http://www.mdpi.com/journal/molecules/special_issues/microwave-assisted-synthesis/ 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. Submitted papers should not have been previously published nor be currently under consideration for publication elsewhere. All papers are refereed through a peer review process. A guide for authors, sample copies and other relevant information for submitting papers are available on the Instructions for Authors page. Molecules is an international peer-reviewed monthly journal published by Molecular Diversity Preservation International. Please visit the Instructions for Authors page before submitting a paper. Open Access publication fees are 800 CHF per paper. English correction fees (250 CHF) will be added in certain cases (1050 CHF per paper for those papers that require extensive additional formatting and/or English corrections.). http://www.mdpi.com/1420-3049/15/2/813/ A sustainable Knoevenagel condensation of a series of aldehydes with malononitrile and ethyl cyanoacetate is described. The process is based on the combination of microwave activation and hydroxyapatite catalysis under solvent-free conditions. Products are obtained in and high yields after short reaction times. The effects of the specific surface of porous calcium hydroxyapatite and microwave activation are discussed. http://www.mdpi.com/1420-3049/15/2/813/ Thu, 04 Feb 2010 00:00:00 CET Molecules 2010-02-04 15 2 Article 813 823 1420-3049 Microwave-Assisted and Efficient Solvent-free Knoevenagel Condensation. A Sustainable Protocol Using Porous Calcium Hydroxyapatite as Catalyst 2010-02-04 doi: 10.3390/molecules15020813 Siham Mallouk Khalid Bougrin Abdelaziz Laghzizil Rachid Benhida http://www.mdpi.com/1420-3049/14/12/4936/ In the manner that very important research is often 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 microwave multicomponent synthesis (MMS) that have been achieved over the last five years. http://www.mdpi.com/1420-3049/14/12/4936/ Tue, 01 Dec 2009 00:00:00 CET Molecules 2009-12-01 14 12 Review 4936 4972 1420-3049 Microwave Multicomponent Synthesis 2009-12-01 doi: 10.3390/molecules14124936 Helmut M. Hügel http://www.mdpi.com/1420-3049/14/10/4079/ The molecular combing technique was used to dissociate the nanostructural units of starch granules from the starch fragments after a gelatinization process. With the help of atomic force microscopy (AFM), we observed that some nanostructural chains were just flowing out of the granules. It proves that there are substantive nanostructural units in the starch granules, a phenomenon not previously observed, so these nanostructural units were defined as suspected intermediates. Furthermore, we conclude that blocklets of starch granules are formed through twisting or distortion of nanochains. http://www.mdpi.com/1420-3049/14/10/4079/ Mon, 12 Oct 2009 00:00:00 CEST Molecules 2009-10-12 14 10 Article 4079 4086 1420-3049 Application of the Molecular Combing Technique to Starch Granules 2009-10-12 doi: 10.3390/molecules14104079 Hua Li Zhong-Dong Liu Liu Boxiang Jian-Hui Chen You-Ning Sun Xiao-Ling Lv Ze-Sheng Zhang Pin Sun Pin Zhang Yang-Li Wang http://www.mdpi.com/1420-3049/14/9/3610/ The oxodiperoxo complex MoO(O2)2(tbbpy) (tbbpy = 4,4'-di-tert-butyl-2,2'- bipyridine) was isolated from the reaction of MoO2Cl2(tbbpy) in water under microwaveassisted heating at 120 ºC for 4 h. The structure of the oxodiperoxo complex was determined by single crystal X-ray diffraction. The MoVI centre is seven-coordinated with a geometry which strongly resembles a highly distorted bipyramid. Individual MoO(O2)2(tbbpy) complexes are interdigitated along the [010] direction to form a column. The crystal structure is formed by the close packing of the columnar-stacked complexes. Interactions between neighbouring columns are essentially of van der Waals type mediated by the need to effectively fill the available space. http://www.mdpi.com/1420-3049/14/9/3610/ Wed, 16 Sep 2009 00:00:00 CEST Molecules 2009-09-16 14 9 Article 3610 3620 1420-3049 Microwave-Assisted Synthesis and Crystal Structure of Oxo(diperoxo)(4,4'-di-tert-butyl-2,2'-bipyridine)-molybdenum(VI) 2009-09-16 doi: 10.3390/molecules14093610 Tatiana R. Amarante Filipe A. Almeida Paz Sandra Gago Isabel S. Gonçalves Martyn Pillinger Alírio E. Rodrigues Marta Abrantes http://www.mdpi.com/1420-3049/14/9/3551/ In this work an optimization of the solvent-free acetylation of cellulose with acetic anhydride under microwave heating with iodine as a catalyst was performed. The optimized parameters included the microwave irradiation power from 300 W to 800 W, the reaction time between 5 to 40 min, the reaction temperature from 80 to 130 °C, and the amount of iodine from 1 to 15 mol%. The extent of the acetylation was measured by yield and the degree of substitution (DS), which was determined by a back-titration method. Acetylated cellulose was characterized by FT-IR, CP/MAS 13C-NMR, WRXD, and thermogravimetric analysis. The results showed that within the range of catalyst amounts studied, the DS increased as the amount of iodine used increased, however, it was barely affected by microwave output. It was also found that the reaction time and temperature had an active influence on the extent of acetylation, however, this did not mean that at the higher temperature a better acetylation of cellulose would be obtained. The optimal reaction time and temperature found in this work were 30 min and 130 °C. http://www.mdpi.com/1420-3049/14/9/3551/ Fri, 11 Sep 2009 00:00:00 CEST Molecules 2009-09-11 14 9 Article 3551 3566 1420-3049 Microwave-Assisted Solvent-Free Acetylation of Cellulose with Acetic Anhydride in the Presence of Iodine as a Catalyst 2009-09-11 doi: 10.3390/molecules14093551 Jing Li Li-Ping Zhang Feng Peng Jing Bian Tong-Qi Yuan Feng Xu Run-Cang Sun http://www.mdpi.com/1420-3049/14/9/3411/ Essential oil allylbenzenes from have been converted quickly and efficiently into the corresponding benzaldehydes in good yields by a two-step “green” reaction pathway based on a solventless alkene group isomerization by KF/Al2O3 to form the corresponding 1-arylpropene and a subsequent solventless oxidation of the latter to the corresponding benzaldehyde by KMnO4/CuSO4·5H2O. The assistance by microwave irradiation results in very short reaction times (<15 minutes). The green conversion of eugenol (4-allyl-2-methoxyphenol) into vanillin (4-hydroxy-3-methoxybenzaldehyde) has been carried out in a similar way, requiring however two additional microwave-assisted synthetic steps for acetylation of the hydroxy group prior to the oxidation reaction, and for the final deacetylation of vanillin acetate (4-acetoxy-3-methoxybenzaldehyde) by KF/Al2O3 under solvent-free conditions, respectively. http://www.mdpi.com/1420-3049/14/9/3411/ Thu, 03 Sep 2009 00:00:00 CEST Molecules 2009-09-03 14 9 Article 3411 3424 1420-3049 Fast and Green Microwave-Assisted Conversion of Essential Oil Allylbenzenes into the Corresponding Aldehydes via Alkene Isomerization and Subsequent Potassium Permanganate Promoted Oxidative Alkene Group Cleavage 2009-09-03 doi: 10.3390/molecules14093411 Thi X. Thi Luu Trinh To Lam Thach Ngoc Le Fritz Duus http://www.mdpi.com/1420-3049/14/8/2918/ Microwave assisted CpCo(CO)2 catalyzed cross-cyclotrimerizations of 1,7,9,15-hexadecatetrayne with two different nitriles to give unsymmetrically substituted bis(tetrahydroisoquinolines) was studied. The reaction proceeded with a range of alkyl and aryl nitriles with reasonable isolated yields. http://www.mdpi.com/1420-3049/14/8/2918/ Mon, 10 Aug 2009 00:00:00 CEST Molecules 2009-08-10 14 8 Article 2918 2926 1420-3049 Cross-Cyclotrimerization with Two Nitriles as a Synthetic Pathway to Unsymmetrically 3,3’-Disubstituted bis(Tetrahydroisoquinolines) 2009-08-10 doi: 10.3390/molecules14082918 Aneta Kadlčíková Martin Kotora http://www.mdpi.com/1420-3049/14/8/2836/ Aqueous in situ one-pot N-Boc-deprotection-cyclization of Nα-Boc-dipeptidyl-tert-butyl and methyl esters under microwave irradiation afforded 2,5-diketopiperazines (DKPs) in excellent yields. This protocol is rapid, safe, environmentally friendly, and highly efficient, and showed that the tert-butoxy moiety is also an excellent leaving group for these cyclizations. http://www.mdpi.com/1420-3049/14/8/2836/ Fri, 31 Jul 2009 00:00:00 CEST Molecules 2009-07-31 14 8 Article 2836 2849 1420-3049 Efficient Microwave Assisted Syntheses of 2,5-Diketopiperazines in Aqueous Media 2009-07-31 doi: 10.3390/molecules14082836 Lemuel Pérez-Picaso Jaime Escalante Horacio F. Olivo María Yolanda Rios http://www.mdpi.com/1420-3049/14/6/2160/ A synthesis of 2-methyl-6-vinylpyrazine was carried out by way of a ‘one pot’ reaction. In order to establish the efficiency of this synthesis the extraction of the volatiles released by male papaya fruit flies was performed by SPME (solid phase micro-extraction). The compound was separated and identified using GC/MSD (gas chromatography/mass spectrometry detector). http://www.mdpi.com/1420-3049/14/6/2160/ Mon, 15 Jun 2009 00:00:00 CEST Molecules 2009-06-15 14 6 Article 2160 2166 1420-3049 Extraction with SPME and Synthesis of 2-Methyl-6-vinylpyrazine by a ‘One Pot’ Reaction Using Microwaves 2009-06-15 doi: 10.3390/molecules14062160 Norma Robledo Jaime Escalante René Arzuffi http://www.mdpi.com/1420-3049/14/4/1595/ A simple and efficient protocol has been developed for the direct synthesis of γ-nitrobutyric acid methyl esters under microwave irradiation. This methodology reduces reaction times from days to minutes, compared to conventional conditions. Additionally, these conditions increased yields and provided cleaner reactions. http://www.mdpi.com/1420-3049/14/4/1595/ Tue, 21 Apr 2009 00:00:00 CEST Molecules 2009-04-21 14 4 Article 1595 1604 1420-3049 Synthesis of γ-Nitro Aliphatic Methyl Esters Via Michael Additions Promoted by Microwave Irradiation 2009-04-21 doi: 10.3390/molecules14041595 Jaime Escalante Francisco D. Díaz-Coutiño http://www.mdpi.com/1420-3049/14/3/1126/ Phosphotungstic acid (H3PW12O40) was used as an efficient and recyclable catalyst for the synthesis of polysubstituted quinolines through the Friedländer condensation of 2-aminoarylketone with carbonyl compounds, which was achieved by conventional heating under solvent-free conditions. http://www.mdpi.com/1420-3049/14/3/1126/ Thu, 12 Mar 2009 00:00:00 CET Molecules 2009-03-12 14 3 Communication 1126 1133 1420-3049 Phosphotungstic Acid: An Efficient, Cost-effective and Recyclable Catalyst for the Synthesis of Polysubstituted Quinolines 2009-03-12 doi: 10.3390/molecules14031126 Minoo Dabiri Sahareh Bashiribod http://www.mdpi.com/1420-3049/14/1/403/ A fast, general, environmentally friendly and facile method for preparation of five- and six-membered ring diazaheterocylic salts under microwave irradiation is presented. The N-alkylation reactions of imidazole, pyrimidine, pyridazine and phthalazine have been studied. The microwaves remarkably accelerated these N-alkylations, the reaction times decreased dramatically, the reaction conditions were milder, the consumed energy decreased considerably and the amount of solvents used was reduced substantially. Consequently, the microwave assisted alkylation of N-containing heterocycles could be considered eco-friendly. In some cases, under MW irradiation the yields are also higher. A comparative study of microwave vs. classical conditions (liquid solvents) has been done. Twelve new diazaheterocylic salts of potential practical interest were obtained. http://www.mdpi.com/1420-3049/14/1/403/ Thu, 15 Jan 2009 00:00:00 CET Molecules 2009-01-15 14 1 Article 403 411 1420-3049 Microwave Assisted Reactions of Some Azaheterocylic Compounds 2009-01-15 doi: 10.3390/molecules14010403 Gheorghita Zbancioc Vasilichia Bejan Marian Risca Costel Moldoveanu Ionel I. Mangalagiu http://www.mdpi.com/1420-3049/13/12/3246/ We found that dodecatungstophosphoric acid (H3PW12O40), samarium and ruthenium(III) chloride act as efficient catalysts for synthesis of unsaturated 2-phenyl-5(4H)oxazolone derivatives under solvent-free conditions. The key features of the reported protocols are short reaction times, high yields of products, ambient conditions and simple workup. http://www.mdpi.com/1420-3049/13/12/3246/ Thu, 18 Dec 2008 00:00:00 CET Molecules 2008-12-18 13 12 Article 3246 3252 1420-3049 Dodecatungstophosphoric Acid (H3PW12O40), Samarium and Ruthenium (ІІІ) Chloride Catalyzed Synthesis of Unsaturated 2-Phenyl-5(4H)-oxazolone Derivatives under Solvent-free Conditions 2008-12-18 doi: 10.3390/molecules13123246 Ahmad Momeni Tikdari Samieh Fozooni Hooshang Hamidian