The Technical University of Valencia is a Spanish university located in Valencia, with a focus on science and technology. It was founded in 1968 as the Higher Polytechnic School of Valencia and became a university in 1971, but some of its schools are more than 100 years old. Wikipedia.
Merino E.,Polytechnic University of Valencia
Chemical Society Reviews | Year: 2011
Azobenzenes are ubiquitous motifs very important in many areas of science. Azo compounds display crucial properties for important applications, mainly for the chemical industry. Because of their discovery, the main application of aromatic azo compounds has been their use as dyes. These compounds are excellent candidates to function as molecular switches because of their efficient cis-trans isomerization in the presence of appropriate radiation. The classical methods for the synthesis of azo compounds are the azo coupling reaction (coupling of diazonium salts with activated aromatic compounds), the Mills reaction (reaction between aromatic nitroso derivatives and anilines) and the Wallach reaction (transformation of azoxybenzenes into 4-hydroxy substituted azoderivatives in acid media). More recently, other preparative methods have been reported. This critical review covers the various synthetic methods reported on azo compounds with special emphasis on the more recent ones and their mechanistic aspects (170 references). © 2011 The Royal Society of Chemistry.
Moliner M.,Polytechnic University of Valencia
Dalton Transactions | Year: 2014
The former synthesis of TS-1 opened new catalytic opportunities for zeolites, especially for their application as selective redox catalysts in several fine chemistry processes. Interestingly, isolated Ti species in the framework positions of hydrophobic zeolites, such as high silica zeolites, offer unique Lewis acid sites even in the presence of protic polar solvents (such as water). Following this discovery, other transition metals (such as Sn, Zr, V, Nb, among others) have been introduced in the framework positions of different hydrophobic zeolitic structures, allowing their application in new fine chemistry processes as very active and selective redox catalysts. Recently, these hydrophobic metallozeolites have been successfully applied as efficient catalysts for several biomass-transformation processes in bulk water. The acquired knowledge from the former catalytic descriptions in fine chemistry processes using hydrophobic Lewis acid-containing zeolites has been essential for their application in these novel biomass transformations. In the present review, I will describe the recent advances in the synthesis of new transition metal-containing zeolites presenting Lewis acid character, and their unique catalytic applications in both fine chemistry and novel biomass-transformations. © 2014 The Royal Society of Chemistry.
Dhakshinamoorthy A.,Madurai Kamaraj University |
Garcia H.,Polytechnic University of Valencia |
Garcia H.,King Abdulaziz University
Chemical Society Reviews | Year: 2014
Metal-organic frameworks (MOFs) are finding increasing application as solid catalysts for liquid phase reactions leading to the synthesis of fine chemicals. In the present review we have focused on those reports describing the use of MOFs as catalysts for the synthesis of N-containing heterocycles that is a class of organic compounds with high added value due to their therapeutic use as drugs and their remarkable biological activities. After an introduction describing relevant structural features of MOFs and the nature of their active sites, this manuscript is organized according to the type of N-containing heterocycle synthesized employing MOFs as catalysts including pyrimidines, N-substituted piperidines, quinolines, indoles, N-substituted imidazoles, triazoles and heterocyclic amides. Special attention has been paid to the structural stability of MOFs under the reaction conditions, to the occurrence of metal leaching and reusability. The final section of this review provides some concluding remarks and future prospects for the field, with emphasis on showing the superiority of MOFs with respect to other solid catalysts for this type of liquid phase organic reactions and pointing out that the final goal in this research would be the use of these materials as catalysts in real industrial synthesis. This journal is © the Partner Organisations 2014.
Grirrane A.,Polytechnic University of Valencia
Nature protocols | Year: 2010
This protocol describes the aerobic oxidation of aromatic anilines to aromatic azo compounds using gold (Au) nanoparticles supported on TiO(2) as a catalyst. Yields above 98% are achieved under a few bars of oxygen pressure. It should be noted that the use of stoichiometric amounts of environmentally unfriendly reagents, e.g., transition metals and nitrites, commonly used in current syntheses of azo compounds, is avoided using this approach. The protocol is illustrated with the synthesis of parent azobenzene from aniline, and this reaction takes 22 h. Au on TiO(2) can also be used as a hydrogenation catalyst, making it possible to prepare azo compounds directly from nitroaromatics through a two-step (hydrogenation followed by aerobic oxidation), one-pot, one-catalyst reaction. In addition, the catalytic process is efficient for the synthesis of symmetric and a range of asymmetric aromatic azo compounds from the mixtures of two anilines substituted with electron-donor and electron-acceptor substituents.
Stratakis M.,University of Crete |
Garcia H.,Polytechnic University of Valencia
Chemical Reviews | Year: 2012
Recent achievements in the activation of dihydrogen, epoxides, alcohols, carbonyl compounds, alkynes, hydrosilanes, or boron hydrides, and on CO 2 fixation, C-C crosscoupling reactions, hydrogen transfer catalysis, are presented. Hardacre and co-workers used heterogenized Au nanoparticles supported on silica to achieve good to excellent selectivity in the benzylation of substituted benzenes with benzyl alcohol. Ying and co-workers used successfully a heterogeneous air- and water-stable reusable PbS-supported gold catalyst for the three-component coupling reaction. Keane and co-workers studied in detail the influence of support and particle size on activity and selectivity regarding the hydrogenation of mdinitrobenzene and chloronitrobenzene. Hii and co-workers developed a flow reactor for the highly selective direct alkylation of amines by alcohols using Au/TiO 2 as catalyst, without the requirement for an inert atmosphere or base.