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Optimisation of detailed combustion mechanisms means that the corresponding kinetic model is fitted to experimental data via optimising their important rate and thermodynamic parameters within their domain of uncertainty. Typically, several dozen parameters are fitted to several hundred to several thousand data points. Many numerical optimisation methods have been used, but the efficiency of these methods has not been compared systematically. In this work, parameters of an H2/O2/NOx mechanism (214 reaction steps of 35 species) were fitted to 1552 indirect (ignition delay times measured in shock tubes and concentrations measured in flow reactors) and 755 direct measurements. Three test cases were investigated: (1) fitting the Arrhenius parameters of 2 reaction steps to 732 data points; (2) fitting the Arrhenius parameters of 4 reaction steps to 1077 data points; (3) fitting the Arrhenius parameters of 10 reaction steps to 2307 data points. All 3 cases were investigated in 2 ways: fitting the A-parameters only and fitting all Arrhenius parameters (5, 11 and 29 parameters, respectively). A series of global (FOCTOPUS, genetic algorithm, simulated annealing, particle swarm optimisation, covariance matrix adaptation evolutionary strategy (CMA-ES)) and local (simplex, pattern search, interior-point, quasi-Newton, BOBYQA, NEWUOA) optimisation methods were tested on these cases, some of them in two variants. The methods were compared in terms of the final error function value and number of error function evaluations. The main conclusions are that the FOCTOPUS resulted in the lowest final error value in all cases, but this method required relatively many error function evaluations. As the task became more difficult, more and more methods failed. A variant of the BOBYQA method looked stable and efficient in all cases.

The aim of several combustion experiments is the determination of the rate coefficients of important elementary reactions. The experimental conditions are usually selected on the basis of local sen...

The ring opening of 2α,3α- and 2β,3β-epoxy-5α-androstan-17-one with halide reagents (AlCl3, TMSCl, LiCl, and LiBr) was investigated using imidazolium ionic liquids in the dual role of solvent and catalyst. The application of the ionic liquid was shown to result in an increase in the amount of the unusual diequatorial halohydrins especially at temperatures above 100 °C. With a careful choice of reaction conditions, the latter derivatives could be produced with 43–96% selectivity depending on the nature of the halide ion. Moreover, the usual diaxial products could also be isolated in 70–85% yields by a proper change in the reaction conditions. The reusability of the ionic liquid was demonstrated in both types of reactions. The structures of the products were proved unequivocally by nuclear magnetic resonance (NMR) measurements including two-dimensional (2D) techniques as well as high-resolution mass spectrometry (HRMS). Based on quantum chemical calculations, the effect of the ionic liquid could be explained by the stabilization of the transition state leading to the diequatorial product.

Ammonia is a potential fuel for the storage of thermal energy. Experimental data were collected for homogeneous ammonia combustion: ignition delay times measured in shock tubes (247 data points in 28 datasets from four publications) and species concentration measurements from flow reactors (194/22/4). The measurements cover wide ranges of temperature T, pressure p, equivalence ratio φ and dilution. The experimental data were encoded in ReSpecTh Kinetics Data Format version 2.2 XML files. The standard deviations of the experimental datasets used were determined based on the experimental errors reported in the publications and also on error estimations obtained using program MinimalSplineFit. Simulations were carried out with eight recently published mechanisms at the conditions of these experiments using the Optima++ framework code, and the FlameMaster and OpenSmoke++ solver packages. The performance of the mechanisms was compared using a sum-of-square error function to quantify the agreement between the simulations and the experimental data. Ignition delay times were well reproduced by five mechanisms, the best ones were Glarborg-2018 and Shrestha-2018. None of the mechanisms were able to reproduce well the profiles of NO, N2O and NH3 concentrations measured in flow reactors.

Palladium-catalyzed carbonylation in the presence of organic and organometallic nucleophiles serves as a powerful tool for the conversion of aryl/alkenyl halides or halide equivalents to carbonyl compounds and carboxylic acid derivatives. To circumvent the difficulties in product separation and recovery and reuse of the catalysts, associated with homogeneous reactions, supported counterparts of the homogeneous palladium catalysts were developed. The review intends to summarize the huge development that has been witnessed in recent years in the field of heterogeneous carbonylation. A great plethora of supports, organic modifiers on solid surfaces stabilizing metal particles, transition metal precursors, as well as alternative sources for CO was investigated. In most cases, careful optimization of reaction conditions was carried out. Besides simple model reactions, the synthesis of carbonyl compounds and carboxylic acid derivatives from substrates with different functionalities was performed. In some cases, causes of palladium leaching were clarified with detailed investigations. The advantages of immobilized catalysts were shown by several examples. The possibility of catalystrecycling was proved besides proving that metal contamination of the products could often be kept below the detection limit. At the same time, detailed investigations should be carried out to gain a better insight into the real nature of these processes.

Silica modified with organic dicationic moieties proved to be an excellent support for palladium catalysts used in the aminocarbonylation of aryl iodides. By an appropriate choice of the reaction conditions, the same catalyst could be used for selective mono- or double carbonylations leading to amide and α-ketoamide products, respectively. The best catalyst could be recycled for at least 10 consecutive runs with a loss of palladium below the detection limit. By the application of the new support, efficient catalyst recycling could be achieved under mild reaction conditions (under low pressure and in a short reaction time). Palladium-leaching data support a mechanism with dissolution—re-precipitation of the active palladium species.

Novel 2-ureido-4-ferrocenylpyrimidines have been synthesized from iodoferrocene by a three-step reaction sequence. XRD analysis and spectroscopic data support the presence of an intramolecular hydrogen bond between a nitrogen atom of the pyrimidine ring and an NH group of the urea moiety. Both theoretical calculations and NMR investigations prove the existence of two isomeric forms in solution, both of which can form hydrogen bonds with an appropriate guest via an acceptor-donor-acceptor bonding pattern. Complexation with 2,6-diaminopyridine can be proved either by NMR spectroscopy or by electrochemical measurements. © 2016 American Chemical Society.

A great number of organic reactions catalyzed by the ionic liquid product of chlorosulfonation of 1-methylimidazole have been reported recently. At the same time controversial assumptions have appeared on the real structure of the catalyst. In the present report the primarily formed chlorosulfonation product is proved to be 1-methylimidazolium chlorosulfate ([HMim]+[SO3Cl]−) instead of 1-methyl-3-sulfonic acid imidazolium chloride, reported previously. The former structure is confirmed by X-ray crystallography and NMR spectroscopy, including 1H-, 13C-, 17O- and 15N–1H HSQC measurements. 1H and 17O NMR experiments support fast hydrolysis of [HMim] [SO3Cl] resulting in the formation of [HMim][HSO4] in the presence of traces of water.

Heterogeneous palladium catalysts were prepared by the immobilisation of palladium on supported ionic liquid phases (SILP) obtained by physisorption or grafting. They were characterised by different techniques such as 13C CP MAS NMR, 31P CP MAS NMR, FT-IR, XPS and ICP. The catalysts were used efficiently under solvent-free conditions. They led to the formation of amide products with good to excellent selectivity. Recyclability at 5–10 bar CO pressure has also been demonstrated. The same reusable catalysts were proved to lead to the selective formation of double carbonylation products under higher pressure in DMF.

The efficiency of a palladium catalyst, immobilised on a supported ionic liquid phase (SILP) with adsorbed 1-butyl-4-methylpyridinium chloride, was investigated in aminocarbonylation reactions. Double carbonylation was found to be the main reaction using different iodoarenes and aliphatic amines as substrates. Application of aniline derivatives as nucleophiles led to the exclusive formation of substituted benzamides. The stabilisation effect of the adsorbed pyridinium ionic liquid was compared to that of imidazolium and phosphonium derivatives. It was proved that the pyridinium SILP-palladium catalyst could be reused in at least 10 cycles. Recyclability was tested in five successive runs for all of the substrates.

Literature experimental data were collected about hydrogen–oxygen combustion systems doped with NO, NO2 or N2O or about H2/N2O combustion systems. The data included ignition delay times, laminar burning velocities, and concentrations measured in flow reactors, JSRs and burner stabilized flames. In total, 4949 data points in 207 data sets from 35 publications were used. These experimental data were reproduced using sixteen NOx mechanisms. The performance of the Nakamura-2017, Glarborg-2018 and Zhang-2017 mechanisms were the best. Nine elementary reactions were selected from the Glarborg-2018 mechanism based on sensitivity analysis and the Arrhenius parameters (A, n, E) of these reactions were fitted not only to the indirect experimental data, but also direct experimental and theoretical determinations of the rate coefficients. This way more accurate rate parameters of these reactions could be obtained and the temperature dependent uncertainty of the rate coefficients was calculated. The Glarborg-2018 mechanism modified with the optimized rate parameters described the experimental data better than any other investigated reaction mechanism.

Various silica-supported palladium catalysts were prepared and tested in the carbonylation of aryl iodides in the presence of aliphatic amines and aniline. In the former reaction, the main products are the α-ketoamides, whereas monocarbonylation is favoured with aniline. Small modification of the support, of the palladium precursor, or of the conditions of immobilisation were found to affect considerably the outcome of the reactions and recyclability of the catalysts. Under optimum conditions, the phosphine-free palladium catalysts can be reused six to ten times without considerable loss of activity. By the proper selection of the solvent, the leaching of palladium into the reaction mixtures can be reduced considerably.

Various palladium catalysts were obtained by the immobilisation of palladium on silica, modified with imidazolium salts. The efficiency of the catalysts was greatly dependent on the choice of the anion of the imidazolium salt, the palladium precursor and on the conditions of heterogenisation. Palladium acetate immobilised on silica with grafted imidazolium chloride moieties was shown to be a selective and recyclable catalyst for atmospheric aminocarbonylation of aryl iodides with aromatic amines in DMF. It was proved that the greater loss of palladium in DMSO can be explained by the formation of soluble palladium complexes.

Supported ionic liquids (SILPs), prepared via the immobilization of ionic liquids on solid material, can efficiently be used in catalytic reactions as catalysts, or as supports for transition metal catalysts. The SILP concept combines the advantages of homogeneous catalysis with those of heterogeneous systems. In the present paper, this is demonstrated with two examples. In the first application, acidic SILPs are shown to be selective and recyclable catalyst for the trimerization of isobutene. In the second example, neutral SILPs are proved to be excellent supports stabilizing palladium catalysts for carbonylation reactions, as well as ensuring effective catalyst recycling.

Various silica supported palladium catalysts were prepared and tested in the double carbonylation of iodobenzene in the presence of secondary amines. The catalysts were proved to produce α-ketoamide products with excellent selectivity in most cases. At the same time, bulky amines hindered double carbonylation and led to the formation of amides as the main products. Under optimal conditions, the catalysts could be recycled at least six times. An increase in the reaction time led to a decrease in the amount of leached palladium.

Szilárd Borbély’s Berlin & Hamlet may raise a number of questions about the subjectivity of postmodern text creation. Berlin has a special place in the ambivalent relationship between the literary tradition evoked by the poems and the author’s unexpressed intention. All of these broaden and narrow down the range of possible interpretations of this book. The streets, statues, museums of the place called ”Urbangod” stand as the crumbling sets of the declining European culture. Parallel with this, the tools of poetry seem to peel off the disappearing character of the poet, who represents an existence without a centre. The language of the poems is a mixture of sceptical and elegic tones, while the textual world is enigmatic, fragmented and it relativizes the allegorical speech – all these give way to a number of assumptions about the lyrical self which is revealed in poetical roles, and which, at times, exposes itself. A monological dialogue stems from the implications of the hiding lyrical self and the summoned spectre, in which the distance between the speakers and the addressees is insurmountable. This distance can be partially covered by an analysis, as the author, lost in the labirynth of sounds, can only fill the space between the texts by his own absence.