JOURNAL OF APPLIED RESEARCHES IN CHEMISTRY (JARC)
Year:2010 | Volume:4 | Issue:13

Epoxidized polybutadiene was synthesized using in situ generated dimethyl dioxitanb (DMD) as an oxidant and Cloisite 30B as a phase transfer catalyst (PIC). The formation of epoxy groups monitored by using FT-IR and NMR spectrospopy methods in various reaction times. addition, a significant selectivity and significant yield increments have been perceived toward Cis carbon-carbon double bonds epoxidation in comparison with Trans epoxidation. The method was fast and eco-friendly and can be considered as a versatile method in polybutadiene epoxidation.

In recent years, biotechnology has formed many applications in dyeing and finishing sectors of textile industry. Enzymes are protein compounds which can participate in many reactions in textile wet processing. The purpose of this study is to improve nylon 66 fiber structures and to study different properties including dye ability, moisture absorption, surface changes and color fastness using lipase enzyme. To that end, nylon 66 fabrics were first treated with different concentrations of protease enzyme in water solution including 3, 6 and 9% o.w.f.. The dyeing process was then carried out on the treated fabrics with acid dyes. The results of color measurement on enzyme treated/dyed with these two class of dyes showed that the L* values of enzyme treated samples decreased and more decrease in L* value was observed with an increase in the enzyme percentage. The results of acid dyes exhaustion on treated fibers showed higher absorption of dyes on fibers. Tensile strength studies indicated that enzymatic processing decrease tenacity, modulus and elongation at break of nylon 6 fabric. Thermal studies of enzyme treated sample did not show significant changes on orientation of fiber after enzyme treatment up to the temperature of 300°C. But increase in heating temperature of the sample in the range of 300-400°C showed considerable decrease in thermal degradation temperature of enzyme treated sample compared to non-treated one. The wash and light fastness properties of samples were measured according to ISO 105-CO5 and Daylight ISO 105-BO1. Enzyme treatment before dyeing process improves wash and light fastness of samples which could be the result of dyes penetration into the fibers.

Tetrahydroquinoline derivatives are widely found in many natural products, which exhibit various biological activities. For the synthesis of tetrahydroquinolines, the imino Diels-Alder reaction of N-arylimine with olefins is highly efficient. In recent years, great efforts have been made to develop organic reactions in an environment-friendly manner (green chemistry).In this research Oxalic acid /Silica Gel was found to be an efficient catalyst for the imino Diels-Alder (povarov) reaction of synthesized N-aryl-substituted aldimines and various alkenes to provide tetrahydroquinolines in good yields. The influence of the loading of oxalic acid, the structure of imines and alkenes was studied. Mild reaction conditions, facile experimental procedure, low price of oxalic acid and Silica Gel and good yields of products render this new method attractive for practical synthesis of many tetrahydroquinoline derivatives.

Oxidation of alcohols to aldehydes and ketones is one of the most important transformations in organic synthesis. Some of these reactions have to be performed under severe conditions, such as high temperature and high oxygen pressure. In many cases the reactions are carried out in environmentally undesired solvents, typically chlorinated hydrocarbons. Due to these limitations, there is significant interest for doing safe catalytic oxidation reaction of alcohols using molecular oxygen or air as an oxidant in the solvent. In continuation of our research works, we report a mixture of nanocrystal-CeO2/Al2O3 as an efficient catalyst for oxidation of benzyl alcohol derivatives.

Incorporating the dye molecules in the structure of porous materials provides adsorbtion medium as well as hybridic systems which can be used in different fields as sensing, indicators, lasers and optoelectronic. In the present work several system of dye-containing mesoporous system and Congo red such as CR-MCM-41 were prepared. The samples were characterized by XRD, UV-Vis, DRS, BET and FTIR methods. Ion exchange MCM-41, calcined MCM-41 and functionalized MCM-41 were also prepared. The functionalized MCM-41 provided active adsorption sites for the interaction between solid surface and Congo red. Langmuir and Frendlich isotherms were calculated. This hybrid system can behave as a pH indicator and sensor for HCl and ammonia.

Biodiesel is a clean and renewable energy that its use as a suitable substitute for diesel fuel is spreading in all around the world. Biodiesel can be used as pure or mixed with diesel fuel. In this research safflower seed was considered as a suitable raw material and after the extraction of oil and transesterification reaction the physical and chemical characterization of biodiesel and its 20 percent mixture with diesel fuels was studied using standard test. Our study shows that the 20 percent mixture gives the best result compared with pure safflower biodiesel and fuel, and all its specifications were in standard ranges defined in EN 14214, ASTM D6751.

In this work, a packed bed reactor of methyl acetate hydrolysis process has been studied. First, mass transfer limitations from bulk fluid to catalyst surface and then from surface into catalyst body were investigated quantitatively. Whereas diffusion had no any limitation on the overall rate of reaction, a pseudo homogeneous one dimensional model considering axial dispersion coefficients was developed. A LHHW kinetic model for rate of reaction and a Longmuir model for equilibrium adsorption of species on the catalyst, developed experimentally, were used in the mathematical model. An experiment of pulse-input feed to reactor was performed and concentration of reactor product versus time was determined. The model were solved by the numerical method of lines and the absolute difference between calculated concentration profile and those measured experimentally was defined as the objective function which was optimized by Levenberg-Marquardt optimization algorithm. A comparison of our model with ideal Plug Flow model and also with previous model in literature shows that this model is more accurate and more comprehensive than the others and can be used in many comparable industrial cases.

A relatively easy method to synthesize pure and stable crystalline hydroxyapatite (HA) at low temperature by sol-gel route is presented. In this study phase purity of HA synthesized by sol-gel route was explored using calcium nitrate tetrahydrate and triethyl phosphate as calcium and phosphorus precursors, respectively. For some of samples, phosphorus sol was first hydrolyzed for 24 h with distilled water. Effects of sol-gel process parameters including mixed sol solution temperature, aging time and heat treatment on apatite phase evolution were systematically studied. Infrared (IR) spectroscopy, X-ray diffraction (XRD), thermal behavior (DTA) and elemental analysis of electron microscopy examination (SEM) were used for structural evolution investigation during the synthesis of HA. Increasing the aging time favors the reduction of CaO formation. Also, increasing the mixed sol solution temperature up to 80 had a positive effect on the elimination of impurity phases. With the increase of the calcination temperature > 600 °C, calcium phosphate impurity phases disappeared. The SEM micrographs showed highly agglomerated micro structure at nanoscale for calcined powders.

The aim of this work is to synthesis a polyaniline with high conductivity by chemical oxidative polymerization under ultrasonic irradiation. The aniline chemical polymerization carried out by addition of initiator such an ammonium peroxydisulfate (APS) in aqueous medium under ultrasonic irradiation in inert atmosphere. The influence of synthesis conditions such as the duration of reaction time, concentration of the oxidant, concentration of HCl and presence of air atmospher or inert gas in the obtained polyaniline were investigated.The optimum conditions for the synthesis of polyaniline with better conductivity were determined. Our results demonstrate that polyaniline conductivity depends on the conditions such as, concentration of HCl, presence of oxygen in the reaction medium and monomer molar ration of the initiator. The optimum molar ration of the initiator to the monomer aniline is 2.5:2 .The electrical conductivity of polyaniline synthesis by optimized condition was 23.46 S/cm measured at -5 - 0°C. The obtained polyaniline characterized by FT-IR, UV-Vis, XRD, DSC and SEM.

Highly use of epoxy polymers as coatings, adhesives, composites are due to their high chemical resistant, hardness, cohesion and coasting. The most common epoxy prepolymers ae forme the reaction between bisphenol A and epichlorohydrine most cured, with various hardeners. In this article efforts have been made to synthesize different diamines with imide linkages for curing epoxy to improve heat oxidation resistance property as a high performance polymer. Two novel diamine diimids have been synthesized through the reaction of 1,3-diamino benzene with pyromelitic dianhydride (PMDA) and 4,4'- (hexafluoroisopropylidene) diphthalicanhydride (6FDA), FT-IR and 1H-NMR spectroscopies confirmed the structure of these products. The curing temperature, time, physical properties, solubility, inherent viscosity were registered after curing. Heat properties of following epoxy resins were investigated by DSC and TGA. The results show that cured resin with hardener contain PMDA has more heat resistance and also curing time of resin will increase by this hardener.

In many cases in concentrate factory of Sarcheshmeh copper co., the grade of copper in molibdenite concentrate exceeds its permissible limits. This causes economic reduction in value of product. So, with sodium cyanide addition, the copper content in concentrate is controlled. Sodium cyanide is very toxic and environmentally hazardous. In this investigation, studying the feasibility use of micro–organism ability is considered. At first after sampling of molibdenite concentrate of Sarcheshmeh Co., and chemical and mineralogical of obtained samples were under the bio-leaching process by mesophile bacteria mix culture of, (acidi thio bacilous thiooxidance acidi thibacilous ferroxidanse and leptosperilom feroxidance) and Thermophile (acidianous berili ,sulfo-lobous acido caldarious) bacteria.In this investigation, bio- leaching reactor and microbial study in shaking methods are considered. The results of microbial methods in shaking flasks, copper removal by mesophile bacteria is 55% and by thermophile bacteria is 75%. The results in bioleaching reactor showed, the rate of copper removal from molibdenite concentrate by mesophile bacteria is 50% (temp. 35°C, pH =2, solid % =10 and bacterial inoculation =12%) and by thermophile bacteria is 60% (temp.65°C, pH=2, solid%=10 and bacterial inoculation=12%). Therefore, the use of bacteria is important for copper removal from molybdenite concentrate. This approach also prevents contamination of the environment.