Branco, Luis C.; Afonso, Carlos A. M. published the artcile< Ionic Liquids as a Convenient New Medium for the Catalytic Asymmetric Dihydroxylation of Olefins Using a Recoverable and Reusable Osmium/Ligand>, Quality Control of 112-63-0, the main research area is diol vicinal asym synthesis; alkene Sharpless asym dihydroxylation osmium catalyst ionic liquid solvent; ionic liquid cosolvent osmium catalyzed Sharpless asym dihydroxylation kinetics.
The use of room-temperature ionic liquids (RTILs) in the Sharpless catalytic asym. dihydroxylation (AD) as a cosolvent or replacement of the tert-butanol was studied in detail by screening 11 different RTILs. The AD reaction is faster in 1-n-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] as a cosolvent than in the conventional system of tert-butanol/H2O. For the range of six substrates tested, comparable or even higher yields and enantiomeric excess (ee) were found using [C4mim][PF6] or 1-n-octyl-3-methylimidazolium hexafluorophosphate [C8mim][PF6] compared to the conventional solvent system. Due to high affinity of the catalytic osmium/chiral ligand system to the ionic liquid, the use of ionic liquid/water (biphasic) or ionic liquid/water/tert-butanol (monophasic) solvent systems provides a recoverable, reusable, robust, efficient, and simple system for the AD reaction. On dihydroxylation of 1-hexene using [C4mim][PF6] as RTIL, it was possible to reuse the catalytic system for 9 cycles with only a 5% of yield reduction from the first cycle, allowing an overall yield of 87%, TON = 1566, and with similar ee. Addnl., for each cycle, after extraction of the reaction mixture with di-Et ether, the osmium content in the organic phase (containing the AD product) and in the aqueous phase was in the range of the detection limit (é?%, é? ppb) and 3-6% of initial amount, resp. In contrast, the ionic liquid phase retained more than 90% of the osmium content of the previous cycle.
Journal of Organic Chemistry published new progress about Alkenes Role: RCT (Reactant), RACT (Reactant or Reagent). 112-63-0 belongs to class esters-buliding-blocks, and the molecular formula is C19H34O2, Quality Control of 112-63-0.
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics