手性硫代磷酸及其衍生物的研究——Ⅷ.O-乙基苯基硫代膦酸O-乙基O-苯基硫代磷酸混合酐某些反应的立体化学

本文研究了(+)-(R)-(R)-O-乙基苯基硫代膦酸O-乙基O-苯基硫代磷酸混合酐1的(1)碱性甲醇解反应;(2)酸性甲醇解反应;(3)碱性水解反应;(4)氨解反应;(5)与硫氢化钾反应以及(6)与五氯化磷反应的立体化学。发现所研究的反应均使P—O—P键断裂。在反应(1)—(4)中,亲核试剂的进攻发生在膦酰基磷原子上,得到构型翻转的产物;而未受亲核进攻的磷酰基磷原子构型保留。在反应(5)中,亲核试剂~-SH的进攻也发生在膦酰基磷原子上,但由于生成Ph(EtO)P(S)S~-而失去手性,使之消旋化;未受进攻的磷酰基磷原子仍为构型保留。在反应(6)中,膦酰基和磷酰基均被氯化,分别得到构型翻转的产物硫代膦酰氯14和硫代磷酰氯16,前者有明显的消旋化。本文还探讨了个别反应的反应机理。     

手性硫代磷酸及其衍生物的研究——Ⅵ.旋光活性的 O-乙基苯基硫代膦酸的绝对构型及有关反应的立体化学

Ohkawa 首先用番木鳖碱(Brucine)拆分了 O-乙基苯基硫代膦酸(1).随后,Nomeir用( )-及(-)-α-苯乙胺也拆分了1.但是1的绝对构型一直未予确定.我们用 Ohkawa 方法拆分了1,并通过化学相关法确定了1的绝对构型.如图所示,在1→2的甲基化反应中,P—S 及 P—O 键均未断裂,因而构型保留.Ohkawa用2摩尔 PCl_5与1摩尔1反应,Nomeir 用等摩尔 PCl_5与1反应,都得到立体专一性的产     

钢结构异形梁的计算研究

近年来,钢结构建筑发展迅速,各种结构形式、异形截面构件大量采用,异形钢构件的简化计算需慎重考虑．对于钢结构错层处梁的常用几种形式的研究中,针对某钢结构错层处异型粱按简支集中荷载作用时进行计算对比,发现工字形梁上加T形梁强度简化计算与考虑整个截面强度计算存在较大差异．结合“钢结构设计规范”对受弯构件强度计算的规定,根据剪应力推导公式计算截面的最大剪应力,比较理论计算与有限元计算结果之间的误差,简化计算的局限性较大,建议此形式异形钢梁工程应用计算应以全截面作为计算对象．     

STUDIES ON CHIRAL THIOPHOSPHORIC ACIDS AND THEIR DERIVATIVES [ⅤⅢ]——THE STEREOCHEMISTRY OF SOME REACTIONS OF THE MIXED ANHYDRIDE OF O-ETHYL PHENYLPHOSPHONOTHIOIC AND O-ETHYL O-PHENYL PHOSPHOROTHIOIC ACIDS

In this paper, (1) alkaline methanolysis, (2) acid methanolysis, (3) alkaline hydro-lysis, (4) aminolysis of (+)-(R)-(R)-mixed anhydride 1 of O-ethyl phenylphosphonothioic:and O-ethyl O-phenylphosphorothioic acid, (5) its reactions with KSH and (6) with PCl_5have been studied. The cleavage of P-O-P bonds in all the reactions studied has beenfound. In reactions (1)-(4), attacks of nucleophiles occur to the phosphorus atoms of phos-phonyl groups forming the products with inversion of configuration, while the configurationof the phosphorus atoms of phosphoryl groups which are not attacked is retained. Inreaction (5), the uncleophile -SH attacks the phosphorus atom of the phosphonyl group,but a racemic product results because of the formation of ph(EtO)P(S)~- which loseschirality; the configuration of the phosphorus atom of the phosphoryl group which is notattacked is still retained. In reaction (6), both the phosphonyl and phosphoryl groups arechlorinated giving as products (-)-(R)-thiophophonyl chloride 1