Microwave-induced Organic Reaction Enhancement Research Articles

Microwave-Induced Synthesis of Carboxymethyl Hemicelluloses and Their Rheological Properties

In this article, a facile, rapid, and efficient method was developed for the preparation of carboxymethyl hemicelluloses using microwave-induced organic reaction enhancement chemistry. The influences of the factors including reaction time, temperature, and the amount of sodium monochloroacetate and sodium hydroxide on the degree of substitution (DS) of the products were investigated. The rheological properties and the chemical structure of the resulting polymers were also studied. It was found that microwave irradiation could significantly promote the chemical reaction efficiency and accelerate the carboxymethylation of hemicelluloses with sodium monochloroacetate. Therefore, carboxymethyl hemicelluloses with higher DS of 1.02 could be obtained in much shorter time scales as compared to the conventional heating method. Results from rheological analysis indicated that carboxymethyl hemicellulose solutions exhibited shear-thinning behavior in the range of shear rates tested and showed lower viscosity and modulus in comparison with those of the native hemicelluloses due to lower molecular weight and the role of carboxymethyl groups in reducing the entanglements between hemicelluloses chains.

ChemInform Abstract: Microwave-Induced Organic Reaction Enhancement (MORE) Chemistry. Part 13. Microwave-Assisted Rapid and Simplified Hydrogenation.

ChemInform Abstract: Microwave-Induced Organic Reaction Enhancement (MORE) Chemistry. Part 13. Microwave-Assisted Rapid and Simplified Hydrogenation.

Exploring microwave synthesis for co-ordination: synthesis, spectral characterization and comparative study of transition metal complexes with binuclear core derived from 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one

A series of transition metal complexes of Cu(II), Ni(II), Co(II), Mn(II), Zn(II), Hg(II), and Sn(II) has been synthesized from the Schiff base (L) derived from 4-aminoantipyrine and 4-fluoro-benzaldehyde using traditional synthetic methodology and microwave-induced organic reaction enhancement (MORE) technique. A benign, simple, and versatile route to a Schiff-base ligand and its metal complexes has been explored. Neat reactants were subjected to microwave irradiation giving the required products more quickly and in better yield compared to the classical methodology. Structural features were obtained from elemental analysis, molar conductivity, 1H-NMR, mass, UV-Vis, and FTIR spectroscopy and X-ray diffraction. The data show that these complexes are ML2. The MORE method for synthesis is easy, convenient, and ecofriendly as compared to the traditional synthetic method.

The synthesis of 2′-amino-5α-cholest-6-eno [6,7- d] thiazole derivatives under microwave irradiation using dry-media conditions

A convenient, rapid and efficient method for the synthesis of substituted steroidal [6,7- d] thiazoles using microwave-induced organic reaction enhancement chemistry has been developed. The additional features of this methodology include a much faster reaction, easy workup, high yield, high purity of the products and an environment friendly approach.

Microwave promoted energy-efficient N-formylation with aqueous formic acid

Microwave-induced organic reaction enhancement (‘MORE’) chemistry technique (open vessel; controlled microwave energy to stay below the boiling point of the reaction mixture) was used for the N-formylation of aliphatic and aromatic amines and amino heterocycles with aq formic acid (80%) on a multiple gram scale in a few minutes.

Diels–Alder Cycloadditions: A MORE Experiment in the Organic Laboratory Including A Diene Identification Exercise Involving NMR Spectroscopy and Molecular Modeling

The MORE (microwave-induced organic reaction enhancement) technique has been used successfully to prepare two Diels–Alder [π2 + π4] cycloaddition adducts, racemic exo, endo-2,3-dibenzoylbicyclo[2.2.1]hept-5-ene and racemic exo, endo-2,3-dibenzoylbicyclo[2.2.2]octa-5-ene, in high purity and good yields. Microwave synthesis of these two dienes serves as an excellent organic laboratory experiment to demonstrate the rate enhancement advantage of using microwave heating over conventional heating in preparing selected Diels–Alder cycloaddition products. When the splitting patterns of vinyl protons in the NMR spectra of these compounds are used in conjunction with molecular modeling, a pedagogically sound exercise of diene identification emerges from this MORE experiment.

MORE Chemistry for Less Pollution: Applications for Process Development.

AbstractFor Abstract see ChemInform Abstract in Full Text.

MORE Chemistry for Less Pollution: Applications for Process Development

Microwave-assisted rapid organic reactions constitute an emerging technology that could make industrially important organic syntheses more eco-friendly than conventional reactions. In our laboratory Microwave-Induced Organic Reaction Enhancement (MORE) chemistry techniques have been developed that are safe since all reactions are conducted in open systems to avoid any chance of explosions that have been observed in sealed systems. MORE chemistry can be conducted without an added solvent if one or more of the reactants is a liquid that absorbs microwaves efficiently. When it is necessary to add a dipolar solvent for transferring microwave energy to the reactants, it is adequate to add just enough solvent to form a slurry at room temperature. The growing concern about the effect of organic solvents and chemical wastes on the environment is attracting attention to non-traditional synthetic approaches that might 'reduce pollution at the source'. In this context MORE chemistry techniques are potentially valuable as they reduce the need for organic solvents and also increase 'atom economy' by improving product selectivity and chemical yield.

Vinyl-β-lactams as Efficient Synthons. Eco-friendly Approaches via Microwave Assisted Reactions

Vinyl-β-lactams are efficient synthons for a variety of compounds of biomedical interest—such as isocephalosporins, carbapenem and thienamycin intermediates, and pyrrolidine alkaloids. Convenient methods are described for obtaining both enantiomers of some of these synthons. Microwave-induced Organic Reaction Enhancement (MORE) chemistry techniques allow highly accelerated synthesis of variously substituted vinyl-β-lactams using limited amounts of solvents and with efficient stereocontrol—thus achieving high ‘atom economy’. The effect (if any) of microwaves on bond angles and bond lengths and the geometry of transition states are not well understood yet. Nonetheless, reactions under microwave irradiation in open systems are rapid, safe, and cost-effective for synthetic approaches that are much more friendly to the environment than conventional processes.

ChemInform Abstract: Microwave‐Induced Organic Reaction Enhancement (MORE) Chemistry: Techniques for Rapid, Safe and Inexpensive Synthesis

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Microwave-induced organic reaction enhancement (more) chemistry: Techniques for rapid, safe and inexpensive synthesis

Synthetic organic reactions have been conducted under microwave irradiation in open vessels in unaltered domestic microwave ovens. Reaction times vary from a few seconds for sub-milligram reactions to about 15 minutes for reactions carried out on a scale of hundreds of grams. Promising results have been obtained for several condensations, as well as the Bischler-Napieralski reaction, the Wolff-Kishner reduction, free radical dehalogenation reactions, and other standard synthetic operations. Rapid catalytic transfer hydrogenation using ammonium formate as the source of hydrogen has been conducted at about 100-130 °C under microwave irradiation.

ChemInform Abstract: Microwave‐Induced Organic Reaction Enhancement Chemistry. Part 2. Simplified Techniques.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Microwave-induced organic reaction enhancement chemistry.4 convenient synthesis of enantiopure α-hydroxy-β-lactams 1

A convenient and rapid synthesis of enantiopure α-hydroxy-β-lactams using microwave-induced organic reaction enhancement chemistry has been developed. Reactions in domestic microwave ovens, which are very convenient and economical for small scale work in research or teaching laboratories, can also be conducted on a preparative scale of 100–500g in simple beakers or flasks.

Microwave-induced organic reaction enhancement chemistry. 2. Simplified techniques

Microwave-induced organic reaction enhancement chemistry. 2. Simplified techniques