Wyniki wyszukiwania - BazTech

1

2,2’-dihydroksy-1,1’-binaftyl (BINOL) i jego pochodne. Wybrane syntezy i zastosowanie. Część. II

Krasowska D.

Wiadomości Chemiczne

|

2013

|

[Z] 67, 1-2

55--92

EN

An invention of new catalytic strategies for stereoselective synthesis is of current interest to many laboratories worldwide . Over the past few decades a remark - able progress in the field of stereocontrolled synthesis has been achieved with chiral 1,1’-binaphthyl compounds. Optically active 1,1’-binaphthyl-2,2’-diol (BINOL) and its derivatives due to their axial dissymmetry and molecular flexibility have been widely utilized as chiral ligands and auxiliaries in stoichiometric or catalytic asymmetric reactions, such as metal-catalysed transformations and enantioselective organocatalysis. BINOL and its functionalized analogues have demonstrated remark - able chiral discrimination properties. Extensive studies on molecular recognition provided the successful results in the application of BINOL as a host for an optical resolution of racemic guests and as a chiral NMR shift reagent for the determination of chiral compounds. It has been found that the axial chirality of binaphthyl units in host molecules is crucial contribution to their stereoselctive complexation with chiral guests.

2

2,2'- Dihydroksy-1,1'-binaftyl (BINOL ) i jego pochodne. Wybrane syntezy i zastosowanie. Część I

Krasowska D.

Wiadomości Chemiczne

|

2012

|

[Z] 66, 5-6

485-528

EN

1,1’-Binaphthyl and its derivatives represent a particular class of chemical molecules which chirality results from the restricted rotation about single bond of the two naphthalene rings. This generates the chirality axis. Therefore 1,1’-binaphthyl derivatives exist as two enantiomeric forms called atropoisomers. Moreover, 1,1’- binaphthyls with substituents at 2,2’ position exhibit higher rotational barriers around the 1,1’-axis, which affect a very stable chiral configuration. The classical examples of such molecules is 2,2-dihydroxy-1,1’-binaphthyl (BINOL ), which has become one of the most utilized chiral ligand and auxiliary for diverse asymmetric syntheses. The unchallenged success of BINOL and its derivatives in the field of transition metal-catalyzed asymmetric reactions or C-C bond forming reactions promoted worldwide an advancement of organic synthesis. The first synthesis of BINOL as racemate was described in 1873. Since then there have been found numerous efficient methods of racemic or enantiomerically pure BINOL preparation and its derivatization. In order to present a brief overview of the most convenient and facile routes to obtain racemic and nonracemic symmetrically substituted 1,1’-binaphthyls based on stoichiometric and catalytic oxidative coupling, classical optical resolution, kinetic enzymatic resolution of racemic mixture or regioselective modification of the binaphthol scaffold the following article is presented.

3

Utleniająca konwersja metanu w obecności O2 i CO2 na wybranych katalizatorach tlenkowych

Litawa B., Michorczyk P., Ogonowski J., Vogt O.

Czasopismo Techniczne. Chemia

|

2009

|

R. 106, z. 1-Ch

37-42

PL

Zbadano proces utleniającej konwersji metanu wobec mieszanek O2 z CO2 o składzie molowym: CH4:O2:CO2 = 7.5:2:0, 7.5:1.5:0.5, 7.5:1:1 i 7.5:0.5:1.5 w temperaturze 850°C. Do badań wytypowano nośnikowe tlenkowe katalizatory 2Mn/SiO2, 2La/SiO2 lub 5Na2WO4/SiO2 oraz mieszane tlenkowe katalizatory o składzie: 2Mn5Na2WO4/SiO2, 2La5Na2WO4/SiO2, 2La2Mn5Na2WO4/SiO2 (gdzie liczby w zapisie katalizatorów oznaczają udział w % mas. odpowiedniego metalu lub Na2WO4). Stwierdzono, że we wszystkich otrzymanych katalizatorach stopniowe zmniejszanie zawartości O2 w surowcu przez zastępowanie go CO2 wpływa na zwiększenie selektywności do węglowodorów C2 oraz na obniżenie stopnia konwersji metanu. Najwyższy wzrost selektywności do węglowodorów C2 stwierdzono w obecności katalizatora o składzie 2La2Mn5Na2WO4/SiO2.

EN

The oxidative coupling of methane in the presence of O2 and CO2 using mixtures with the molar ratio of CH4:O2:CO2=7.5:2:0, 7.5:1.5:0.5, 7.5:1:1 and 7.5:0.5:1.5 at 850°C was investigated. In the catalytic tests, 2Mn/SiO2, 2La/SiO2 and 5Na2WO4/SiO2 catalysts as well as mixed oxide 2Mn5Na2WO4/SiO2, 2La5Na2WO4/SiO2, 2La2Mn5Na2WO4/SiO2 catalysts were studied (where: the number in the description of catalyst represents a content in wt% of metal or Na2WO4). It has been found that replacement of O2 by CO2 leads to conversion of methane decrease, while in the same time the selectivity to C2 gradually raised. Over the 2La2Mn5Na2WO4/SiO2 the highest increase of selectivity to hydrocarbons C2 were observed.