7020-34-0Relevant articles and documents
Catalytic oxidative transformation of betulin to its valuable oxo-derivatives over gold supported catalysts: Effect of support nature
Kolobova,M?ki-Arvela,Grigoreva,Pakrieva,Carabineiro,Peltonen,Kazantsev,Bogdanchikova,Pestryakov,Murzin, D.Yu.
, p. 95 - 110 (2020/08/26)
Liquid-phase oxidation of betulin extracted from birch bark was studied over gold catalysts supported on a range of supports (hydrotalcite, ZrO2, ZnO, MgO, CeO2, La2O3, HMS and various alumina) with different morphology and properties. Gold catalysts as well as the corresponding supports were characterized by XRD, BET, ICP-OES, XPS and TEM. It was found that the nature of the support plays a decisive role in betulin oxidation over gold-based catalysts, expressed in the influence on the average size and distribution of gold nanoparticles and, thereby, on their catalytic performance (activity and selectivity) in betulin oxidation. Moreover, it was revealed that betulin oxidation catalyzed by gold is a structure sensitive reaction, requiring an optimal size of gold nanoparticles of ca. 3.3 nm. The most suitable support for gold was found to be alumina. Kinetic studies allowed determination of reaction orders and conditions favorable for selective formation of a particular oxo-derivative of betulin (betulone, betulinic and betulonic aldehydes, betulinic acid).
Oxidation of a wood extractive betulin to biologically active oxo-derivatives using supported gold catalysts
Kolobova, Ekaterina N.,Pakrieva, Ekaterina G.,Carabineiro, Sónia A. C.,Bogdanchikova, Nina,Kharlanov, Andrey N.,Kazantsev, Sergey O.,Hemming, Jarl,M?ki-Arvela, P?ivi,Pestryakov, Alexey N.,Murzin, Dmitry Yu.
, p. 3370 - 3382 (2019/06/24)
Betulin (90-94%) was extracted from birch with a non-polar solvent and recrystallized from 2-propanol. Liquid-phase oxidation of betulin aimed at obtaining its biologically active oxo-derivatives (betulone, betulonic and betulinic aldehydes), exhibiting e.g. antitumor, anti-inflammatory, antiparasitic, anticancer and anti-HIV properties, was demonstrated for the first time over gold-based catalysts. Gold was deposited on pristine TiO2 and the same support modified with ceria and lanthana, followed by pretreatment with a H2 or O2 atmosphere. The catalysts were characterized by XRD, BET, ICP, TEM, XPS, DRIFT CO, TPD of NH3 and CO2 methods. The nature of the support, type of modification and the pretreatment atmosphere through the metal-support interactions significantly influenced the average particle size of gold, its distribution and the electronic state of gold, as well as the acid-base properties and, thereby, the catalytic performance (activity and selectivity) in betulin oxidation. Au/La2O3/TiO2 pretreated in H2 displayed the highest catalytic activity in betulin oxidation among the studied catalysts with selectivities to betulone, betulonic and betulinic aldehydes of 42, 32 and 27%, respectively, at 69% conversion. Side reactions resulting in oligomerization/polymerization products occurred on the catalyst surface with the participation of strong acid sites, diminishing the yield of the desired compounds. The latter was improved by adding hydrotalcite with the basic properties to the reaction mixture containing the catalyst. Kinetic modelling through numerical data fitting was performed to quantify the impact of such side reactions and determine the values of rate constants.
Preparation of Betulone Via Betulin Oxidation Over Ru Nanoparticles Deposited on Graphitic Carbon Nitride
Shcherban,M?ki-Arvela,Aho,Sergiienko,Skoryk,Kolobova,Simakova,Er?nen,Smeds,Hemming,Murzin, D. Yu.
, p. 723 - 732 (2019/01/25)
Derivatives of betulin obtained by oxidation have broad pharmacological applications, demonstrating anti-inflammatory, antioxidant, hepatoprotective, and anticancer activity. Ru supported catalysts based on graphitic carbon nitride or N-doped carbon were prepared via a mild reduction of the initial Ru precursor with hydrazine. These catalysts along with Ru supported on carbon nanofibers and a mesoporous carbon support Sibunit were studied in catalytic oxidation of betulin. Ru/carbon nitride demonstrated catalytic activity in betulin oxidation higher than Ru/N-doped carbon (conversion of betulin up to ca. 70% and 30%, respectively). Selectivity to different oxidation products was dependent on the properties of the carbon supports.
Selective oxidation of betulin for the preparation of betulinic acid, an antitumoral compound
Pichette, Andre,Liu, Hongyan,Roy, Christian,Tanguay, Steve,Simard, Francois,Lavoie, Serge
, p. 3925 - 3937 (2007/10/03)
This paper describes a semisynthetic approach for the preparation of betulinic acid from betulin. The main step of this synthetic approach is the selective oxidation of primary alcohol function of betulin. This reaction is accomplished with chromic oxide adsorbed on silica gel to obtain betulinal in an adequate yield. Betulinal is then almost quantitatively oxidized to betulinic acid by potassium permanganate action.
Selective oxidation of betulin by Cr(VI) reagents
Komissarova,Belenkova,Spirikhin,Shitikova,Yunusov
, p. 58 - 61 (2007/10/03)
Oxidation of betulin by pyridinium dichromate, pyridinium chlorochromate, and K2Cr2O7 - H2SO4 in the presence of tetrabutylammonium bromide was studied. Products of regioselective C-3, C-28-, and exha
