3-arylcoumarins are prepared in good yields by microwave assisted solvent-free condensation of phenylacetic acids and phenylacetic esters, using potassium tert-butoxide as base.

The chief features of the microwave reactions are the enhanced selectivity, much improved reaction rates, milder reaction conditions and formation of cleaner products. These reactions are an efficient and mild methodology for oxidation of some organic compound is described using cetyltrimethylammonium bromochromate (CTMABC) under microwave irradiation.

The compound, 1, 1'-(1,4- butanediyl)bis(imidazole), has been synthesized by the reaction between imidazole, NaOH, and 1,4-dichlorobutane, under a fast and efficient method microwave irradiation. The title compound has been characterized by spectral methods (1H-, 13C NMR and IR spectroscopy).

Synthesis of substituted 3,3- dimethyl trihydro benzothiazolo[2,3-b]quinazoline-2Hones a class of well established medicinally important compound is developed by the multicomponent condensation reaction of 2-amino-6-chloro-benzothiazole (1), substituted benzaldehydes (2) and 5,5-dimethylcyclohexane-1,3-dione (dimedone, 3) under different reactions conditions and energy sources, e.g. microwave irradiation, sonication and classical heating for comparison purposes. The use of a monomode oven allowed an accurate consideration of the temperature distribution in the microwave reaction vessel, which revealed a very strong and unexpected thermal heterogeneity. The reaction was facilitated by the presence of a trace of DMF, the catalytic role of which is demonstrated.

A fast and efficient method has been developed for the synthesis of N,N bis(salicylidene)-2,2-dimethylpropane-1,3-diamine, H2[salpnMe], under microwave irradiation. The tetradenatate Schiff-base H2[salpnMe] has been prepared and characterized by IR, 13CNMR, 1HNMR.

The sequential [2+2]/[2+1] and [2+2+1]/[2+1] multicomponent reactions that occur thermally when treating alkoxy alkynyl Fischer carbene complexes with 2,3-dihydrofuran or norbornene may be accelerated by MW irradiation. They lead to the same adducts in similar yields and diastereoselectivities and, therefore, MW irradiation does not cause a different chemical behaviour but just an accelerating effect.

Microwave organic chemistry is a novel technique which allows for the rapid high yield synthesis of products. As conventional syntheses are converted into microwave reactions, optimizations of these processes can help identify baseline parameters that are common in all microwave environments. Specifically, the optimizations of the Diels-Alder reactions, a common reaction in organic chemistry, were found to range between 5 and 10 minutes and 125 oC to 150 oC in the CEM microwave. This can be used as a baseline when an unknown Diels-Alder reaction is attempted.

Microwave organic chemistry is a green chemical method that improves reaction conditions and product yields, while reducing solvent amounts and reaction times. Although microwave syntheses can decrease the amount of harmful pollutants, little attention has focus on the search for novel eco-friendly catalysts used in microwave reactions. Surface active agents, also called surfactants, are amphiphilic molecules that have the ability to be both catalytic and biodegradable making them an eco-friendly alternative to harmful catalyst commonly used. Although surfactants have been used as catalysts in conventional reactions, no literature has been cited which uses catalytic surfactants in microwave organic synthesis.

The role of the host size on stoichiometry, structure and strength of supramolecular association between a fluorescent probe, coumarin 460 (C460), and the three natural cyclodextrins (CDs) with increasing cavity sizes (a, ß and γ-cyclodextrin) is analyzed, using fluorescence spectroscopy. The variations of the fluorescence emission spectra of C460 with CD concentration can be explained with a 1:1 complexation equilibrium model for a-CD and ß-CD, but also a 1:2 complex has to be included in the case of γ-CD. Nevertheless, the photophysical properties and the stability of the complexes do not correlate in a simple way with the cavity size. For instance, the association between C460 and ß-CD, which is the CD with medium cavity size, is much stronger than with the other CDs but it does not provoke fluorescence enhancement as in those cases. Detailed analysis of fluorescence quantum yields and fluorescence lifetimes of the complexes help us to propose an explanation for this unexpected behaviour. This is the formation of two types of 1:1 complexes with ß-CD and γ-CD which differ in the side groups of C460 which are included in the CD cavity and how much effect this has on the photoinduced charge-transfer processes in the coumarins. This system is a nice example how subtle variations in the host-cavity size can induce big structural changes in the supramolecular complexes.

Alginate, a material extracted from brown seaweeds, is a polymer of D-mannuronic acid and Lguluronic acid. The structure of alginate has carboxylic acid functionalities and is water soluble, particularly as the sodium salt, thereby possessing a wide range of commercial uses such as a rheology modifier. Here we report a simple procedure to evaluate some chemical properties of sodium alginate samples by conventional 1D- and 2D NMR experiments using mild conditions and without preliminary partial acidic hydrolysis.