Synthesis and Biological Evaluation of Novel Isonucleosides with 1,2,4‐Triazole‐3‐Carboxamide

Novel 1,2,4‐triazole isonucleosides (1 and 2) were efficiently synthesized starting from D‐ribose and D‐xylose, respectively. The key steps were condensation of cyclic sulfate 8 with methyl‐1,2,4‐triazole‐3‐carboxylate and nucleophilic displacement of the tosylate 15 with methyl‐1,2,4‐triazole‐3‐carboxylate, respectively.     

Efficient and Industrially Viable Synthesis of Donepezil

An efficient, economically viable process has been developed for large‐scale preparation of donepezil HCl (1), an anti‐Alzheimer's agent. The process involves the condensation of 5,6‐dimethoxy‐1‐indanone (3) and 1‐benzyl‐4‐piperidinecarboxaldehyde (4) in the presence of alkalimetal carbonates at elevated temperature to yield 1‐benzyl‐4‐[(5,6‐dimethoxy‐1‐indanone)‐2‐yidenyl] methyl piperidine (2), the key intermediate in the synthesis of donepezil. Hydrogenation of 2 yields donepezil.     

PCC-Promoted Dehydration of Aldoximes: A Convenient Access to Aromatic,Heteroaromatic, and Aliphatic Nitriles

A simple and convenient procedure for the synthesis of nitriles by dehydration of aldoximes using a PCC (pyridiniumchlorochromate) has been developed. A variety of aromatic, heteroaromatic, and aliphatic aldoximes are converted.

Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the full spectral details.     

Synthesis of gemini surfactants with twelve symmetric fluorine atoms and one singlet F MR signal as novel F MRI agents

A family of fluorinated gemini surfactants derived from perfluoropinacol has been synthesized as novel ¹⁹F magnetic resonance imaging (¹⁹F MRI) agents. These fluorinated surfactants with 12 symmetric fluorine atoms and one singlet ¹⁹F MR peak can be conveniently prepared from perfluoropinacol and oligo(ethylene glycols) on multi-gram scales. Solubility, hydrophilicity (log P), and critical micelle concentration (CMC) measurements of these fluorinated surfactants indicated that high aqueous solubility can be achieved by introducing oligo(ethylene glycols) with appropriate length into perfluoropinacol, i.e., manipulating the fluorine content (F%). One of these fluorinated surfactants with high aqueous solubility and excellent ¹⁹F MR properties has been identified by ¹⁹F MRI phantom experiments as a promising ¹⁹F MRI agent.     

Poly(ethylene terephthalate) waste derived chemicals as an antistripping additive for bitumen – An environment friendly approach for disposal of environmentally hazardous material

The increasing accumulation of poly(ethylene terephthalate) polymer and poor recycle/disposal practices have made them omnipresent and a major culprit for environmental pollution. Currently global research efforts are focused on primary and secondary recycling of PET waste or through landfills. Chemical recycling of PET through hydrolytic or aminolytic route has been attempted by many researchers however with limited end applications. In our investigations we have used PET waste as a synthon and chemically converted it through a new non-catalytic route into several benzamide derivatives. We have successfully tested them for antistripping performance in bitumen. Our results as elaborated in the paper indicate a comparable performance of the new chemistry products based on PET, to commercially used antistripping chemicals. Our research work thus opens a new route for the recycling of used PET in bituminous concrete roads which may help in alleviating a major environmental problem and disposal of waste PET polymer in large scale.     

Solubilization and Transfer Free Energy of Some Organic Compounds from Bulk Aqueous Phase to Micelle of a New Type of Surfactant

A new type of surfactant, 3‐alkoxyl‐2‐hydroxylpropyltrimethyl ammonium bromide (C_nH_2n+1OCH₂CH(OH)CH₂N(CH₃)₃ ⁺Br^?, abbreviated as R_nTAB, n=8, 12, 14, 16) was synthesized. The solubilization of n‐pentanol, n‐hexanol, n‐heptanol, benzyl alcohol, n‐hexane, benzene, toluene, heptane, and carbon tetrachloride in aqueous solutions of R_nTAB, sodium dodecyl sulfonic(R₁₂SO₃N_a), and in the mixed solution of R₁₆TAB/R₁₂SO₃N_a have been studied by the microtitration method. The experimental results show that the solubilized amounts of the organic compounds increase with the growing of the hydrocarbon chain of R_nTAB, and the solubilizing ability of the binary system is lower for polar substances than for a mono‐surfactant aqueous solution. “V” isothermal curves of the solubilized amount of polar substances have been observed, and the minimum solubilized amount is at the molar ratio 1∶1 of R₁₆TAB/R₁₂SO₃N_a. However, the solubilizing ability of mixed surfactants for non polar substances is higher than that for a mono‐surfactant solution, the solubilizing isotherm curves present a “saddle” shape, and the maximum solubilized amount is at the molar ratio 1∶1 of R₁₆TAB/R₁₂SO₃N_a too. The length of hydrophobic chains of surfactant and the polarity of the organic compound affect the transfer free energy from aqueous to micelle phase. The longer the hydrophobic chain of R_nTAB and the lower the polarity of the organic compound, the more easily will the compound transfer from aqueous phase to micelle phase.     

The Hydrotrope Action of Vitamin C

The effects of vitamin C are determined in the oil-in-water(0/ W) and water-in-oil(W/ 0) microemulsion regions of CTAB/ pentanol/ p-xylene/ H20 system. The addition of Vc joins the O/ W and W/ O areas in the phase diagram and expands the bicontinous region by reducing the lamellar liquid crystal one. The results show that the “ coupling action” of Vc is in fact a structural transition from lamellar crystal to isotropic phase with W/ O, O/ W and bicontinous structure.     

Dielectric behaviour of binary dual-frequency nematics with low crossover frequencies

Binary dual-frequency nematic liquid crystals synthesised at the Military University of Technology were measured by dielectric means. All the investigated materials exhibit low crossover frequency. They were composed of only two molecules with longitudinal and transverse dipole moments. The main difference is the molecular weight of the molecules. Results of relaxation parameters of detected mode and crossover frequency are shown. The influence of structure on ion conductivity is discussed. The broad phase transition from an isotropic phase to a nematic one was observed.     

Side group functionalized liquid crystalline polymers and blends VIII. Nematic and SmAre phase formation in hydrogen-bonded blends of smectic side group LC polymers and a low molar mass dopant

Hydrogen-bonded blends based on smectic side group functionalized LC copolymers containing 4-alkyloxybenzoic acid fragments (proton donor) and a non-mesogenic low molecular mass dopant 4-cyanophenyl pyridine-4-carboxylate or 4-methoxyphenyl-d₄ pyridine-4-carboxylate (proton acceptor) were obtained. The blends containing 10-35 mol % of low molecular weight dopant form nematic (I-N-SmA) or re-entrant SmA phases (I-SmA-N-SmAre). The temperature dependence of the order parameter S, the birefringence Δn, and the splay K ₁ and bend K ₃ elastic constants of the nematic phase were studied by ²H NMR spectroscopy and the Fréedericksz method of threshold transitions in a magnetic field. A mechanism for the destruction of the SmA phase and the formation of the nematic phase in the hydrogen-bonded blends is suggested.     

Ca(Ⅱ)、Mg(Ⅱ)和Zn(Ⅱ)与丙二醇-水混合体系中L-多巴的二元配合物的生成平衡

在303 K恒温条件下,以NaCl为电解质保持离子强度为0.16 mol·L^-1,用pH滴定法研究了M(Ⅱ)-Dopa(多巴)二元配合物在0～60%(V/V)的丙二醇(PG)-水体系中的生成平衡。在PG-水体系中,Ca(Ⅱ)和Mg(Ⅱ)的典型配合物为MLH,ML₂,ML₂H和ML₂H₂,而Zn(Ⅱ)的典型配合物为ML,MLH,ML₂,ML₂H和ML₂H₂。根据静电和非静电力解释了稳定常数随介质的介电常数而变化的倾向。还讨论了在不同组成的丙二醇(PG)-水体系中配合物物种随pH值变化的情况。