László Kótai

The Effect of HCl on the Copper(II) Chloride/Pyridine/Water System: Synthesis, Properties and Crystal Structure of [(pyH)2CuCl4] and [(pyH)2Cu3Cl8(H2O)2]n

Bis(pyridinium) tetrachlorocuprate monomer 1 and bis(pyridinium) octachlorodiaquatricuprate polymer 2 were synthesized and their crystal structures were determined. Both complexes contain pyridinium cations with bifurcated H-bridges. These H-bridges stabilize the monomeric structure of the tetrachlorocuprate anion together with the steric demand of the relatively large pyridinium ions in the crystal lattice of 1. Conversely, at the lower pyridinium ion:copper(II) ratio of 2, the bifurcated hydrogen bonds reduce the electron density on the chloride ions in such a way that the electron repulsion decreases and coordination spheres with more ligand interactions develop. Obviously, water may be a successful competitor for ligand sites in 2 as well. The octahedral and square-pyramidal structural units condense into polymeric chains which are stabilized by the interchain hydrogen bond networks of the water molecules. The structure motif of SP-5-[OC-6-SP-5-SP-5]-OC-6 (−CuCl5-[CuCl4(OH2)2-CuCl5CuCl5]-CuCl4(OH2)2-) were observed in 2, and the two neighboring square-pyramidal units were found to be localized in a transoid position. The IR and ESR spectroscopical characterization of complexes was also performed.

Acylation of alcohols and amines with carboxylic acids: a first report catalyzed by iron(III) oxide-containing activated carbon ☆

Abstract An efficient and selective acylation of alcohols and amines employing carboxylic acids as acylating agents is realized through the metal oxide containing activated carbon catalyst achieved by carbonization of organic ion-exchangers after incorporation of Fe 3+ -ions with exchangeable cations present in resin for the first time.

An Unprecedented-Type Intramolecular Redox Reaction of Solid Tetraamminecopper(2) Bis(permanganate) ((Cu(NH3)4)(MnO4)2 )±A Low-Temperature Synthesis of Copper Dimanganese Tetraoxide-Type (CuMn2O4) Nanocrystalline Catalyst Precursors

b ), Istva ¬ n Sajo ¬ a ), Ja ¬ nos Kristo ¬f c Tetraamminecopper(2) bis(permanganate) ((Cu(NH3)4)(MnO4)2; 1) was prepared, and its properties were studied in both aqueous solution and the solid phase. The presence of H-bond interactions between the ammonia ligand of the complex cation and an O-atom of the permanganate ion was detected by IR and Raman methods. The solid-phase thermal deammoniation of 1 led to an unusual intramolecular redox reaction between the MnO¥¥¥H N linkage with formation of NH4NO3 and CuMn2O4-type mixed oxides instead of stepwise deammoniation, even below 100. The thermal deammoniation of 1 in aqueous solution led, instead of to hydrated copper(2) bis(permanganate), to the formation of NH4MnO4 (2). Since the temperature of the thermal deammoniation of 1 is lower than the decomposition temperature of the permanganate ion, the regulated solid-phase decomposition of 1 allowed preparation of CuMn2O4-type oxides with mixing of copper and manganese at the atomic level.

Three Reagents in One: Ammonium Permanganate in the Oxidation of Benzyl Alcohol

The oxidation or consecutive ammoxidation reaction of benzyl alcohol with solid ammonium permanganate was studied. The first oxidation step leads to the formation of benzaldehyde, ammonia, and MnO2. The MnO2 is present in the system in a colloidal form which facilitates the reaction between aldehyde and ammonia, and this latter reaction then yields benzonitrile. All these products are formed in a heterogeneous system under relatively mild conditions. The yield of benzaldehyde has an optimum at room temperature and increases with increasing reaction time. At higher temperature (e.g. 80 °C) benzonitrile is formed together with minor amounts of benzyl benzoate

Biobutanol from Renewable Agricultural and Lignocellulose Resources and Its Perspectives as Alternative of Liquid Fuels

Biobutanol (n-C4H9OH, available as fermentation product of various carbohydrate derivatives obtained from different resources of agricultural production such as crops and wastes) is one of the most promising biofuels in the near future. It can be produced by the so-called ABE (acetone-butanol-ethanol) type anaerobic fermentation discovered by Pasteur [1, 2] and industrialized by Weizmann [3]. Main problems associated with industrial production of biobutanol include high energy demand for processing of dilute ferment liquors and high volume of wastewater. A bioreactor with a volume of 100 m3 produces at 90% filling ratio 1053 kg of butanol, 526 kg of acetone and 175 kg of ethanol together with 2900 kg of carbon dioxide, 117 kg of hydrogen and 84150 kg of wastewater. Efforts to increase productivity and decrease production costs resulted in many new methods. This chapter summarizes some selected results on methods of biobutanol production.

Kinetics and mechanism of the oxidation of substituted benzylamines by cetyltrimethylammonium permanganate

Oxidation of meta- and para-substituted benzylamines by cetyltrimethylammonium permanganate (CTAP) to the corresponding aldimines is first order with respect to both the amine and CTAP. Oxidation of deuteriated benzylamine (PhCD2NH2) exhibited the presence of a substantial kinetic isotope effect (kH/kD = 5.60 at 293 K). This confirmed the cleavage of an α-C-H bond in the rate-determining step. Correlation analyses of the rates of oxidation of 19 monosubstituted benzylamines were performed with various single and multiparametric equations. The rates of the oxidation showed excellent correlations in terms of Yukawa—Tsuno and Brown’s equations. The polar reaction constants are negative. The oxidation exhibited an extensive cross-conjugation, in the transition state, between the electron-donating substituents and the reaction centre. A mechanism involving a hydride-ion transfer from the amine to CTAP in the rate-determining step has been proposed.

An Integrated Waste-Free Biomass Utilization System for an Increased Productivity of Biofuel and Bioenergy

The increase in production and utilization of biomass and other renewable sources of energy are important challenges of the energy industry. It generates, however, demands for ecologically and economically acceptable production systems. Here we report an integrated system of known and new technologies developed for biomass conversion to biofuels. This includes classical and biobutanol based new biodiesels, biogas and electricity production, and an agricultural production system involving fertilization with the ash of the biomass power plants. Basically, three types of agricultural production system are needed for the agricultural segment of the integrated system, namely: A – plants for combustion in biomass power plants (energy grass) B – plants for production of vegetable oils for biodiesel production C – plants for conversion of sugar derivatives to price alcohols, mainly butanol as a diesel fuel source Depending on the climate, the soil type, the agricultural experiences, and the type of the plants (A,B,C), the produced biomass materials can fulfill more than one requirement as it can be seen in Fig. 1. Depending on the constituents of the biomass (cellulose, starch, lignin, oil, proteins), the energy production can be performed via direct combustion or, after digestion in biogas systems, by using the biogas. The biomass power plants, biogas combustion plants/engines produce hot water, steam and electricity. In plants type B soybean, rape, sunflower or likes are pressed to obtain the oil, while the pressing cake can be used as optimal raw material for biogas plants due to its high protein content, while the

Quasi-intramolecular acid-base reactions in aqueous solutions of metal-complexes of basic ligands. I. Generalized theoretical considerations on the deammoniation of [MLm]Xn type ammonia complexes

The theoretical investigation on the distribution of chemical species obtainable as a function of the temperature of the aqueous solutions of metal complexes containing a basic ligand, altogether with the solubility relationship of the compounds to be formed, offers a simple means of planning the preparation of various types of complexes, double and single salts of the central metal cation and onium type compounds of protonated ligand of the central ion and the anion.

Study on the Existence of Hydrogen Bonds in Ammonium Permanganate

The crystal structures of ammonium permanganate and ammonium perchlorate at 293 K were determined and compared. X-ray and vibrational spectroscopic data confirmed the existence of weak hydrogen bonds in NH4MnO4. These hydrogen bonds proved to be slightly stronger than H-bonds in ammonium perchlorate. Difference between the results of diffuse reflectance and KBr matrix pellet IR spectra of NH4MnO4 has been explained. Untersuchung uber die Existenz von Wasserstoffbruckenbindungen in Ammoniumpermanganat Die Kristallstrukturen von Ammoniumpermanganat und -perchlorat wurden bei 293 K bestimmt und miteinander verglichen. Die Rontgen- und schwingungsspektroskopischen Daten bestatigen die Existenz von schwachen Wasserstoffbruckenbindungen im NH4MnO4. Diese sind etwas starker als die H-Brucken im Ammoniumperchlorat. Unterschiede zwischen den Ergebnissen der Reflexions- und IR-Spektren von NH4MnO4 werden erklart.

Kinetics and mechanism of the oxidative regeneration of carbonyl compounds from oximes by cetyltrimethylammonium permanganate

The oxidative deoximination of several aldo- and keto-oximes by cetyltrimethylammonium permanganate (CTAP), in dichloromethane, proceeding through the formation of a cyclic intermediate, in the rate-determining step, has been proposed.