Selective Halogenation Using an Aniline Catalyst

Electrophilic halogenation is used to produce a wide variety of halogenated compounds. Previously reported methods have been developed mainly using a reagent‐based approach. Unfortunately, a suitable “catalytic” process for halogen transfer reactions has yet to be achieved. In this study, arylamines have been found to generate an N‐halo arylamine intermediate, which acts as a highly reactive but selective catalytic electrophilic halogen source. A wide variety of heteroaromatic and aromatic compounds are halogenated using commercially available N‐halosuccinimides, for example, NCS, NBS, and NIS, with good to excellent yields and with very high selectivity. In the case of unactivated double bonds, allylic chlorides are obtained under chlorination conditions, whereas bromocyclization occurs for polyolefin. The reactivity of the catalyst can be tuned by varying the electronic properties of the arene moiety of catalyst.     

Quantitative conditions for the formation of p-wave neutron halos

With the experimental binding energies and configurations, the root-mean-square radii of p-wave valence neutron distributions for nuclei up to the second p-shell have been calculated in the framework of the single-particle potential model. By analyzing the relations between the radii and the binding energies, the scaling laws of p-wave valence neutron distributions are obtained. The quantitative conditions for the formation of p-wave neutron halos are deduced from these scaling laws. Based on the investigation on the probability of finding the valence nucleon outside the range of the interaction potential, a 2p_3/2 halo state in ⁴⁷S is anticipated for the first time. These obtained results might provide reference for searching for p-wave neutron halos in nuclei up to the second p-shell.     

Micellar Mediated Halodecarboxylation of α,β‐Unsaturated Aliphatic and Aromatic Carboxylic Acids—A Novel Green Hunsdiecker–Borodin Reaction

A Novel Hunsdiecker‐Borodin reaction (HBR) has been carried out efficiently with α,β‐unsaturated aliphatic and aromatic carboxylic acids by using N‐halo succinimides such as N‐chloro succinimide (NCS), N‐bromo succinimide (NBS), and N‐iodo succinimide (NIS) under micellar media. The reaction with α,β‐unsaturated aromatic carboxylic acids afforded β‐halo styrenes in excellent yield while α,β‐unsaturated aliphatic carboxylic acids underwent decarboxylation and to give corresponding halo derivatives. The reactions are dramatically accelerated in micellar media. This procedure works efficiently in CTAB (cetyl trimethyl ammonium bromide), SDS (sodium dodecyl sulfate), and TX (Triton‐X‐100) media under stirred conditions at room temperature. At reflux temperatures the yield of reaction products were further enhanced from good to excellent.     

Nanoparticle Halos Mechanism in Stabilizing of Colloidal Suspensions: Polymeric Binder and Dispersant Effects

Dispersion behavior of colloidal Al₂O₃ aqueous suspensions was investigated in the presence of highly charged CeO₂ nanoparticles and polymeric additives. It was found that among the investigated parameters, ceria nanoparticles concentration had the highest significant effect on the stability of Al₂O₃-CeO₂ suspensions. However, the low influence of dispersant concentration may be due to significant role of ceria nanoparticles stabilizing alumina microspheres by “nanoparticle halo” formation. The stabilization of the bidispersed suspensions was also evidenced by scanning electron microscopy and elemental analysis of the sediment layers after three weeks.     

研测动态问题的旋转孔径散斑照相法Ⅱ:矩位、平四位、直三位孔径

本文提出了旋转孔径散斑照相法中三种新颖的基本孔径:矩位孔、平四位孔和直三位孔,进行了理论分析和实验证明。采用新孔径拍摄散斑照相,散斑信息利用率高,衍射晕能量分布合理,信噪比提高,因而散斑条纹清晰度得到改善,相应的实验误差减小。     

直接俘获截面中的核晕效应

恒星能量下俘获截面非常难于直接测量.因此,通常借助于非直接方法或从最低能量下的实验数据外推到天体物理感兴趣能区.首先证明了用渐近归一化常数方法得到的结果近似与模型无关.因此,转移反应的渐近归一化常数方法处理提供了一可靠的途径用以确定恒星能量下的俘获截面. 鉴于此优点, 用渐近归一化常数方法计算了¹⁰Be(n,γ)¹¹Be反应的俘获截面. ¹¹Be是一个众所周知的具有两弱束缚态的晕核.作为一个典型的例子,演示了俘获到晕态的辐射俘获截面明显增大, 证明了入射中子波函数与晕的伸展尾部有较大重叠是俘获截面异常增大的原因.     

Observation and analysis of halo current in EAST

Plasma in a typically elongated cross-section tokamak （for example, EAST） is inherently unstable against vertical displacement. When plasma loses the vertical position control, it moves downward or upward, leading to disruption, and a large halo current is generated helically in EAST typically in the scrape-off layer. When flowing into the vacuum vessel through in-vessel components, the halo current will give rise to a large J × B force acting on the vessel and the in-vessel components. In EAST VDE experiment, part of the eddy current is measured in halo sensors, due to the large loop voltage. Primary experimental data demonstrate that the halo current first lands on the outer plate and then flows clockwise, and the analysis of the information indicates that the maximum halo current estimated in EAST is about 0.4 times the plasma current and the maximum value of TPF × Ih/Ip0 is 0.65, furthermore Ih/Ipo and TPF × Ih/Ipo tend to increase with the increase of Ip0. The test of the strong gas injection system shows good success in increasing the radiated power, which may be effective in reducing the halo current.     

Analytical estimation of ATF beam halo distribution

In order to study the backgrounds in the ATF2 beam line and the interaction point (IP), this paper has developed an analytical method to give an estimation of the ATF beam halo distribution based on K. Hirata and K. Yokoya''s theory. The equilibrium particle distribution of the beam tail in the ATF damping ring is presented, with each electron affected by several stochastic processes such as beam-gas scattering, beam-gas bremsstrahlung and intra-beam scattering, in addition to the synchrotron radiation damping effects. This is a general method which can also be applied to other electron rings.     

手性膦酸二酯类化合物的合成与结构

手性呋喃酮1a,1b与亚磷酸三酯2a,2b通过串联的不对称Michael加成／分子内Michalis-Arbazov重排反应,得到含磷官能团的新手性化合物5－（S）－（1S）－冰片氧基－4－膦酸二酯基－3－卤素－2（5H）－呋喃酮（3a-3d）。该反应具有条件温和,产率高（69％－93％）,光学纯度单一（d.e.≥98％）等特点,通过元素分析,IR,UV,^1H NMR,^13C NMR,MS,[α]D^20等分析数据以及X射线四圆衍射确定了它们的化学结构和绝对构型。     

Synthesis of 4‐halo‐2 (5H)‐furanones and their suzuki‐coupling reactions with organoboronic acids. A general route to 4‐aryl‐2 (5 H) ‐furanones

4‐Halo‐2(5H)‐furanones were prepared by the halolactonization of 2,3‐allenoic acids. The subsequent Suzuki coupling reaction of 4‐halo 2(5H)‐furanones with aryl boronic acids was carried out to produce 4‐aryl‐2(5H)‐furanones in excellent yields.