Unveiling the mechanism and selectivity of [3+2] cycloaddition reactions of benzonitrile oxide to ethyl trans-cinnamate, ethyl crotonate and trans-2-penten-1-ol through DFT analysis.

The mechanism and regioselectivity of [3+2] cycloaddition (32CA) reactions of benzonitrile oxide with ethyl trans-cinnamate, ethyl crotonate and trans-2-penten-1-ol has been studied in gas phase and in acetonitrile, ethyl acetate and tetrahydrofuran using the B3LYP functional in connection with 6-31G(d) basis set. The 32CA reactions followed one-step mechanism with asynchronous TSs. The calculated global electron density transfer (GEDT) at the TSs showed electronic flux from benzonitrile oxide to ethyl trans-cinnamate and ethyl crotonate, while the electronic flux from trans-2-penten-1-ol to benzonitrile oxide was predicted, in complete agreement with the Conceptual Density Functional Theory (CDFT) indices. The regioselectivity is correctly described in coherence with the experiment data. The intermolecular interaction at the TSs was realized through visualization and quantification by means of independent gradient model (IGM) analysis based on promolecular density.

Cinnamaldehyde-modified chitosan as a bio-derived corrosion inhibitor for acid pickling of copper: Microwave synthesis, experimental and computational study.

Chitosan (CS) was cross-linked using cinnamaldehyde (Cinn) in a single step procedure following microwave irradiation to produce cinnamaldehyde-modified chitosan (Cinn-CS). The synthesized Cinn-CS was used as a novel corrosion inhibitor for copper in 1 M hydrochloric acid. A comprehensive electrochemical investigation using the impedance measurements, and potentiodynamic polarization was undertaken, supported with surface analysis and computational studies. The inhibitor Cinn-CS functioned by adsorption on the copper surface and showed an inhibition efficiency of >89% at a dose of 1000 mgL-1. The charge transfer resistance showed a rise with increase in inhibitor dosage to the corrosive medium, and the corrosion currents showed a significant decrease with the addition of the inhibitor. The Cinn-CS displayed a mixed type of inhibition performance with cathodic nature. The study of the copper surface using scanning electron microscopy depicted a considerably smooth morphology in the presence of the adsorbed Cinn-CS. The computational studies indicated that the Cinn-CS Schiff base shows better adsorption behavior compared to the parent molecules of chitosan and cinnamaldehyde and can show an inhibition performance in the neutral, and the protonated form.

A comparative study of electrochemical oxidation of methidation organophosphorous pesticide on SnO2 and boron-doped diamond anodes.

BACKGROUND: Electrochemical oxidation considered to be among the best methods in waste water desalination and removing toxic metals and organic pesticides from wastewater like Methidathion. The objective of this work is to study the electrochemical oxidation of aqueous wastes containing Methidathion using boron doped diamond thin-film electrodes and SnO2, and to determine the calculated partial charge and frontier electron density parameters. RESULTS: Electrolysis parameters such as current density, temperature, supporting electrolyte (NaCl) have been optimized. The influences of the electrode materials on methidathion degradation show that BDD is the best electrode material to oxidize this pesticide organophosphorous. Energetic cost has been determinate for all experiments. The results provide that 2 % of NaCl, 60 mA cm(-2) and 25 ºC like the optimized values to carry out the treatment. For BDD the achieved Chemical Oxidation Demand reduction was about 85 %, while for SnO2 it was about 73 %. The BDD anode appears to be the more promising one for the effective electrochemical treatment of methidathion. Finally the theoretical calculation was done by using the calculation program Gaussian 03W, they are a permit to identify the phenomena engaged near the electrode and to completely determine the structures of the products of electrochemical oxidation formed during the degradation and which they are not quantifiable in experiments because of their high reactivity. CONCLUSIONS: The comparison of the results relating to the two electrodes indicates that these materials have a power to reduce the quantity of the organic matter in the electrolyzed solution. But the speed of oxidation of these compounds is different according to the materials of the electrodes used. Graphical abstract:Structural of methidathion [O,O-dimethyl-S-(5-methoxy-1,3,4-thiadiazolinyl-3-methyl) dithiophosphate] used for study the electrochemical oxidation.

Contents of cadmium, mercury and lead in fish from the Atlantic sea (Morocco) determined by atomic absorption spectrometry.

As a part of a specific monitoring program, lead (Pb) cadmium (Cd) and mercury (Hg) concentrations in important species of fish from various fishing ports of the southern Kingdom of Morocco (Sardina pilchardus, Scomber scombrus, Plectorhinchus mediterraneus, Trachurus trachurus, Octopus vulgaris, Boops boops, Sarda sarda, Trisopterus capelanus, and Conger conger) were investigated by the Moroccan Reference Laboratory (NRL) for trace elements in foodstuffs of animal origin. The samples were analysed for lead and cadmium by a graphite furnace atomic absorption spectrometry (GFAAS); and for mercury by cold vapour atomic absorption spectrometry (CVAAS). The results were expressed as µg/g of wet weight (w/w). The levels of Cd, Pb and Hg in muscles of fish were 0.009-0.036, 0.013-0.114 and 0.049-0.194 µg/g, respectively. The present study showed that different metals were present in the sample at different levels but within the maximum residual levels prescribed by the EU for the fish and shellfish from these areas, in general, should cause no health problems for consumers.