Physicochemical Studies of Demetalation of Light-harvesting Bacteriochlorophyll Isomers Purified from Green Sulfur Photosynthetic Bacteria

Demetalation kinetics of bacteriochlorophylls (BChls) c, d and e from green sulfur photosynthetic bacteria were studied under weakly acidic conditions. Demetalation rate constants of BChl e possessing a formyl group at the 7-position were significantly smaller than those of BChls c and d , which had a methyl group at this position. The activation energy of demetalation of 3¹ R -8,12-diethyl([E,E])-BChl e was 1.5-times larger than that of 3¹ R -[E,E]-BChl c . ¹⁵N-labeled 3¹ R -[E,E]-BChls c and e were purified from cells of green sulfur bacteria grown in a medium containing ¹⁵NH₄Cl, and their ¹⁵N NMR spectra were measured. The chemical shifts of N₂₁, N₂₂ and N₂₃ atoms of 3¹ R -[E,E]-BChl e were lower-field shifted than those of 3¹ R -[E,E]-BChl c , respectively, and especially the difference in chemical shifts of N₂₂ was significantly large. These results suggest that the electron-withdrawing formyl group at the 7-position of BChl e affected an electronic state of the chlorin macrocycle and caused BChl e to be more tolerant for removal of the central magnesium compared with BChls c and d .     

银和硫团簇的反应

研究气相中原子或团簇的化学反应可以使我们从分子水平上研究化学反应的机理．激光溅射固体样品产生团簇,进而研究所形成团族的化学反应是研究团簇反应的一种方法．用高强度激光使固体样品气化,气化物彼此碰撞反应并在真空中膨胀冷却形成团簇和团簇离子,这一类反应是成...     

A Ferrocenylsulfide-mediated Sulfur Ylide Epoxidation Reaction

A ferrocenylsulfides 1-2 mediated sulfur ylide epoxidation reaction was found to stereoselectively afford trans-oxiranes in excellent yields with recoverable starting material.     

硫和氧化铜反应实验再探究*

针对硫和氧化铜的反应进行理论分析和实验探究,在已有研究基础上改进实验装置,提高实验的科学性和严谨性。对不同条件下的反应产物,进行X射线粉末衍射(XRD)表征,得出更精确的实验结论。     

对铁与硫反应实验的探讨

1 提出问题 在现行人教版高中化学教材中叙述到"加热时,铁还能与硫反应" [1].对该实验的研究资料比较多,但这些研究结果中存在反应物铁与硫的质量比不清楚[2,3]、混合物质量不准确[2,4]、实验的危险性描述过度[2,3,5]等问题.为此,在参考他人研究成果的基础上,在对这个实验进行验证和研究的过程中,发现实验中取用的铁与硫混合物质量较大和反应结束后的冷却方式是引起试管炸裂的主要原因,而SO2的产生来自试管的炸裂.笔者从减少实验药品的用量出发,使反应能够在普通小试管中进行,克服了该实验过程中试管炸裂和产生SO2等"危险",取得了很好的实验效果.     

硫与铜实验的改革

一、教具的改革 1.把肉罐头筒打开成二个矩形平面,长18cm,宽13cm。在该平面上写一个尽可能大的连续的笔划较粗的硫化亚铜分子式,把此分子式用剪刀剪下来,用钳子把分子式沿同外边缘分别翘起0.5cm,然后把起笔处和收笔处也分别翘起0.5cm,此时形成了槽式的硫化亚铜字样。     

Reaction of Sulfur Chlorides with Metal β-Diketonates

Metal β-diketonates react with sulfur dichloride to form sulfenyl chlorides irrespective of β-substituent. Bulky phenyl and tert-butyl groups do not prevent formation of fully substituted complexes. The possibility of preparing sulfenyl chloride derivatives of rhodium, ruthenium, and vanadium β-diketonates was demonstrated. A new procedure was suggested for preparing chlorosulfenyl-substituted β-diketonates. Disulfur dichloride reacts with metal chelates with the substitution of both chlorine atoms and formation of polynuclear complexes in which the diketonate groups are linked by disulfide bridges.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 367–374.Original Russian Text Copyright © 2005 by Svistunova, Shapkin, Nikolaeva.     

电化学的绿色作用

本文从电化学工业、化学电源、金属腐蚀和防护、水的电化学消毒等方面阐述了电化学在绿色化学中的作用及其前景展望。     

脱硫菌在自然界硫循环中的作用与意义

硫是生命必需的大量元素,硫循环失衡会造成生态的破坏。通过对硫循环、脱硫细菌的概念的阐述以及对生物脱硫作用机理的介绍,综合分析了脱硫菌脱除不同硫分的作用方式以及脱硫的不同途径,并初步探讨了其在自然界硫循环中的作用与意义。     

带有致钝取代基的萘衍生物和SO3的反应研究

研究了一系列带有醛基、苯甲酮基、羧基、酯基和硝基等致钝取代基的萘衍生物与SO₃的反应。1-萘甲醛的单磺化得到比例为55:9:6:30的5-、6-、7-和8-磺酸取代物。1-苯甲酮萘则以83:11:6的比例得到5-、6-和7-磺酸取代物。1-硝基萘专一地得到5位磺化产物,1-萘甲酸和1-萘甲酸甲酯得到5位和8位取代产物。所有的2位取代萘衍生物均先得到5和8位取代产物,在过量磺化中生成的主产物为5,7-二磺酸取代物,提出了生成SO₃络合物及迫位磺化的历程,报道了8-磺酸-1-萘甲酸酐的物理数据。     

硫和氧化铜反应的实验探究

硫能和金属单质、非金属单质、强碱、强氧化性酸发生反应,表现出一定的氧化性和还原性。氧化铜是一种氧化性较强的金属氧化物,在一定的条件下,硫和氧化铜能发生反应生成氧化亚铜和二氧化硫,氧化亚铜和硫蒸气在高温下还能继续反应生成硫化亚铜和二氧化硫。     

Note Phenomenology and Kinetics of the Reaction Between Sulfur and Atactic Polypropylene

While sulfur has been widely used as a dehydrogenating agent, in particular to obtain conjugated dienes [1-4], there is no kinetic information available about its effect on atactic polypropylene (APP), only Dontsov et al. [5] mentioning the products of this reaction, while Stefanovskaya et al. [6] studied the kinetics of the rather similar reaction with tetrachloro-o-benzoquinone. Also worth mentioning are the kinetic studies carried out by Dontsov et al. [7-11] on the reaction kinetics of polyethylene with sulfur, unsaturation, crosslinks, and mercaptides being the main products and the processes being first-order with activation energies of approximately 120 kJ/mol.     

Study on the Kinetics and Transformation Products of Sulfur Mustard Sulfoxide and Sulfur Mustard Sulfone in Various Reaction Media

Considering postulates of the Chemical Weapons Convention, this article is an attempt to improve the decontamination methods of mustard gas (HD) and studying its products of decontamination. It is widely known that mustard gas sulfoxide (HDO; O═S(CH₂CH₂Cl)₂) and sulfone (HDO₂; O₂═S(CH₂CH₂Cl)₂) undergo further transformations to another compounds, but so far kinetics of these processes have not yet been investigated neither carefully nor thoroughly. This study is focused on determination of kinetics and mechanisms of transformation of HD oxidation products. The primary objective of this study is to assess the impact of selected factors on the kinetics of the HCl elimination reaction and to determine the conditions in which cyclization reactions of divinyl sulfoxide and sulfone proceed. The HDO and HDO₂ decay kinetics were monitored in an aqueous solution of the desired pH. The rate of HCl elimination from HDO and HDO₂ is strongly dependent on pH. For example, with pH increasing from 9 to 12 the rate of HCl elimination from HDO increased over 1200 times. In solutions of pH 9, HDO loses hydrogen chloride at approximately 100 times slower compared to HDO₂, and the difference is reduced with increasing pH. In pH 12 solutions, the rate of hydrogen chloride loss from HDO₂ is only 20 times higher than the HCl loss from HDO. Divinyl sulfoxide and sulfone undergo a further transformation in a strongly alkaline environment, leading to cyclization and formation of 1,4‐thioxane sulfoxide and sulfone, respectively. Elimination of HCl from HDO and HDO₂ goes with a rapidly increasing rate with increasing pH if alkalinity of the reaction medium is relatively very high (the range of pH 9–12). Furthermore, the conversion of divinyl sulfone and sulfoxide to sulfoxide and sulfone thioxane, respectively, occurs at a measurable rate when the pH of the solution is in the range of 12–14.     

On Reaction of Sulfur Dioxide with Aqueous Solutions of Carbamide

A mechanism of SO₂ chemisorption by aqueous solutions of carbamide was suggested. The effective rate constants of accumulation of hydrogen ions in the reaction of sulfur dioxide with aqueous solutions of carbamide in the range 278-313 K were determined.     

铅、硫团簇的形成、反应与光解

用激光直接溅射和串级溅射两种方法产生铅／硫二元团簇,并用串级飞行时间质谱仪研究了二元团簇的组份及光解规律,用激光直接溅射铜＋硫混合样品时,组成为PbnSn-1 和PbnSn-的团簇丰度最大,是二元团簇的结构骨架和稳定组份,而用激光串级溅射铅样品和硫样品,通过铅团簇与硫团簇的反应,则可得到PbnSm (n=1-3,m=0-9)和PbnSm-(n=1-7,m=0-9)。这两种二元团簇的产生方法对应两种不同的团簇形成机理。     

二氧化硫与氢氧化铜悬浊液反应的研究

通过实验研究说明二氧化硫在与氢氧化铜悬浊液发生化学反应时,有一部分二氧化硫与氢氧化铜发生复分解反应,有一部分二氧化硫与氢氧化铜发生氧化还原反应。