Jędrzej Walkowiak

An effective catalytic hydroboration of alkynes in supercritical CO2 under repetitive batch mode

A facile method for the synthesis of unsaturated organoboron compounds by hydroboration of terminal and internal alkynes in supercritical (sc) CO2 has been presented for the first time. The reactions performed in scCO2 in the presence of Ru catalysts (selectivity, productivity) are compared with those in a traditionally used solvent or without it. Moreover, the catalytic systems based on the application of scCO2 have been successfully tested for the processes under repetitive batch conditions. This strategy permitted us to obtain boryl‐substituted olefins with high yields and selectivities up to the 16th catalytic cycle if using Ru(CO)Cl(H)(PPh3)3 as a catalyst. The process applied the self‐dosing catalyst, which is gradually released to the reaction mixture under supercritical conditions in the individual batch. Such an approach has a positive impact on process sustainability and economy.

Isolation of chlorophylls and carotenoids from freshwater algae using different extraction methods: Pigments extraction of freshwater algae

Usually marine algae are an excellent source of pigments for different commercial sectors. Freshwater macroalgae can be exploited as a good source of biologically active compounds provided an appropriate extraction method is developed. The efficiency of four methods, like microwave‐assisted (MAE), ultrasound‐assisted extraction (UAE), supercritical fluid extraction (SFE) with ethanol as a co‐solvent, as well as conventional Soxhlet extraction were studied in the same conditions (time, solvent and temperature) for the recovery of chlorophylls and carotenoids from three freshwater green algae species: Cladophora glomerata, Cladophora rivularis and Ulva flexuosa. UV‐Vis spectrophotometry was used to determine chlorophyll a, chlorophyll b and total carotenoid content in obtained extracts. The results of this study showed that the advantages of novel extraction techniques (MAE and UAE) include higher yield and, in consequence, lower costs compared to traditional solvent extraction techniques. These methods were much more efficient in freshwater green algae pigment recovery than the classic Soxhlet extraction as well as SFE.

Selective Hydrosilylation of Alkynes with Octaspherosilicate (HSiMe2O)8Si8O12

Comprehensive studies on platinum-catalyzed hydrosilylation of a wide range of terminal and internal alkynes with spherosilicate (HSiMe2 O)8 Si8 O12 (1 a) were performed. The influence of the reaction parameters and the types of reagents and catalysts on the efficiency of the process, which enabled the creation of a versatile and selective method to synthesize olefin octafunctionalized octaspherosilicates, was studied in detail. Within this work, twenty novel 1,2-(E)-disubstituted and 1,1,2-(E)-trisubstituted alkenyl-octaspherosilicates (3 a-m, 6 n-t) were selectively obtained with high yields, and fully characterized (1 H, 13 C, 29 Si NMR, FTIR, MALDI TOF or TOF MS ES+ analysis). Moreover, the molecular structure of the compound (Me3 Si(H)C=C(H)SiMe2 O)8 Si8 O12 (3 a) was determined by X-ray crystallography for the first time. The developed procedures are the first that allow selective hydrosilylation of terminal silyl, germyl, aryl, and alkyl alkynes with 1 a, as well as the direct introduction of sixteen functional groups into the 1 a structure by the hydrosilylation of internal alkynes. This method constituted a powerful tool for the synthesis of hyperbranched compounds with a Si-O based cubic core. The resulting products, owing to their unique structure and physicochemical properties, are considered novel, multifunctional, hybrid, and nanometric building blocks, intended for the synthesis of star-shaped molecules or macromolecules, as well as nanofillers and polymer modifiers. In the presented syntheses, commercially available reagents and catalysts were used, so these methods can be easily repeated, rapidly scaled up, and widely applied.

Effective one-pot synthesis of (E)-poly(vinyl arylenes) via trans-borylation/Suzuki coupling protocol

Abstract A new stereoselective method for the synthesis of (E)-poly(vinylarenes) on the basis of the Ru-H catalyzed trans-borylation reaction and sequential Suzuki coupling is described. Two different strategies of Pd-catalyzed polycondensation leading to unsaturated organic macromolecular compounds are discussed. Development of a one-pot procedure reduces costs and time, needed for the separation of intermediates, the amount of organic solvents used for purification and therefore has a positive influence on the process sustainability.