Electrochemical Study Of Substituted Polyparaphenylene Derivatives In Aqueous And Organic Medium

In recent years, organic conducting polymers have made concrete inroads in the field of battery materials. In the present communication we report, the synthesis and oxidation potentials of poly-p-phenylene (PPP) , polymethylphenylene (PPPmethyl), polypropylphenylene (PPPpropyl), polysulphophenylene (PPPS03H), polychlorophenylene (PPPCl), polynitrophenylene (PPPN02) and polyaminophenylene (PPPNHz). A mixture of polyvinylidene fluoride (PVF) and acetylenic carbon was used as conducting adhesive to study electrochemical properties of PPP and derivatives in acetonitrile containing 0.2 M LiCl0₄ and aqueous sulphuric acid media. We discuss the effects of the substituent groups on PPP and possibilities of its use as a battery material in the light of EPR, conductivity and electrochemical results.     

KAl(SO4)2 · 12H2O (alum) a reusable catalyst for the synthesis of some 4-substituted coumarins via Pechmann reaction under solvent-free conditions

A simple, efficient, and practical procedure for the Pechmann condensation using KAl(SO₄)₂ · 12H₂O (alum) as a non-toxic, reusable, inexpensive, and easily available catalyst is described under solvent-free condition at 65°C. These improved reaction conditions allow the preparation of a wide variety of some new substituted coumarins in high yields (86–96%) and purity under mild reaction conditions. Compared to the classical Pechmann condensation, this new method consistently has the advantage of high yields. Correspondence: Ali A. Mohammadi, Department of Chemistry, Shahid Beheshti University, P.O. Box 19839-4716, Tehran, Iran.     

Two intermediates in the reaction between dibenzoylacetylene and enol systems in the presence of triphenylphosphine in THF/H2O

Abstract  The reaction between dibenzoylacetylene and enol systems, such as acetylaceton or cyclohexane-1,3-dione in the presence of triphenylphosphine in THF/H₂O, leads to 4-acetyl-3-benzoyl-1-phenyl-1,5-hexanedione and 2-hydroxy-3-(2-oxo-2-phenylethyl)-2-phenyl-3,5,6,7-tetrahydro-1-benzofuran-4(2H)-one. Subsequently, these compounds undergo cyclization and elemination reactions in acidic dichloromethane at room temperature to produce known highly functionalized furan derivatives. Graphical abstract        

Synthesis and some transformations of functionally substituted lactones

Reactions of functionally substituted unsaturated five- and six-membered cyanolactones with α- and β-hydroxy ketones in the presence of sulfuric acid gave substituted 2-oxofuran- and 2-oxopyran-3-carboxamides. Hydrolysis of some keto amides thus obtained afforded the corresponding carboxylic acids, and reactions with hydrazines and semicarbazides led to hydrazones and semicarbazones at the side-chain oxo group.     

Al_n(n﹤10000)团簇熔化行为的分子动力学模拟

采用半经验的Gupta原子间多体势,运用分子动力学模拟结合退火技术,由不同初始结构(密堆积满壳层Ih、Oh结构及退火结构)出发,研究了尺寸在10000个原子之内的Al团簇的熔化行为.结果表明:在所研究团簇尺寸范围内,Ih结构均具有高的动力学稳定性;Oh结构的动力学稳定性与团簇尺寸密切相关:尺寸较小(1000个原子以内)时不稳定(熔化前会发生向类Ih结构的转变),在中间尺寸(1000~2000原子间)时动力学稳定性发生转变,尺寸较大(2000原子以上)时显示出完整的动力学稳定性;从不同初始结构出发所得相同尺寸团簇熔点基本相同;在200原子以上时,团簇熔点随尺寸变大而升高且体现出近似的线性关系.