Drug-Delivery by Ion-Exchange: Part II: Physico-Chemical Properties of Ester Pro-Drugs of Propranolol

Abstract

The pKa values, solubilities and partition coefficients of a series of O-n-acyl propranolol pro-drugs have been estimated. The direct measurement of solubilities is limited by the instability of the esters and pK values are difficult to estimate by potentiometric titration due to low solubilities. Titrations in a range of aqueous methanolic solutions provide an estimate of the pK_a while titration under non-logarithmic conditions, when excess, undissolved base is present in the system, allows the determination of solubility.     

Polymerization kinetics of acrylonitrile by oxidation: Reduction system using potassium persulfate/ascorbic acid in an aqueous medium

The kinetics of acrylonitrile polymerization initiated by free radicals formed in situ in a potassium persulfate/ascorbic acid redox system was investigated in an aqueous sulfuric acid medium in the temperature range of 40–70°C. The rate of polymerization and the rate of the disappearance of potassium persulfate were measured. A kinetic scheme involving the production of initiating radicals from the oxidation of ascorbic acid by potassium persulfate ions and termination exclusively by the interaction of chain radicals with persulfate ions is proposed. The effects of some water‐miscible organic solvents on the rate of polymerization were investigated. The temperature dependence of the rate was studied. A possible mechanism consistent with the experimental data is proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of new aromatic polyimides containing redox‐active anthraquinone moieties

A novel anthraquinone‐containing bis(ether amine) monomer, 2,6‐bis(4‐aminophenoxy)anthraquinone, was synthesized from readily available reagents. A series of novel aromatic polyimides were prepared from the newly synthesized diamine monomer with various aromatic tetracarboxylic dianhydrides. The intermediate poly(amic acid)s had inherent viscosities of 0.67–1.12 dL g^?1, and those derived from less stiff dianhydrides could be solution‐cast and thermally cyclodehydrated into flexible and tough polyimide films. The polyimides exhibited glass transition temperatures between 270 and 297 °C, and they were fairly stable up to a temperature of 500 °C in air or nitrogen. The electrochemical and electrochromic properties of one of the polyimides were investigated. The polymer could undergo two reversible steps of electrochemical reduction, with a color change from a colorless neutral state to pink and rose‐red reduced states. © 2012 Society of Chemical Industry     

有机硅氧烷改性VAE乳液的研究

在醋酸乙烯-乙烯共聚乳液（vAE乳液）聚合过程中添加有机硅氧烷单体制备改性VAE乳液。对比分析了不同种类、不同用量的有机硅氧烷对改性vAE乳液性能的影响。确定了有机硅氧烷单体在vAE乳液聚合过程中的最佳添加方式，筛选了聚合引发体系。研究表明，在反应过程中以H2O2--ZFS作为氧化-还原引发体系，选用长链的含水解阻碍官能团的硅氧烷，有机硅氧烷采用后添加的方式，能够合理而有效地控制反应节奏。制备出性能优异的改性VAE乳液。     

Anaerobic Adhesive Cure Mechanism-I

Anaerobic adhesives are single-component acrylic adhesives which cure rapidly at or below room temperature when air is excluded, but they remain in an uncured stage over a long time when they are exposed to an adequate supply of air. Thus, anaerobic adhesives are widely used in retaining compounds for nuts and bolts, in sealants, and for impregnation. Recently, anaerobic adhesives have also been used in electrical and electronic applications because of their fast room temperature cure capability and their convenience.¹     

Reaction kinetics of metal deposition via surface limited red-ox replacement of underpotentially deposited metal monolayers

The study of the kinetics of metal deposition via surface limited red-ox replacement of underpotentially deposited metal monolayers is presented. The model system was Pt submonolayer deposition on Au(1 1 1) via red-ox replacement of Pb and Cu UPD monolayers on Au(1 1 1). The kinetics of a single replacement reaction was studied using the formalism of the comprehensive analytical model developed to fit the open circuit potential transients from deposition experiments. The practical reaction kinetics parameters like reaction half life, reaction order and reaction rate constant are determined and discussed with their relevance to design and control of deposition experiments. The effects of transport limitation and the role of the anions/electrolyte on deposition kinetics are investigated and their significance to design of effective deposition process is discussed.     

Acid-Base Properties of Ion Exchangers. IV. Synthesis and Potentiometric Analysis of Polyampholytes on the Base of Polyacrylonitrile Fibers

A model for potentiometric analysis of spatial polyampholytes has been developed. It allows calculation of acidity parameters for all kinds of functional groups in the sorbent and reconstruction of the full titration curve of polyampholyte from the state of complete protonation (strong acid medium) to the state of complete deprotonation. Synthesis of new amino-carboxylic polyampholytes by reacting a PAN fiber with hydrazine and sodium sulphide is described. Computer analysis of potentiometric titration curves shows that the new polyampholytes contain four types of functional groups.     

连续滴定法测定矿石及合金中砷锑含量

用浓硫酸溶样,在一定温度下,先用硫酸铈滴定,再用溴酸钾滴定,可分别计算出Sb和As的含量.该法操作简单、测定快速,相对标准偏差小于1.5%,适用于常规的矿石和合金中砷锑的测定.