133721-87-6Relevant articles and documents
Structures of Racemic Monofluoro-Substituted Mandelic Acids, Their Relation to the Thermochemical Properties and an Analysis of Short Intermolecular Fluorine-Carbon Contacts
Larsen, Sine,Marthi, Katalin
, p. 373 - 381 (1994)
The structures of the three monofluoro-substituted mandelic acids (C8H7FO3, Mr=170.14) have been determined from low-temperature X-ray diffraction data . o-Fluoromandelic acid, monoclinic, P21/c, a=8.4238 (12), b=5.4766 (7), c=15.959 (2) Angstroem, β=95.962 (11)o, V=732.3 (3) Angstroem3, Z=4, Dx=1.543 g cm-3, μ=11.25 cm-1, F(000)=352, R=0.040 for 1357 contributing reflections, m.p. 388.3 (5) K. m-Fluoromandelic acid (metastable modification), monoclinic, P21/a, a=10.8657 (14), b=9.2663 (10), c=15.722 (2) Angstroem, β=107.474 (10)o, V=1509.9 (6) Angstroem3, Z=8, Dx=1.497 g cm-3, μ=10.92 cm-1, F(000)=704, R=0.048 for 2977 contributing reflections, m.p. 368.4 (5) K. p-Fluoromandelic acid, orthorhombic, Pbca, a=9.4685 (9), b=16.497 (2), c=9.7677 (8) Angstroem, V=1525.7 (5) Angstroem3, Z=8, Dx=1.481 g cm-3, μ=10.80 cm-1, F(000)=704, R=0.042 for 1489 contributing reflections, m.p. 408.9 (5) K.The results obtained from the structure determination are related to their physico-chemical properties examined by differential scanning calorimetry (DSC).The DSC measurements showed that m-fluoromandelic acid is prepared as a metastable modification.The distortions of the angles of the benzene rings observed in the three acids are identical, within experimental error, to those predicted from the sum of the substituent effects.Hydrogen bonds are important for the crystal packing in all these structures, and in addition very short distances are observed in the ortho- and para-substituted acids between the F atom and the C atom of the carboxylic acid group.Semi-empirical calculations indicated that these short distances correspond to attractive electrostatic interactions.The carbon-fluorine interactions were also elucidated by a search in the Cambridge Structural Database. m-Fluoromandelic acid has the lowest melting enthalpy and entropy.This is consistent with the lack of C...F interactions and the presence of two molecules per asymmetric unit in this compound.The ortho and para acids which have similar intermolecular interactions have similar melting enthalpies and entropies, which are higher than those observed in m-fluoromandelic acid.
Synthesis of Acrylonitriles via Mild Base Promoted Tandem Nucleophilic Substitution-Isomerization of α-Cyanohydrin Methanesulfonates
Liu, Shiwen,Meng, Lingling,Zeng, Xiaojun,Hammond, Gerald B.,Xu, Bo
supporting information, p. 913 - 917 (2021/04/05)
Main observation and conclusion: We have developed an efficient synthesis of acrylonitriles via mild base promoted tandem nucleophilic substitution-isomerization of α-cyanohydrin methanesulfonates with alkenylboronic acids. This transition metal-free protocol works under simple and mild conditions and offers good chemical yields for a wide range of substrates and demonstrates good functional group tolerance. (Figure presented.).
Hydroxynitrile Lyase Isozymes from Prunus communis: Identification, Characterization and Synthetic Applications
Zheng, Yu-Cong,Xu, Jian-He,Wang, Hui,Lin, Guo-Qiang,Hong, Ran,Yu, Hui-Lei
, p. 1185 - 1193 (2017/04/13)
Biocatalysts originating from Badamu (Prunus communis) have been applied to catalyze the asymmetric synthesis of (R)-4-methylsulfanylmandelonitrile, a key building block of thiamphenicol and florfenicol. Here, four hydroxynitrile lyase (HNL) isozymes from Badamu were cloned and heterologously expressed in Pichia pastoris. The biochemical properties and catalytic performances of these isozymes were comprehensively explored to evaluate their efficiency and selectivity in asymmetric synthesis. Among then, PcHNL5 was identified with outstanding activity and enantioselectivity in asymmetric hydrocyanation. Under the optimized mild biphasic reaction conditions, seventeen prochiral aromatic aldehydes were converted to valuable chiral cyanohydrins with good yields (up to 94%) and excellent optical purities (up to >99.9% ee), which provide a facile access to numerous chiral amino alcohols, hypoglycemic agents, angiotension converting enzyme (ACE) inhibitors and β-blockers. This work therefore underlines the importance of discovering the most potent biocatalyst among a group of isozymes for converting unnatural substrates into value-added products. (Figure presented.).
