Sharif Digital Repository

Series of quaternary ammonium salts of substituted five-membered-ring iron complexes were prepared by reaction of allyl(cyclopentadienyl)iron(II) dicarbonyl with iminium salts. Also, reactions of allyl-(cyclopentadienyl) iron(II) dicarbonyl with in situ prepared iminium salts afford the same products in good to excellent isolated yields. © 2007 American Chemical Society  

Impure rhenium and molybdenum bearing solution was passed through a column of Varian strong base anionic resin for selective adsorption of rhenium and molybdenum ions from the solution. Elution of molybdenum and rhenium was carried out using 2 N NaOH and 0.2 N NH4SCN, respectively. The effect of resin bed height on breakthrough time was investigated. Experimental and theoretical curves were compared with good agreement. The results showed that the behavior pattern of these curves was repeatable and almost constant. © 2006 Elsevier B.V. All rights reserved  

In this article, we synthesize a novel gelatin-based superabsorbent hydrogel via graft copolymerization of mixtures of acrylic acid (AA) and acrylamide (AAm) onto gelatin backbones. The polymerization reaction was carried out in an aqueous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N-methylene bisacrylamide (MBA) as a crosslinker. The hydrogel structures were confirmed by FTIR spectroscopy. The effect of grafting variables, i.e. concentration of MBA and APS, AA/AAm weight ratio, and reaction time and temperature, was systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The swelling behavior of these absorbent polymers... 

Novel hydrogels based on zwitterionic monomer [3-(methacrylamido)propyl] dimethyl (3-sulfopropyl) ammonium hydroxide (MPDSAH) and a strong acid monomer (2-acrylamido-2-methylpropane sulfonic acid, AMPS) were synthesized through solution polymerization under normal conditions to achieve nearly quantitative gel yield. The structure of the gels was confirmed using infrared spectroscopy. Thermal properties were simultaneously studied by differential scanning calorimetry and thermogravimetric analysis (DSC/TGA). The effects of the polymerization variables on the swelling capacity of the products were investigated. It was found that, in a certain range of the monomers mol ratio, increase of AMPS... 

In this paper, LM pectin production from commercial apple pectin by using acid, alkali and ammonia methods in the presence of ethanol was studied. Also, the effect of different parameters such as, temperature, time, acid, alkali and ammonia treatment in LM pectin production were evaluated. In all the experiments, low temperature showed a better influence from a recovery, purity and low de-polymerization viewpoint. Optimum conditions in the acid method reached at pH = 2, t = 17 hrs and T = 30°C, in the alkaline method reached at pH = 11, t = 3 hrs and T = 5°C and in the ammonia method reached at 2 N ammonia and T = 5°C, were determined. © Sharif University of Technology