Copper‐Catalyzed Aerobic Oxidative Transformation of Ketone‐Derived N‐Tosyl Hydrazones: An Entry to Alkynes

A novel strategy involving Cu‐catalyzed oxidative transformation of ketone‐derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal alkynes and symmetrical diynes. Cross‐coupling reactions of hydrazones with halides and terminal alkynes were performed to afford functionalized alkynes and unsymmetrical conjugated diynes. A mechanism proceeding through a Cu‐carbene intermediate is proposed for the C? C triple bond formation.     

Palladium-catalyzed regioselective cascade reaction of carbon dioxide,amines and allenes for the synthesis of functionalized carbamates

A palladium-catalyzed regioselective three-component cascade reaction of carbon dioxide,amines and allenes has been developed,providing an expedient and practical method for the construction of a range of functionalized carbamates containing dihydrobenzofuran or indole moiety in moderate to excellent yields.The broad substrate scope,good functional group tolerance and excellent chemo-and regioselectivity are the features of the transformation.     

Base‐Promoted Coupling of Carbon Dioxide,Amines, and N‐Tosylhydrazones: A Novel and Versatile Approach to Carbamates

A base‐promoted three‐component coupling of carbon dioxide, amines, and N‐tosylhydrazones has been developed. The reaction is suggested to proceed via a carbocation intermediate and constitutes an efficient and versatile approach for the synthesis of a wide range of organic carbamates. The advantages of this method include the use of readily available substrates, excellent functional group tolerance, wide substrate scope, and a facile work‐up procedure.     

轴向变速粘弹性Rayleigh梁参数共振稳定性

运用近似解析方法和数值方法研究轴向变速运动黏弹性Rayleigh梁的次谐波共振和组合共振的稳定性区域。基于变分原理,考虑梁断面旋转惯性的影响,推导轴向速度有周期波动的微变形梁横向振动的数学模型;采用多尺度方法建立前两阶次谐波共振和组合共振范围内的参数振动的可解性条件;进而确定梁两端简支边界条件下,因共振而产生的失稳区域;通过微分求积方法求解表征细长Rayleigh梁横向振动的运动微分方程。数值算例分析了黏弹性系数和扭转系数对梁振动失稳区域的影响,将数值仿真结果与近似解析方法的结论进行比较。算例表明:近似解析解的精度较高,第一、第二阶主共振的最大误差分别为3.206%、4.213%。     

某些酸性磷(膦)酸酯VO(Ⅱ)配合物在四氢呋喃中的氧化过程的ESR研究

本文用电子顺磁共振法对某些酸性磷(膦)酸酯VO(Ⅱ)配合物在四氢呋中的氧化过程进行了动力学研究,研究了温度、浓度和配合物性质对反应速度及反应可逆性的影响,并计算得到动力学参数-氧化反应级数,反应速度常数和反应的表观活化能。     

VO(Ⅱ)-邻菲啰啉络合物的ESR波谱研究

该文考察了VOSO₄与1,10-邻菲啰啉(Phen)和3,4,7,8-四甲基-1,10-邻菲啰啉(TMP)在不同酸度(pH=1-14)的乙二醇/水(1:1)溶液中,在-100℃下的ESR波谱.发现在pH<1.0和pH>11范围内,二种配体均不能与VO(Ⅱ)生成络合物,当pH<1.0时,A=118×10^-4T归属于[VO(H₂O)₅]²⁺;当pH>11时,A=90×10^-4T归属于[VO(OCH₂CH₂O)₂]^2-.在1.4 < pH < 6之间,VO(Ⅱ)与phen生成三种不同络合物,在1.0 < pH < 7之间,VO(Ⅱ)则可与TMP生成四种络合物.本文推测了它们的可能结构.利用测得的波谱参数,计算了键参数和电子能级.利用电子光谱数据计算了晶体场参数.     

S=1/2体系的EPR波谱模拟

用一个以Fortran语言编制的S=1/2体系的EPR模拟谱程序.并引入了弛豫项,图谱线型得到了改善,使模拟谱与实验谱更为接近;对超超精细分裂的考虑,使该程序可适合于复杂图谱的模拟;求积分方法的近似处理,缩短了模拟谱的耗时,使复杂图谱的模拟在微机上成为现实.     

Nano‐Cu2O‐Catalyzed Formation of C?C and C?O Bonds: One‐Pot Domino Process for Regioselective Synthesis of α‐Carbonyl Furans from Electron‐Deficient Alkynes and 2‐Yn‐1‐ols

The formation of carbon–carbon and carbon–oxygen bonds continues to be an active and challenging field of chemical research. Nanoparticle catalysis has attracted considerable attention owing to its environmentally benign and high activity toward the reactions. Herein, we described a novel and effective nano‐Cu₂O‐catalyzed one‐pot domino process for the regioselective synthesis of α‐carbonyl furans. Various electron‐deficient alkynes with 2‐yn‐1‐ols underwent this process smoothly in moderate to good yields in the presence of air at atmospheric pressure. It is especially noteworthy that a novel 2,4,5‐trisubstituted 3‐ynylfuran was formed in an extremely direct manner without tedious stepwise synthesis. Additionally, as all of the starting materials are readily available, this method may allow the synthesis of more complex α‐carbonyl furans. An experiment to elucidate the mechanism suggested that the process involved a carbene intermediate.     

超临界二氧化碳中无水相涂料的合成与表征

为了减小传统纸张涂布中涂料水分对涂布能耗、涂布质量以及对涂布原纸质量的影响,研究了以超临界二氧化碳为反应介质,制备聚甲基丙烯酸甲酯(PMMA)和碳酸钙颜料混合的粉末涂料粒子.通过FTIR、GPC-十八角度激光光散射联用技术对PMMA组成结构进行了表征,考察了反应体系中引发剂浓度、单体浓度、稳定剂浓度、反应温度和反应时间对聚合反应的转化率和聚合产物的分子量的影响.实验表明,当反应条件为反应压力10MPa,反应温度75℃,反应时间8h,单体浓度0.10g/mL,引发剂浓度0.10×10-2g/mL,稳定剂浓度0.06×10-2g/mL时,其聚合反应的转化率较高,同时PMMA的分子量适中,分子量分布窄.SEM观察到混合涂料粒子颗粒均匀,表明颜料在粉末涂料体系中分散性良好.