Mosher's acid

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Mosher's acid
IUPAC name (R/S)-3,3,3-trifluoro-2-
methoxy-2-phenylpropanoic acid
Other names Methoxytrifluorophenylaceticacid, MTPA
Identifiers
CAS number [20445-31-2](R), [17257-71-5](S),
[81655-41-6] racemic
SMILES COC(C(O)=O)(c1ccccc1)C(F)(F)F
Properties
Molecular formula C10H9F3O3
Molar mass 234.17
Appearance solid
Melting point

46-49°C (? K)
Boiling point

105 - 107 °C at 1 torr
Hazards
R-phrases R36/37/38
S-phrases Template:S26-36
Flash point 110°C
Related compounds
Related ? Mosher's acid chloride
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Mosher's acid, or α-methoxytrifluorophenylacetic acid is a carboxylic acid which was first by Harry S. Mosher used as a chiral derivitizing agent [1] [2] [3] [4]. It is a chiral molecule, consisting of R and S enantiomers.

[edit] Applications

As a chiral derivitizing 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 NMR spectroscopy.

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

[edit] 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): 4230–4230. 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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