23), C(sp²)-O-C(sp³) : 117.4(6), O=C(sp²)-O : 122.6(6), C(sp³)-C(sp²)-O : 111.8(7), C(sp³)-C(sp²)=O : 125.5(4)°. The atoms of acetate groups are in coplanar. There are no particularly short intermolecular contacts and the molecules are held together by van der Waals force only.