Highly Efficient Process for Production of Biofuel from Ethanol Catalyzed by Ruthenium Pincer Complexes

Phosphine-free pincer-ruthenium catalyzed biofuel production: high rates, yields and turnovers of solventless alcohol alkylation

High TONs and TOFs are observed for the β-alkylation of alcohols using phosphine-free pincer-ruthenium catalysts at a very low base loading. Kinetic studies and DFT calculations were complementary and provide a clear understanding on the mechanism.

α-Alkylation of Ketones with Secondary Alcohols Catalyzed by Well-Defined Cp*CoIII -Complexes

Although α-alkylation of ketones with primary alcohols by transition-metal catalysis is well-known, the same process with secondary alcohols is arduous and complicated by self-condensation. Herein a well-defined, high-valence cobalt(III)-catalyst was applied for successful α-alkylation of ketones with secondary alcohols. A wide-variety of secondary alcohols, which include cyclic, acyclic, symmetrical, and unsymmetrical compounds, was employed as alkylating agents to produce β-alkyl aryl ketones.

Manganese-Catalyzed Selective Upgrading of Ethanol with Methanol into Isobutanol

Isobutanol serves as an ideal gasoline additive owing to its good compatibility with current engine technology, high energy density, and high octane number. Herein, an efficient and selective Mn-catalyzed upgrading of ethanol with methanol into isobutanol is reported. This is the first example of deoxygenative coupling of lower alcohols to isobutanol by using a homogeneous non-noble-metal catalyst. This transformation proceeded at very low catalyst loading with a high turnover number (9233) and up to 96 % isobutanol selectivity.

Barriers of Biodiesel Adoption by Transportation Companies: A Case of Malaysian Transportation Industry

The need to develop an alternative fuel to fossil fuel is growing day by day, especially for the transportation industry, as the supply of fossil fuels is limited and is depleting at a rapid rate. One available resource that has emerged recently is biodiesel. However, the usage of biodiesel is very low among transportation companies. An investigation into the barriers of adopting biodiesel by transportation companies is the focus of the present study. A survey of 147 transportation companies in Malaysia was undertaken, and the data gathered were analyzed using partial least squares technique. Lack of government support, lack of environmental–commercial benefits, and lack of competitive pressure were found to be the barriers to biodiesel adoption. The results also indicated that differentiation strategy moderates the impact of lack of government support, lack of customer demand, lack of environmental-commercial benefits and lack of competitive pressure on biodiesel adoption. The results of this study could benefit policy makers by providing them key focus areas in which they can modify their strategies to actively and successfully promote the use of biodiesel among transportation companies in developing countries.

Catalytic upgrading of ethanol to n-butanol using an aliphatic Mn–PNP complex: theoretical insights into reaction mechanisms and product selectivity

Understanding the product selectivity, conversion, and rate-determining steps in the catalytic upgrading of ethanol to butanol.

A pincer ligand enabled ruthenium catalyzed highly selective N-monomethylation of nitroarenes with methanol as the C1 source

A straightforward and highly selective N-monomethylation of nitroarenes with methanol as the C1 source was developed.

New Acridine-Based Tridentate Ligand for Ruthenium(II): Coordination with a Twist

A new tridentate ligand based on acridine has been synthetized. The central acridine heterocycle bears two pyridine coordinating units at positions 4 and 5. The terdentate 2,7-di- tert-butyl-4,5-di(pyridin-2-yl)acridine (dtdpa) was then coordinated to a ruthenium(II) cation. The corresponding homoleptic complex could only be obtained where both ligands coordinate to the ruthenium in a fac fashion. Thus, a heteroleptic compound (2) was constructed in combination with a terpyridine ligand in order to constrain the ligand to adopt a mer geometry. Such a coordination imposes a dramatic twist on the acridine heterocycle, resulting in an unexpected photophysical behavior. The electrochemical and photophysical properties of both complexes were studied, and the molecular structure of 2 was determined by X-ray diffraction. The two compounds absorb at low energy wavelengths, and a very weak luminescence is detected only for complex 2 in the near-infrared region.

Catalytic Upgrading of Ethanol to n-Butanol: Progress in Catalyst Development

Because n-butanol as a fuel additive has more advantageous physicochemical properties than those of ethanol, ethanol valorization to n-butanol through homo- or heterogeneous catalysis has received much attention in recent decades in both scientific and industrial fields. Recent progress in catalyst development for upgrading ethanol to n-butanol, which involves homogeneous catalysts, such as iridium and ruthenium complexes, and heterogeneous catalysts, including metal oxides, hydroxyapatite (HAP), and, in particular, supported metal catalysts, is reviewed herein. The structure-activity relationships of catalysts and underlying reaction mechanisms are critically examined, and future research directions on the design and improvement of catalysts are also proposed.

Two isomers of a bis(diphenylphosphino)phosphinine, and the synthesis and reactivity of Ru arene/Cp* phosphinophosphinine complexes

Two isomers of a bis(diphenylphosphino)phosphinine have been synthesised, and the Ru coordination chemistry of a 2-phosphinophosphinine extended to include reactions of H₂O across a PC double bond.

Iridium Clusters Encapsulated in Carbon Nanospheres as Nanocatalysts for Methylation of (Bio)Alcohols

C-H methylation is an attractive chemical transformation for C-C bonds construction in organic chemistry, yet efficient methylation of readily available (bio)alcohols in water using methanol as sustainable C1 feedstock is limited. Herein, iridium nanocatalysts encapsulated in yolk-shell-structured mesoporous carbon nanospheres (Ir@YSMCNs) were synthesized for this transformation. Monodispersed Ir clusters (ca. 1.0 nm) were encapsulated in situ and spatially isolated within YSMCNs by a silica-assisted sol-gel emulsion strategy. A selection of (bio)alcohols (19 examples) was selectively methylated in aqueous phase with good-to-high yields over the developed Ir@YSMCNs. The improved catalytic efficiencies in terms of activity and selectivity together with the good stability and recyclability were contributable to the ultrasmall Ir clusters with oxidation chemical state as a consequence of the confinement effect of YSMCNs with interconnected nanostructures.

Dialing in single-site reactivity of a supported calixarene-protected tetrairidium cluster catalyst

A closed Ir₄ carbonyl cluster, 1, comprising a tetrahedral metal frame and three sterically bulky tert-butyl-calix[4]arene(OPr)₃(OCH₂PPh₂) (Ph = phenyl; Pr = propyl) ligands at the basal plane, was characterized with variable-temperature ¹³C NMR spectroscopy, which show the absence of scrambling of the CO ligands at temperatures up to 313 K. This demonstration of distinct sites for the CO ligands was found to extend to the reactivity and catalytic properties, as shown by selective decarbonylation in a reaction with trimethylamine N-oxide (TMAO) as an oxidant, which, reacting in the presence of ethylene, leads to the selective bonding of an ethyl ligand at the apical Ir site. These clusters were supported intact on porous silica and found to catalyze ethylene hydrogenation, and a comparison of the kinetics of the single-hydrogenation reaction and steady-state hydrogenation catalysis demonstrates a unique single-site catalyst-with each site having the same catalytic activity. Reaction orders in the catalytic ethylene hydrogenation reaction of approximately 1/2 and 0 for H₂ and C₂H₄, respectively, nearly match those for conventional noble-metal catalysts. In contrast to oxidative decarbonylation, thermal desorption of CO from silica-supported cluster 1 occurred exclusively at the basal plane, giving rise to sites that do not react with ethylene and are catalytically inactive for ethylene hydrogenation. The evidence of distinctive sites on the cluster catalyst leads to a model that links to hydrogen-transfer catalysis on metals-involving some surface sites that bond to both hydrocarbon and hydrogen and are catalytically engaged (so-called "*" sites) and others, at the basal plane, which bond hydrogen and CO but not hydrocarbon and are reservoir sites (so-called "S" sites).

Towards the upgrading of fermentation broths to advanced biofuels: a water tolerant catalyst for the conversion of ethanol to isobutanol

The conversion of methanol/ethanol mixtures to isobutanol with the pre-catalyst trans-[RuCl₂(dppm)₂] (1) is tolerant to the addition of water to the system, achieving an isobutanol yield of 36% at 78% selectivity with water concentrations typical of that of a crude fermentation broth.

Dehydrogenative coupling promoted by copper catalysts: a way to optimise and upgrade bio-alcohols

A one-pot one-step transformation of butanol into butyl butanoate takes place with excellent yield on a Cu/ZrO₂ catalyst.