乙酰丙酮光二聚产物C10H16O4的晶体结构和分子力学计算

α,β-不饱和羰基化合物与共轭烯烃的光聚合是一类饶有兴趣的反应,通常认为是一激发态分子与一基态分子发生2 2]加成.在考察乙酰丙酮的光聚合反应产物的谱学数据时,发现产物可能系结构(Ⅰ),(Ⅱ),(Ⅲ)或(Ⅳ)中的一种但难以作出唯一的指定。这与我们研究乙酰丙酮和1-萘甲酸甲酯的光环加成产物结构所遇到的问题相似。为全面了解乙酰丙酮光二聚反应,本文报导X射线单晶结构分析和分子力学能量优化的结果,讨论了其可能的反应途径。

CRYSTAL STRUCTURE AND MOLECULAR MECHANICS CALCULATIONS OF THE PHOTODIMERIZATION PRODUCT OF ACETYLACETONE, C_(10)H_(16)O_4

The structure of the product from photodimerization in non-polar solvent of acetylacetone, C_(10)H_(16)O_4, Mr=200.2, was determined from three-dimensional X-ray data. It crystallizes in the monoclinic, space group P2_1/c, a=1.6766(2), b=0.7736(2), c=1.1024(l) nm, β=130.44(2)°, V=1.0882 nm, Z=4, D_o=1.23, D_c=1.222 g·cm~(-3), μ(MoK_a) =0.877 cm~(-1), F(000) =432. The structure was solved by direct methods and refined to R=0.040 for 1861 observed MoK_a reflections. The ultimate product is a furanoid derivative which has a minimum steric energy according to the molecular mechanics calculations. Possible reaction pathway of the photocycloaddition was also discussed.