Ammonium carbamate type self-derivative salts of (R-)- and racemic α-methylbenzylamine

Madarász, János; Székely, Edit; Halász, József; Bánsághi, György; Varga, Dániel; Simándi, Béla; Pokol, György

doi:10.1007/s10973-011-2174-5

Cited by 9 publications

(10 citation statements)

References 28 publications

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“…The in situ resolution of CPA could not be realized using PhEA: no enantiomer selectivity was observed in the CO 2 phase; however, the raffinate yields were high varying between 82 % and 100 % with ee < 10 %. PhEA easily reacts with CO 2 by forming a carbamate‐type salt 10, however, XRD measurements showed that the formed compound is not the PhEA‐CO 2 carbamate. Thus, the obtained high yield and the low ee values indicate the nonselective formation of the diastereomer salt, i.e., PhEA reacts with both enantiomers.…”

Section: Resultsmentioning

confidence: 98%

Chiral Resolution of Racemic Cyclopropanecarboxylic Acids in Supercritical Carbon Dioxide

et al. 2014

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The chiral resolution of two racemic cyclopropanecarboxylic acids with the resolving agents (S)-2-(N-benzylamino)butan-1-ol and (R)-1-phenylethanamine was investigated. The resolutions were based on diastereomer salt crystallization in supercritical carbon dioxide. Unreacted compounds were removed by an extraction step. Experiments were performed in a continuously stirred tank reactor and good enantioselectivities were obtained in a single step. Pressure, temperature, and density were found to strongly affect both the optical purity and the selectivity of the resolutions. The crystal structures of the formed diastereomer salts were also studied via X-ray diffraction.

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Section: Resultsmentioning

confidence: 98%

Chiral Resolution of Racemic Cyclopropanecarboxylic Acids in Supercritical Carbon Dioxide

et al. 2014

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“…7 c) and d)). They are compared to the diffractograms of 4-chloromandelic acid and the self-derivative carbamate-type salt that is formed from 1-phenylethanamine and carbon dioxide [27]. Based on the 2Θ angles and relative intensities of the characteristic peaks of the compounds, one can conclude that the possible carbamate-type by-product is not formed and that unreacted 4-chloromandelic acid cannot be found in the samples.…”

Section: Powder X-ray Diffractionmentioning

confidence: 99%

Gas Antisolvent Fractionation: A New Approach for the Optical Resolution of 4-chloromandelic Acid

Zodge

Kőrösi

Madarász

et al. 2019

Period. Polytech. Chem. Eng.

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A new, rapid optical resolution method of 4-chloromandelic acid is presented using (R)-1-phenylethanamine as the resolving agent. Gas antisolvent fractionation was investigated as the separation method, studying the effect of pressure, temperature and carbon dioxide to organic solvent mass ratio in details. Generally, the method offers green operation using supercritical carbon dioxide as the precipitative agent, and can be less time- and organic solvent-intensive than conventional processes. By upscaling, the possibility of controlling the crystal-morphology might also be improved. At 16 MPa, 40 °C and 7.5 carbon dioxide to methanol ratio 72 % enantiomeric excess was reached in the crystalline product, along a 73 % yield. The resolution efficiency was not affected by any of the operational parameters. Enantiomeric enrichment beyond 90 % can be carried out by repeated resolution of a scalemic mixture of the acid. Solid products were investigated using differential scanning calorimetry, powder X-ray diffraction and scanning electron microscopy confirming the formation of a crystalline (R)-1-phenylethanammonium-4-chloromandelate salt.

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“…Then the cell was sealed and pressurized with CO 2 by an ISCO 260D syringe pump (1). The injected mass of CO 2 was calculated from the volume change in the pump and with the CO 2 density obtained from NIST Chemistry Webbook 17 calculated with measured pressure and temperature conditions at (1). Pressure was increased by decreasing the cell volume at constant temperature until a homogeneous solution was observed.…”

Section: View Cell Experimentsmentioning

confidence: 99%

“…The carbamate formed by the carbon dioxide content of air and that formed in scCO 2 are similar. 17 If stirring is not applied, the formed solid saves the remaining liquid (R)-CHEA from being consumed by CO 2 . Neither (R)-CHEA nor its carbamate has any reasonable solubility in pure carbon dioxide.…”

Section: Determination Of Solubilitymentioning

confidence: 99%

Gas Antisolvent Approach for the Precipitation of α-Methoxyphenylacetic Acid – (R)-1-Cyclohexylethylamine Diateromeric Salt

Zodge

Kőrösi

Tárkányi

et al. 2017

Chem.Biochem.Eng.Q.

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One of the major drawbacks of diastereomeric salt precipitation based enantioseparation is the time and solvent requirement of crystallization. In the gas antisolvent (GAS) approach, supercritical carbon dioxide is applied as an antisolvent, and the precipitation takes place in a couple of minutes. By setting the process parameters diastereomeric excess, yields, and selectivity can be controlled. Applicability of the process is demonstrated on the resolution of racemic 2-methoxyphenylacetic acid with enantiopure (R)-(−)-1-cyclohexylethylamine. Diastereomeric excess values over 55 % along with 80 % yields were achieved at optimal conditions in a single step.

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Ammonium carbamate type self-derivative salts of (R-)- and racemic α-methylbenzylamine

Cited by 9 publications

References 28 publications

Chiral Resolution of Racemic Cyclopropanecarboxylic Acids in Supercritical Carbon Dioxide

Chiral Resolution of Racemic Cyclopropanecarboxylic Acids in Supercritical Carbon Dioxide

Gas Antisolvent Fractionation: A New Approach for the Optical Resolution of 4-chloromandelic Acid

Gas Antisolvent Approach for the Precipitation of α-Methoxyphenylacetic Acid – (R)-1-Cyclohexylethylamine Diateromeric Salt

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