نتایج جستجو برای: multicomponent condensation

تعداد نتایج: 42157  

Journal: :Molecules 2012
Heiner Eckert

A collection of smart multicomponent reactions (MCRs) with continuative post condensation cyclizations (PCCs) is presented to construct conventional three- to seven-membered heterocyclic compounds in diversity oriented syntheses (DOS). These will provide a high degree of applying economical and ecological advantages as well as of practicability. Water, ionic liquids, and solvent-less syntheses ...

Journal: :Accounts of chemical research 2000
C O Kappe

In 1893, P. Biginelli reported the synthesis of functionalized 3, 4-dihydropyrimidin-2(1H)-ones (DHPMs) via three-component condensation reaction of an aromatic aldehyde, urea, and ethyl acetoacetate. In the past decade, this long-neglected multicomponent reaction has experienced a remarkable revival, mainly due to the interesting pharmacological properties associated with this dihydropyrimidin...

2011
Bruno Piqani Wei Zhang

Dihydropyrimidinones and dihydropyrimidinethiones generated from the Biginelli reactions of perfluorooctanesulfonyl-attached benzaldehydes are used as common intermediates for post-condensation modifications such as cycloaddition, Liebeskind-Srogl reaction and Suzuki coupling to form biaryl-substituted dihydropyrimidinone, dihydropyrimidine, and thiazolopyrimidine compounds. The high efficiency...

2004
H. Korhonen

A size-segregated aerosol dynamics model UHMA (University of Helsinki Multicomponent Aerosol model) was developed for studies of multicomponent tropospheric aerosol particles. The model includes major aerosol microphysical processes in the atmosphere with a focus on new particle formation and growth; thus it incorporates particle coagulation and multicomponent condensation, applying a revised t...

2017
James F. Davies Rachael E. H. Miles Allen E. Haddrell Jonathan P. Reid

Uncertainties in quantifying the kinetics of evaporation and condensation of water from atmospheric aerosol are a significant contributor to the uncertainty in predicting cloud droplet number and the indirect effect of aerosols on climate. The influence of aerosol particle surface composition, particularly the impact of surface active organic films, on the condensation and evaporation coefficie...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2013
James F Davies Rachael E H Miles Allen E Haddrell Jonathan P Reid

Uncertainties in quantifying the kinetics of evaporation and condensation of water from atmospheric aerosol are a significant contributor to the uncertainty in predicting cloud droplet number and the indirect effect of aerosols on climate. The influence of aerosol particle surface composition, particularly the impact of surface active organic films, on the condensation and evaporation coefficie...

2003
D. J. Joswiak D. E. Brownlee

Introduction: Spinel minerals with 'normal' structure are common in extraterrestrial materials and can form via a large range of processes including nebular condensation, crystallization from liquid melts and sub-solidus metamor-phic reactions. Owing to their ability to accept a large range of cations in their crystal structures these minerals can be regarded as useful petrogenetic indicators w...

Journal: :iranian chemical communication 2015
seyyedeh cobra azimi esmayeel abbaspour-gilandeh

a green and convenient method for the synthesis of 14-aryl-14h-dibenzo[a,i]xanthene-8,13-diones and spiro[dibenzo[a,i]-xanthene-14,3'-indoline]-2',8,13-triones in the presence of a catalytic amount of cellulose sulfuric acid (csa) as an efficient biopolymer-based catalyst under solvent-free conditions at 100 °c is described. the condensation reactions of β-naphtol, 2-hydroxynaphthalene-1,4-dion...

2003
S. Prabakar R. A. Assink N. K. Raman S. A. Myers C. J. Brinker

High resolution 295i and 170 NMR spectroscopy has been used to identify selfand cross-condensation products in sols prepared from tetraethoxysilane (TEOS) and organically modified triethoxysilanes (RTES, where R is a methyl, ethyl or phenyl group). The sols were prepared by the acid catalyzed hydrolysis of TEOS and RTES with H20/Si mole ratios of 0.15, 0.3 or 0.5. Resonance assignments were mad...

2010
Jan F. Maćkowiak Andrzej Górak

In this work modelling and experimental validation of an integrated process for the removal of carbon dioxide from ammonia solutions is presented (decarbonisation). In this process, carbon dioxide is stripped out from the solution simultaneously with small amounts of ammonia at ambient pressure in a packed column. Recovery of the stripped ammonia can be reached by combining absorption of ammoni...

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