Coal from carbohydrates: The “chimie douce” of carbon

The production of porous materials together with their associated applications using cheap precursors demonstrates the potential of a “chimie douce” based on carbohydrates and their hydrothermal decomposition products to replace same of the standard organic monomers, fulfilling the today's requirements towards greener chemistry processes and the sustainability of the starting products.     

Synthesis and asymmetric alkylation of glucose-derived bicyclic oxazinones: An evaluation of their use as “chiral glycines”

We have prepared structurally novel bicyclic oxazinones based on D-glucopyranose. The lithium enolates of these compounds undergo highly diastereoselective alkylation reactions with reactive alkyl halides, in modest yields. Use of the phosphazene P4 base enhances the yields of these processes, suggesting that metal enolate aggregation is at least partly responsible for the depressed yields. The stereochemistry of the products has been unequivocally ascertained by nOe measurements and ab initio calculations.     

A Review of: “Aquatic Chemistry (An Introduction Emphasizing Chemical Equilibria in Natural Waters)”

Abstract

2nd Edition, by Prof. Dr. Werner Stumm, Swiss Federal Institute of Technology, Zurich, and Prof. Dr. James J. Morgan, California Institute of Technology, Pasadena, 780 pages (including 97 tables, 167 figures, an appendix of 8 pages “Thermodynamic Properties of Common Chemical Species in Aquatic Systems”, an author index of 10 pages, and a subject index of 14 pages), stiff paper cover, format 234 ± 161 mm, ISBN 0-471-04831-3, John Wiley & Sons, New York (1981)     

Catalyst deactivation kinetics: An apparent delay in decreasing of catalyst activity, “inflection point” and data interpretation

Problems of catalyst deactivation kinetics and catalyst stability testing are considered. An apparent delay of deactivation and its interpretation is discussed. The coordinates of inflection points on the curves of conversion decay are also considered. The influence of reaction and deactivation kinetics, as well as type of laboratory reactor on inflection point is analysed. Several helpful and practical equations, as well as real examples are presented.     

An IARC Manual Series Aimed at Assisting Cancer Epidemiology and Prevention. “Environmental Carcinogens: Selected Methods of Analysis”

Abstract

Since 1975, the IARC has been preparing a series of volumes entitled “Environmental Carcinogens: Selected Methods of Analysis” (IARC Manual Series) of which the purposes are to assist analysts, epidemiologists and regulatory authorities in planning or performing exposure measurements that are truly comparable between different studies. The Manual series provides expert information within each volume on multimedia sampling, methods of analyses and some background of epidemiology, metabolism, use/occurrence for a group of known or suspect carcinogens. So far, eleven volumes have been published or are in preparation on the following subjects: (1) N-nitrosamines, (2) vinyl chloride, (3) PAH, (4) aromatic amines, (5) mycotoxins, (6) N-nitroso compounds, (7) volatile halogenated hydrocarbons, (8) metals, (9) passive smoking, (10) benzene and alkylated benzenes, (1) dioxins, PCDFs and PCBs.     

“An efficient synthesis of ethyl (R)-2-hydroxy-4-phenylbutyrate: A useful intermediate in the synthesis of converting enzymeinhibitors”

Optically pure Ethyl (R)-2-hydroxy-4-phenylbutyrate has beensynthesized stereoselectively in 24% overall yield.     

Sol–gel derived silica-based organic–inorganic hybrid materials as “composite precursors” for the synthesis of highly homogeneous nanostructured mixed oxides: an overview

The present contribution reports on our results concerning the synthesis of different binary and ternary oxide systems by using hybrid materials as “composite” precursors. In the last years, we have developed and explored a valuable strategy to yield a very homogeneous dispersion of nanoparticles of early metal transition oxide, MO₂ (M = Zr, Hf) inside a silica matrix. This route is based on the use of the sol–gel process to obtain organic–inorganic hybrid silica-based materials embedding the oxide precursors (Zr and/or Hf oxoclusters), which are then calcined at high (T > 500 °C) temperatures to give the desired oxides. The “precursor” hybrid materials are prepared by a modified sol–gel process, involving the copolymerisation of the organically modified oxozirconium or oxohafnium clusters (M₄O₂(OMc)₁₂ (M = Zr, Hf and OMc = methacrylate) with (methacryloxymethyl)triethoxysilane (MAMTES) or (methacryloxypropyl)trimethoxysilane (MAPTMS). Free radical copolymerisation of the 12 methacrylate groups of the oxoclusters with the methacrylate-functionalised siloxanes allows a stable anchoring of the oxoclusters to the silica network formed by the hydrolysis and condensation of the alkoxy groups. The sol–gel reactions of the two methacrylate-modified silanes methacryloxymethyltriethoxysilane and methacryloxypropyltrimethoxysilane were followed by using two independent time-resolved spectroscopic methods, viz., IR ATR and NMR with the aim to optimise their pre-hydrolysis times and consequently their use as precursors for hybrid materials. As mentioned, thermal treatment at high temperature of the hybrid yields a very homogeneous dispersion of ZrO₂ and/or HfO₂ nanoparticles in the silica matrix, since the molecular homogeneity of the starting hybrid is retained in the final mixed oxide. This route was successfully applied both to the synthesis of bulk materials and thin films characterised by different compositions (in term of M/Si molar ratios and M nature), heating route (conventional or microwave-assisted) and final temperature of annealing (from RT to 1,100 °C). The first example of the ZrO₂–HfO₂–SiO₂ ternary oxide system was also prepared by this approach. The prepared systems, both in the form of hybrid materials as well as in the final form of binary or ternary oxides, were thoroughly characterised by a wide variety of analytical tools from a compositional, structural, morphological point of view. Moreover, in the case of the binary ZrO₂–SiO₂ bulk materials, also the evolution under heating was followed by different methods. In particular, the composition of the hybrid as well as of the final oxidic materials was determined by X-Ray Photoelectron Spectroscopy and elemental analysis, whereas FT-IR and multinuclear solid-state NMR spectroscopies shed light on the changes occurring in the composition upon thermal heating and the degree of condensation of the silica network. The morphology and the microstructure of the hybrids and of the oxides were studied by nitrogen sorption and Scanning Electron Microscopy. X-Ray Diffraction, Transmission Electron Microscopy and X-ray Absorption Fine Structure Spectroscopy X-ray Absorption Fine Structure Spectroscopy were used to follow the conversion of the amorphous oxides to the final materials consisting of crystalline zirconia or hafnia dispersed in amorphous silica. On selected systems, functional properties (surface reactivity, dielectric properties) were furthermore investigated. The obtained binary oxides were also used as substrates for functionalisation experiments with (1) dialkycarbamates and (2) long alkyl chains to produce functional materials for catalysis and HPLC applications, respectively.     

“In situ” extraction of essential oils by use of Dean–Stark glassware and a Vigreux column inside a microwave oven: a procedure for teaching green analytical chemistry

One of the principal objectives of sustainable and green processing development remains the dissemination and teaching of green chemistry in colleges, high schools, and academic laboratories. This paper describes simple glassware that illustrates the phenomenon of extraction in a conventional microwave oven as energy source and a process for green analytical chemistry. Simple glassware comprising a Dean-Stark apparatus (for extraction of aromatic plant material and recovery of essential oils and distilled water) and a Vigreux column (as an air-cooled condenser inside the microwave oven) was designed as an in-situ extraction vessel inside a microwave oven. The efficiency of this experiment was validated for extraction of essential oils from 30 g fresh orange peel, a by-product in the production of orange juice. Every laboratory throughout the world can use this equipment. The microwave power is 100 W and the irradiation time 15 min. The method is performed at atmospheric pressure without added solvent or water and furnishes essential oils similar to those obtained by conventional hydro or steam distillation. By use of GC-MS, 22 compounds in orange peel were separated and identified; the main compounds were limonene (72.1%), β-pinene (8.4%), and γ-terpinene (6.9%). This procedure is appropriate for the teaching laboratory, does not require any special microwave equipment, and enables the students to learn the skills of extraction, and chromatographic and spectroscopic analysis. They are also exposed to a dramatic visual example of rapid, sustainable, and green extraction of an essential oil, and are introduced to successful sustainable and green analytical chemistry.     

Response to “Impact of Zeolite Structure on Entropic–Enthalpic Contributions to Alkane Monomolecular Cracking: An IR Operando Study”

This is a response to the paper published by S. A. Kadam, H. Li, R. F. Wormsbacher, A. Travert, Chem. Eur. J. 2018 , 24, 5489. Key consistencies between our reported results and those reported in this work are also highlighted.     

Commentary On “Extended Hildebrand Approach: An Empirical Model for Solubility Prediction of Etodolac in 1,4-Dioxane and Water Mixtures”

Several mathematical errors in the published paper by Rathi and Deshpande (J Solution Chem 43:1886–1903, 2014) are identified. The errors concern the incorrect conversion of mass fraction to volume fraction concentrations of 1,4-dioxane, the incorrect conversion of mole fraction solubilities to molar solubilities of Etodolac, and the incorrect calculation of the ideal mole fraction solubility of Etodolac.     

An unexpected reactivity of simple heterogeneous mixture of γ-alumina and potassium fluoride : 1-hydroxyalkane phosphonic esters synthesis from non-activated ketones in “dry media”.

1-Hydroxyalkane phosphonic esters are readily obtained from non-activated ketones and dialkylphosphites by adsorbing them together on a heterogeneous γ-alumina-potassium fluoride mixture.