Search results for "Microwave"

Microwave-assisted synthesis of novel cyclodextrin–cucurbituril complexes

2011

Microwave irradiation was successfully used in order to obtain stable supramolecular aggregates between cyclodextrins and cucurbiturils, without the participation of any long-chain common ‘molecular thread’ guest. These aggregates were characterised by means of various different techniques, namely NMR, thermogravimetry, polarimetry and ESI-MS. Cross-analysis of experimental data allowed us to obtain insights on the stoichiometries of the composites and their thermal stabilities. The possible structures of the composites are briefly discussed, as well as the actual nature of their intrinsic stability.

Microwave-Assisted Synthesis of Polysubstituted 4-Quinolones from Deprotonated α-Aminonitriles

2010

The α-alkylation of deprotonated N-aryl-α-aminonitriles with α-bromoesters furnishes intermediates that can be cyclized to 4-quinolones upon microwave irradiation. Alternatively, base-induced dehydrocyanation of the alkylation products furnishes enaminoesters, which can, for example, be converted into quinoline-3-carboxylates.

ChemInform Abstract: Cyclocondensation of α-Aminonitriles and Enones: A Short Access to 3,4-Dihydro-2H-pyrrole 2-Carbonitriles and 2,3,5-Trisubstitut…

2010

The reaction of α,β-unsaturated carbonyl compounds with aminoacetonitrile hydrochloride furnishes 3,5-disubstituted 3,4-dihydro-2H-pyrrole-2-carbonitriles in a one-pot reaction sequence. While these products can serve as starting materials for the preparation of polysubstituted pyrrolizidines, they are kinetically stable against the base-induced elimination of HCN. In contrast, their 2-substituted analogues obtained from α-substituted α-aminonitriles can be readily converted to the corresponding 2,3,5-trisubstituted pyrroles under microwave irradiation. The key step presumably involves the thermal electrocyclization of a stabilized 2-azapentadienyl anion formed by condensation of the reacta…

Microwave-Driven Hydrothermal Synthesis of Oxide Nanopowders for Applications in Optoelectronics

2005

Hydrolysis of Phytic Acid by Microwave Treatment: Application to Phytic Acid Analysis in Pharmaceutical Preparations

1998

Abstract The acid hydrolysis of phytic acid in a Teflon reactor using a domestic microwave oven has been studied and compared with other reported procedures. In 0.44 M HCl quantitative hydrolysis was achieved with six heating stages of 2 min each. A lower yield was obtained with H 2 SO 4 and HNO 3 . The analytical use of this hydrolysis to determine phytic acid by indirect determination of phosphate has been demonstrated by analysis of three pharmaceutical formulations. No sample pretreatment other than obtaining a homogeneous suspension was necessary.

ChemInform Abstract: Green Conditions for the Suzuki Reaction Using Microwave Irradiation and a New HNT-Supported Ionic Liquid-Like Phase (HNT-SILLP)…

2014

Aryl iodides are coupled with conversions comparable to aryl bromides whereas conversions of aryl chlorides are significantly lower.

Synthesis of Carbolines via Microwave-Assisted Cadogan Reactions of Aryl-Nitropyridines

2018

Development and Design of Reactors in Microwave‐Assisted Chemistry

2012

Critical-state effects on microwave losses in type-II superconductors

2006

We discuss the microwave energy losses in superconductors in the critical state. The field-induced variations of the surface resistance are determined, in the framework of the Coffey and Clem model, by taking into account the distribution of the vortex magnetic field inside the sample. It is shown that the effects of the critical state cannot generally be disregarded to account for the experimental data. Results obtained in bulk niobium at low temperatures are quantitatively justified.

Thermoelectric Radiation Detector Based on Superconductor-Ferromagnet Systems

2017

We suggest an ultrasensitive detector of electromagnetic fields exploiting the giant thermoelectric effect recently found in superconductor-ferromagnet hybrid structures. Compared with other types of superconducting detectors where the detected signal is based on variations of the detector impedance, the thermoelectric detector has the advantage of requiring no external driving fields. This is especially relevant in multipixel detectors, where the number of bias lines and the heating induced by them are an issue. We propose different material combinations to implement the detector and provide a detailed analysis of its sensitivity and speed. In particular, we perform a proper noise analysis…