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Special Issue "Solvent-Free Synthesis"

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A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (30 April 2012)

Special Issue Editor

Guest Editor
Dr. Cynthia Kellen-Yuen

Department of Chemistry, California State University, Sacramento, 6000 J Street, Sacramento, CA 95819, USA
Website | E-Mail
Interests: microwave assisted organic synthesis; greener synthetic approaches to biologically active heterocycles

Special Issue Information

Dear Colleagues,

The phrase “solvent-free synthesis” conjures up a wide variety of images and ideas amongst the chemistry community.  Solvent-free could refer to anything from a mixture of reagents combined without the addition of added solvent—i.e. simply running a reaction “neat”, to the increasingly broad area of chemistry often referred to as solid-state synthesis.  This synthetic approach is of particular interest in the modern world since it explores new ways to control the transformation of molecules without the necessity of employing large volumes of solvents, which often add to the cost and environmental impact of the reaction itself.  Additional benefits of this approach are often seen in higher product yields and lower energy costs associated with both the running of the reactions and the subsequent clean-up of product. Overall, this makes many of the reactions performed under solvent-free conditions also appeal to those of us interested in the field of Green Chemistry.

This Special Issue on Solvent-Free Synthesis will offer a forum to present papers focused on the synthesis of molecules using a variety of novel and environmentally-friendly strategies.  I hope that this issue will reflect the innovation and diversity of this growing field of chemistry.

Dr. Cynthia Kellen-Yuen
Guest Editor

Keywords

  • solvent free
  • solid state
  • zeolite
  • green chemistry
  • heterogeneous catalysis
  • materials
  • mesoporous catalysis

Published Papers (5 papers)

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Research

Open AccessArticle Solvent-Free Synthesis, DNA-Topoisomerase II Activity and Molecular Docking Study of New Asymmetrically N,N'-Substituted Ureas
Molecules 2012, 17(11), 12882-12894; doi:10.3390/molecules171112882
Received: 28 August 2012 / Revised: 26 September 2012 / Accepted: 26 October 2012 / Published: 1 November 2012
Cited by 4 | PDF Full-text (325 KB) | HTML Full-text | XML Full-text
Abstract
A new series of asymmetrically N,N'-substituted ureas 2025 was prepared using solvent free conditions, which is an eco-friendly methodology, starting with Schiff bases derived from cinnamaldehyde and p-substituted anilines, which are subsequently submitted to reduction reactions that afford the
[...] Read more.
A new series of asymmetrically N,N'-substituted ureas 2025 was prepared using solvent free conditions, which is an eco-friendly methodology, starting with Schiff bases derived from cinnamaldehyde and p-substituted anilines, which are subsequently submitted to reduction reactions that afford the corresponding asymmetric secondary amines. All of the intermediates were prepared using solvent free reactions, which were compared to traditional methodologies. All of the reactions required a remarkably short amount of time and provided good yields when solvent free conditions were employed compared to other methodologies. The DNA-topoisomerase II-α (topo II-α) activity was evaluated in relaxation assays, which showed that all of the compounds inhibited the enzyme activity at 10 μM, except for urea 24. Furthermore, a molecular docking study indicated that the compounds 2025 binding to the topo II-α are able to interact with the same binding site as the anticancer drug etoposide, suggesting that the ureas could inhibit the enzyme by the same mechanism of action observed for etoposide, which prevents re-ligation of the DNA strands. Full article
(This article belongs to the Special Issue Solvent-Free Synthesis)
Open AccessCommunication Solvent-Free Synthesis of Modified Pectin Compounds Promoted by Microwave Irradiation
Molecules 2012, 17(10), 12234-12242; doi:10.3390/molecules171012234
Received: 14 September 2012 / Revised: 1 October 2012 / Accepted: 16 October 2012 / Published: 18 October 2012
Cited by 14 | PDF Full-text (268 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Microwave-assisted solvent-free modification of pectin was successfully accomplished, consisting in the esterification of several fatty acids by pectin alcoholic functions. The reaction was performed by simply mixing the reagents with a catalytic amount of the inorganic base (potassium carbonate) and irradiating the obtained
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Microwave-assisted solvent-free modification of pectin was successfully accomplished, consisting in the esterification of several fatty acids by pectin alcoholic functions. The reaction was performed by simply mixing the reagents with a catalytic amount of the inorganic base (potassium carbonate) and irradiating the obtained mixture with microwaves for a short time (3–6 min). The replacement of the traditional heating with a microwave source allowed the development of a new synthetic protocol which provided increased yield of the final products, since it eliminates the small amount of degraded polysaccharide produced during traditional oil bath heating. The desired esters were fully characterized by FT-IR spectroscopy and thermogravimetric analysis. Full article
(This article belongs to the Special Issue Solvent-Free Synthesis)
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Open AccessArticle Silica Gel-Mediated Organic Reactions under Organic Solvent-Free Conditions
Molecules 2012, 17(10), 11469-11483; doi:10.3390/molecules171011469
Received: 24 August 2012 / Revised: 18 September 2012 / Accepted: 20 September 2012 / Published: 27 September 2012
Cited by 3 | PDF Full-text (271 KB)
Abstract
Silica gel was found to be an excellent medium for some useful organic transformations under organic solvent-free conditions, such as (1) the Friedel-Crafts-type nitration of arenes using commercial aqueous 69% nitric acid alone at room temperature, (2) one-pot Wittig-type olefination of aldehydes with
[...] Read more.
Silica gel was found to be an excellent medium for some useful organic transformations under organic solvent-free conditions, such as (1) the Friedel-Crafts-type nitration of arenes using commercial aqueous 69% nitric acid alone at room temperature, (2) one-pot Wittig-type olefination of aldehydes with activated organic halides in the presence of tributyl- or triphenylphosphine and Hunig’s base, and (3) the Morita-Baylis-Hillman reaction of aldehydes with methyl acrylate. After the reactions, the desired products were easily obtained in good to excellent yields through simple manipulation. Full article
(This article belongs to the Special Issue Solvent-Free Synthesis)
Open AccessArticle Microwave Synthesis Under Solvent-Free Conditions and Spectral Studies of Some Mesoporphyrinic Complexes
Molecules 2012, 17(5), 5592-5603; doi:10.3390/molecules17055592
Received: 20 March 2012 / Revised: 4 May 2012 / Accepted: 7 May 2012 / Published: 10 May 2012
Cited by 5 | PDF Full-text (220 KB)
Abstract
A series of A3B and A4 type mesoporphyrinic complexes were synthesized with superior yields using microwave irradiation under solvent-free conditions. The structures of the complexes were confirmed using elemental analysis, FT-IR, UV-Vis, EPR and NMR spectral data. The influence of
[...] Read more.
A series of A3B and A4 type mesoporphyrinic complexes were synthesized with superior yields using microwave irradiation under solvent-free conditions. The structures of the complexes were confirmed using elemental analysis, FT-IR, UV-Vis, EPR and NMR spectral data. The influence of environmental polarity on spectral properties of the mesoporphyrinic complexes was investigated. The obtained results indicate that the shape of absorption and fluorescence spectra does not depend on the solvent polarity under the experimental conditions used. The small shifts of the absorption and emission maximums that occur by increasing of solvent polarity reflects the physical interaction between the porphyrinic substituents and the solvent molecules. Full article
(This article belongs to the Special Issue Solvent-Free Synthesis)
Open AccessArticle Large-Scale Solvent-Free Chlorination of Hydroxy-Pyrimidines, -Pyridines, -Pyrazines and -Amides Using Equimolar POCl3
Molecules 2012, 17(4), 4533-4544; doi:10.3390/molecules17044533
Received: 7 March 2012 / Revised: 31 March 2012 / Accepted: 6 April 2012 / Published: 16 April 2012
Cited by 9 | PDF Full-text (232 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Chlorination with equimolar POCl3 can be efficiently achieved not only for hydroxypyrimidines, but also for many other substrates such as 2-hydroxy-pyridines, -quinoxalines, or even -amides. The procedure is solvent-free and involves heating in a sealed reactor at high temperatures using one equivalent
[...] Read more.
Chlorination with equimolar POCl3 can be efficiently achieved not only for hydroxypyrimidines, but also for many other substrates such as 2-hydroxy-pyridines, -quinoxalines, or even -amides. The procedure is solvent-free and involves heating in a sealed reactor at high temperatures using one equivalent of pyridine as base. It is suitable for large scale (multigram) batch preparations. Full article
(This article belongs to the Special Issue Solvent-Free Synthesis)
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