BOOK REVIEWS

Book reviewed in this article: Minerals of the World , Walter Schumann. A-Z of Snake Keeping , Chris Mattison.     

Semi-automated continuous sample drop flow microextraction with swift preconcentration and atomic absorption spectrometry determination of lead in water and apple leaves

In this paper, we present novel developments to our recently developed method so-called “continuous sample drop flow microextraction (CSDF-ME)” technique. Previously, we showed that the CSDF-ME technique offers several advantages, including stability of extraction solvent, no need for holder device, and easy to operate. The merit of current study is to make the extraction steps faster with sample required for the analysis. The key novelty of proposed method includes usage of a solvent mixture (i.e., methanol and carbon disulfide), allowing to pump aqueous samples with a higher flow rate than the former technique which led to reduce the extraction time. Results show that the technique is cable to become faster by five times with an enrichment factor of 93 for 4.0 mL of aqueous sample. The linear range and limit of detection for Pb are found to be 0.1–6.0 and 0.03 µg L^?1, respectively. The relative standard deviation for determination of 1.0 µg L^?1 of Pb in a sample is 2.9% (n?=?5). Furthermore, the relative recoveries of the developed CSDF-ME method for Pb in tap water, mineral water, and Standard Reference Material for apple leaves (1515) are shown to be 98, 100, and 94%, respectively.     

Microwave-assisted asymmetric ring opening of meso-epoxides with aromatic amines catalyzed by a Ti-S-(−)-BINOL complex

Catalytic asymmetric ring opening of cyclohexene oxide and meso-stilbene oxide with anilines was catalyzed by a Ti-(S)-(−)-BINOL complex to afford β-amino alcohols in high yield (up to 95%) and good enantioselectivities (ee up to 55%) under microwave irradiation. The reaction using a microwave was found to be 10 times faster than traditional oil-bath heating with retention of enantioselectivity.     

Asymmetric Epoxidation of Non-Functionalized Alkenes Using Transition Metal Complexes

Asymmetric catalytic epoxidation of alkenes such as styrenes, chromenes and indene using transition metal complexes both inhomogeneous and heterogeneous phase has been discussed in this review. The various strategies to make the catalysts recyclable by introducing in-built phase transfer ability, converting these to dimeric form, exchanging into clays and supporting on polymeric or inorganic supports are discussed at length.     

Electrolytically produced copper(I) chloride on the copper wire as an excellent sorbent for some amines

A new solid-phase microextraction (SPME) fiber has been developed and applied for the determination of some amines (n-pentylamine, tripropylamine, dibutylamine, diisobutylamine and tributylamine). In this study two copper wires were immersed in sodium chloride solution and electrolysis was performed at a constant potential. Anode was oxidized to copper(I) to produce copper(I) chloride as a sorbent for the studied amines on the copper wire. Several parameters affecting the fiber preparation and SPME procedure such as electrolysis time, selection of the SPME coating, extraction time and temperature were optimized. The copper(I) chloride fiber was the most appropriate one for the determination of amines by SPME-GC-FID. The optimized method was linear over the range studied (1-100 μg L⁻¹) and showed good precision, with R.S.D values less than 3% for all analytes. Fiber production was reproducible and R.S.D for fiber-to-fiber was less than 8%. The proposed SPME-GC method showed some advantages such as lower detection limits, a shorter analysis time and the avoidance of expensive commercial fibers.     

A New Turbidimetric Method for Determination of Melamine Based on its Reaction with Mercury(II)

A turbidimetric technique based on a reaction between Hg(II) and melamine is described for the measurement of melamine content of wastewater of a petrochemical company. The present technique is rapid and simple, uses a small amount of reagent and is set up with low‐cost equipment, making this system economically viable. The experimental conditions such as volume of reagent, pH of buffer, stirring time, stirring speed, ionic strength, etc. were optimized and used in plotting the calibration curve. The linear dynamic range was 1–70 mg/L with a limit of detection of 0.3 mg/L. Repeatability of the proposed method is good, and the relative standard deviation (RSD%) is less than 1.5%. Interferences studies showed that the common compounds existing in wastewater have no negative effect on the efficiency of the method at relatively high concentrations. Finally, the proposed method has been successfully used in determination of melamine in wastewater of Urmia Petrochemical Company.     

Caro's Acid–Silica Gel: An Efficient and Versatile Catalyst for the One-Pot Synthesis of Tetrahydrobenzo[b]pyran Derivatives

An efficient one-pot synthesis of tetrahydrobenzo[b]pyran is described. This involved the three-component reaction of aromatic aldehydes, molononitrile, and dimedone in the presence of a catalytic amount of Caro's acid supported on silica gel in ethanol/water under reflux.