A Review of: “Polycyclic Aromatic Hydrocarbons: Chemistry and Carcinogenicity”

Abstract

Ronald G. Harvey, Cambridge University Press, Cambridge 1991. 396 pages. £80. ISBN 0 521 36458 2.     

An Oxidation System for Green Chemistry: The Oxidation of Alcohols and Hydrocarbons in the Presence of Metal–Polymer Complexes

Environmental and economic factors make the use of harmful oxidants increasingly unacceptable except on a small scale. Accordingly, we have investigated the use of dioxygen and hydrogen peroxide as oxidants. For this oxidation reaction of hydrocarbons, transition metal complexes and polymer-bound transition metal complexes were effective as catalysts. Earlier investigations indicated that the catalytic site was a bi- or multinuclear complex. Thus, several binuclear complexes of Cu and Mn [Eqs. (9)–(11)] were designed and their effectiveness in oxidizing phenols to biphenols and benzoquinones and in monooxygenase activity was demonstrated. In the oxidation of phenols, the system did not produce poly(phenylene oxide) since the intermediate phenoxy radical underwent C–C coupling to biphenol or underwent attack by hydroxyl radical to a hydroquinone that could be oxidized to a quinone. A reaction mechanism involving the binuclear complex for the oxidation is proposed.     

“TRU-SANEX”: A variation on the EURO-GANEX and i-SANEX processes for heterogeneous recycling of actinides Np-Cm

A novel separation process for recovering transuranic actinides has been tested in centrifugal contactors using a surrogate feed solution. This “TRU-SANEX” (transuranic element-selective actinide extraction) process uses solvent extraction between nitric acid and an organic phase containing 0.2 mol/L N,N,N′,N′-tetraoctyl diglycolamide with 0.5 mol/L N,N′-dimethyl-N,N′-dioctylhexylethoxy-malonamide to co-extract actinides and lanthanides followed by separate sections for plutonium–neptunium and americium–curium stripping. Overall, good performance was achieved with good recoveries of plutonium and americium in the products and only small amounts of cross-contamination between products. Decontamination factors for selected lanthanides in the americium–curium product ranged from ~40 to >1300.     

A study of the effect of iron oxide nanoparticles on the optical and adhesive properties of thermal control coatings of the “solar reflector” and “true absorber” class

The ability to acquire thermal control coatings of the “solar reflector” and “true absorber” class modified with iron oxide nanoparticles has been studied. The optical and adhesive properties of thermal control coatings have also been established.     

Contents Lists and Abstracts from the China Journal “Chemistry and Adhesion”

In order to study the effect of surfactants on the adhesive properties, peel measurements were performed with two series of model polymers of ethylhexylmethacrylate (PEHMA), the first prepared by emulsion polymerization with four anionic surfactants, and the second by post-adding the same surfactants to a surfactant-free latex. Cohesive fracture is observed at low peel rates; the peel strength depends on the bulk mechanical properties and is independent of the emulsifier. A transition to another type of separation occurs at higher peel rates, which seems to be an interfacial failure by visual inspection. Surface analytical studies, however, give evidence that this “interfacial” failure is, in fact, a mixed failure, leaving traces of the polymer on the substrate surface. The peel rate at this transition as well as the peel strength at mixed fracture are influenced by the surfactants. Large differences were observed between the four surfactants as well as between both series of polymers, leading to the conclusion that the surfactants have a different mobility within the film. This is also reflected by a different aging behaviour of the films.     

Fast retention of isoniazid on organobentonite prepared using green chemistry approach: contribution of the π interactions

ABSTRACT

In the present study, a new organoclay adsorbent for the adsorption of isoniazid (INH) was produced with the modification of bentonite using green chemistry approach. Glycine was used for the modification because of being environmentally friendly and biocompatible. Then the removal of INH was studied in aqueous solutions. Experiments were conducted as a function of contact time, initial concentration and solution pH to understand the adsorption mechanism. The equilibrium time for the adsorption was found as 20 min. Adsorption capacity of the adsorbent was increased from 21.10 mg/g to 33.90 mg/g after modification. The maximum adsorption was observed at pH 1.5. The results showed that INH was physisorbed on the adsorbents with the contribution of π dispersion interactions.     

Special Issue on“High-throughput Experimental and Modeling Research toward Advanced Batteries”

正1.Summary and Scope Advanced batteries play a key role in the development of、portable and wearable electronics,electric and hybrid vehicles,smart grids and back-up power sources,and many more emerging applications.In most cases,exploration of new and     

Crosslinkable surfactants based on linoleic acid-functionalized block copolymers of ethylene oxide and ε-caprolactone for the preparation of stable PMMA latices

Amphiphilic diblock and triblock copolymers consisting of poly(ethylene oxide) (PEO) as (central) hydrophilic segment and poly(ε-caprolactone) (PCL) as hydrophobic segment(s) were prepared by ring opening polymerization. The length of the PEO segment was kept constant , whereas the length of the PCL block(s) was either 6 or 10 units for diblock copolymers and 3 or 5 units at each end for the triblock copolymers. These block copolymers were end-functionalized by esterification with linoleic acid (LA), which contains reactive double bonds. The autoxidative behavior of PEO₄₅-(CL₃-LA)₂ functionalized triblock copolymers was investigated by exposure of films to air at ambient conditions. Ninety percent of the double bonds had disappeared in 15 d and a crosslinked structure was obtained after 30 d. Critical micelle concentrations (CMC) of the crosslinkable surfactants were in the range of 0.08-0.19 mmol/l for the diblock copolymer and of 0.19-0.26 mmol/l for the triblock copolymer. The surface tension of aqueous surfactant solutions at the CMC (γ_CMC) (25 °C) varied from 47.1 to 51.4 mN/m for the diblock and from 45.6 to 48.1 mN/m for the triblock systems. For both systems CMC and γ_CMC increase with increasing HLB values. These surfactants were used in PMMA latex preparations. The latices of PMMA prepared with LA-functionalized diblock and triblock copolymers yielded narrow particle size distributions and particle sizes of 180 and 370 nm, respectively, whereas latices prepared with SDS had a particle size of 90 nm. After extraction of the latex particles with methanol, the amounts of the unextractable (either buried or copolymerized) LA-functionalized diblock and triblock copolymers found in extracted PMMA latex particles were 10 and 24% of the initial amount of surfactant added respectively. Control experiments with a stearic acid (SA) containing diblock copolymer showed that the amount of buried surfactant in PMMA latices was 6.5%. By comparing the overall latex characteristics and stability (shelf stability, freeze-thaw testing and addition of electrolyte solutions and ethanol) it was concluded that an LA-functionalized diblock copolymer (MPEO₄₅-CL₁₀-LA) gave better stabilization of PMMA latices than an LA-functionalized triblock copolymer of comparable composition and HLB value.     

The 20th anniversary of the Journal of Supercritical Fluids–A special issue on future directions in supercritical fluid science and technology

1. Download : Download full-size image

     

An Appreciation of Organic Solid-State Chemistry and Challenges in the Field of “Molecules,Materials, Medicines”

Over many years, much of what has motivated a considerable amount of research in the general area of organic solid-state chemistry concerns an understanding of how molecular packing within an organic solid affects its physical and chemical properties. Whilst the motivation for this understanding may have changed over time, the fundamental issues remain the same. An understanding of the effect of crystal attributes (e.g., polymorph, habit and particle size) on chemical, physical, photophysical and electronic properties is still vital to the development of organic solids with optimised properties. While progress has been made in analytical skills (including sophisticated developments in instrumentation), along with major developments in computational techniques, there are still many challenges. This paper, with a primary focus on pharmaceuticals, provides a brief, and not comprehensive, personal overview of the progress that has been made and has yet to be made. Amongst the chemists and crystallographers who have contributed significantly to the subject is Jack Dunitz and some of his seminal papers appear in several of the issues discussed.     

Cucurbituril: At the Interface of Small Molecule Host–Guest Chemistry and Dynamic Aggregates

The remarkable guest binding behavior of the synthetic receptors, cucurbit[n]uril, has gained tremendous attention over the past few decades. The stronger and more selective encapsulation of small guests has opened up the possibility to develop multi-component, dynamic yet controlled supramolecular aggregated architectures for a wide variety of applications. Isolation of larger homologues and derivatives have expanded the scope further, and interest has grown exponentially. Applications of these unique synthetic receptors presently range from polymeric smart materials and wet nanotechnology to sensing and protein conjugation. This review highlights such examples from recent literature on the development of new dynamic supramolecular aggregates and composites using cucurbituril host–guest chemistry.     

3-cis-hexenal,the “Green” reversion flavor of soybean oil

By means of gas-liquid-chromatography the neutral volatile products obtained by stripping oxidized soybean oil were fractionated. The fraction with “green bean” odor (a well-known offflavor of soybean oil) was investigated. By the application of various methods it was possible to isolate the flavor carrier proper and, in spite of its small amount, to complete the analysis to a point at which the structure 3-cis-hexenal seemed highly probable. Synthesis and subsequent comparison with the natural product confirmed the correctness of the assumption. n-Hexanal and 3-trans-hexenal, also found in this fraction, play no significant role in the reversion flavor.