Thioglycolic Acid (TGA) CAS 68-11-1

Thioglycolic Acid (TGA) – Versatile Reducing Agent for Cosmetics and Industry

Basic Information

• CAS Number: 68-11-1

• Molecular Formula: C₂H₄O₂S (HS‑CH₂‑COOH)

• Molecular Weight: 92.11 g/mol

• Appearance: Colorless to pale yellow oily liquid

• Odor: Pungent, characteristic mercaptan odor (detectable at 0.1 ppm)

• Density: 1.325 g/mL at 25°C

• Melting Point: –16°C

• Boiling Point: 229–232°C (decomposes)

• Flash Point: 138°C

• Solubility: Miscible with water, alcohols, acetone; limited solubility in hydrocarbons

• Packaging: 250 kg plastic drums or IBC containers

• UN/Class: UN1940 / Class 8 / Packing Group II

Overview
Thioglycolic acid (also known as mercaptoacetic acid, TGA) is a small α‑thiol carboxylic acid that has defined the era of cold chemical perms and cream depilatories. Its strong reducing power towards keratin disulfide bonds is combined with active complexation and anticorrosive functions, broadening its industrial applications.

Mechanism of Action
TGA reduces disulfide bonds (–S–S–) in keratin to thiol groups (–SH), weakening the hair shaft. At pH 9–9.5, this reaction reduces hair strength by up to 80% within 10 minutes. For permanent waving, the broken bonds are reformed to give hair a new shape. For depilation, the weakened hair is simply wiped away. The thiol group also forms stable complexes with metal ions such as Cu²⁺ and Fe³⁺.

Applications

• Cosmetics: Calcium and potassium thioglycolate salts used in cream depilatories and shaving lotions; ammonium thioglycolate used in cold permanent wave formulations.

• Chemical intermediate: Precursor for the production of thioglycolates (ammonium, sodium, calcium, potassium salts) used in various industrial processes.

• Bacteriology: Used in the preparation of thioglycolate media for anaerobic bacterial culture.

• Indicator and analysis: Used as an acidity indicator and in the study of condensed tannins via thioglycolysis reactions.

• Corrosion inhibition: Functions as an anticorrosive agent in HCl pickling systems.

• Mining: Acts as a collector reagent in Cu/Mo ore flotation.

• Semiconductor industry: Used in etching of oxides on silicon wafers.

• Nanotechnology: SH‑anchor for modifying gold nanoparticles in biosensor development.

Reactivity

• The thiol group is readily oxidized to disulfide.

• Forms stable salts with metals (Group I and II).

• Complexes with Cu(II), Fe(III) – used in chelate dye systems.

Toxicity and Safety

• Oral LD₅₀ (rat): 55 mg/kg

• Classification: Skin Corrosive 1B

• Avoid strong oxidizers and strong acids.

• Store in a cool, dry place in tightly sealed containers.

• Use appropriate personal protective equipment (gloves, safety goggles, protective clothing) when handling.

• In case of skin contact, wash thoroughly with soap and water.

Quality Assurance
Each batch is tested for purity, density, and acid value to ensure consistent quality.