Chirality Switching in Optical Resolution of Mandelic Acid in C1–C4 Alcohols: Elucidation of Solvent Effects Based on X-ray Crystal Structures of Diastereomeric Salts

2014 ◽  
Vol 14 (7) ◽  
pp. 3549-3556 ◽  
Author(s):  
Koichi Kodama ◽  
Hiroaki Shitara ◽  
Takuji Hirose
Keyword(s):  
Crystal Structures ◽  
Solvent Effects ◽  
Mandelic Acid ◽  
Optical Resolution ◽  
X Ray ◽  
Diastereomeric Salts

scholarly journals Microwave-Assisted Synthesis of(±)-Mandelic Acid-d5, Optical Resolution, and Absolute Configuration Determination

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Claudio Bruno ◽  
Giovanni Lentini ◽  
Angelo Lovece ◽  
Maria Maddalena Cavalluzzi ◽  
Alessia Carocci ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Mandelic Acid ◽  
Optical Resolution ◽  
Racemic Mixture ◽  
Microwave Assisted Synthesis ◽  
Salt Formation ◽  
Microwave Assisted ◽  
Diastereomeric Salts ◽  
Chiral Capillary Electrophoresis ◽  
Resolving Agents

An efficient microwave-assisted synthesis of(±)-mandelic acid-d5was developed. The racemic mixture was resolved by diastereomeric salt formation using 1-phenylethylamine enantiomers as resolving agents. At each step, the resolution process was checked by determining mandelic acid-d5enantiomer ee values directly on fractional crystallized diastereomeric salts by chiral capillary electrophoresis analysis. Highly enriched (−)- and (+)-mandelic acid-d5(95% and 90% ee, resp.) were obtained and their absolute configurations—RandS, respectively—were determined by correlation of the (−)-mandelic acid-d5circular dichroism spectrum to the (R)-mandelic acid one.

Selten-Erd-Mandelate. Synthese und Kristallstrukturen von Pr(Man)3(ManH) und Er(Man)3(H2O)2 / Synthesis and Crystal Structures of Pr(Man)3(ManH) and Er(Man)3(H2O)2

2005 ◽  
Vol 60 (7) ◽  
pp. 753-757 ◽  
Author(s):  
Claudia Bromant ◽  
Wassiliki Nika ◽  
Ingo Pantenburg ◽  
Gerd Meyer
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Mandelic Acid ◽  
Hydroxyl Group ◽  
Water Molecules ◽  
X Ray ◽  
Carboxylate Oxygen ◽  
Rare Earth Salts ◽  
Alcoholic Hydroxyl ◽  
Oxygen Atoms

Pr(Man)3(ManH) and Er(Man)3(H2O)2 (ManH = mandelic acid) have been synthesized by slow evaporation of aqueous solutions of rare-earth salts (Pr(OH)3, ErCl3 · 6H2O) with mandelic acid (α-hydroxy-phenyl acetic acid, C8H8O3) and their crystal structures were determined on the basis of X-ray data. In the crystal structure of Pr(Man)3(ManH) (1) (monoclinic, P21, a = 574.8(1), b = 3042.5(4), c = 908.4(1) pm, β = 92.09(2)°, Z = 2) the Pr(III) ions are surrounded by eight oxygen atoms in a distorted square antiprismatic fashion with distances Pr-O in the range 241 to 254 pm. These polyhedra are connected by coordinative bonds to chains paralleling the crystallographic [100] direction. In Er(Man)3(H2O)2 (2) (orthorhombic, P212121, a = 577.7(3), b = 1816.3(13), c = 2329.4(13) pm, Z = 4) the crystal structure contains isolated complexes with octa-coordinated erbium atoms chelated by three mandelate anions through one of their carboxylate oxygen atoms and the alcoholic hydroxyl group. Two water molecules complete the distorted square antiprismatic coordination sphere.

A Study of Diastereomeric Mandelate Salts of Cinchonidine and the Relation to Their Quasidiastereomeric Analogues

1997 ◽  
Vol 53 (4) ◽  
pp. 708-718 ◽  
Author(s):  
A. Gjerløv ◽  
S. Larsen
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Mandelic Acid ◽  
Crystal Packing ◽  
Steric Effects ◽  
Quinoline Ring ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diastereomeric Salts ◽  
Vinyl Group

The crystal structures have been determined for the diastereomeric salts formed by cinchonidine and the two enantiomers of mandelic acid using low-temperature [122 (1) K] X-ray diffraction data. The less soluble salt is cinchonidinium (S)-mandelate, C19H23N20O+.C8H7O3 −, M r = 446.53, monoclinic, C2, a = 21.400 (2), b = 6.2777 (6), c = 17.853 (2) Å3, \beta = 109.304 (8)°, V = 2263.6 (4) Å3, Z = 4, D x = 1.310 g cm−3, \lambda(Cu K\alpha = 1.54184 Å, Z = 7.08 cm−1, F(000) = 952, R 1 = 0.0259 for 2684 observed reflections. The cinchonidine salt with (R)-mandelic acid, C19H23N2O+.C8H7O3, has M r = 446.53, monoclinic, P21, a = 6.410 (3), b = 32.808 (11), c = 11.222 (2) Å, \beta = 100.67 (2)°, V = 2319.2 (13) Å3, Z = 4, D x = 1.279 g cm−3, \lambda(Cu K\alpha) = 1.54184 Å, \mu = 6.91 cm−1, F(000) = 952, R 1 = 0.0380 for 8951 observed reflections. The two salts have virtually identical hydrogen-bond patterns and similar herringbone stacking of the quinoline ring systems. The crystal packing of the two salts differ only with respect to the packing of the phenyl groups. The packing of the cinchonidinium mandelates is significantly different from the crystal packing in the corresponding mandelates of cinchonine. The lack of a quasidiastereomeric relationship between the two sets of salts can be attributed to the steric effects of the vinyl group. The similarities between the two cinchonidinium mandelate structures is a possible explanation to the similar solubilities of the salts. DSC and NMR measurements showed that the cinchonidinium salts undergo a chemical opening reaction in the solid state. The arrangement of hydrogen-bonded chains of alternating cations and anions appear to be important for the solid-state reaction to take place.

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