Obituary: Arthur Cruickshank 1932 - 2011. A native Gondwanan, who studied the former continent's fossil tetrapods

Dr Arthur Richard Ivor Cruickshank died on 4th December 2011, aged 79, in the Borders General Hospital, Melrose, Scotland. Arthur Cruickshank was part of the post-war generation of palaeontologists who laid the foundations on which today’s researchers build. Appropriately for someone from an expatriate Scots family living in Kenya, much of his work was on the extinct reptiles of the great southern palaeocontinent of Gondwana

Ionic Liquids Made with Dimethylcarbonate: Solvents as well as Boosted Basic Catalysts for the Michael Reaction

Abstract: This article describes 1) a methodology for the green synthesis of a class of methylammonium and methylphosphonium ionic liquids (ILs), 2) how to tune their acid–base properties by anion exchange, 3) complete neat-phase NMR spectroscopic characterisation of these materials and 4) their application as active organocatalysts for base-promoted carbon– carbon bond-forming reactions. Methylation of tertiary amines or phosphines with dimethyl carbonate leads to the formation of the halogen-free methyl-onium methyl carbonate salts, and these can be easily anion-exchanged to yield a range of derivatives with different melting points, solubility, acid–base properties, stability and viscosity. Treatment with water, in particular, yields bicarbonate-exchanged liquid onium salts. These proved strongly basic, enough to efficiently catalyse the Michael reaction; experiments suggest that in these systems the bicarbonate basicity is boosted by two orders of magnitude with respect to inorganic bicarbonate salts. These basic ionic liquids used in catalytic amounts are better even than traditional strong organic bases. The present work also introduces neat NMR spectroscopy of the ionic liquids as a probe for solute– solvent interactions as well as a tool for characterisation. Our studies show that high catalytic efficacy of functional ionic liquids can be achieved by integrating their green synthesis, along with a fine-tuning of their structure. Demonstrating that ionic liquid solvents can be made by a truly green procedure, and that their properties and reactivity can be tailored to the point of bridging the gap between their use as solvents and as catalysts. Keywords: dimethyl carbonate · green chemistry · ionic liquids · Michael addition · NMR spectroscop

The tail of the Jurassic fish Leedsichthys problematicus (Osteichthyes: Actinopterygii) collected by Alfred Nicholson Leeds - an example of the importance of historical records in palaeontology

The specimen of the tail of <i>Leedsichthys problematicus</i>, now in The Natural History Museum, London, was one of the most spectacular fossil vertebrates from the Oxford Clay Formation of Peterborough, but as an isolated find it shares no bones in common with the holotype of the genus and species. However, a letter from Alfred Nicholson Leeds and related documents cast valuable new light on the excavation of the tail, indicating that it was discovered with cranial bones, gill-rakers, and two pectoral fins, thereby including elements that can potentially be compared with those of the holotype. The documents also clearly indicate that The Natural History Museum's specimen is not part of the same individual as any other numbered specimen of <i>Leedsichthys</i> as had been speculated on other occasions. The maximum size of the animal represented by The Natural History Museum's specimen was possibly around 9 metres, considerably less than previous estimates of up to 27.6 metres for <i>Leedsichthys</i>. Historical documentary evidence should therefore be rigorously checked both when studying historical specimens in science, and in preparing text for museum display labels

New UV-Curable Anticorrosion Coatings from Vegetable Oils

Bio-based epoxy resins are attracting widespread interest in the field of polymer thermosets as environmentally friendly building block. In the present study, the feasibility of applying UV-curable epoxidized vegetable oils (EVOs) as anti-corrosion coating is investigated. Rheological characterization of EVOs is carried out, and their viscosity-shear relationship is evaluated. The cationic UV-curing of EVOs successfully gives rise to crosslinked materials with a wide range of thermo-mechanical properties, evaluated by differential scanning calorimetric analysis and dynamic thermal mechanical analysis. A high epoxy-group conversion, ranging from 93% to 99%, is always obtained. The thermal stability and surface properties of the bio-based coatings, such as, pencil hardness, adhesion, solvent resistance, and contact angle, are analyzed. Moreover, the corrosion protection effectiveness of the coatings is characterized by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. In addition, field emission scanning electron microscopy is used to assess the samples morphology after corrosion tests

Methylcarbonate and Bicarbonate Phosphonium Salts as Catalysts for the Nitroaldol (Henry) Reaction

Phosphonium ionic liquids exchanged with bicarbonate and methylcarbonate anions (CILs) exhibit catalytic performances comparable to those of sterically hindered (non nucleophilic) organosuperbases such as DBU. At 25–50 °C, under solventless conditions, CILs efficiently catalyze the Henry addition of different aldehydes and ketones to nitroalkanes: not only they allow the selective formation of nitroaldols but they unlock a novel high-yielding access to dinitromethyl derivatives of ketones

Cooperative nucleophilic-electrophilic organocatalysis by ionic liquids

The anionic and the cationic partners of ionic liquids may act cooperatively and independently as nucleophilic and electrophilic catalysts. This ambiphilic propensity was demonstrated by kinetically discriminating the contributions of the anion (nucleophilic catalyst) and of the cation (electrophilic catalyst) to the solvent-free Baylis–Hillman dimerization of cyclohexenone catalysed by ionic liquids

Phosphonium ionic liquids (PILs) as organocatalysts for green reactions: nucleophilic electrophilic cooperative catalysis

With the aim of developing a green synthesis of phosphonium ionic liquids (PILs), we prepared a series of methyltrialkylphosphonium methyl carbonates [Pn,n,n,1]+[O(CO)OCH3]- by the alkylation of trialkylphosphines with the non toxic dimethylcarbonate. These compounds proved to be active organocatalysts for a number of base-promoted organic reactions such as Michael, Henry, and Baylis-Hillman condensations, and transesterification reactions. In addition methyl carbonate salts were a convenient starting material to synthesise a large array of ionic liquids where the phosphonium cation was coupled to weakly basic anions such as bicarbonate, acetate, trifluoroacetate, phenate, chloride, bromide and many more. Mechanistic studies indicated that the anionic and the cationic partners of such ionic liquids acted cooperatively and independently as nucleophilic and electrophilic catalysts. The ambiphilic propensity of these salts was demonstrated by kinetically discriminating the contributions of the anion (nucleophilic catalyst) and of the cation (electrophilic catalyst) on the model solvent-free Baylis–Hillman dimerization of cyclohexenone