Didecyldimethylammonium bromide (DDAB): a universal, robust, and highly potent phase-transfer catalyst for diverse organic transformations

Didecyldimethylammonium bromide (DDAB) has been scrutinized in comparison with traditional phase-transfer catalysts in variety of liquid-liquid reactions. It was found to be an exceptionally comprehensive, durable, and highly efficient phase-transfer catalyst (PTC) in a number of representative organic transformations such as C- and N-alkylations, isomerization, esterification, elimination, cyanation, bromination, and oxidation under very mild conditions of temperature and mixing. It was confirmed that DDAB is an exceedingly accessible and concurrently a highly liphophilic phase-transfer catalyst. This unprecedented characteristic renders DDAB to be a multipurpose catalyst that functions effectively both in mass transfer controlled and chemically controlled phase-transfer reactions.     

Nonlinear response of microbubbles coated with surfactant membrane developed as ultrasound contrast agent—experimental study and numerical calculations

Nonlinear response of microbubbles illuminated with ultrasound pulse was investigated through experiments and numerical calculations to build the basis for ultrasound blood flow image enhancement system (harmonic imaging system) using higher harmonic components based on nonlinear behavior of microbubbles for ultrasound contrast agents. The effects of membrane coating, size distribution and randomness of spatial distribution of microbubbles were examined. The relationship between the number of cycles in illuminated pulse and the higher harmonic component excitation efficiency, in particular, was studied and a tendency was found for the number of cycles larger than six cycles to cause gradual increase in the second harmonic component excitation efficiency. The simulated and experimental results were in good agreement. Furthermore, the simulated results using the conventional mathematical model ignoring the compressibility of liquid around bubbles showed a tendency of variation opposite to that of experimental results in the relationship between the illuminated ultrasound frequency and the second harmonic component excitation efficiency. On the contrary, the simulated results taking account of compressibility showed a good agreement with the experimental results.     

2,3-二羟墓-5-甲氧羰基苄基胺羧酰胺螯合剂促排铀酰的计算机模拟研究

用改进的计算机模型模拟研究了铀酰离子中毒血液体系在加入２，３－二羟基－５－甲氧羰基苄基胺羧酰胺螯合剂前后的各种配位平衡，讨论了铀酰离子的中毒浓度和螯合剂的剂量对螯合效率的关系，评估了这些螯合剂对铀酰离子的迁移能力和对体内必需金属离子的影响。     

High-load, oligomeric phosphonyl dichloride: facile generation via ROM polymerization and application to scavenging amines

A new ROMP-derived scavenging reagent, oligomeric phosphonyl dichloride (OPC), with high-load and selectivity is reported. This reagent can be readily generated via the ROM polymerization of bicyclo[2.2.1]hept-5-en-2-ylphosphonic dichloride, which is conveniently assembled from the Diels-Alder reaction of cyclopentadiene and vinyl phosphonic dichloride. The OPC has been exploited in the rapid, efficient scavenging of primary and secondary amines that are present in excess following a common benzoylation event at room temperature (30-60 min) or under microwave conditions in shorter duration (<5 min).     

Fluorine in medicinal chemistry: A review of anti-cancer agents

In this review those fluorinated compounds which have found a role as anti-cancer agents are summarized. The emphasis is to highlight the important drugs but also to highlight the latest developments on emerging compounds. This has been done as comprehensively as possible with the objective of informing readers of some of the latest developments in this area.     

亚微米级聚苯乙烯/聚硅氧烷核壳粒子的制备及其应用

以乳液聚合制备的聚苯乙烯乳液为种子,加入甲基三甲氧基硅烷(MTMS)水解溶液进行缩聚反应,合成亚微米级聚苯乙烯/聚硅氧烷核壳粒子,并以此作为光散射剂添加至聚甲基丙烯酸甲酯(PMMA)树脂中,制备了光散射材料;考察了亚微米级核壳粒子添加在PMMA树脂中的分散性。结果表明:经过双螺杆剪切作用的挤出加工后,可以实现核壳粒子在PMMA树脂中的良好分散。核壳粒子可以大幅度提高PMMA的雾度,当聚苯乙烯/聚硅氧烷核壳粒子(NS82)的含量为1%时,制得的PMMA样片(厚度为2 mm)的雾度为89%,透光率为69%,有效光散射系数为61%。     

固体进样法气相色谱质谱分析表面活性剂

采用气相色谱质谱电子轰击技术以固体直接进样方法成功地对表面活性剂进行了分离定性，测定了表面活性剂中各个成分的加成环氧乙烷数，定出了各个组分的分子量。     

STUDIES ON IPE OF POLYACRYLAMIDE INVERSE EMULSION AND MODIFIDE UREA-FORMALDEHYDE RESIN

The selective water plugging agent was prepared by heating the blends of the polyacry-lamide inverse latex, modified urea formaldehyde resin, crosslinking agent and catalysts.The results show that using different types of polymers and additives or changing in theirproportion of the blends, the gelling viscosity, starting point of gelling and other propertiesof the IPN can be controlled.     

Organotins as a Locking Agent in the Formation of Dinuclear Complexes

In this paper the synthesis and characterization of new heterobimetallic compounds with a ligand derived from diacetylpyridine, hydrazine and salicylaldehyde has been reported. The open end of the ligand was locked with R₂SnCl₂ followed by the insertion of a transition metal ion in the cavity thus formed by locking the ligand. These compounds are characterized by TGA/DSC, IR, ¹H and ¹³CNMR, electronic spectra, magnetic moment and conductivity measurements. The disappearance of ν(O–H) and appearance of ν(Sn–O) in the IR spectrum of the Sn(saldp)R₂ {where saldp = bis(salicylaldehydehydrazone)diacetylpyridine and R = –CH₃, –C₄H₉} suggests the complex formation with R₂SnCl₂. The IR spectra of the complexes exhibited a blue shift in ν(C=N) indicating coordination of the azomethine nitrogen. The complexes are non-electrolytes in DMSO. The ¹HNMR and ¹³CNMR spectra of the complexes are not much different from that of the free ligand except for the disappearance of the signal at 9 ppm due to phenolic protons. The methyl or butyl protons attached to the tin appear at their usual places. The TGA profile of the ligand and its mononuclear complexes exhibit a three-step pyrolysis, although the binuclear complexes decompose in two steps leaving behind tin oxide as the final product.     

Biosynthetic study of FR-900848: unusual observation on polyketide biosynthesis that did not accept acetate as origin of acetyl-CoA

The biosynthetic pathway of a potent antifungal agent, FR-900848, has been examined by administration of several ¹³C-labeled precursors to Streptoverticillium fervens HP-891. Although none of the ¹³C-labeled acetate was incorporated into FR-900848, the labeling pattern of FR-900848 derived from d-[U-¹³C₆]glucose revealed that the fatty acid backbone of FR-900848 has been biosynthesized via a polyketide pathway. These unusual results strongly show that the major pathway to provide acetyl-CoA in this microorganism is glycolysis. Feeding experiments with d-[U-¹³C₆]glucose, [1,3-¹³C₂]glycerol, and l-[Me-¹³C]methionine provided information on the biosynthetic origin of structurally unusual parts (polycyclopropane and aminonucleoside) in this antibiotic.