Mosher's acid

Mosher's acid

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Names
IUPAC names (R)-3,3,3-trifluoro-2- methoxy-2-phenylpropanoic acid (S)-3,3,3-trifluoro-2- methoxy-2-phenylpropanoic acid
Other names Methoxy(trifluoromethyl)phenylacetic acid, MTPA
Identifiers
CAS Number	81655-41-6 (racemic) 20445-31-2 (R) 17257-71-5 (S)
ChemSpider	78043
Jmol 3D model	Interactive image
InChI InChI=1S/C10H9F3O3/c1-16-9(8(14)15,10(11,12)13)7-5-3-2-4-6-7/h2-6H,1H3,(H,14,15) Key: JJYKJUXBWFATTE-UHFFFAOYSA-N InChI=1/C10H9F3O3/c1-16-9(8(14)15,10(11,12)13)7-5-3-2-4-6-7/h2-6H,1H3,(H,14,15) Key: JJYKJUXBWFATTE-UHFFFAOYAJ
SMILES COC(C(O)=O)(c1ccccc1)C(F)(F)F
Properties
Chemical formula	C10H9F3O3
Molar mass	234.17
Appearance	solid
Melting point	46 to 49 °C (115 to 120 °F; 319 to 322 K)
Boiling point	105 to 107 °C (221 to 225 °F; 378 to 380 K) at 1 torr
Vapor pressure	{{{value}}}
Related compounds
Related acyl chloride	Mosher's acid chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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. It is a chiral molecule, consisting of R and S enantiomers.

Applications

As a chiral derivatizing agent, it reacts with an alcohol or amine 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.