Kinetic modeling of ZnO-rGO catalyzed degradation of methylene blue

Photodegradation of organic pollutants strongly depends on design of metal oxide semiconductor photocatalysts. Graphene, if composited with ZnO, can effectively enhance its photocatalytic performance for the eradication of pollutants from aqueous medium. Here in, ZnO-rGO is reported as highly active catalyst for degradation of methylene blue. A 200-mg/L solution of methylene blue dye was completely degraded within 1 h in comparison to 74% and 56% degradation over ZnO and rGO, respectively. The commonly used mechanisms of heterogeneous catalytic reactions, the Langmuir-Hinshelwood mechanism, and the Eley-Rideal mechanisms, were used to describe the reaction kinetics. The Langmuir-Hinshelwood mechanism was found as more favorable in this study. Apparent activation energy, E_ap, true activation energy, E_T, entropy, ΔS, and enthalpy, ΔH were calculated as 36.2 kJ/mol, 13.1 kJ/mol, 197.5 J/mol, and 23.1 kJ/mol, respectively.     

SOME HETEROCYCLIC PHOSPHOROCHLORIDATES AND THE FORMATION OF OTHER HETEROCYCLIC ORGANOPHOSPHORUS COMPOUNDS

Abstract

Pyrrolidine, morpholine, and β-hydroxyethylmorpholine have been phosphorylated with phosphorus oxychloride, phenylphosphorodichloridate, p-chlorophenylphosphorodichloridate and thiophosphoryl chloride. The resultant phosphorodichloridates have been condensed with a wied range of nucleophilic reagents, e.g. amines, hydrazines, phenols and isobutanol. Piperazine with phosphorus oxychloride (2 mols) gave the N(1) N(4)-diphosphorotetrachloridate, which was characterized as the tetracyclohexylamidate. β-Hydroxyethylpiperazine was similarly phosphorylated to the N,O-diphosphorotetrachloridate which was characterized as the tetraphenylhydrazidate.

Condensation of pyrrolidine (2 mols) with phosphorus oxychloride (1 mol) afforded N,N′-dipyrrolidinophosphorochloridate which was reacted with phenylhydrazide and sodium azide. The phosphoroazide with triphenylphosphine afforded the corresponding triphenylphosphinimine. N-Phenyl N′-pyrrolidinophosphorochloridate with aqueous pyridine gave the corresponding pyrophosphoramide and the stability of the pyrophosphoramide towards hydrolysis was examined. 1,2-Cyclohexanediol was phosphorylated with phenylphosphorodichloridate and thiophosphorylchloride. Trans-4-t-Butylcyclohexyl N,N′-diphenylhydrazinophosphorothioate by reaction with formaldehyde gave a tetra-azaphosphorine P-sulfide. Trans-4-t-Butylcyclohexyl N-phenyl N′-phenylphosphorodiamidic hydrazide reacted with 1,4-dibromobut-2-ene to give a 1,2-diazahex-4-ene.     

The Synthesis,Characterization and DC Electrical Conductivity of Polypyrrole‐Zirconium Complex

Polypyrrole‐zirconium complex has been synthesized by reacting 2‐amino‐3,4‐dicyano‐5‐mercaptopyrrole with zirconium nitrate in absolute ethanol under reflux for 24 h. The product has been characterized by elemental analyses, FTIR spectroscopy, in addition to thermal analysis (TGA and DSC) and its solubility has been investigated. The DC electrical conductivity variation of polypyrrole‐zirconium complex has been studied in the temperature range 300–500 K after annealing for 24 h at 100°C and doping with I₂, FeCl₃ and CuCl₂ · H₂O for comparison. An attempt has been made to interpret the DC electrical conductivity behavior and thermal properties to chain length, dopant used, polymer structure and attached groups.     

Simple and Convenient Synthesis of 21‐Thioalkylether Derivatives of Methyl 16‐Prednisolone Carboxylates

The antedrug approach for corticosteroids has been described as a fundamentally sound approach for the development of safer anti‐inflammatory and anti‐asthmatic therapy. However, the derivatization of prednisolone and its congeners have been considered to be major pitfalls, because their syntheses are complicated by the presence of numerous carboxylate esters and hydroxyl functions in the steroid nucleus. A simple and direct synthesis of 21‐thioalkylether derivatives of methyl 16‐prednisolonecarboxylates is described. The 21‐mesylate of the methyl 16‐prednisolonecarboxylate and 9‐fluoro‐17‐dehydro methyl 16‐prednisolonecarboxylate were reacted with Na‐thioalkoxides to furnish the desired thioethers in good yields. A previously published method for the methanolysis of 16‐cyanoprednisolone to methylcarboxylate has been reexamined, and the conditions are explained clearly. The reaction conditions for all these reactions were critical.     

Inhibition effect of horehound (Marrubium vulgare L.) extract towards C38 steel corrosion in HCl solution

The corrosion inhibition properties of horehound (Marrubium vulgare L.) extract (HE) in 1 M hydrochloric acid medium was carried out using electrochemical methods (polarization curve and electrochemical impedance spectroscopy). Experiments were performed by concentration of the inhibitor and temperature effect. The results showed variation in inhibition performance of this plant extract. The Langmuir model was tested to describe the adsorption behavior of the inhibitor on the C38 steel surface. Some thermodynamic functions of dissolution processes were also determined.     

Synthesis of some new pyrimidine derivatives and evaluation of their anticancer and antibacterial activities

Starting from the reaction of ethyl cyanoacetate with thiourea and the appropriate aldehydes, a series of new pyrimidine derivatives were prepared. Ten selected pyrimidine derivatives were subjected to a screening system for the investigation of their antitumor potency against liver (HEPG2) cell line. The antitumor activity results indicated that most of the selected pyrimidine derivatives showed moderate growth inhibition activity against the tested cell line, but with varying intensities in comparison to the known anticancer drugs: 5-fluorouracil and doxorubicin. Some of the synthesized compounds were also tested for their antimicrobial activity against bacteria as well as fungal isolates.