20585-34-6Relevant articles and documents
Equilibrium studies on reactive extraction of α-cyclohexylmandelic enantiomers using hydrophilic β-Cyclodextrin derivatives extractants
Tang, Kewen,Miao, Jiabing,Liu, Yongbing,Zhou, Tao,Song, Litao
, p. 1444 - 1450 (2010)
β-Cyclodextrin (β-CD) is negligibly soluble in organic liquids and can be modified to achieve a higher solubility in water. In this paper, racemic α-cyclohexyl-mandelic acid (α-CHMA) was separated by chiral reactive extraction with aqueous β-cyclodextrin derivatives. Hydroxypropyl-β-cyclodextrin (HP-β-CD), hydroxyethyl-β- cyclodextrin (HE-β-CD), and methyl-β-cyclodextrin (Me-β-CD) were selected as chiral selectors for reactive extraction of α-CHMA enantiomers from organic phase to aqueous phase. Factors affecting the extraction efficiency were investigated, including the types of organic solvents and β-CD derivatives, the concentrations of the chiral selector and α-CHMA enantiomers, pH and temperature. The experimental results demonstrate that HP-β-CD, HE-β-CD, and Me-β-CD have stronger recognition abilities for S-α-CHMA than for R-α-CHMA. Among the three derivatives, HP-β-CD shows the strongest separation factor for α-CHMA enantiomers. A high enantioseparation efficiency with a maximum separation factor (α) of 2.02 is observed at pH 2.5 and 5 °C.
Isothiourea-Catalyzed Acylative Kinetic Resolution of Tertiary α-Hydroxy Esters
Greenhalgh, Mark D.,Laina-Martín, Víctor,Neyyappadath, Rifahath M.,Qu, Shen,Smith, Andrew D.,Smith, Samuel M.
supporting information, p. 16572 - 16578 (2020/09/09)
A highly enantioselective isothiourea-catalyzed acylative kinetic resolution (KR) of acyclic tertiary alcohols has been developed. Selectivity factors of up to 200 were achieved for the KR of tertiary alcohols bearing an adjacent ester substituent, with both reaction conversion and enantioselectivity found to be sensitive to the steric and electronic environment at the stereogenic tertiary carbinol centre. For more sterically congested alcohols, the use of a recently-developed isoselenourea catalyst was optimal, with equivalent enantioselectivity but higher conversion achieved in comparison to the isothiourea HyperBTM. Diastereomeric acylation transition state models are proposed to rationalize the origins of enantiodiscrimination in this process. This KR procedure was also translated to a continuous-flow process using a polymer-supported variant of the catalyst.
Nitrilases, nucleic acids encoding them and methods for making and using them
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Page/Page column 53; 60, (2016/01/09)
The invention relates to nitrilases and to nucleic acids encoding the nitrilases. In addition methods of designing new nitrilases and method of use thereof are also provided. The nitrilases have increased activity and stability at increased pH and temperature.
Enantioseparation of mandelic acid and α-Cyclohexylmandelic acid using an alcohol/salt-based aqueous two-Phase system
Li, Fen-Fang,Tan, Zhi-Jian,Guo, Zhi-Feng
, p. 1539 - 1545 (2015/02/19)
An alcohol/salt-based aqueous two-phase system (ATPS) was employed for enantioseparation of (R,S)-mandelic acid (MA) and (R,S)-a-cyclohexylmandelic acid (a-CHMA). Sulfonated β-cyclodextrin (Sf-β-CD) with different degrees of substitution (DS) was consider