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Gamma-valerolactone is a valuable chemical that can be obtained by catalytic methods from nonedible vegetable biomass. However, the demand is felt for more environmentally friendly and cost-effective production processes. The topic is reviewed in this paper from the perspective of catalyst design. Focus is on those systems enabling one-pot reaction sequences in the liquid phase at low energy expenses and combining metal and acid sites, spanning from homogeneous to heterogeneous catalysts. A final section is dedicated to continuous flow applications. The 230 references cover the most significant achievements published in the literature from January 2011 to July 2014 and highlight critical issues and future trends.

Rigid diols catalytically produced from biomass derivatives have been proposed as bisphenol A functional replacements.

The reaction of [CpRu(PPh(3))(2)Cl] (1) with half an equivalent of P(4) or P(4)S(3) in the presence of AgCF(3)SO(3) as chloride scavenger affords the stable dimetal complexes [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(4))][CF(3)SO(3)](2).3 CH(2)Cl(2) (2) and [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(apical)-P(basal)-P(4)S(3))][CF(3)SO(3)](2).0.5 C(7)H(8) (3), in which the tetrahedral P(4) and mixed-cage P(4)S(3) molecules are respectively bound to two CpRu(PPh(3))(2) fragments through two phosphorus atoms. The coordinated cage molecules, at variance with the free ligands, readily react with an excess of water in THF under mild conditions. Among the hydrolysis products, the new, remarkably stable complexes [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(2)H(4))][CF(3)SO(3)](2) (4) and [CpRu(PPh(3))(2)(eta(1)-PH(2)SH)]CF(3)SO(3) (8) were isolated. In the former, diphosphane, P(2)H(4), is coordinated to two CpRu(PPh(3))(2) fragments, and in the latter thiophosphinous acid, H(2)PSH, is coordinated to the metal centre through the phosphorus atom. All compounds were characterised by elemental analyses and IR and NMR spectroscopy. The crystal structures of 2, 3, 4 and 8 were determined by X-ray diffraction.

Pd nanoparticles are immobilized by a green procedure onto unconventional dual porosity titania monoliths. The material is used in catalytic continuous-flow hydrogenation reactions showing excellent efficiency, selectivity, and durability. C ontinuous-flow catalytic processes represent a convenient alternative to heterogeneous phase batch systems in terms of efficiency, safety, waste emission, purification, automation, space and energy consumption, 1−3 thus providing a considerable contribution to the sustainability of long-term production of chemical compounds, particularly fine-chemicals. 4,5 To this purpose, different types of microfluidic flow reactors have been developed so far. 6−10 Monolith-based reactors have attracted increasing interest in recent years 11 because of their significant advantages compared to conventional packed-bed systems, including better heat and mass transfer, lower pressure drop, narrow residence time distribution, which ultimately result in higher productivities. 12 Polymeric materials were the first to demonstrate the utility of monoliths in the catalytic fine-chemicals production under flow. 13−16 However, despite their unquestionable interest, polymer-based monoliths may present some drawbacks from an engineering point of view, such as volume and porosity changes with swelling, thermal, mechanical, and chemical stability, shrinking phenomena, back pressure evolution at high flow rate due to limited porosity, which adversely affect their performance as catalyst supports. 17−19 To avoid these problems different types of inorganic monoliths have been synthesized, including conventional ceramic monoliths obtained by extrusion, that are largely employed in conversion of raw materials, pollutant abatement, and automotive exhaust gas treatment. 20,21 Only two types of unconventional inorganic monolith materials were reported for continuous flow operations in fine chemical synthesis, and both based on silica. One was obtained by emulsion templating synthesis and featured a disordered macropores network for transesterification reactions; 22 the other one, showing a well-defined hierarchical porosity network of flow-through macropores (2−10 μm) and diffusive mesopores within the struts (2−20 nm), was obtained by a combination of spinodal decomposition and sol−gel transition, and it was used for diverse organic catalysis. 23 These latter materials can be particularly useful in the synthesis of fine chemicals, being able to address the need of both efficient processing (within small pores) and fast diffusion (by macropores). 24,25 Despite these favorable features, this type of monoliths have never been explored in highly selective transition-metal catalyzed reactions, for example, in hydrogenation reactions. Selective hydrogenation of hydrocarbons with multiple CC and/or CC bonds to achieve partial hydrogenation products is a highly desired and challenging process in the pharmaceutical, agrochemical, and petrochemical industries. 26,27 Particularly, the stereo-and chemo-selective hydrogen...

Short-chain phospholiponucleosides, namely diC8P-adenosine and diC8P-uridine have been, for the first time, synthesized through an enzymatic pathway that allows transphosphatidylation of phosphatidylcholines. Phospholiponucleosides, which have a number of potential applications in several areas such as anticancer therapy, are able to give in water self-organized aggregates. diC8P-adenosine and diC8P-uridine phosphatidylnucleosides form micelles in water solution with critical micellar concentrations around 10-3 M. Mixed micelles, formed from equimolar mixture of phosphatidylnucleosides, show nonideal mixing, suggesting specific interactions between the polar heads of the nucleolipids. We show through NMR, UV−vis, and CD spectroscopies that in mixed micelles formed from diC8P-adenosine and diC8P-uridine phosphatidylnucleosides, both stacking and hydrogen-bonding interactions are present between the bases at the micellar surface. NMR indicates that a H-bonded Watson−Crick adduct is formed despite the exposure of the bases to the highly competitive aqueous environment. This suggests a specific molecular recognition pattern between the complementary bases adenosine and uridine that resembles polynucleotides' behavior.

A bifunctional heterogeneous catalyst based on sulfonated cation exchange resin and embedded Ru nanoparticles shows complete conversion and selectivity at low temperatures and H 2 pressure in the direct, one-pot conversion of levulinic acid to GVL under continuous flow conditions, with excellent durability and no need for additives.

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