Jakub Adamek

Thermal decomposition of different types of asbestos

Given the known carcinogenic effects, asbestos minerals are considered as general health hazard. Therefore, the elimination of asbestos materials from the environment is necessary. Asbestos minerals should be entirely transformed to a non-hazardous material. One of these methods is destructing the fibers structure of asbestos minerals by thermal treatment. Asbestos minerals are naturally occurring hydrous silicates, so that they decompose to release water by heating at high temperatures which may lead to changes in crystal structure and the formation of new phases without the dangerous properties. In this article, thermal behavior of asbestos minerals is investigated to observe the disappearance of this hazardous structure and to characterize products obtained by this way. Ten samples of asbestos minerals (six chrysotile samples from different locations, two samples of crocidolite, one amosite, and one tremolite) from different locations were tested. Mineralogical and morphological data (X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy) were obtained before and after differential thermal analysis.

Evaluation of new natural deep eutectic solvents for the extraction of isoflavones from soy products

Natural deep eutectic solvents (NADESs) are considered to be new, safe solvents in green chemistry that can be widely used in many chemical processes such as extraction or synthesis. In this study, a simple extraction method based on NADES was used for the isolation of isoflavones (daidzin, genistin, genistein, daidzein) from soy products. Seventeen different NADES systems each including two or three components were tested. Multivariate data analysis revealed that NADES based on a 30% solution of choline chloride: citric acid (molar ratio of 1:1) are the most effective systems for the extraction of isoflavones from soy products. After extraction, the analytes were detected and quantified using ultra-high performance liquid chromatography with ultraviolet detection (UHPLC-UV). The proposed NADES extraction procedure achieved enrichment factors up to 598 for isoflavones and the recoveries of the analytes were in the range 64.7-99.2%. The developed NADES extraction procedure and UHPLC-UV determination method was successfully applied for the analysis of isoflavones in soy-containing food samples. The obtained results indicated that new natural deep eutectic solvents could be an alternative to traditional solvents for the extraction of isoflavones and can be used as sustainable and safe extraction media for another applications.

α-Amidoalkylating Agents: Structure, Synthesis, Reactivity and Application

Abstract This review provides a summary of a wide range of α-amidoalkylating reagents and their precursors, especially novel developments in their synthesis and applications in a wide variety of inter- and intramolecular α-amidoalkylation reactions with O , N , S , P , C and other nucleophiles. A special attention is paid to (1) the introduction of new α-amidoalkylation reagents that join easy access from simple starting materials, structural diversity, high stability, easy handling and storage and high reactivity toward nucleophilic reagents under mild conditions; (2) the development of intramolecular α-amidoalkylation reactions to cyclic products via N -acyliminium ion or N -acylimine cyclizations; (3) the recent development of stereoselective α-amidoalkylation reactions using asymmetric catalysis, and (4) the application of α-amidoalkylation reactions for the synthesis of natural and/or bioactive compounds.This review provides a summary of a wide range of α-amidoalkylating reagents and their precursors, especially novel developments in their synthesis and applications in a wide variety of inter- and intramolecular α-amidoalkylation reactions with O, N, S, P, C and other nucleophiles. A special attention is paid to (1) the introduction of new α-amidoalkylation reagents that join easy access from simple starting materials, structural diversity, high stability, easy handling and storage and high reactivity toward nucleophilic reagents under mild conditions; (2) the development of intramolecular α-amidoalkylation reactions to cyclic products via N-acyliminium ion or N-acylimine cyclizations; (3) the recent development of stereoselective α-amidoalkylation reactions using asymmetric catalysis, and (4) the application of α-amidoalkylation reactions for the synthesis of natural and/or bioactive compounds.

α-Amidoalkylating Agents from N-Acyl-α-amino Acids: 1-(N-Acylamino)alkyltriphenylphosphonium Salts

N-Acyl-α-amino acids were efficiently transformed in a two-step procedure into 1-N-(acylamino)alkyltriphenylphosphonium salts, new powerful α-amidoalkylating agents. The effect of the α-amino acid structure, the base used [MeONa or a silica gel-supported piperidine (SiO(2)-Pip)], and the main electrolysis parameters (current density, charge consumption) on the yield and selectivity of the electrochemical decarboxylative α-methoxylation of N-acyl-α-amino acids (Hofer-Moest reaction) was investigated. For most proteinogenic and all studied unproteinogenic α-amino acids, very good results were obtained using a substoichiometric amount of SiO(2)-Pip as the base. Only in the cases of N-acylated cysteine, methionine, and tryptophan, attempts to carry out the Hofer-Moest reaction in the applied conditions failed, probably because of the susceptibility of these α-amino acids to an electrochemical oxidation on the side chain. The methoxy group of N-(1-methoxyalkyl)amides was effectively displaced with the triphenylphosphonium group by dissolving an equimolar amount of N-(1-methoxyalkyl)amide and triphenylphosphonium tetrafluoroborate in CH(2)Cl(2) at room temperature for 30 min, followed by the precipitation of 1-N-(acylamino)alkyltriphenylphosphonium salt with Et(2)O.

Amidoalkylating Properties of 1-(N-Acylamino)Alkyltriphenylphosphonium Salts

Abstract Easily accessible 1-(N-acylamino)alkyltriphenylphosphonium salts react smoothly with nitrogen, sulfur, phosphorus and oxygen nucleophiles in the presence of (i-Pr)2EtN to give the expected α-amidoalkylation products, usually in good or very good yields. α-Amidoalkylation of dialkyl malonates or acetylacetates requires the application of a much stronger base (DBU) and gives the best results under the influence of microwave irradiation. α-Amidoalkylation of enamines was carried out successfully in the presence of (i-Pr)2EtN in a microwave reactor. 1-(N-Acylamino)alkyltriphenylphosphonium salts can be considered as new, convenient and effective α-amidoalkylation agents. GRAPHICAL ABSTRACT

Comparative Studies on the Amidoalkylating Properties of N-(1-Methoxyalkyl)Amides and 1-(N-Acylamino)Alkyltriphenylphosphonium Salts in the Michaelis–Arbuzov-Like Reaction: A New One-Pot Transformation of N-(1-Methoxyalkyl)Amides into Phosphonic or Phosphinic Analogs of N-Acyl-α-Amino Acids

Abstract It was demonstrated that N-(1-methoxyalkyl)amides do not react with trimethyl phosphite under neutral or basic conditions. The treatment of N-(1-methoxyalkyl)amides with trialkyl phosphites or dialkyl phosphonites, triphenylphosphonium tetrafluoroborate, and Hünigs base caused immediate formation of the corresponding 1-(N-acylamino)-alkyltriphenylphosphonium tetrafluoroborates, followed by the slow Michaelis–Arbuzov-like reaction of phosphonium salt with phosphites or phosphonites to α-(N-acylamino)-alkanephosphonic or α-(N-acylamino)alkanephosphinic acid esters, respectively. A plausible mechanism of the considered transformations, assuming an equilibrium between N-(1-alkoxyalkyl)amide, triphenylphosphonium tetrafluoroborate, 1-(N-acylamino)alkyltriphenyl-phosphonium salt, N-acylimine, and N-acyliminium salts, is discussed. GRAPHICAL ABSTRACT

1-Imidoalkylphosphonium salts with modulated Cα–P+ bond strength: synthesis and application as new active α-imidoalkylating agents

An effective synthesis of the hitherto unknown 1-imidoalkylphosphonium salts has been developed in the reported study. The crucial step in the method included the decarboxylative α-methoxylation of N-phthaloyl- or N-succinylamino acids to the corresponding N-(1-methoxyalkyl)imides, followed by the displacement of the methoxy group by the triarylphosphonium group through melting of the imide derivative with triarylphosphonium tetrafluoroborate. The imidoalkylating properties of the obtained 1-imidoalkylphosphonium salts were tested using the Tscherniac–Einhorn-type reaction with aromatic hydrocarbons as a model reaction. It was found that the Cα–P+ bond strength can be considerably reduced and the imidoalkylation of arenes can be markedly facilitated using 1-imidoalkylphosphonium salts derived from triarylphosphines with electron-withdrawing substituents such as tris(m-chorophenyl)phosphine, tris(p-chlorophenyl)phosphine and tris[p-(trifluoromethyl)phenyl]phosphine. Microwave irradiation also considerably facilitates the cleavage of the highly polar Cα–P+ bond.

1-(N-Acylamino)alkyltriarylphosphonium Salts with Weakened Cα-P+ Bond Strength—Synthetic Applications

The α-amidoalkylating properties of 1-(N-acylamino)alkyltriarylphosphonium salts with weakened Cα-P+ bond strength are discussed and examined. It is demonstrated that such type of phosphonium salts reacts smoothly with a diverse array of carbon- and heteroatom-based nucleophiles, including 1-morpholinocyclohexene, 1,3-dicarbonyl compounds, benzotriazole sodium salt, p-toluenesulfinate sodium salt, benzylamine, triarylphosphines, and other P-nucleophiles. Reactions are conducted at room temperature, in a short time (5–15 min) and mostly without catalysts. Simple work-up procedures result in good or very good yields of products. The structures of known compounds were established by spectroscopic methods and all new compounds have been fully characterized using 1H-, 13C-, 31P-NMR, IR spectroscopy, and high-resolution mass spectrometry. Mechanistic aspects of described transformations are also performed and discussed. It was demonstrated that unique properties make 1-(N-acylamino)alkyl-triarylphosphonium salts with weakened Cα-P+ bond strength interesting building blocks with great potential, especially in α-amidoalkylation reactions.