Spectroscopic Evidence for the Involvement of a Radical Intermediate in the Friedel-Crafts Benzylation Using Ion-Exchanged K10 Catalysts

For Friedel-Crafts alkylation of aromatic hydrocarbons an ionic reaction path is considered as classical reaction mechanism. The alkylation with benzyl chloride in the presence of ion-exchanged K10 montmorillonite catalysts containing multivalent, reducible cations had an outstanding activity, therefore a radical initial step as a supplement to the ionic mechanism was proposed earlier. We made ESR investigations to clarify the existence and the nature of the suggested radical species. The ESR experiments verified that the reaction involves a radical step

Comparison the Soxhlet and Supercritical Fluid Extraction of Nettle Root (Urtica dioica L.)

The leaves of stinging nettle (Urtica dioica L.) are used for medical purposes since centuries while the nettle roots are applied only in the last decades. According to the latest researches the root of nettle contains many important ingredients, for example scopoletin, sterols, fatty acids, polysaccharides, polyphenols, minerals, etc. The polyphenols have antioxidant effect, reduce the hematological disorders, but also have anti-cancer and anti-bacteriological effects. The H-donating ability expresses the antioxidant activity.In this study two kinds of extraction techniques and three kinds of solvents have been applied. The extraction techniques were: Soxhlet extraction with 96% ethanol, Soxhlet extraction with n-hexane and supercritical fluid extraction (SFE) with CO2. All the measurements and the analysises were repeated three times.Comparing the yields of the three extraction methods it was established that the highest yield value was reached by Soxhlet extraction with ethanol. The Soxhlet extraction and the supercritical extraction has lower yield, the total polyphenol content and the H-donating ability of these extracts were low

Management of acquired aplastic anemia in children

The diagnosis of aplastic anemia in children requires exclusion of a variety of inherited or acquired BM failure syndromes with similar phenotypes. An efficient diagnostic plan is important because time from diagnosis to 'final' treatment is directly related to outcome regardless of the therapeutic option chosen. The gold standard of therapy remains hematopoietic SCT with a graft of BM cells for those children with matched sibling donors. Conversely for children without a sibling donor the high response and markedly improved overall survival rates of combined immunosuppressive therapy have proven robust, especially when horse derived anti-thymocyte globuline plus ciclosporine A are used. Incomplete response, relapse and progression to myelodysplasia/leukemia however have emerged as significant long-term issues. Improvements in outcome of alternative donor transplantation and the use of established and novel immunosuppressive agents provide multiple alternatives for treating refractory or relapsed patients. Regardless of the type of therapeutic approach, patients require centralized treatment in a center of excellence, ongoing monitoring for recurrence of disease and/or therapy-related immediate side effects and long-ternn effects. Bone Marrow Transplantation (2013) 48, 191-195; doi:10.1038/bmt.2012.235; published online 7 January 201

COMPLEX STUDIES ON INDUSTRIAL NICKEL CATALYSTS

Selected results of more than 20 year research work are summarized below. The aim has been to reveal relationships between the metal-H system, the catalysts structure and catalytic properties by using magnetic, electrochemical, TPD and X-ray measurements. Furthermore, a new technique has been introduced for the preparation and industrial production of skeleton catalysts and a triple promoted catalyst has been developed for industrial purposes. The development work has been aided by X-ray, SIMS, electron microprobe analysis measurements

Szilárdbázis- és szilárdsav-katalizátorok vizsgálata szerves szintézisekben = Examination of solid base and solid acid catalysts in organic syntheses

Vizsgáltuk aralkil-hidroperoxidok bontását különböző fémionokkal módosított K10 montmorillonitok jelenlétében. Meghatároztuk egyes reakciók aktiválási, ill. kinetikai paramétereit. Vizsgáltuk difenolok Friedel-Crafts acilezésében a módosító fémionoknak a montmorillonit aktivitására gyakorolt hatását. Új, gyökös reakciómechanizmust igazoltunk a benzolszármazékok benzil-kloriddal, módosított montmorillonitok jelenlétében végrehajtott Friedel-Crafts alkilezésére. Sikeresen alkalmaztuk az Ersorb zeolit adszorbenscsalád képviselőit katalizátorként különböző környezetkímélő szerves kémiai reakciókban, például aromás aldoximok nitrillé alakítására mikrohullámú reaktorban, alkoholok THP-védésére, valamint új eljárást dolgoztunk ki számos heterociklusos vegyület előállítására. A bázikus katalizátorok vizsgálata során sikerrel hajtottuk végre bisz-[3-aril-3-oxopropil]-aminok gyűrűzárását 4-hidroxi-arilpiperidinekké Mg:Al 2:1 hidrotalcittal, új reakciómechanizmust javasoltunk az aldehidek és nitrometán reakciója során keletkező 1,3-dinitropropánok képződésére. Mg:Al 3:1 hidrotalcittal megvalósítottuk N-etoxikarbonil-aminoalkoholok oxazolidinonokat eredményező gyűrűzárását, a nitroecetsav-etilészter és olefinek reakciójában pedig 5-szubsztituált-4,5-dihidro-izoxazol-3-karbonsavésztereket kaptunk. Új Pd/MgLa vegyes oxid katalizátort készítettünk és használtunk fel sikeresen a Heck-, Sonogashira és Suzuki-reakcióban. | The decomposition of aralkyl hydroperoxides was investigated in the presence of K10 montmorillonites modified with different metal ions the activation and kinetic parameters were determined. The effect of the metal ions to the activity of montmorillonites was investigated in the Friedel-Crafts acylation of diphenols. A new mechanism was confirmed to the Friedel-Crafts alkylation of benzene derivatives with benzyl chloride in the presence of modified montmorillonites. The members of the zeolite product line Ersorb have succesfully been applied as catalysts in environmentally-friendly organic syntheses, such as the conversion of aromatic aldimines into nitriles using microvawe irradiation, tetrahydropyranylation of alcohols, and new methods were developed for the preparation of different heterocycles. During the investigation of basic catalysts successful cyclisation of bis-[3-aryl-3-oxopropyl]-amines were performed into 4-hydroxy-arylpiperidines in the presence of Mg:Al 2:1 hydrotalcite, a new mechanism was proposed for the formation of 1,3-dinitropropanes in the reaction of aldehydes with nitromethane. With Mg:Al 3:1 hydrotalcite the cyclisation of carbamates yielding oxazolidinone derivatives was performed successfully. In the reaction of ethyl nitroacetate and olefines 5-substituted 4,5-dihydro-isoxazol-3-carboxylic acid derivatives were obtained. A new Pd/MgLa mixed oxide catalyst was developed and was applied successfully in the Heck, Sonogashira and Suzuki reactions

Changes in Total Polyphenol Content and Antioxidant Capacity of Stinging Nettle (Urtica dioica L.) from Spring to Autumn

Total polyphenol content and antioxidant/reducing capacity of stinging nettle (Urtica dioica L.) leaves and roots collected from wild-grown plants were investigated during the vegetation period. From both fresh and dried samples of leaves and roots, water extracts were prepared by brewing at 60, 80 and 100 °C for 3 hours, and ethanolic extracts of 20 % (v/v) and 70 % (v/v) by extracting at room temperature for 72 hours. The total polyphenol content was determined spectrophotometrically with Folin-Cioceltau reagent and the antioxidant capacity was measured by ferric reducing ability of plasma (FRAP) assay. Our results showed that the optimal harvest time is in the spring (April). Water extracts had the highest total polyphenol content and antioxidant capacity in this period. The amount of valuable compounds released increased by higher extraction temperature in both plant parts. In water extracts of nettle leaves, two times higher polyphenol content was obtained than in that of roots. Both kind of ethanolic extractions resulted in a higher polyphenol content in the leaves harvested in the spring period. For the roots, it was higher for samples collected in the autumn, which is also reflected in the values of antioxidant capacity. Water extracts of fresh leaves harvested in April had more than twice higher total polyphenol content than in October. For dried samples, raising the temperature did not cause a significant change in the total polyphenol content, however, it has resulted in increased antioxidant capacity both for the dried leaf and root samples

Molar Mass Distribution of Hydroxyethylated Aralkyl Alcohols

The molar mass distribution was investigated at the hydroxyethylation of aralkyl alcohols (benzyl-, beta;-phenylethyl- and gamma;-phenylpropyl) in the presence of conventional homogeneous and a heterogeneous catalyst, K10. While the widely used NaOH and SnCl4 catalysts gave the expected results in molar mass distribution (with base it is of Weibull-Nycander-Gold type, with the Lewis acid of Flory type), the K10 caused a narrower Flory type distribution which is effected by the length of alkyl chain in the aralkyl alcohols and by the modification of the pure K10 with metal ions (Cu2+ and Fe3+). By this way with a substrate- and MMD-friend hydroxyethylation can be achieved