An Investigation on the Production of Random Copolymer with Monothiocarbonate and Trithiocarbonate Units over Cyclic Thiocarbonate via Metal‐free Catalysis

Synthesis of poly(thiocarbonate)s from the copolymerization of epoxides and carbon disulfide (CS₂) remains a tough challenge, due to inevitable oxygen‐sulfur atom scrambling process. In this work, we utilized the oxygen‐sulfur exchange reaction (O‐S ER) to synthesize a random copolymer with monothiocarbonate and trithiocarbonate units from CS₂ and phenyl glycidyl ether (PGE) via metal‐free Lewis pairs. The copolymers contained monothiocarbonate and trithiocarbonate units of which the molar fraction could be tuned by varying either the types of Lewis pairs or the reaction temperature. Keeping track on the intermediate provided an insight in the process of O‐S ER and thus gave a hint to control the product structure. Production and consumption of phenyl thioglycidyl ether was the key process to regulate the chain structure. Remarkably, the oxygen atoms of PGE could be excluded out of the chain, resulting in the nearly complete production of poly(trithiocarbonate)s. Correspondingly, the refractive index of this kind of copolymer could be regulated in a wide range of 1.73—1.79 (at 590 nm).     

煤焦在燃烧过程中孔隙结构变化的模拟

煤焦在燃烧过程中的物理特性，如比表面积和孔径分布会发生连续变化，直接测量煤焦在燃烧过程中的孔隙结构变化很困难，但可以通过合适的数学模型来观察，二维的圆柱孔模型已大量用来对煤焦气化与燃烧过程中表面积和孔隙结构的变化进行模拟，这个模型把孔隙分成两大部分－－大孔与小孔，因为小孔构成比表面的绝大部分，所以在反应过程中比表面积的变化可以由单一小孔模型来拟合，本文采用了用Ｔｓｅｎｇ和Ｅｄｇａｒ提出的孔模型对几     

Three New Lanostane Triterpenoids from Inonotus obliquus

Three new lanostane‐type triterpenoids, inonotsulides A, B, and C ( 1 – 3 , resp.) were isolated from the sclerotia of Inonotus obliquus (Pers .: Fr.) (Japanese name: Kabanoanatake; Russian name: Chaga). Their structures were determined to be (20R,24S)‐3β,25‐dihydroxylanost‐8‐en‐20,24‐olide ( 1 ), (20R,24R)‐3β,25‐dihydroxylanost‐8‐en‐20,24‐olide ( 2 ), and (20R,24S)‐3β,25‐dihydroxylanosta‐7,9(11)‐dien‐20,24‐olide ( 3 ) on the basis of chemical transformation, NMR spectroscopy including 1D and 2D (¹H,¹H‐COSY, NOESY, HMQC, HMBC), EI‐MS, and single‐crystal X‐ray analysis.     

Synthesis of a Novel Type of Phosphates of Puerarin

A novel type of phosphated puerarin derivatives were synthesized through a simplified Atheron‐Todd reaction for the first time. The structure of these compounds were elucidated by IR, ESI‐MS and NMR. Moreover, the reason the dialkylphophite reagent had different chemselectivities toward different hydroxys on the puerarin was discussed.     

Method for Visible Light‐Induced Photocatalytic Degradation of Methylparaben in Water Using Nanostructured Ag/AgBr@m‐WO3

An efficient method of photocatalytic degradation of methylparaben in water using Ag nanoparticles (NPs) loaded AgBr‐mesoporous‐WO₃ composite photocatalyst (Ag/AgBr@m‐WO₃), under visible light is presented. In this process, quantification of methylparaben in water was carried out by high‐performance liquid chromatography (HPLC) and the HPLC results showed a significant reduction of methylparaben in water due to the enhanced of photocatalytic degradation efficiency of Ag/AgBr@m‐WO₃. For the material synthesis, highly ordered mesoporous‐WO₃ (m‐WO₃) was initially synthesized by sol–gel method and AgBr nanoparticles (NPs) were subsequently introduced in the pores of m‐WO₃, and finally, the Ag nanoparticles were introduced by light irradiation. The enhanced photocatalytic degradation of methylparaben in water is attributed to the formation of surface plasmonic resonance (SPR) due to the introduction of Ag NPs on the surface of the catalyst. Also, the formation of heterojunction between AgBr and mesoporous‐WO₃ in Ag/AgBr@m‐WO₃ significantly inhibited the recombination of light‐induced electron‐hole pairs in the semiconductor composite. The morphological and optical characterizations of the synthesized photocatalysts (Ag/AgBr@m‐WO₃) were carried out using SEM, TEM, XDR, N₂ adsorption–desorption, UV‐VIS diffuse reflectance spectroscopy (DRS). Also, the photocatalytic studies using radical scavengers were carried out and the results indicated that ${\text{O}}_2^{·-}$ is the main reactive species.     

A Mild Isomerization Reaction for β,γ‐Unsaturated Ketone to α,β‐Unsaturated Ketone

A series of β,γ‐unsaturated ketones were isomerized to their corresponding α,β‐unsaturated ketones by the introduction of DABCO in iPrOH at room temperature. The endo‐cyclic double bond (β,γ‐position) on ketone was rearranged to exo‐cyclic double bond (α,β‐position) under the reaction conditions.     

One—Pot Synthese of 3,4—Dihydropyrimidine—2（1H）—thiones Catalyzed by La（OTf）3

A general and practical procedure for the syntheses of 3,4-di-hydropyrimidine-2(1H)-thiones by a one-pot condensation of aldehyde,β-ketoester or β-diketone and thiourea using La(OTf)3 as the catalyst is described.Mild reaction conditions,excellent yields as well as the environmentally friendly character of La(OTf)3 make it an important alternative to the classic acid-catalyzed Biginelli‘s reaction.     

Application of a contactless conductometric detector for the simultaneous determination of small anions and cations by capillary electrophoresis with dual-opposite end injection

A contactless conductometric detection (CCD) system for capillary electrophoresis (CE) with a flexible detection cell was applied for the simultaneous determination of small anions and/or cations in rain, surface and drainage water samples. The applied frequency, the amplitude of the input signal, the electrolyte conductivity and electrode distance were found to be the most significant factors affecting the detection sensitivity. 2-(N-Morpholino)ethanesulfonic acid/histidine-based (MES/His) electrolytes were used for direct conductivity detection of anions and cations, while ammonium acetate was selected for indirect conductivity determination of alkylammonium salts. For the simultaneous separation procedure, involving dual-opposite end injection, an electrolyte consisting of 20 mM MES/His, 1.5 mM 18-crown-6 and 20 microM cetyltrimethylammonium bromide provided baseline separation of 13 anions and cations in less than 6 min. The detection limits achieved were 7-30 micrograms/l for direct conductometric detection of various common inorganic cations and anions, excluding F- (62 micrograms/l) and H2PO4- (250 micrograms/l), and 35-178 micrograms/l for indirect conductometric detection of alkyl ammonium cations. The developed electrophoretic method with conductometric detection was compared to ion chromatography.     

Synthesis of comb‐shaped poly(methyl methacrylate)‐b‐poly(polytetrahydrofuran acrylate) under 60Co γ‐ray irradiation

Comb‐shaped graft copolymers with poly(methyl methacrylate) as a handle were synthesized by the macromonomer technique in two steps. First, polytetrahydrofuran acrylate (A‐PTHF), prepared by the living cationic ring‐opening polymerization of tetrahydrofuran, underwent homopolymerization with 1‐(ethoxycarbonyl)prop‐1‐yl dithiobenzoate as an initiator under ⁶⁰Co γ irradiation at room temperature; Second, the handle of the comb‐shaped copolymers was prepared by the block copolymerization of methyl methacrylate with P(A‐PTHF) as a macroinitiator under ⁶⁰Co γ irradiation. The two‐step polymerizations were proved to be controlled with the following evidence: the straight line of ln[M]₀/[M] versus the polymerization time, the linear increase in the number‐average molecular weight with the conversion, and the relatively narrow molecular weight distribution. The structures of the P(A‐PTHF) and final comb‐shaped copolymers were characterized by ¹H NMR spectroscopy and gel permeation chromatography. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3367–3378, 2002     

The effect of molecular planarity on crystal non‐centrosymmetry in benzyl­idene–aniline derivatives

In the title compound, N‐(2‐methoxy­phenyl)‐4‐nitro­benzyli­deneamine, C₁₄H₁₂N₂O₃, the two phenyl rings make a dihedral angle of 48.0 (2)° and the nitro group is at an angle of 6.5 (1)° with respect to its attached phenyl ring. In the crystal structure, mol­ecules are related as centrosymmetric pairs through π–π interactions and are further connected through strong C—H?O hydrogen bonds [C?O 3.4259 (17) Å and C—H?O 167°], forming molecular stacks along [100]. These stacks associate further through longer C—H?O interactions, forming two‐dimensional networks. In the c direction, there are only weak van der Waals interactions. The relationship between the molecular planarity and its centrosymmetry is also briefly described.