Dependence of Biofuel Ignition Chemistry on OH-Initiated Branching Fractions

Abstraction of hydrogen by ȮH is the dominant initiation step in low-temperature oxidation of biofuels. Theoretical chemical kinetics calculations for such reactions provide a direct means of quantifying rates of abstraction, which are critical to modeling biofuel combustion. However, in several cases and despite agreement on total rate coefficients, branching fractions (i.e. the distribution of initial radicals) can vary depending on the level of theory, which leads to variations in ignition delay time predictions. To examine the connection between branching fractions and ignition delay time predictions, simulations were conducted for 1-butanol, cyclopentanone, and methyl propanoate at 10 atm and from 500–1000 K. For each case, the simulations utilized recent combustion mechanisms to produce an initial set of ignition delay time trends. H-abstraction rates were then replaced using rates from the literature to examine the effects of ȮH-initiated branching fractions on ignition chemistry. Branching fractions were found to significantly influence ignition chemistry, specifically in the case of 1-butanol, even when total rate coefficients were relatively consistent. From comparison of site-specific rates in the literature, branching fractions for initiation of 1-butanol and methyl propanoate are not consistent, which resulted in ignition delay times differing by factors of up to 6.3 and 1.2 respectively. Conversely, in the case of cyclopentanone, for which both the total and the site-specific rate coefficients agree, ignition delay times were unaffected. From the observed dependence of ignition delay times on ȮH-initiated branching fractions, an intermediate step in the development of combustion mechanisms is necessary to validate site-specific rate coefficients and ensure accurate model predictions. Speciation measurements are one example that can provide a critical link to radical-specific, fundamental chemical pathways and determine accurate branching fractions.

Ferrocenylmethylphosphanes and the Alpha Process for Methoxycarbonylation: The Original Story

The Lucite Alpha process is the predominant technology for the preparation of acrylics. This two-stage process involves the palladium-catalysed formation of methyl propanoate from ethene, CO, and methanol, followed by the oxidative formylation of methyl propanoate into methyl methacrylate. A range of bis-1,2-disubstituted aminomethylferrocenes has been prepared and characterised. These complexes serve as precursors to a variety of bulky ferrocenylmethyldiphosphanes that, in turn, function as ligands in the palladium-catalysed process. We describe the crystal structures of five ligand precursors and provide a rationale for their design. In situ catalyst testing on palladium complexes derived from ferrocenylphosphanes demonstrates that these are highly selective (>99.5%) catalysts for the formation of methyl propanoate from ethene, CO, and methanol and have turnover numbers exceeding 50,000. This article credits those researchers who worked on this project in the early days, who received little or no credit for their achievements and endeavours.

Antioxidant, biofilm inhibition and mutagenic activities of newly substituted fibrates

Purpose: A series of benzylidene-2-(4-bromophenoxy)-2-methyl propane hydrazides (1-10) were synthesized and assay them for their biofilm inhibition, antioxidant and mutagenic. Methods: All derivatives were prepared by condensation of various substituted benzaldehyde and acetophenones with 2-(4-bromorophenoxy)-2-methyl propane hydrazide, which was itself prepared by hydrazinolysis of ethyl-2-(4-bromophenoxy)-2-methyl propanoate and were characterized by FTIR, 1H NMR 13C NMR, mass spectrometry. They were screened for their in-vitro anti-oxidant, biofilm inhibition and mutagenicity by established methods. Results: Anti-oxidant results revealed that the electron donating group enhanced the scavenging ability of the compounds as seen in compounds 4b, 4h and 4i. In biofilm inhibition studies, all compounds were more active against Gram –ive bacterial strain when compared to gram +ive strain. The mutagenicity assay results indicate that the compound having chloro group substitution is mutagenic. Conclusion: The benzylidine compounds of 2-(4-bromophenoxy)-2-methyl hydrazide possessing electron donating substituents exhibit superior activities to the electron withdrawing group substituents.

A W1 Computational Study on the Kinetics of Initial Pyrolysis of Biodiesel Model: Methyl Propanoate

This work reports on the thermochemistry and kinetics of methyl propanoate (MePr) pyrolysis using high ab initio multi-level composite W1 method over the temperature range 400-2000 K. Pyrolysis of MePr...

Exploring the Typicality, Sensory Space, and Chemical Composition of Swedish Solaris Wines

The Swedish wine industry has exponentially grown in the last decade. However, Swedish wines remain largely unknown internationally. In this study, the typicality and sensory space of a set of twelve wines, including five Swedish Solaris wines, was evaluated blind by Swedish wine experts. The aim of the work was to evaluate whether the Swedish wine experts have a common concept of what a typical Solaris wines should smell and taste like or not and, also, to bring out more information about the sensory space and chemical composition of Solaris wines. The results showed a lack of agreement among the wine experts regarding the typicality of Solaris wines. This, together with the results from the sensory evaluation, could suggest the possibility of different wine styles for Solaris wines. From a chemical perspective, the global volatile profile showed a larger variability between individual wines than between Solaris and non-Solaris. However, 4MMP, ethyl propionate, ethyl 2-Methyl propanoate, and diethyl succinate were significantly higher in Solaris wines. Concerning non-volatile compounds, the results showed a significant discrimination between Solaris and non-Solaris wines, the former being characterized by higher ethanol %, Mg, succinic acid, tartaric acid, and sucrose levels.