Scielo RSS <![CDATA[South African Journal of Chemistry]]> http://www.scielo.org.za/rss.php?pid=0379-435020200001&lang=en vol. 73 num. lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Photocatalytic Degradation of Direct Red 16 Dye using Ag/Ag<sub>3</sub>VO<sub>4</sub>/AgVO<sub>3</sub>/GO Nanocomposite</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0379-43502020000100001&lng=en&nrm=iso&tlng=en In this research, synthesized Ag NPs/Ag3VO4/AgVO3/GO was applied as a visible-light sensitive photocatalyst for photocatalytic degradation of Direct Red 16 dye (DR16) from aqueous solutions. The synthesized nanocomposite was analyzed by XRD, FESEM, TEM, EDX and Dot mapping. The effect of DR16 dye concentration, AgNPs/Ag3VO4/AgVO3/GO dosage, time and pH on photocatalytic removal of DR16 were studied. Results revealed thatpH, dosage and DR16 concentration are more important parameters than time on photocatalytic removal of the dye. The results indicate that 58.98 % of DR16 removal was obtained under the following optimized conditions: DR16 concentration = 32 mg L-1; Ag NPs/Ag3VO4/AgVO3/GO dosage = 0.2 g 50 mL-1; pH = 4.5; 300 W visible light for 155 min. So, it was concluded that the new nanocomposite can be used as an efficient visible-light photocatalyst for degradation of Direct Red 16 dye. <![CDATA[<b>The Activities of the Eastern Province Section of the South African Chemical Institute 1935-1965</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0379-43502020000100002&lng=en&nrm=iso&tlng=en This article traces the activities of the Eastern Province (EP) Section of the South African Chemical Institute (SACI) from its founding in 1935 to the formation of the University of Port Elizabeth in 1965. The EP Section was only the third Section of the Institute to be formed in South Africa and was very active with regular meetings being scheduled. These meetings dealtpredominantly with industrial and applied chemistry topics, indicating very strong interaction between industry and the Chemical Institute. Pure academic topics were presented under the auspices of the Chemistry Department of Rhodes University in Grahamstown (Makhanda). During this period, the EP Section hosted three National Conventions and produced two Presidents of SACI. <![CDATA[<b>C-H activation</b><b>: </b><b>a Critical Evaluation of a Published Method and its Application Towards Inherently Chiral Calix[4]arenes</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0379-43502020000100003&lng=en&nrm=iso&tlng=en C-H activation offers an intriguing access into inherently chiral calix[4]arenes, but has been little explored in the literature. In this article, we report our investigation into a published C-H activation method that uses carbamates to direct a palladium catalyzed C-H activation and subsequent reaction with N-bromosuccinimide. However, we show that this report is unfortunately flawed on a number of points. An earlier reported study revealed the more likely S E Ar mechanism of the bromination reaction, which did not involve palladium catalysis. We nevertheless employed the S E Ar bromination in an attempt to form inherently chiral calix[4]arenes, using a chiral (+)-menthyl carbamate as a directing group. Unfortunately, although the reaction was high yielding, the diastereomers formed were inseparable and we were unable to quantify their ratio. Subsequent removal of the chiral (+)-menthyl carbamate, returned a small positive optical rotation, suggesting that at least a level of asymmetric induction was achieved in the bromination to afford a non-racemic product. <![CDATA[<b>Flower of <i>Typha latifolia </i>as a Low-cost Adsorbent for Quantitative Uptake of Multiclass Pesticide Residues from Contaminated Waters</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0379-43502020000100004&lng=en&nrm=iso&tlng=en The quantitative removal of atrazine, diazinon, chlorothalonil, ametryn, chlorpytrifos and dimethametryn from contaminated water was studied using flower of the Typha latifolia. The surface chemistry of this adsorbent was analyzed by FT-IR and the adsorption efficiency was studied using batch adsorption technique. The potential experimental parameters studied were pH (5-9), the dose of adsorbent (0.1-0.5 g), contact time (100-140 min), shaking speed (100-300 rpm) and initial pesticide concentration (3.15-100 jug L-1). The effects of concentration and contact time at the optimum conditions were used to study equilibrium and kinetic models for pesticide sorption. Results of the sorption equilibria were found to fit better to the Langmuir isotherm model than the Freundlich adsorption model indicating monolayer homogeneous surface conditions. On the other hand, kinetics of all pesticides sorption on the adsorbent was well defined by the pseudo-second-order model. The results obtained showed that the use of this plant be considered as one of the promising, natural, easily accessible and low-cost adsorbent for efficient and quantitative removal of pesticides from contaminated water. <![CDATA[<b>Formation of 3,3,4-Trimethyl-1,7-dibromonorbornane-2-one: a Spectroscopic and Computational Study</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0379-43502020000100005&lng=en&nrm=iso&tlng=en The structure and origin of the major by-product in the synthesis of 8-bromocamphor from (+)-3,3,8-tribromocamphor has been confirmed using NMR, coset and single crystal X-ray analysis and DFT-level computational techniques. <![CDATA[<b>Ultrasound Promoted Stereoselective Synthesis of 2,3-Dihydrobenzofuran Appended Chalcones at Ambient Temperature</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0379-43502020000100006&lng=en&nrm=iso&tlng=en In the present investigation, an ultrasound promoted the synthesis of a series of (£)-3-(2,3-dihydrobenzofuran 5-yl)-1-(aryl)prop-2-en-1-one derivatives from 2,3-dihydrobenzofuran-5-carbaldehyde and various aromatic ketones under clean conditions. The application of ultrasound irradiation in organic reactions is one of the incredible tools of green chemistry as reactions can be carried out rapidly under neat conditions. A library of a novel (E)-3-(2,3-dihydrobenzofuran-5-yl)-1-(aryl)prop-2-en-1-one chalcone derivatives were synthesized in good to excellent yield under ultrasonic irradiation. The structures of all synthesized chalcone derivatives synthesized in this study have been established by using FT-IR, ¹H NMR, 13C NMR, and HRMS techniques. The stereochemistry around C=C in the chalcones was shown to be trans by 'HNMR (Jab = 15.5Hz). The benefits of the present synthesis include mild reaction conditions, high yield, purification by non-chromatographic strategy and short reaction times, demonstrating the significance of this protocol in terms of waste reduction and energy efficiency.