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CAS 63547-22-8 Modafinil/Armodafinil Impurity Modafinil/Armodafinil Impurity High Purity GMP Grade

2-Diphenyl Methyl Thioacetic Acid

IUPAC: 2-[(Diphenylmethyl)thio]acetic acid View on PubChem
CAS NUMBER
63547-22-8
MOL. FORMULA
C15H14O2S
MOL. WEIGHT
258.34 g/mol
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Scientific Overview

This compound is the carboxylic acid analog of the modafinil thioether intermediate family --- structurally positioned between the amide (diphenylmethyl thioacetamide) and the fully oxidized sulfinyl acid (modafinil acid/modafinilic acid) in the synthetic and metabolic pathway. It is closely related to modafinil acid (2-[(diphenylmethyl)sulfinyl]acetic acid, CAS 63547-24-0), differing by the absence of sulfoxide oxygen, and is monitored as a specified impurity in armodafinil quality control per regulatory guidelines.

2-(Diphenylmethyl)thioacetic acid (also known as benzhydrylthioacetic acid) is a thioether carboxylic acid that serves as both a synthetic intermediate and a recognized pharmacopeial impurity in the manufacture of modafinil and armodafinil, the wakefulness-promoting agents used to treat narcolepsy, sleep apnea-related excessive sleepiness, and shift work disorder.

Full Technical Data
Chemical Name 2-(Diphenylmethyl)thioacetic Acid (Benzhydrylthioacetic Acid)
CAS Number 63547-22-8
IUPAC Name 2-[(Diphenylmethyl)thio]acetic acid
Molecular Formula C15H14O2S
Molecular Weight 258.34 g/mol g/mol
Reaction Scheme
Diphenylmethyl Thioacetamide (or Benzhydryl Mercaptan
Chloroacetic Acid)
NA
2-(Diphenylmethyl)thioacetic Acid
NA
Commercial Applications

Modafinil/Armodafinil Impurity Reference Standard

Used for pharmacopeial impurity testing and quality control of armodafinil drug substance.

Analytical Method Development

Reference material for HPLC method development and validation (AMV) supporting ANDA submissions.

API Process Chemistry

Intermediate in synthetic routes toward modafinil acid and downstream modafinil/armodafinil manufacturing.

Bioanalytical Research

Used in chromatographic method studies for quantifying modafinil-related compounds in biological matrices.

Market Therapeutic Focus
MODAFINIL/ARMODAFINIL IMPURITY PHARMACEUTICAL MANUFACTURING CNS / WAKEFULNESS-PROMOTING THERAPEUTICS ANALYTICAL REFERENCE STANDARDS API PROCESS CHEMISTRY CRO/CDMO
Scientific Literature

Determination of Modafinil Enantiomers and Related Substances by Achiral-Chiral Chromatography

Authors: Cass, Q.B.; Ferreira Galatti, T.

J. Pharm. Biomed. Anal.

DOI: 10.1016/j.jpba.2007.02.024

Synthesis and Structure-Activity Relationships of Modafinil Analogs

Authors: Stark, H. et al.

Eur. J. Med. Chem.

DOI: 10.1016/0223-5234(94)90079-5

Adjunct Armodafinil Improves Wakefulness and Memory in Obstructive Sleep Apnea/Hypopnea Syndrome

Authors: Various

Respir. Med.

DOI: 10.1016/j.rmed.2006.06.007
Peer Queries & FAQs
How does this compound relate to modafinil acid?
It is the non-oxidized thioether precursor to modafinil acid (modafinilic acid); oxidation of the sulfur atom converts the thioether to the sulfinyl group present in the active metabolite.
Is this the same as the thioacetamide intermediate?
No --- this is the carboxylic acid form (thioacetic acid), distinct from diphenylmethyl thioacetamide (the amide form, CAS 68524-30-1), though both belong to the same modafinil synthetic family.
Why is it used in regulatory submissions?
As a characterized impurity reference standard, it supports analytical method validation (AMV) and quality control testing required for ANDA filings on armodafinil/modafinil products.
What is the recommended storage condition?
Store in a tightly sealed container at room temperature (or +20°C as specified by supplier), protected from light and moisture.

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