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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 10, Number 2
BKCSDE 10(2)
February 20, 1989 

 
Title
The Crystal and Molecular Struture of Cholesteryl Isobutyrate
Author
Mi Hye Kim, Young Ja Park*, Choong Tai Ahn
Keywords
Abstract
The structure of cholesteryl isobutyrate, (CH3)2CHCOOC27H45, was determined by single crystal X-ray diffraction methods. Cholesteryl isobutyrate crystallized monoclinic space group P21, with a = 15.115 (8)Å, b = 9.636 (5)Å, c = 20.224 (9)Å, β = 93.15 (5)°, z = 4, Dc = 1.03 g/cm3 and Dm= 1.04 g/cm3. The intensity data were measured for the 3417 reflections, within sinθ/λ = 0.59Å-1, using an automatic four-circle diffractometer and graphite monochromated Mo-Kα radiation. The structure was solved by fragment search Patterson methods and direct methods and refined by full-matrix least-squares methods. The final R factor was 0.129 for 2984 observed reflections. The two symmetry-independent molecules (A) and (B) are almost fully extended. The molecules are in antiparallel array forming monolayers with thickness d100 = 15.2Å, and molecular long axes are nearly parallel to the [101] directions. The two distinct molecules form separate stacks with almost the same orientations, but with differing degrees of steroid overlap. Thers is a close packing of cholesteryl groups within the monolayers. The packing type is similar to those of cholesteryl hexanoate and cholesteryl oleate.
Page
177 - 185
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