Mosher's acid

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Mosher's acid
R and S MTPA
General
Systematic name	(R/S)-3,3,3-trifluoro-2- methoxy-2-phenylpropanoic acid
Other names	Methoxytrifluorophenylaceticacid, MTPA
Molecular formula	C₁₀H₉F₃O₃
SMILES	COC(C(O)=O)(c1ccccc1)C(F)(F)F
Molar mass	234.17
Appearance	? solid
CAS number	[20445-31-2](R), [17257-71-5](S), [81655-41-6] racemic
Properties
Density and phase	1.303 g/mL, liquid
Solubility in water	? g/100 ml (?°C)
Melting point	46-49°C (? K)
Boiling point	105 - 107 °C 1 torr
Acidity (pK_a)	?
Basicity (pK_b)	?
Chiral rotation [α]_D	+73° (R) -73° (s)
Viscosity	? cP at ?°C
Structure
Dipole moment	? D
Hazards
MSDS	External MSDS
Main hazards	?
NFPA 704
Flash point	110°C
R/S statement	R: R36/37/38 S: Template:S26-36
RTECS number	?
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related ?	Mosher's acid chloride
Related compounds	?
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. 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 of unknown stereochemistry to form an ester or amide. The 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.

[edit] References

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.
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.
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.
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.
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.