By using acetonitrile as the sole nitrogen source, a microbial strain with high nitrilase activity, named as Alcaligenes sp. ECU0401, was newly isolated from soil, which could enantioselectively transform racemic mand...By using acetonitrile as the sole nitrogen source, a microbial strain with high nitrilase activity, named as Alcaligenes sp. ECU0401, was newly isolated from soil, which could enantioselectively transform racemic mandelonitrile into (R)-(?)-mandelic acid, with an enantiomeric excess of >99.9%.展开更多
Soy protein isolate(SPI)biopolymeric films were prepared by adding different contents of mandelic acid(1 to 5%wrt SPI)to glycerol plasticized SPI by solution casting method.Also,SPI was fermented by Bacillus subtilis ...Soy protein isolate(SPI)biopolymeric films were prepared by adding different contents of mandelic acid(1 to 5%wrt SPI)to glycerol plasticized SPI by solution casting method.Also,SPI was fermented by Bacillus subtilis to get fermented SPI films by solution casting.Molecular mass determination of mandelic acid incorporated and fermented SPI films was carried out by sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE).Mandelic acid incorporated and fermented SPI films were characterized by Fourier-transform infrared spectroscopy(FT-IR),dynamic mechanical analysis(DMA),tensile strength,water uptake and optical transmittance studies.Results indicated that incorporation of mandelic acid in SPI resulted in high tensile strength(8.03 MPa)and highα-relaxation(Tα)as well as low water uptake.On the other hand,films cannot be prepared from fermented SPI with SPI contents of 8%and 12%.However,film from fermented SPI with 16%SPI content could be prepared but it exhibited low tensile strength(3.18 MPa)and low Tαas well as high water uptake.The resulting mandelic acid incorporated SPI films were also subjected to antimicrobial studies.At all the concentration of mandelic acid,we can easily observe the antimicrobial effect in mandelic acid incorporated SPI films unlike fermented SPI films.This work will be helpful in fabricating antimicrobial SPI film from renewable resources.展开更多
Based on the chiral ligand exchange, the distribution behavior of mandelic acid enantiomers, and the partition of Cu2+ at different pH values were studied in a water/alcohol two-phase system containing Cu2+ and N-n-（...Based on the chiral ligand exchange, the distribution behavior of mandelic acid enantiomers, and the partition of Cu2+ at different pH values were studied in a water/alcohol two-phase system containing Cu2+ and N-n-（dodecyl-L-proline（A）.） The influences of the solvent sort, the pH value, the concentrations of Cu2+ and chiral ligand on the partition coefficient（K） and separation factor（α） were discussed. The experimental results show that the A formed has more stable ternary complex with D-mandelic acid enantiomer than with L-mandelic acid enantiomer. There is an important influence of the pH value on K and α. When the pH values are less than 3.5, the formation of binary complexes is thermodynamically unfavourable. K and α become maximum when pH values are above 3.5 and the molar ratio of the chiral ligand to Cu2+ is 2∶1.展开更多
The racemic phenylalanine has been separated by (R)-mandelic acid through the formation of diastereomeric molecular complex. The crystal of the title chiral complex (C8H8O3 C9H11NO2, Mr = 317.33) belongs to monoclinic...The racemic phenylalanine has been separated by (R)-mandelic acid through the formation of diastereomeric molecular complex. The crystal of the title chiral complex (C8H8O3 C9H11NO2, Mr = 317.33) belongs to monoclinic, space group C2 with a = 19.391(3), b = 5.715(4), c = 15.755(3) ? b = 115.23(1), V = 1579(1) 3, Z = 4, Dc = 1.335 g/cm3, F(000) = 672, m = 0.099 mm-1, R = 0.033 and wR = 0.060 for 1278 observed reflections (I > 2s(I)). The complex consists of (R)-mandelic acid and (R)-phenylalanine in 1:1 molar ratio, and the complex molecules form layered crystal structure by self-assembly through intermolecular H-bonding between carboxyl and carboxylate of the neighboring molecules.展开更多
Mandelic acid is an enantiomer of interest in many areas,in particular for the pharmaceutical industry.One of the approaches to produce enantiopure mandelic acid is through crystallization from an aqueous solution.We ...Mandelic acid is an enantiomer of interest in many areas,in particular for the pharmaceutical industry.One of the approaches to produce enantiopure mandelic acid is through crystallization from an aqueous solution.We propose in this study a numerical tool based on lattice Boltzmann simulations to model crystallization dynamics of(S)-mandelic acid.The solver is first validated against experimental data.It is then used to perform parametric studies concerning the effects of important parameters such as supersaturation and seed size on the growth rate.It is finally extended to investigate the impact of forced convection on the crystal habits.Based on there parametric studies,a modification of the reactor geometry is proposed that should reduce the observed deviations from symmetrical growth with a five-fold habit.展开更多
The stereospecific hydrolysis of mandelate can be effectively catalyzed by hyperthermophilic acylpeptide esterase APE 1547（Aeropyrum pernix esterase 1547）. APE 1547 used in this reaction showed a remarkable stereodi...The stereospecific hydrolysis of mandelate can be effectively catalyzed by hyperthermophilic acylpeptide esterase APE 1547（Aeropyrum pernix esterase 1547）. APE 1547 used in this reaction showed a remarkable stereodi-scrimination in favour of R-mandelic acid（99% e.e.） with an enantiomeric ratio E〉200. The results of computer simulation are consistent with the experimental results. It can be inferred that the R-substrate adopted a binding mode productive of the reaction due to the formation of the hydrogen bond at the active site of APE 1547.展开更多
A new liquid chromatographic method has been developed for the chiral separation of the enantiomers of mandelic acid and their derivatives 2-chloromandelic acid, 4-hydroxymandelic acid, 4-methoxymandelic acid, and 3,4...A new liquid chromatographic method has been developed for the chiral separation of the enantiomers of mandelic acid and their derivatives 2-chloromandelic acid, 4-hydroxymandelic acid, 4-methoxymandelic acid, and 3,4,5-trismethoxymandelic acid. The enantiomers were separated by a CHIRALPAKIC (250 mm×4.6 mm, 5 μm). Mandelic acid, 4-methoxymandelic acid, and 3,4,5-trismethoxymandelic acid were baseline resolved (resolution factor (RS )=2.21, RS =2.14, and RS =3.70, respectively). In contrast, the enantioselectivities between CHIRALPAKIC and 2-chloromandelic acid and 4-hydroxymandelic acid investigated were low. By comparing the chromatographs of mandelic acid enantiomers and mandelic acid spiked with (R)-mandelic acid, it was determined that the first effluent was (R)-mandelic acid.展开更多
This paper presents a new chiral separation technology:two-phase(O/W)recognition chiral extraction.Distribution behavior of alpha-cyclohexyl-mandelic acid enantiomers was studied in the extraction system with D(L)-iso...This paper presents a new chiral separation technology:two-phase(O/W)recognition chiral extraction.Distribution behavior of alpha-cyclohexyl-mandelic acid enantiomers was studied in the extraction system with D(L)-isobutyl tartrate in 1,2-dichloroethane organic phase and beta-CD derivatives in aqueous phase,and the influence of the kind and concentration of extractant and pH on extraction performance was investigated.The experimental results indicate that two-phase(O/W)recognition chiral extraction is of strong chiral separation ability.HP-^-CD,HE-beta-CD and Me-beta-CD have higher recognition ability for S-CHMA than that for R-CHMA,among which HP-beta-CD has the strongest ability;whereas,D-isobutyl tartrate has reversed recognition ability for them.In the extraction system containing HP-beta-CD and D-isobutyl tartrate,e.e.% of S-CHMA in aqueous phase reached 27.6% by one stage extraction,and the distribution ratio for R-CHMA(k_R)and for S-CHMA(k_S)and separation factor(alpha)are 2.44,0.89 and 2.49,respectively.Meanwhile,pH and concentration of extractant have great effects on chiral separation ability.Two-phase(O/W)recognition chiral extraction has great significance for preparative separation of racemic compounds.展开更多
The Eu^3＋ complexes with S（＋）-mandelic acid were synthesized in the form of powders by mixing aqueous solutions of EuCl3, S（＋）-mandelic acid and NaOH in different molar ratios. The powders were characterized by...The Eu^3＋ complexes with S（＋）-mandelic acid were synthesized in the form of powders by mixing aqueous solutions of EuCl3, S（＋）-mandelic acid and NaOH in different molar ratios. The powders were characterized by elemental analysis, X-ray powder diffraction （XRPD.） method, Fourier transform infrared （FTIR） and Raman spectroscopy, UV-vis reflectance and luminescence spectra as well as luminescence lifetime measurements. It was found that all studied powders of Eu^3＋ complexes with S（＋）-mandelic acid were isostructural and crystalline and formed compounds with the formula Eu（Man）3（H2O）2.展开更多
文摘By using acetonitrile as the sole nitrogen source, a microbial strain with high nitrilase activity, named as Alcaligenes sp. ECU0401, was newly isolated from soil, which could enantioselectively transform racemic mandelonitrile into (R)-(?)-mandelic acid, with an enantiomeric excess of >99.9%.
文摘Soy protein isolate(SPI)biopolymeric films were prepared by adding different contents of mandelic acid(1 to 5%wrt SPI)to glycerol plasticized SPI by solution casting method.Also,SPI was fermented by Bacillus subtilis to get fermented SPI films by solution casting.Molecular mass determination of mandelic acid incorporated and fermented SPI films was carried out by sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE).Mandelic acid incorporated and fermented SPI films were characterized by Fourier-transform infrared spectroscopy(FT-IR),dynamic mechanical analysis(DMA),tensile strength,water uptake and optical transmittance studies.Results indicated that incorporation of mandelic acid in SPI resulted in high tensile strength(8.03 MPa)and highα-relaxation(Tα)as well as low water uptake.On the other hand,films cannot be prepared from fermented SPI with SPI contents of 8%and 12%.However,film from fermented SPI with 16%SPI content could be prepared but it exhibited low tensile strength(3.18 MPa)and low Tαas well as high water uptake.The resulting mandelic acid incorporated SPI films were also subjected to antimicrobial studies.At all the concentration of mandelic acid,we can easily observe the antimicrobial effect in mandelic acid incorporated SPI films unlike fermented SPI films.This work will be helpful in fabricating antimicrobial SPI film from renewable resources.
基金Project(20376085) supported by the National Natural Science Foundation of China
文摘Based on the chiral ligand exchange, the distribution behavior of mandelic acid enantiomers, and the partition of Cu2+ at different pH values were studied in a water/alcohol two-phase system containing Cu2+ and N-n-（dodecyl-L-proline（A）.） The influences of the solvent sort, the pH value, the concentrations of Cu2+ and chiral ligand on the partition coefficient（K） and separation factor（α） were discussed. The experimental results show that the A formed has more stable ternary complex with D-mandelic acid enantiomer than with L-mandelic acid enantiomer. There is an important influence of the pH value on K and α. When the pH values are less than 3.5, the formation of binary complexes is thermodynamically unfavourable. K and α become maximum when pH values are above 3.5 and the molar ratio of the chiral ligand to Cu2+ is 2∶1.
基金The work was supported by the National Natural Science Foundation of China (29973036)
文摘The racemic phenylalanine has been separated by (R)-mandelic acid through the formation of diastereomeric molecular complex. The crystal of the title chiral complex (C8H8O3 C9H11NO2, Mr = 317.33) belongs to monoclinic, space group C2 with a = 19.391(3), b = 5.715(4), c = 15.755(3) ? b = 115.23(1), V = 1579(1) 3, Z = 4, Dc = 1.335 g/cm3, F(000) = 672, m = 0.099 mm-1, R = 0.033 and wR = 0.060 for 1278 observed reflections (I > 2s(I)). The complex consists of (R)-mandelic acid and (R)-phenylalanine in 1:1 molar ratio, and the complex molecules form layered crystal structure by self-assembly through intermolecular H-bonding between carboxyl and carboxylate of the neighboring molecules.
基金support by the EU-program ERDF(European Regional Development Fund)within the Research Center for Dynamic Systems(CDS).S.A.H.acknowledges the financial support of the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)in TRR 287(Project-ID 422037413).
文摘Mandelic acid is an enantiomer of interest in many areas,in particular for the pharmaceutical industry.One of the approaches to produce enantiopure mandelic acid is through crystallization from an aqueous solution.We propose in this study a numerical tool based on lattice Boltzmann simulations to model crystallization dynamics of(S)-mandelic acid.The solver is first validated against experimental data.It is then used to perform parametric studies concerning the effects of important parameters such as supersaturation and seed size on the growth rate.It is finally extended to investigate the impact of forced convection on the crystal habits.Based on there parametric studies,a modification of the reactor geometry is proposed that should reduce the observed deviations from symmetrical growth with a five-fold habit.
基金Supported by the National Natural Science Foundation of China(Nos.30870539, 21072075)the 38th Postdoctoral Foundation of China(No.801050321413)
文摘The stereospecific hydrolysis of mandelate can be effectively catalyzed by hyperthermophilic acylpeptide esterase APE 1547（Aeropyrum pernix esterase 1547）. APE 1547 used in this reaction showed a remarkable stereodi-scrimination in favour of R-mandelic acid（99% e.e.） with an enantiomeric ratio E〉200. The results of computer simulation are consistent with the experimental results. It can be inferred that the R-substrate adopted a binding mode productive of the reaction due to the formation of the hydrogen bond at the active site of APE 1547.
文摘A new liquid chromatographic method has been developed for the chiral separation of the enantiomers of mandelic acid and their derivatives 2-chloromandelic acid, 4-hydroxymandelic acid, 4-methoxymandelic acid, and 3,4,5-trismethoxymandelic acid. The enantiomers were separated by a CHIRALPAKIC (250 mm×4.6 mm, 5 μm). Mandelic acid, 4-methoxymandelic acid, and 3,4,5-trismethoxymandelic acid were baseline resolved (resolution factor (RS )=2.21, RS =2.14, and RS =3.70, respectively). In contrast, the enantioselectivities between CHIRALPAKIC and 2-chloromandelic acid and 4-hydroxymandelic acid investigated were low. By comparing the chromatographs of mandelic acid enantiomers and mandelic acid spiked with (R)-mandelic acid, it was determined that the first effluent was (R)-mandelic acid.
基金Supported by the National Natural Science Foundation of China (Grant No. 20776038)
文摘This paper presents a new chiral separation technology:two-phase(O/W)recognition chiral extraction.Distribution behavior of alpha-cyclohexyl-mandelic acid enantiomers was studied in the extraction system with D(L)-isobutyl tartrate in 1,2-dichloroethane organic phase and beta-CD derivatives in aqueous phase,and the influence of the kind and concentration of extractant and pH on extraction performance was investigated.The experimental results indicate that two-phase(O/W)recognition chiral extraction is of strong chiral separation ability.HP-^-CD,HE-beta-CD and Me-beta-CD have higher recognition ability for S-CHMA than that for R-CHMA,among which HP-beta-CD has the strongest ability;whereas,D-isobutyl tartrate has reversed recognition ability for them.In the extraction system containing HP-beta-CD and D-isobutyl tartrate,e.e.% of S-CHMA in aqueous phase reached 27.6% by one stage extraction,and the distribution ratio for R-CHMA(k_R)and for S-CHMA(k_S)and separation factor(alpha)are 2.44,0.89 and 2.49,respectively.Meanwhile,pH and concentration of extractant have great effects on chiral separation ability.Two-phase(O/W)recognition chiral extraction has great significance for preparative separation of racemic compounds.
文摘The Eu^3＋ complexes with S（＋）-mandelic acid were synthesized in the form of powders by mixing aqueous solutions of EuCl3, S（＋）-mandelic acid and NaOH in different molar ratios. The powders were characterized by elemental analysis, X-ray powder diffraction （XRPD.） method, Fourier transform infrared （FTIR） and Raman spectroscopy, UV-vis reflectance and luminescence spectra as well as luminescence lifetime measurements. It was found that all studied powders of Eu^3＋ complexes with S（＋）-mandelic acid were isostructural and crystalline and formed compounds with the formula Eu（Man）3（H2O）2.
