Halogenation

Graphene has attracted great interest for its superior physical, chemical, mechanical, and electrical properties that enable a wide range of applications from electronics to nanoelectromechanical systems. Functionalization is among the significant vectors that drive graphene towards technological applications. While the physical properties of graphene have been at the center of attention, we still lack the knowledge framework for targeted graphene functionalization. In this critical review, we describe some of the important ...

The spread of aquatic invasive species through ballast water is a major ecological and economical threat. Because of this, the International Maritime Organization (IMO) set limits to the concentrations of organisms allowed in ballast water. To meet these limits, ballast water treatment systems (BWTSs) were developed. The main techniques used for ballast water treatment are ultraviolet (UV) radiation and electrochlorination (EC). In this study, phytoplankton regrowth after treatment was followed for six BWTSs. Natural plankton communities were treated and incubated for 20 days. Growth, photosystem II efficiency and species composition were followed. The three UV systems all showed similar patterns of decrease in phytoplankton concentrations followed by regrowth. The two EC and the chlorine dioxide systems showed comparable results. However, UV- and chlorine-based treatment systems showed significantly different responses. Overall, all BWTSs reduced phytoplankton concentrations to bel...

Microbial effects are believed to be a major contributor to membrane fouling in drinking water treatment. Sodium hypochlorite (NaClO) is commonly applied in membrane cleaning, but its potential use as a pretreatment for controlling operational fouling has received little attention. In this study, the effect of adding a continuous low dose of NaClO (1 mg/l as active Cl) in combination with alum, before ultrafiltration, was compared with only alum as pretreatment. The results showed that the addition of NaClO substantially reduced membrane fouling both in terms of the rate of TMP development and the properties of the membrane cake layer. Although the size of nano-scale primary coagulant flocs changed little by the addition of NaClO, the cake layer on the membrane had a greater porosity and a substantially reduced thickness. NaClO was found to inactivate bacteria in the influent flow, which reduced both microbial proliferation and the production of proteins and polysaccharides in the c...

An efficient method for the synthesis of chlorinated
arenes is disclosed. The method involves the use of NaClO3 as
oxidant and HCl as chlorinating agent in aqueous medium under
mild conditions to chlorinate the aromatic compounds in good to
excellent yields (75-96%). The reagent system is  efficient,
organic solvent-free and easy to handle.

The interface produced between a chlorinated thermoplastic styrene-butadiene-styrene rubber and a polychloroprene (PCP) adhesive has been studied and compared to the interface produced using a polyurethane (PU) adhesive. Chlorination of the rubber was produced by spin coating solutions of trichloroisocyanuric acid in methyl ethyl ketone. The adhesive solution was spin coated on to the chlorinated rubber and the interface between the chlorinated rubber and the adhesive was analyzed by infrared spectroscopy.Chlorination of the rubber produces cross-linking of the outermost chlorinated and oxidized rubber surface, which becomes insoluble in toluene. The chlorinated rubber chains are able to migrate through the chlorinated rubber/adhesive interface and produce a cross-linked interface. Similar interfaces are obtained with PU or PCP adhesive. However it is the addition of a thermoreactive phenolic tackifier resin to the PCP adhesive, which imparts appropriate rheological properties to the PCP adhesive, responsible for the increased adhesion properties. Copyright © 2008 John Wiley & Sons, Ltd.

A selection of carbon-fluorine bond-forming reactions that have been developed in the recent past are presented. An overview of the most common fluorination reagents is followed by descriptions of fluorination reactions that are organized by reactivity. The distinction between nucleophilic and electrophilic fluorinations is highlighted, as well as between aliphatic and aromatic fluorinations. Each section is divided into more specific reaction classes and examples for the synthesis of pharmaceuticals, [18F]radiolabeling and mechanistic investigations are provided.

A facile, efficient, simple, environmentally safe,
regioselective, controllable and economical method for the
oxybromination of aromatic compounds using sodium molybdate
in presence of mineral acids and H2O2. The use of sodium
molybdate as catalyst accelerates the rate of reaction in presence
of mineral acids and hydrogen peroxide.

A simple, quantitative and rapid method for total brominated vegetable oil (BVO) using ion chromatography (IC) with suppressed conductivity detection was developed and successfully applied to soft drinks with results expressed as inorganic bromide anion. The procedure involves extraction of BVO with diethyl ether and treatment with zinc dust in a solution of acetic acid, giving recoveries ranging between 92.5 and 98.5%. The calibration curves obtained were linear with correlation coefficients (r 2) of 0.998, a coefficient of variation (CV) of less than 5% and limit of detection (LOD) and limit of quantification (LOQ) of 250 and 750 µg l−1, respectively. The method was successfully applied to the determination of BVO in several commercial soft drinks which were found to contain BVO in the range 1.8–14.510 mg l−1. The method has less sources of error compared to previously published methods.