Nowadays the bioresources including plant polysaccharides stay in focus of many researches according to ecological politics as well as oil reserves depleting. The well-known polysaccharide modification methods very often suffer from toxic by-products or difficult processing. In order to solve the problem a new method for corn starch oxidation is presented. The process allows oxidizing the hydroxyl groups of anhydroglucose units of amylose and amylopectin (starch) by means of urea- hydrogen peroxide (UHP) action. Oxidation reaction was carried out without pasting the starch, so the granular structure was not destroyed. In a product –CHO as well as –COOH group content was established. The degradation of polysaccharide chains was investigated using gel permeation chromatography. Finally the topology of granule surface before and after modification was observed using SEM microscopy. The rate of oxidant consumption and efficiency of oxidation was monitored by permanganate titration. All the reaction was compared to process that employed hydrogen peroxide water solution. As a result a series of new starch modification products were obtained. The degree of modification (oxidation) was similar to those obtained using hydrogen peroxide. On the other hand the consumption of oxidant is slower what allows the full controlling of the process. Additionally the lower degradation of starch components (amylose and amylopectin) was detected and the surface of the starch granules is less destroyed. In fact the important advantage of the UHP process is also the safe and easy set-up when solid but green oxidant is replacing relatively unstable liquid solutions of H₂O₂. The application of UHP for starch oxidation opens a new path for safe and green renewable material processing for industrial application.

The use of dibutyl tin oxide in microwave assisted synthesis of esters from alcohols and acids under solvent free conditions (MASFOS) in high yields is described.

Over recent years, heating and driving chemical reactions by microwave (MW) energy has been a significant interest in the scientific community, in particular applied to microwave-assisted organic synthesis (MAOS) and drug discovery. Ammonium trichloro[1,2-ethanediolato-O,O\']-tellurate (AS101) is the most important synthetic Te compound from the standpoint of its biological activity. It is a potent immunomodulator with a variety of potential therapeutic applications. Continuing with our studies on MAOS we draw our attention to this compound. The effect of microwave power, synthesis temperature and time on AS101 obtention was examined in this work. An easy, efficient and fast procedure for syntheses of AS101 by MAOS is presented. We believe that the proposed procedure has the potential to evolve to incorporate new processes for obtaining AS101 derivatives, since the optimization of newly discovered lead compounds, relies upon the advancement of synthetic technologies.

Despite the ease of obtaining aluminum carbenoids by the reaction of CH₂I₂ and trialkylaluminums, their chemistry has been little studied. Over the last few years the authors have developed a new approach to the synthesis of cyclopropane compounds based on the reaction of substituted alkynes and allenes with aluminum carbenoids [1,2]. Substituted propargyl alcohol and amines have been successfully involved in the reaction [3,4]. At the same time, only a few examples for the cyclopropanation of functionally-substituted alkenes by aluminum carbenoid are known, such as geraniol, perillyl alcohol, γ-silicon substituted allylic alcohols [5-7]. In order to develop a general method for the preparation of functionally-substituted cyclopropanes, in this paper we have studied the reaction of aluminum carbenoids with unsaturated amines. We found that the reaction of substituted allyl amines and enamines (allyldiethylamine, allyl piperidine, allyl tert-octyl amine, (E)-N,N-diethyl-1-penten-1-amine, (Z)-N,N-diethyl-2-phenyl-1-ethenamine) with two equivalents of Et₃Al and CH₂I₂ at room temperature in CH₂Cl₂ results in the formation of corresponding cyclopropyl amines in high yields (71-87%). The reaction is complete in 3-18 hours depending on the amine structure. The transformation proceeds with retention of configuration of the substituents at the double bond. The paper demonstrates the advantage of using aluminum carbenoids over traditional cyclopropanation reagents (diazomethane, Simmons-Smith and Furukawa reagents) for the preparation of cyclopropyl amines. References [1] I. R. Ramazanov, L. K. Dil\'mukhametova, U. M. Dzhemilev, O. M. Nefedov, J. Organomet. Chem., 2010, 695, 1761-1767; [2] I. R. Ramazanov, A. V. Yaroslavova, U. M. Dzhemilev, O. M. Nefedov, Tetrahedron Lett., 2010, 51, 6268-6269; [3] I. R. Ramazanov, A. V. Yumagulova, U. M. Dzhemilev and O. M. Nefedov, Tetrahedron Lett., 2009, 50, 4233-4235;[4] I. R. Ramazanov, A. V. Yaroslavova, L. M. Khalilov, U. M. Dzhemilev, O. M. Nefedov, Russ. Chem. Bull., 2010, 59, 1668-1670; [5] К. Maruoka, Y. Fukutani, H. Yamamoto, J. Org. Chem., 1985, 50, 4412–4414; [6] A. B. Charette, A. Beauchemin , J. Organomet. Chem., 2001, 617-618, 702-708; [7] Y. Ukaji, K. Inomata, Chem. Lett., 1992, 2353-2356.

Solar energy is the greatest source for production renewable energy carriers on the earth. Organic and inorganic dyes anchored to semiconductor nanoparticles, have been found important applications as photosensitizes for solar cells and other optoelectronic systems. In this study, the influence of hydroxyphenyl, methoxyphenyl and methylthiophenyl substitution on the (E)-2-(2-hydroxyphenyl) diazenesulfonate dye were investigated. Calculations were done using software Gaussian 98. Dye molecules were optimized by DFT/6-31G (d, p) method in gas phase. Dyes were optimized in Chloroform, Ethanol and THF solvents by using CPCM model and DFT/6-31G (d, p) method. Different functional groups effects were studied in the ability of diazensulfonate dye to absorption sunlight. According to the results of our computational, methoxyphenyl substitution in Ethanol solvent, red shift is caused.

The capacities of natural sorbents in removing of dyes from synthetic wastewater have been investigated. The investigated sorbents were two natural wood samples (silver fir and beech) for the removal of two disazo direct dyes derived from 4,4\'-diamonibenzanilide (PDP and, RDC). The effects of the support\'s nature, the dose of natural fibres, initial concentration, and temperature on the dye removal were investigated. The obtained results showed a better retention capacity of Beech sawdust. The quantity of dye absorbed per unit of dry natural support decreased, but the efficiency of the dye adsorption (removal percentage) increased when the weight of fibre was doubled. By reducing the apparent area of the fibre the adsorption capacity of natural fibres increased. The uptake of the studied dyes increased with the increase in initial dye concentration and with the decrease in the size of the dye molecules. In order to explain the effect of temperature on the dyes adsorption the experiments were conducted at 298, 313, and 333 K. The adsorption decrease with an increase in temperature indicated that the process is exothermic in nature. Kinetics of adsorption obeyed second order rate equation in case of using investigated sorbents. The best isotherm model that fits the experimental data with lower error was the Sips isotherm model.

Using 4,4\'-diaminostilbene-2,2\'-disulphonic acid an well known eco-friendly middle component and 2-chlorosalicylanilide and 2-bromosalicylanilide as coupling components, two new symmetrical disazo direct dyes were synthesized. The dyes were analyzed by TLC, VIS, FT/IR, ¹³C-NMR spectroscopy, and HPLC technique. The colour assessment of the two new synthesized dyes was made by means of the tri-stimulus colour characteristics lightness (L*), redness (a*), yellowness (b*), chroma (C*) and hue angle (hº) relative to the standard illuminants: D65 (natural day light), A (tungsten light), F2 (fluorescent light) and the standard 10° observer respectively The colour differences (ΔE_ab^*, ΔECMC) calculated against an white standard, namely Pigment White 6 (C.I. 77 891) reveal a good colouring power of these new azo-stilbene dyes

Mucoadhesive polymers are used in pharmaceutical formulations to elaborate drugs applicable in mucous zones, e.g., gastrointestinal/vaginal tracts, ocular mucous membrane and nasal cavity. They can interact and become fixed to mucus via mechanisms, e.g., molecular interpenetration, van der Waals forces, hydrophobic interactions, electrostatic forces, hydrogen bonds, etc., which allows augmenting the residence period in the organism and increasing the bioavailability of the drugs that they deliver. The physicochemical properties of drug/polymers, e.g., molecular weight, grade of ionization, concentration and polymer swelling kinetics, affect formulation mucoadhesion magnitude, rheological behaviour and drug absorption. Drug fractal dimension was examined for homologous series of transdermal-delivery drug models: percutaneous enhancers phenyl alcohols/4-alkylanilines. Here, method is extended to polymers. Hyaluronan is selected as mucoadhesive/biodegradable polymer. Geometric, topological and fractal analyses are carried out with our program TOPO. Reference calculations are performed with our version of program GEPOL. Program TOPO underestimate molecular volume and surface area by 0.7% and 5%, respectively. Molecular globularity is overestimated by 5% and rugosity, underestimated by 5%. Sovent-accessible surface area is underestimated by 3%. When going from hexamer hyaluronan3– to hyaluronan·3Ca to hyaluronan·3Ca·9H2O, the hydrophobic solvent-accessible surface area increases by 42% and decays by 26%; the hydrophilic solvent-accessible surface area decays by 14% and increases by 58%. Fractal dimension of hyaluronan turns out to be 1.57. On going to hyaluronan·3Ca to hyaluronan·3Ca·9H2O, it increases by 2% and 1%. Fractal dimension averaged for non-buried atoms of hyaluronan results 1.73. When going to hyaluronan·3Ca to hyaluronan·3Ca·9H2O, it increases by 4% and 0.3%. Provisional conclusions follow. (1) Hyaluronan is an important component of articular cartilage, where it is present as a coat around each chondrocyte. When aggrecan monomers bind to hyaluronan in the presence of link protein, large highly anionic aggregates form, which imbibe water and are responsible for cartilage resistance to compression. The molecular weight of hyaluronan in cartilage decays with age but the amount increases. (2) Fractal dimension of hyaluronan results 1.57. On going to hyaluronan·3Ca/·9H2O, it increases by 2/1%. Fractal dimension averaged for non-buried atoms of hyaluronan results 1.73. When going to hyaluronan·3Ca/·9H2O, it increases by 4/0.3%. (3) Polymer rheological behaviour formulated in pH 4–7 does not differ, which is proper of unstructured systems. pH < 4 generate gels because of hydrophobic interactions/hydrogen bonds; gels result promising for administration on skin/mucous membranes.

3-nitropyridine and 4-nitropyridine N-oxide were theoretically studied, acting as dienophiles in the Diels-Alder reaction with different dienes. It was observed that both azacycles would suffer the cycloaddition reaching the quinoleine derivatives. Regioselectivity was predicted.The mechanism reaction was also analyzed observing that there is only one asymmetric and asynchronous transition state between the reactants and the primary cycloadduct when isoprene is the diene involved, and two when 1-methoxy-1,3-butadiene and Danishefsky\'s diene were used.

Graphene is the latest allotrope of carbon to be under the spotlight ever since its discovery by Novoselov and coworkers in 2004. Owing to its fascinating structural, electrical, optical, mechanical and thermal properties, graphene can be regarded as as a rapidly rising star in various fields such as supercapacitors, biosensors and batteries. The organic chemistry of graphene has stimulated a great deal of research and is gaining considerable attention. Among the various experimental studies which have been carried out on graphene, it is found that [3+2] cycloadditions (32CA) can also be achieved on graphene sheets and the resulting functionalized graphenes are dispersible in polar organic solvents and water. The outstanding properties of graphene inspire fundamental studies and within the context of our recent publication on the 32CA of nitrile oxides with fullerene, we now explore the 32CA of unsubstituted (HCNO) and substituted nitrile oxides (FCNO and MeCNO) to model of graphenes. We seek to rationalize the energetic, thermodynamic and kinetic parameters of these reactions. To the best of our knowledge this is the first time that transition states structure (TS) for 1,3-DC on graphene models have been reported. Our interest lies in gaining a better insight into the reaction mechanism such as its synchronicity, the nature of the TS, charge transfer, analysis of the reactivity indices and the rate constants. An unexpected behaviour (lowest activation energy) has been observed for the 32CA involving FCNO as these reactions have some pseudodiradical character. The findings of our research should be helpful to experimentalists in their quests for functionalized graphenes.