Mosher's_acid

Mosher's acid

Mosher's acid

Chemical compound


Mosher's acid, or α-methoxy-α-trifluoromethylphenylacetic acid (MTPA) is a carboxylic acid which was first used by Harry Stone Mosher as a chiral derivatizing agent.[1][2][3][4] It is a chiral molecule, consisting of R and S enantiomers.

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Applications

As a chiral derivatizing agent, it reacts with an alcohol or amine[5] of unknown stereochemistry to form an ester or amide. The absolute configuration of the ester or amide is then determined by proton and/or 19F NMR spectroscopy.

Mosher's acid chloride, the acid chloride form, is sometimes used because it has better reactivity.[6]

See also


References

  1. J. A. Dale; D. L. Dull; H. S. Mosher (1969). "α-Methoxy-α-trifluoromethylphenylacetic acid, a versatile reagent for the determination of enantiomeric composition of alcohols and amines". Journal of Organic Chemistry. 34 (9): 2543–2549. doi:10.1021/jo01261a013.
  2. J. A. Dale; H. S. Mosher (1973). "Nuclear magnetic resonance enantiomer regents. Configurational correlations via nuclear magnetic resonance chemical shifts of diastereomeric mandelate, O-methylmandelate, and α-methoxy-α-trifluoromethylphenylacetate (MTPA) esters". Journal of the American Chemical Society. 95 (2): 512–519. doi:10.1021/ja00783a034.
  3. Y. Goldberg; H. Alper (1992). "A new and simple synthesis of Mosher's acid". Journal of Organic Chemistry. 57 (13): 3731–3732. doi:10.1021/jo00039a043.
  4. D. L. Dull; H. S. Mosher (1967). "Aberrant rotatory dispersion curves of α-hydroxy- and α-methoxy-α-trifluoromethylphenylacetic acids". Journal of the American Chemical Society. 89 (16): 4230. doi:10.1021/ja00992a053.
  5. See for example: Mosher Amides: Determining the Absolute Stereochemistry of Optically-Active Amines Allen, Damian A.; Tomaso, Anthony E., Jr.; Priest, Owen P.; Hindson, David F.; Hurlburt, Jamie L. J. Chem. Educ. 2008, 85, 698. Abstract
  6. D. E. Ward; C. K. Rhee (1991). "A simple method for the microscale preparation of Mosher's acid chloride". Tetrahedron Letters. 32 (49): 7165–7166. doi:10.1016/0040-4039(91)80466-J.

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