氧方酸制备方法的改进及其晶体结构

AN IMPROVED PREPARATION METHOD AND CRYSTAL STRUCTURE OF OXOSQUARIC A CID

改进了以全氯代－１，３－丁二烯为原料制备氧方酸的方法，收率为６５％～６８％．测定了氧方酸的晶体结构；三斜晶系，空间群Ｐ＿１，α＝５．０７４１（６）ｎｍ，ｂ＝５．０７１５（５）ｎｍ，ｃ＝５．２９１２（８）ｎｍ，β＝５８．５７（１）°，ｚ＝１，Ｄｃ＝１．９１５ｇ·ｃｍ￣（－３），Ｖｃ＝０．９９１１５ｎｍ￣３，Ｒ＿ｗ＝０．０２５８．其电子云密度图表明四碳环内存在一缺电空间或为１电子陷阱，四个碳碳键键长平均化．

The preparation method of oxosquaric acid from hexachloro butadiene is improved,the yield increaed to 65%～68%. The Crystal structure of oxosquaric acid has been deteimined by four circee X- ray diffracttion on single crystal.The resutls suggests that the crystal belongs totriclinic system, having space gioup P_1 with crystallographic paramebers:α=5.074(6),b=5.0715(5),c=5.2912(8)nm,β=58.57(1)°,z=1,Dc=1.915g·cm￣(-3),Vc=0.99115nm,￣3,R_w=0.0258. The sketch diagram of the density of electrolic clouds distributing over oxoquaricacid indicats that the charge is abence inside the tetracarben ring. This implies that there is anelectrolic trap. the carben-carbon bond length in the oxosquaric acid is averaged. In fact the olefinbend is oxosquaric acid is usually only on expression for convenience rather than real existence.