Dinuclear Lanthanide (III) coordination polymers in a domino reaction

A systematic study was performed to further optimise the catalytic room-temperature synthesis of trans-4,5- diaminocyclopent-2-enones from 2-furaldehyde and primary or secondary amines under a non-inert atmosphere. For this purpose, a series of dinuclear lanthanide (III) coordination polymers were synthesised using a dianionic Schiff base and their catalytic activities were investigated

Hydrodinamic Aspects of a High-Speed SWATH and New Hull Form

The main problems of high-speed ships operating in open seas are their insufficient seaworthiness and speed loss in high sea states. Small Water-plane Area Twin-Hulls (SWATH) are characterised by excellent seaworthiness, but the hull forms of a traditional SWATH are not suited for higher speeds. A new shape of underwater gondola has been developed for a semi-planing (S/P) SWATH. Additionally, hydrofoils can be applied to this ship to provide the optimal dynamic draught and trim, to mitigate motions in rough seas, and even to carry a part of the ship weight. The relative speed of this SWATH can be beneficially increased up to the displacement Froude number 3. Several concept designs addressing naval and civil transportation needs are outlined in this paper

3d/4f Coordination clusters as cooperative catalysts for highly diastereoselective Michael addition reactions

Michael addition (MA) is one of the most well studied chemical transformation in synthetic chemistry. Here, we re-port the synthesis and crystal structures of a library of 3d/4f coordination clusters (CCs) formulated as ZnII2YIII2L4(solv)X(Z)Y and study their catalytic properties towards the MA of nitrostyrenes with barbituric acid deriva-tives. Each CC presents two borderline hard/soft Lewis acidic ZnII centers and two hard Lewis acidic YIII centers in a defect dicubane topology that brings the two different metals into a proximity of {\~{}}3.3 {\AA}. DFT computational studies suggest that these tetrametallic CCs dissociate in solution to give two catalytically active dimers, each containing one 3d and one 4f metal which act cooperatively. The mechanism of catalysis has been corroborated via NMR, EPR and UV-Vis. The present work demonstrates for the first time the successful use of 3d/4f CCs as efficient and high diastereose-lective catalysts in MA reactions

Intensified and safe ozonolysis of fatty acid methyl esters in liquid CO2 in a continuous reactor

We demonstrate a continuous reactor for performing the ozonolysis of fatty acid methyl esters (FAMEs) using liquid CO2 as solvent. The fast reaction kinetics allows the use of small-volume reactors to completely convert the FAMEs, forming secondary ozonides as the primary products. The short residence times also help maximize the yields of the secondary ozonides by minimizing over-oxidation and the formation of oligomeric products. The liquid CO2 medium promotes safe reactor operation by providing an essential fraction of overall reactor cooling and by diluting the vapor phase organics. We also demonstrate a continuous stirred reactor for the safe thermal decomposition of the secondary ozonides to their corresponding acids and aldehydes. Using a lumped kinetic model for the thermal decomposition of the ozonolysis products, we estimate activation energy values of 108.6 +/- 0.6 kJ mol(-1) for the decomposition of secondary ozonides and 122 +/- 3 kJ mol(-1) for the decomposition of the undesired oligomeric species. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 2819-2826, 201

Atomic Details of the Interactions of Glycosaminoglycans with Amyloid-β Fibrils

The amyloid plaques associated with Alzheimer's disease (AD) comprise fibrillar amyloid-β (Aβ) peptides as well as non-protein factors including glycosaminoglycan (GAG) polysaccharides. GAGs affect the kinetics and pathway of Aβ self-assembly and can impede fibril clearance; thus, they may be accessory molecules in AD. Here we report the first high-resolution details of GAG-Aβ fibril interactions from the perspective of the saccharide. Binding analysis indicated that the GAG proxy heparin has a remarkably high affinity for Aβ fibrils with 3-fold cross-sectional symmetry (3Q). Chemical synthesis of a uniformly 13C-labeled octasaccharide heparin analogue enabled magic-angle spinning solid-state NMR of the GAG bound to 3Q fibrils, and measurements of dynamics revealed a tight complex in which all saccharide residues are restrained without undergoing substantial conformational changes. Intramolecular 13C-15N dipolar dephasing is consistent with close (<5 Å) contact between GAG anomeric position(s) and one or more histidine residues in the fibrils. These data provide a detailed model for the interaction between 3Q-seeded Aβ40 fibrils and a major non-protein component of AD plaques, and they reveal that GAG-amyloid interactions display a range of affinities that critically depend on the precise details of the fibril architecture

Tetranuclear Zn/4f coordination clusters as highly efficient catalysts for Friedel-Crafts alkylation

A series of custom-designed, high yield, isoskeletal tetranuclear Zn/4f coordination clusters showing high efficiency as catalysts with low catalytic loadings in Friedel-Crafts alkylation are described for the first time. The possibility of altering the 4f centers in these catalysts without altering the core topology allows us to further confirm their stability via EPR and NMR, as well to gain insights into the plausible reaction mechanism, showcasing the usefulness of these bimetallic systems as catalysts

An efficient preparation of 1,2-dihydropyridazines through a Diels-Alder/palladium-catalysed elimination sequence

© 2019 Elsevier Ltd A convenient, scalable synthesis of 1,2-dihydropyridazines is presented, based on the Diels-Alder cycloaddition of 1-acetoxy-1,3-butadiene with a variety of azo compounds, followed by a palladium-catalysed elimination. The products are produced on multigram scale and the new method is particularly efficient and atom-economical when compared with previous preparations of 1,2-dihydropyridazines

Sustainable catalytic reaction engineering with gas-expanded liquids

Gas-expanded liquids (GXLs) are a continuum of tunable solvents generated by mixing liquid solvents and compressed near-critical gases such as CO2 and light olefins. The compressed gas provides tunability of the physical and transport properties of GXLs making them ideal for performing sustainable catalysis characterized by process intensification at mild conditions, high product selectivity and facile separation of catalyst and products. Sustainable technology alternatives to industrial hydroformylations and epoxidations that employ GXLs as enabling solvents are provided. In these examples, the GXLs involve conventional organic as well as non-traditional solvents such as ionic liquids (ILs) and compressible gases such as CO2 (as inert) or light olefins (as substrates). Such technologies are essential for facilitating sustainable growth of the fledgling biorefining industry

A critical look at reactions in class I and II gas-expanded liquids using CO2 and other gases

This short review aims to give a summary of the publications on reactions in class I and II gas-expanded liquids (GXLs) (those with organic or aqueous liquid components), and to draw conclusions from the trends in the current literature

Pressure drop as a simple method for locating phase transitions in continuous flow high pressure reactors

This paper describes the use of the pressure drop across a packed column to locate phase transitions in high-pressure fluids in continuous flow. The pressure drop method yields data that can be used to locate phase transitions objectively, and an example of an automated searching algorithm is demonstrated as a proof of concept. Finally, we demonstrate the ability of the pressure drop method to be applied in operand to a hydrogenation reaction