Showing papers by "Christian V. Stevens published in 2013"

Ionic liquid thermal stabilities: decomposition mechanisms and analysis tools

Abstract: 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.

Anti-invasive compounds

Abstract: The present invention relates to the field of anti-invasive compounds and methods for predicting the anti-invasive activity of said compounds, as well as their use in the prevention and/or treatment of diseases associated with undesired cell invasion; in particular, this invention relates to the field of anti-invasive chalcone-like compounds.

Governing Parameters of Long-Range Intramolecular S-to-N Acyl Transfers within (S)-Acyl Isopeptides.

Abstract: The governing parameters for the long-range intramolecular S-to-N acyl transfer in (S)-acyl isopeptides are shown by computational and statistical methods (principal component analysis and cluster analysis) to be driven by enthalpic and geometric effects over the range n = 5–20. The results emphasize the dependency of ΔG‡ on the geometrical parameters governing the approach of the reactive termini and the importance of stabilizing intramolecular hydrogen bonds in the transition states (TSs), rather than the effects of TS ring-size. The competition between the intra- (uni-) and inter- (bi)molecular acyl transfers were studied for representative examples.

Development, optimization and scale-up of biodiesel production from crude palm oil and effective use in developing countries

Abstract: An industrial project was developed to optimize the biodiesel production from crude palm oil. This process was developed for a one ton scale application on the palm oil production facility in equatorial Africa, to be used on the plantation to provide fuel for the fleet of the company. Because of the specific conditions (crude palm oil as starting material, application in technologically difficult conditions), it was essential for the developed procedure to be robust and simple, and to use minimum amounts of chemicals. The process was optimised on lab-scale in 2005 and 2006, scaled up in the following year, and is since then successfully applied as intended on the palm oil plantation. The produced biodiesel is used pure, without mixing with diesel fuel and without additives. After several years of continuous use, no negative effects were noticed on the engines. The process efficiency and durability are therefore confirmed.

Synthetic entry into 1‑phosphono-3-azabicyclo[3.1.0]hexanes

Abstract: 3-Azabicyclo[3.1.0]hex-2-en-1-yl phosphonates were prepared in a five-step reaction route from β-ketophosphonates. The key steps in this sequence are an atom-transfer radical cyclization and an unforeseen lithium-halogen exchange with n-BuLi. The cyclization reaction proceeds with excellent diastereoselectivity. The resulting cyclic imines were reduced, and 3-azabicyclo[3.1.0]hexan-1-yl phosphonates were obtained.

Ionic Liquid Thermal Stabilities: Decomposition Mechanisms and Analysis Tools

Abstract: 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.

Synthesis and Properties of Alkoxy‐ and Alkenyl‐Substituted Peralkylated Imidazolium Ionic Liquids

Abstract: Novel peralkylated imidazolium ionic liquids bearing alkoxy and/or alkenyl side chains have been synthesized and studied. Different synthetic routes towards the imidazoles and the ionic liquids comprising bromide, iodide, methanesulfonate, bis(trifluoromethylsulfonyl) imide ([NTf2](-)), and dicyanamide {[N(CN)(2)](-)} as the anion were evaluated, and this led to a library of analogues, for which the melting points, viscosities, and electrochemical windows were determined. Incorporation of alkenyl moieties hindered solidification, except for cations with high symmetry. The alkoxy-derivatized ionic liquids are often crystalline; however, room-temperature ionic liquids (RTILs) were obtained with the weakly coordinating anions [N(CN)(2)](-) and [N(CN)(2)](-). For the viscosities of the peralkylated RTILs, an opposite trend was found, that is, the alkoxy derivatives are less viscous than their alkenyl-substituted analogues. Of the crystalline compounds, X-ray diffraction data were recorded and related to their molecular properties. Upon alkoxy substitution, the electrochemical cathodic limit potential was found to be more positive, whereas the complete electrochemical window of the alkenyl-substituted imidazolium salts was shifted to somewhat more positive potentials.

Membranes, azeotropic & catalytic components

Abstract: This invention relates generally to new findings to improveme a method of thermal energy storage or heat pump, i.e. increase the thermal energy from an external heat source, using a reversible condensation reaction with an inorganic oxoacid compound. It accordingly provides components to be used in said improved process as well as the use thereof in the aforementioned method, including the use in the manufacture of products of the condensation products or in the manufacture of the hydrolysis products.

Isolation and identification of a potent radical scavenger (canolol) from roasted high erucic mustard seed oil and its formation during roasting

Abstract: Roasting of high erucic acid mustard (HEM) seed has been reported to give a typical flavor and increase the oxidative stability of extracted oil. A potent radical scavenging compound was successfully isolated for the first time from roasted HEM seed oil in a single-step chromatographic separation using an amino solid-phase extraction column. Nuclear magnetic resonance, mass spectrometry, ultraviolet and fluorescence spectra revealed the compound as 2,6-dimethoxy-4-vinylphenol (generally known as canolol), and its identity was fully confirmed by chemical synthesis. The formation of canolol together with the loss of free sinapic acid (FSA) and total sinapic acid after basic hydrolysis (TSAH) during roasting was compared among four HEM varieties (Brassica juncea, Brassica juncea var. oriental, Brassica nigra, and Sinapis alba) and a low erucic acid rapeseed. HEM varieties were shown to produce less than one-third of canolol compared to rapeseed at similar roasting conditions. The amount of canolol formed after roasting was far higher compared to the amount of FSA loss in all the varieties (in molar basis). Therefore, partial hydrolysis of sinapic acid derivatives (SADs) into FSA additionally contributed to canolol formation. The lower amount of canolol formation in HEM varieties compared to rapeseed was linked to a lower free FSA content together with a lower loss of SADs in the HEM varieties. Around 50% of the canolol formed in the roasted seed was shown to be extracted in the oil. Roasting of both HEM seed and rapeseed before oil extraction was found to be a beneficial step to obtain canolol-enriched oil, which could improve the oxidative stability.

Electrochemical processes to separate products derived from biological conversions

Abstract: The present invention relates to efficient methods of controlling biological conversions while simultaneously removing and converting some of the generated products. More specifically, and for example, the present invention discloses electrochemical processes to remove and capture potentially toxic ammonium during anaerobic digestions and to remove and capture carboxylic acids during bioethanol production. The invention can thus be used to enhance bioproduction processes via controlling pH and/or reduction/oxidation, in combination with in situ product recovery.

Capture of benzotriazole-based Mannich electrophiles by CH-acidic compounds

Abstract: The Mannich-type capture reaction of aminoalkylbenzotriazoles by CH acidic compounds is documented. The pKa of the benzotriazole counteranion is key to the success of such reactions, whereas the global electrophilicity of the reactive iminium moiety is secondary.