乙酰丙酮光二聚产物C_(10)H_(16)O_4的晶体结构和分子力学计算

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

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。

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 = 16.766(2) ,b = 7.736(2), c = 11.024(l)A,β=130.44(2)°,V = 1088.2A^3, Z = 4,D_o = 1.23, D_c = 1.222 g.cm^(-3), μ(MoK_a) =0.877cm^(-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 photocycioaddition was also discussed