Surface treatment of zinc by Schiff’s bases and its corrosion study

The zinc metal surface is chemically modified by newly synthesized Schiff’s bases and its corrosion protection is investigated. The influence of concentration of Schiff’s bases on modification of zinc surface and immersion time in treatment bath are investigated and optimized for maximum corrosion protection efficiency. The electrochemical studies of treated zinc specimens are performed in aqueous acid solution using galvanostatic polarization technique. The treated zinc samples show good corrosion resistance. The recorded electrochemical data of chemically treated samples indicate a basic modification of the zinc surface. The protection efficiency of organic layer formed on zinc surface is tested by varying the acid concentration and temperature of the corrosive medium. The corrosion protection efficiency increases with the concentration of Schiff’s bases and immersion time. This is due to a strong interaction between zinc and the organic molecules, which results in the formation of a protective layer. This layer prevents the contact of aggressive medium with the zinc surface. The surface modification is confirmed by the scanning electron microscopy images. The interaction between metal atoms and Schiff’s bases is also established by IR studies. Published in Russian in Elektrokhimiya, 2007, Vol. 43, No. 7, pp. 886–892. The text was submitted by the authors in English.     

Ionic liquid mediated efficient reduction of nitroarenes using stannous chloride under sonication

Nitroarenes were rapidly reduced to the corresponding aromatic amines using stannous chloride in ionic liquid as a safe and recyclable reaction medium under sonication. The method is environmentally benign and sensitive functional groups remain unaffected.     

An electroactive co-polymer as corrosion inhibitor for steel in sulphuric acid medium

The corrosion behavior of mild steel in sulphuric acid solution containing various concentrations of a co-polymer formed between maleic anhydride and N-vinyl-2-pyrrolidone (VPMA) was investigated using weight-loss, polarization and electrochemical impedance techniques. The polymer acts as an effective corrosion inhibitor for steel in sulphuric acid medium. The inhibition process is attributed to the formation of an adsorbed film of co-polymer on the metal surface which protects the metal against corrosion. Scanning electron microscopy (SEM) studies of the metal surfaces confirmed the existence of an adsorbed film. The adsorption followed the Langmuir isotherm. The protection efficiency increased with increase in inhibitor concentration and decreased with increase in temperature and acid concentration. The thermodynamic functions of the adsorption and dissolution processes were evaluated.     

Synthesis of oxadiazole-2-oxide analogues as potential antischistosomal agents

The synthesis of several 1,2,5-oxadiazole-2-oxide (Furoxan) analogues is described herein. These compounds were prepared in an effort to probe the SAR around the phenyl substituent and oxadiazole core for our studies toward thioredoxin-glutathione reductase (TGR) inhibition and antischistosomal activity.     

ZSM-5沸石结晶度对乙苯叔丁基化对位选择性的影响(英文)

Highly crystalline ZSM-5 zeolites are important for para-selective alkylation of alkyl aromatics, because they carry few external acid sites for isomerization of p-dialkyl products. Such zeolites (Si/Al = 25, 50, and 75) were synthesized in a fluoride medium between pH 4 and 6. Their crystallinities, crystal sizes, and surface areas were higher than those of a commercial ZSM-5 zeolite. Their para selectivities in alkylation were tested for vapor-phase tert-butylation of ethylbenzene between 200 and 400 °C. As expected, all the catalysts showed more than 90% para selectivity. At 300 °C, ethylbenzene conversion decreased in the order ZSM-5(25, commercial) > ZSM-5(25) > ZSM-5(50) > ZSM-5(75). The catalysts had weak, medium, and strong acid sites, but all the acid sites of ZSM-5(75) were weaker than those of ZSM-5(25) and ZSM-5(50). The high activity of commercial ZSM-5 was caused by its strong acid sites being stronger than those of the synthesized zeolites. Although the activity of the commercial catalyst was higher than those of the present catalysts, the selectivity for 4-t-butylethylbenzene (4-t-BEB) was low. The optimum feed ratio (ethylbenzene:t-butyl alcohol) was 2:1 and the feed rate was 1.65 h?1 for high ethylbenzene conversion and 4-t-BEB selectivity. Time-on-stream studies showed slow catalyst deactivation. Highly crystalline ZSM-5 zeolites are therefore better than a commercial zeolite for para-selective alkylation of alkyl aromatics. They do not require much post-modification for high para selectivity. A fluoride medium is therefore better than an alkaline medium for obtaining highly crystalline para-selective ZSM-5 zeolites.     

Exclusive Formation of 1‐Aryl‐3‐(5‐nitro‐2‐furyl)‐4‐aroylpyrazoles via Regiospecific 1,3‐Dipolar Cycloaddition of 3‐Arylsydnones with α,β‐Acetylenic Ketones

1,3‐Dipolar cycloaddition of 3‐arylsydnones with α,β‐acetylenic ketones containing nitrofuran moiety has been studied, and it was observed that the dipolar cycloaddition is regiospecific, forming 1‐aryl‐3‐(5‐nitro‐2‐furyl)‐4‐aroylpyrazoles exclusively.     

Partially carbonized tungsten oxide as electrode material for asymmetric supercapacitors

Journal of Solid State Electrochemistry - Synthesis of partially carbonized tungsten oxide employing a simple, one-step, and scalable in-situ reduction/carbonization process is reported along with...     

Novel photoisomerization of spirodienones

Spironaphthalenones of the type ($\text{1}$) have been demonstrated to undergo isomerization to ($\text{2}$) upon UV irradiation.