Halo-Michael/Aldol串联反应及其在合成中的应用

Michael加成反应和Aldol反应是有机合成中最基本和最常见的两种反应类型.通过对反应条件的调控和底物的设计,使卤素离子(Cl~—,Br~—,I~—)对α,β-不饱和化合物发生Michael加成之后,生成的活性中间体与醛在同一体系中继续进行Aldol反应得到多官能团产物,这一反应被称为halo-Michael/Aldol串联反应.Halo-Michael/Aldol串联反应可以有效提高有机合成的原子经济性和步骤经济性.总结了不同类型路易斯酸促进的halo-Michael/Aldol串联反应及其在合成中的应用,并展望了该反应的发展趋势.     

173Lu和174gLu衰变数据的测量

175Lu（n;2n）174m,gLu（n;2n）173Lu反应在高能中子通量监测中具有重要作用,其产物的放射性活度通常用HPGe探测器测量,这就需要174m,gLu和173Lu的半衰期和γ射线发射率等衰变数据必须准确无误。在主要的评价核数据库中,只有ENDF/B 7.1和JEFF 3.1.1数据库给出了173Lu和174Lu的半衰期和γ射线的发射几率等衰变数据,其中173Lu的射线发射几率ENDF/B 7.1库比JEFF 3.1.1库总体偏高,其他评价数据两个数据库非常一致。在中国原子能研究院的串列加速器上用20 MeV质子辐照金属Yb靶生产了含有173Lu,174m,gLu的放射性溶液,用激光共振电离质谱（LRIMS）和热表面电离质谱（TIMS）两种同位素稀释法测定了该溶液中173Lu和174m,gLu核素浓度,然后制备测量源在HPGe探测器上进行了近7年的跟踪测量,发现173Lu的半衰期为1.45 a,比目前评价的数据1.37 a高6.1%,636.1 keV射线发射几率的偏差最大,比ENDF/B 7.1的评价数据偏高7%。174gLu半衰期的测量结果3.37 a175Lu（n;2n）174m,gLu（n;2n）173Lu反应在高能中子通量监测中具有重要作用,其产物的放射性活度通常用HPGe探测器测量,这就需要174m,gLu和173Lu的半衰期和γ射线发射率等衰变数据必须准确无误。在主要的评价核数据库中,只有ENDF/B 7.1和JEFF 3.1.1数据库给出了173Lu和174Lu的半衰期和射线的发射几率等衰变数据,其中173Lu的射线发射几率ENDF/B 7.1库比JEFF 3.1.1库总体偏高,其他评价数据两个数据库非常一致。在中国原子能研究院的串列加速器上用20 MeV质子辐照金属Yb靶生产了含有173Lu,174m,gLu的放射性溶液,用激光共振电离质谱（LRIMS）和热表面电离质谱（TIMS）两种同位素稀释法测定了该溶液中173Lu和174m,gLu核素浓度,然后制备测量源在HPGe探测器上进行了近7年的跟踪测量,发现173Lu的半衰期为1.45 a,比目前评价的数据1.37 a高6.1%,636.1 keV γ射线发射几率的偏差最大,比ENDF/B 7.1的评价数据偏高7%。174gLu半衰期的测量结果3.37 a,比评价数据3.31 a高约1.8%,174gLu 76.5 keV和1 241.8 keV γ射线的发射几率比ENDF/B 7.1的评价数据分别低1.87%和12.8%。175Lu(n,2n)174m,gLu(n,2n)173Lu are important neutron reactions to monitor the high energy neutron fluxes and the residual nuclei, 174m,gLu and 173Lu, are usually measured by a HPGe spectrometer conveniently so that the decay data such as half lives and gamma-ray emission probabilities of 174m,gLu and 173Lu must be accurate. There are evaluated decay data only in ENDF/B 7.1 and JEFF 3.1.1 among the major evaluated nuclear data libraries, where the most data are almost same besides the gamma-ray emission probabilities of 173Lu are higher in ENDF/B 7.1 than that in JEFF 3.1.1. Yb metal as a target was irradiated by 20 MeV proton beams on a tandem accelerator in CIAE to produce 174m,gLu and 173Lu, and 176Lu isotopic dilution methods based upon a laser resonance ionization mass spectrometer (LRIMS) and a thermal surface ionization mass spectrometer (TIMS) were employed to determine the numbers of nuclides of 174Lu and 173Lu in a solution containing the irradiated target. Several radioactive sources made from the solution had been measured by a HPGe detector during the past 7 years and the peak intensities of the characteristic gamma-rays from 174gLu and 173Lu were analyzed to determine the half lives and gamma-ray emission probabilities. According to the measurements, the half life of 173Lu is 1.45 a, which is about 6.1% longer than the evaluated 1.37 a, and the gamma-ray emission probabilities of 173Lu is also different from the evaluated data, especially the emission probability of 636.1 keV gamma-ray of 173Lu is 7% higher than the value in ENDF/B 7.1. The half life of 174gLu is 3.37 a, about 1.8% longer than the evaluated 3.31 a, and the emission probabilities of 76.5 keV and 1 241.8 keV gamma-rays of 174Lu are 1.87% and 12.8% lower than the evaluated data in ENDF/B 7.1, respectively.