Christian V. Stevens

Ionic liquid thermal stabilities: decomposition mechanisms and analysis tools.

The increasing amount of papers published on ionic liquids generates an extensive quantity of data. The thermal stability data of divergent ionic liquids are collected in this paper with attention to the experimental set-up. The influence and importance of the latter parameters are broadly addressed. Both ramped temperature and isothermal thermogravimetric analysis are discussed, along with state-of-the-art methods, such as TGA-MS and pyrolysis-GC. The strengths and weaknesses of the different methodologies known to date demonstrate that analysis methods should be in line with the application. The combination of data from advanced analysis methods allows us to obtain in-depth information on the degradation processes. Aided with computational methods, the kinetics and thermodynamics of thermal degradation are revealed piece by piece. The better understanding of the behaviour of ionic liquids at high temperature allows selective and application driven design, as well as mathematical prediction for engineering purposes.

Undecylenic Acid: A Valuable and Physiologically Active Renewable Building Block from Castor Oil

A lot of attention is currently being paid to the transition to a biobased economy. In this movement, most efforts concentrate on the development of bioenergy applications including bioethanol, biodiesel, thermochemical conversion of biomass, and others. However, in the energy sector other nonbiomass alternatives are known, whereas no valuable alternatives are available when thinking about chemical building blocks. Therefore, it is also essential to develop new routes for the synthesis of bio-based chemicals and materials derived thereof. Such intermediates can originate either from plants or from animals. Castor oil is a non-edible oil extracted from the seeds of the castor bean plant Ricinus communis (Euphorbiaceae), which grows in tropical and subtropical areas. Globally, around one million tons of castor seeds are produced every year, the leading producing areas being India, PR China, and Brazil.2 10-Undecenoic acid or undecylenic acid is a fatty acid derived from castor oil that, owing to its bifunctional nature, has many possibilities to develop sustainable applications.

Aminophosphonic Acids - Phosphorus Analogues of Natural Amino Acids.Part 1: Syntheses of α-Aminophosphonic Acids

This review presents a comprehensive account of methods which are commonly applied for the synthesis of alpha- aminophosphonic acids. In the following order, protocols based on the methodologies listed below are discussed: a) simultaneous formation of P-C-N systems; b) nucleophilic substitution with phosphoroorganic nucleophiles; c) additions of the P-H functions to multiple C-N bonds; d) alpha-amination of phosphonates and functionalized alkylphosphonates; e) modifications of the side chain of aminoalkylphosphonates; f) modifications of phosphorus functions and h) modifications of functions containing nitrogen.

Preparation of phosphines through C–P bond formation

Summary Phosphines are an important class of ligands in the field of metal-catalysis. This has spurred the development of new routes toward functionalized phosphines. Some of the most important C–P bond formation strategies were reviewed and organized according to the hybridization of carbon in the newly formed C–P bond.

A gene horizontally transferred from bacteria protects arthropods from host plant cyanide poisoning

Cyanogenic glucosides are among the most widespread defense chemicals of plants. Upon plant tissue disruption, these glucosides are hydrolyzed to a reactive hydroxynitrile that releases toxic hydrogen cyanide (HCN). Yet many mite and lepidopteran species can thrive on plants defended by cyanogenic glucosides. The nature of the enzyme known to detoxify HCN to β-cyanoalanine in arthropods has remained enigmatic. Here we identify this enzyme by transcriptome analysis and functional expression. Phylogenetic analysis showed that the gene is a member of the cysteine synthase family horizontally transferred from bacteria to phytophagous mites and Lepidoptera. The recombinant mite enzyme had both β-cyanoalanine synthase and cysteine synthase activity but enzyme kinetics showed that cyanide detoxification activity was strongly favored. Our results therefore suggest that an ancient horizontal transfer of a gene originally involved in sulfur amino acid biosynthesis in bacteria was co-opted by herbivorous arthropods to detoxify plant produced cyanide. DOI: http://dx.doi.org/10.7554/eLife.02365.001

A HCN-based reaction under microreactor conditions: industrially feasible and continuous synthesis of 3,4-diamino-1H-isochromen-1-ones

Microreactor technology has been studied as a suitable process to produce chemicals via multicomponent reactions. In this study, efforts were made to produce 3,4-diamino-1H-isochromen-1-ones. Based on a known reaction procedure, using in situ generated HCN, a safe reaction setup was created to avoid the release of the hazardous gas during the process. The 3,4-diamino-1H-isochromen-1-ones were produced continuously in moderate to good yields.

Synthesis of isoindoles and related iso-condensed heteroaromatic pyrroles

Over the past few years, isoindoles have found wide application in materials science. Isoindole containing BODIPY dyes are highly fluorescent materials and have been extensively used in various fields of science. Phthalocyanines, metal containing cyclic tetramers of isoindole, form coordination complexes with most elements of the periodic table. These complexes are intensely coloured and are used as pigments and dyes. However, isoindoles are relatively unstable 10π-heteroaromatic systems and few synthetic methods provide these compounds in good yields. This tutorial review will give an overview of the reported synthetic methods towards isoindoles and related heteroaromatic systems over a time span of approximately 10 years (2000 to current), including the applications where they have been reported. The importance of the field will be illustrated and factors influencing product stability will be discussed.

Recent developments in antibacterial and antifungal chitosan and its derivatives.

Chitosan is the deacetylated form of chitin, a biopolymer that can be obtained from various waste streams and shows antimicrobial activity against different fungi, gram positive and gram negative bacteria. Although chitosan has been studied for years, many aspects remain unclear. This review gives an overview of the antimicrobial activity of chitosan and novel chitosan derivatives of the last 15 years. The most important parameters (molecular weight, degree of deacetylation, etc.) are discussed along with a status update on the mode of action of chitosan.

Electrolytic membrane extraction enables production of fine chemicals from biorefinery sidestreams

Short-chain carboxylates such as acetate are easily produced through mixed culture fermentation of many biological waste streams, although routinely digested to biogas and combusted rather than harvested. We developed a pipeline to extract and upgrade short-chain carboxylates to esters via membrane electrolysis and biphasic esterification. Carboxylate-rich broths are electrolyzed in a cathodic chamber from which anions flux across an anion exchange membrane into an anodic chamber, resulting in a clean acid concentrate with neither solids nor biomass. Next, the aqueous carboxylic acid concentrate reacts with added alcohol in a water-excluding phase to generate volatile esters. In a batch extraction, 96 ± 1.6% of the total acetate was extracted in 48 h from biorefinery thin stillage (5 g L(-1) acetate) at 379 g m(-2) d(-1) (36% Coulombic efficiency). With continuously regenerated thin stillage, the anolyte was concentrated to 14 g/L acetic acid, and converted at 2.64 g (acetate) L(-1) h(-1) in the first hour to ethyl acetate by the addition of excess ethanol and heating to 70 °C, with a final total conversion of 58 ± 3%. This processing pipeline enables direct production of fine chemicals following undefined mixed culture fermentation, embedding carbon in industrial chemicals rather than returning them to the atmosphere as carbon dioxide.

Synthetic Entries to and Biological Activity of Pyrrolopyrimidines

This review summarizes recent literature (2000-2015) on the synthesis and pharmaceutical properties of pyrrolopyrimidines. These modified pyrimidine bases, fused to a pyrrole ring, and their corresponding nucleosides display a broad applicability in medicinal chemistry. This overview is divided into three main sections, according to the respective isomers: pyrrolo[2,3-d]pyrimidines, pyrrolo[3,2-d]pyrimidines, and pyrrolo[3,4-d]pyrimidines. Each section contains a description of common retro-synthetic strategies, with particular attention for newly reported synthetic entries to the scaffold. Next, the synthetic strategies and the ways in which the scaffolds can be further modified are exemplified according to the biological properties of the obtained products.