Rafael Martínez-Palou

Microwave-assisted synthesis using ionic liquids

The research and application of green chemistry principles have led to the development of cleaner processes. In this sense, during the present century an ever-growing number of studies have been published describing the use of ionic liquids (ILs) as solvents, catalysts, or templates to develop more environmentally friendly and efficient chemical transformations for their use in both academia and industry. The conjugation of ILs and microwave irradiation as a non-conventional heating source has shown evident advantages when compared to conventional synthetic procedures for the generation of fast, efficient, and environmental friendly synthetic methodologies. This review focuses on the advances in the use of ILs in organic, polymers and materials syntheses under MW irradiation conditions.

Applications of ionic liquids in the removal of contaminants from refinery feedstocks: an industrial perspective

The purpose of this review is to provide appropriate details concerning the applications of ionic liquids for the removal of pollutants from refinery feedstocks, like sulfur-, nitrogen- and fluor-containing compounds, aromatics, naphthenic acids and asphaltenes. Furthermore, critical considerations surrounding the problems and challenges associated with the application of these technologies in the petroleum industry are discussed.

Ionic liquids screening for desulfurization of natural gasoline by liquid–liquid extraction

Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization of NG was performed by means of liquid–liquid extraction method at room temperature and atmospheric pressure. Experimental ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally and under microwave and sonochemical conditions. The effect of the molecular structure of ILs on the desulfurization efficiency of NG with high sulfur content was evaluated. Analysis indicated that the anion type played a more important role than the cation on the desulphurization process. ILs based on halogen–ferrates and halogen–aluminates exhibited the highest efficiency in sulfur removal, and their efficiency is further improved when there is an excess of metallic salt in a ratio of at least 1:1.3 during the synthesis of the corresponding IL. An explanation for the ability of metallic ILs to remove sulfur-containing compounds from natural gasoline based on the ratio of the ionic charge to the atomic radius is proposed. Furthermore, a method to recover and reuse water-sensitive to halogenated precursors is described.

Advances in Microwave-Assisted Combinatorial Chemistry Without Polymer-Supported Reagents

SummaryCombinatorial methodologies have dramatically changed the chemical research and discovery process, offering an unlimited source of new molecule entities to be screened for activity. The application of microwave irradiation in Combinatorial Chemistry and high-throughput synthesis has become increasingly popular. By taking advantage of this energy source, compound libraries for lead generation can be assembled in a fraction of time required by conventional thermal heating. This review focuses on the advances in developing synthetic methodologies in microwave without polymer-supported reagents suitable for combinatorial chemistry, including the advances in microwave-assisted fluorous synthesis technology.

Parallel and automated library synthesis of 2-long alkyl chain benzoazoles and azole[4,5-b]pyridines under microwave irradiation

SummaryA versatile route to 40-membered library of 2-long alkyl chain substituted benzoazoles (1 and 2) and azole[4,5-b]pyridines (3 and 4) via microwave-assisted combinatorial synthesis was developed. The reactions were carried out in both monomode and multimode microwave oven. With the latter, all reactions were performed in high-throughput experimental settings consisting of an 8×5 combinatorial library designed to synthesize 40 compounds. Each step, from the addition of reagents to the recovery of final products, was automated. The microwave-assisted N-long chain alkylation reactions of 2-alkyl-1H-benzimidazole (1) and 2-alkyl-1H-benzimidazole[4,5-b] pyridines (3) were also studied.

Microwave-Assisted Pretreatment of Lignocellulosic Biomass to Produce Biofuels and Value-Added Products

Microwaves have emerged as a very efficient source of heat for accelerating many chemical reactions and processes. Actually, ever growing demand of energy and concerns for the environment have prompted researchers to develop convenient and efficient ways for converting lignocellulosic biomass into valuable chemicals, bio-fuels and useful biomaterials. In this chapter, advances on the application of microwave irradiation technology for the pretreatment of lignocellulosic biomass to produce biofuels and other high value chemicals and the advantages and limitations in the use of microwave technology are reviewed and discussed.

Efficient Microwave-Assisted Synthesis of Ionic Esterified Amino Acids

In this work, an efficient microwave-assisted methodology for the esterification of unprotected α-amino acids is described. Ionic esterified amino acids were synthesized in satisfactory yields in a facile one-pot solventless protocol from unprotected amino acids and alcohols under acid catalysis (MsOH or p-TsOH) to afford the pure products after a simple work-up procedure. This procedure can also be extended to the preparation of long and short chain alkyl and benzyl esters.

Parallel Microwave-Assisted Synthesis of Ionic Liquids and Screening for Denitrogenation of Straight-Run Diesel Feed by Liquid-Liquid Extraction

Fifty-six ionic liquids were efficiently synthesized in parallel format under one-pot, solvent-free microwave-assisted synthesis. These compounds were evaluated as extracting agents of nitrogen-containing compounds from a real Diesel feed before being submitted to the hydrodesulfurization process to obtain ultralow sulfur Diesel. Our results showed that halogenated ionic liquids are an excellent alternative due to these ionic liquids are relatively inexpensive, presenting a high selectivity for the extraction of nitrogen-containing compounds and can be regenerated and recycled.

Supported ionic liquid membranes for separations of gases and liquids: an overview

The separation of mixtures of gases and liquids is a topic of great interest in the oil industry, which in many cases still has not found a technology that could be really efficient, environmentally friendly and technically feasible to obtain pure gases as well as for the removal of pollutants in liquid feedstocks. In this sense, one of the most promising alternatives for the solution of both problems is the use of membrane technology. Particularly, supported-ionic-liquid-membrane-based technology has prompted great interest due to the combined characteristics of this system. On the one hand, supported membranes, using conventional solvents, are more stable and feature long-term performance; on the other hand, ionic liquids are environmental friendly solvents that can be designed for every specific application.In this work, an overview of recent research on supported ionic liquid membranes with special emphasis in potential applications for the Petroleum Industry is offered. Both, gas and liquid separations are highlighted.

Amphiphilic Choline Carboxylates as Demulsifiers of Water-in-Crude Oil Emulsions

Abstract Water/oil emulsions are formed in oil wells due to the presence of natural surfactants. As water/oil phase separation is necessary before oil refining, demulsifiers are used to break water/oil emulsions. In this work, environmentally friendly ionic surface-active choline carboxylates were synthesized from anionic exchange involving choline chloride under microwave dielectric heating. Microwave irradiation was also employed as a fast method for following the kinetics of the demulsification process with the synthesized demulsifiers. Choline palmitate showed the best performance as demulsifier.