Special Issue "Microwave Assisted Synthesis"

Guest Editor
Dr. Julio A. Seijas Vázquez
Departamento de Química Orgánica, Universidad de Santiago de Compostela, Facultad de Ciencias-Campus de Lugo, Alfonso X el Sabio, 27002 Lugo, Spain
Website: http://web.lugo.usc.es/~qoseijas/
E-mail:

Submission

All papers should be submitted to molecules@mdpi.org with a copy to the guest editor. To be published continuously until the deadline and papers will be listed together at the special websites.

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to be added soon

Manuscript ID: molecules-micrasyn-01-it-Brusotti
Type of Paper: Article
Title: Experimental Design Methodology applied to a Microwave assisted Synthesis of a fragrant Compound: Calone 1951^®
Authors: Gloria Brusotti ^1,*, Sandra Furlanetto ²,Carmela De Risi ³,Marco Carando ⁴,Giorgio Marrubini ¹,Carlo Gandini ¹,Gabriella Massolini¹
Affiliations: ¹Department of Pharmaceutical Chemistry, Pavia University, viale Taramelli12, 27100 Pavia,Italy
²Department of Pharmaceutical Science, Florence University, Via U. Schiff 6, 50019 Sesto F.no (FI), Italy
³ Department of Pharmaceutical Science, Via Fossato di Mortara, 17-19, 44100 Ferrara, Italy
⁴ Osmotech Srl, viale Taramelli12, 27100 Pavia,Italy
^* Author to whom correspondence should be addressed; E-mail: gloria.brusotti@unpv.it
Abstract: The first application of experimental design methodology to the microwave assisted organic synthesis (MAOS) is here described for the synthesis of 7-methyl-benzo[b][1,4]dioxepin-3-one 1, or Calone 1951^®, chosen as target compound. The industrial synthesis involves a three steps sequence: Williamson reaction, Dieckmann condensation and acid hydrolysis/decarboxylation. Starting from an European patent we aimed at synthesising 1 reducing the reaction time and the number of steps: the reaction of 4-methyl catechol with dichloroacetone was investigated using microwave heating instead of conventional heating while a widely applicable multivariate approach of experimental design was applied to maximize the synthesis yield and to reduce the number of experiments.
A 12-run D-optimal asymmetrical screening matrix (2²1⁴//12) allowed us toidentify, among different factors, those which really had an influence on the response. A response surface study, carried out in the experimental domain defined by temperature and time, pointed out the best reaction conditions.
Applying microwave heating the reaction can be carried out in one step reducing the time from 6 h to 18 min. and increasing the yield from 56% to 70.5%.
Calone 1951^® was determined and characterized by gas chromatography-mass spectrometry (GC-MSD), gas chromatography with Flame Ionization Detector (GC-FID) and ¹H-NMR analysis.
Keywords: Experimental design/Fragrances/Microwaves irradiation

Manuscript ID: molecules-micrasyn-20081117-bg-Antova
Type of Paper: Article
Title: Studies upon the obtaining of Cellulose Palmitate under Microwave Heating
Authors: Ginka Antova and Magdalen Zlatanov
Affiliation: Department of Chemical Technology, University of Plovdiv, 24 Tzar Assen Street, 4000 Plovdiv, Bulgaria
E-mail: ginant@uni-plovdiv.bg
Abstract: This study presents the possibility for obtaining Cellulose Palmitate by transesterification of methylpalmitate with low - molecular microcrystalline cellulose under microwave heating. The most suitable conditions for carrying out transesterification under microwave heating are: molar ratio - cellulose : methylpalmitate - 1 : 9, catalyst quantity 0,5.10-2 mol p-toluene sulphonic acid per mol cellulose, duration of the process - 10 min. and power of the microwave heating - 600W. The resulting product is Cellulose Palmitate containing 66% of combined palmitic acid and 1,1 degree of substitution of hydroxyl groups.
At direct esterification of microcrystalline cellulose with palmitic acid at analogical conditions was obtained Cellulose Palmitat with a degree of esterification (DS = 0,27) about three times lower than the results gained during the transesterification.
A study has been made upon the influence of duration of the process (respectively - temperature) and quantity of methylpalmitate upon the degree of destruction of cellulose under microwave heating. The degree of destruction of cellulose in the Cellulose Palmitate, obtained by esterification is higher. The destruction of microcrystalline cellulose under these conditions is described by equation of second order.

Manuscript ID: molecules-micrasyn-20081204-au-Hugel
Type of Paper: Review
Title: Multicomponent microwave synthesis
Author: Helmut M. Hügel
Affiliation: School of Applied Sciences (Chemistry), RMIT University, GPO Box 2476V, Melbourne, Victoria 3001, Australia
Abstract: In the manner that very important research is performed by multidisciplinary research teams, the applications of multicomponent reactions involving the combination of multiple starting materials with different functional groups leading to the higher efficiency and environmentally friendly construction of multifunctional/complex target molecules is growing in importance. This review will explore the advances and advantages in multicomponent microwave synthesis that have been achieved over the last five years.