Environmental friendly methods mild conditions

During the last ten years, many research results have shown that oxidative polymerization catalyzed by peroxidases is a convenient, resource-saving, and environmentally friendly method for synthesizing phenol polymers. In contrast to the conventional synthesis of phenol-formaldehyde resins, the peroxidase-catalyzed polymerization of phenol proceeds under mild reaction conditions (room temperature, neutral pH). The polymerization of toxic phenols has promising potential for the cleaning of wastewaters. Moreover, the polymerization of phenols from renewable resources is expected to attract much attention in times of worldwide demand for the replacement of petroleum-derived raw materials. Besides the environment-protecting aspects of this innovative type of polymerization, the enzyme-catalyzed polymerization represents a convenient method to reahze new types of functional polyaromatic polymers. Phenol polymers made by peroxidase catalysis should have much potential for electronic and optical apphcations. The synthesis of functional phenol polymers is facihtated by the fact that poly-... 

H2 serves as the alternative energy source relative to fossil fuels and biomass [181] because it is clean and environmentally friendly. Hence, catalytic hydrogen generation from water under mild conditions is one of the goals for the organometallic catalysis. One of the hopeful methods is the electrochemical reduction of protons by a hydrogenase mimic. 

Current syntheses of SNTs are based on the severe conditions such as extreme pH condition and high temperature and pressure. However, other works which in mild condition required high complicated surfactants as template which requires tedious work-up. We develop the method which provided rather convenient and simple route for the fabrication of SNT at ambient temperature using glycyldodecylamide and in neutral pH. Moreover, the neutral synthetic procedure enabled cost-effective recovery of amphiphiles and environmentally friendly. 

In the last few years we have developed new methods for the photochemical carbamoylation of electron-poor N-heteroaromatic bases. The introduction of Ti02 photocatalysis has supplied new and environmentally friendly synthetic methods that operate under mild conditions (Scheme 14.4) [19, 20]. 

The present procedure is based on the use of fluoroalkyl alcohols as solvents in oxidation reactions. The method is efficient and versatile, and produces disulfides and sulfoxides under mild conditions. These reactions have also been developed using hexafluoroisopropyl alcohol (HFIP) as solvent with a large variety of substrates (alkyl sulfides, alkyl thiols, vinyl sulfides, fiuorinated vinyl sulfides, thioglucosides) by Begue et al."> Replacement of HFIP with trifluoroethanol, a more common and less expensive solvent, also allows the use of mild conditions and affords high yields of disulfides and sulfoxides without contamination. 30% Aqueous hydrogen peroxide is inexpensive and, since water is the sole byproduct, this method is environmentally friendly. 

The transformation of aldehydes to carboxylic acids is a fundamental reaction in organic synthesis. Many successful methods have been developed for these types of oxidations [1], but most of them have limitations as they require stoichiometric amounts of oxidants such as chlorite [2], diromium(VI) reagents [3], potassium permanganate [4], or peroxides [5]. The use of organic solvents e.g., acetonitrile, didiloromethane, cyclohexane, formic add, or benzene is also usually necessary. Despite the fact that these methods have several disadvantages, such as low selectivity and production of waste, some of them have been widely used in industry and are still in use today. The growing awareness of the environment has created a demand for efficient oxidation processes with environmentally friendly oxidants under mild conditions ( green chemistry) [6]. 

Several approaches have been described for the preparation of optically active sulfoxides [5-7]. The three main routes to obtain these compounds are as follows (i) the asymmetric sulfoxidation of prochiral sulfides, (ii) nucleophilic substitution using a chiral sulfur precursor, and (iii) the kinetic resolution of racemic sulfoxides. The first of tiiese methods involves the use of various oxidants and catalysts and has been the most extensively employed. There are many examples in the scientific literature and reviews are available on this approach. In recent years, much attention has been focused on the synthesis of organic sulfoxides by emplo5dng conditions compatible with the green chemistry procedures [8-10]. For this reason, mild oxidants such as molecular oxygen or hydrogen peroxide are considered in combination with novel catalysts in order to develop a mild and environmentally friendly process. 

A facile synthesis of 4-phenyl-1/f-1,5-benzodiazepines from o-phenylenedi-amines and 1,3-diketones in the presence of a catalytic amount of acetic acid has been achieved, in excellent yields (62-97%) in 2-10 min, under microwave irradiation (Tsoleridis et al, 2008). This method is very simple and the reaction conditions are mild, environmentally friendly and quick. 

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