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Send EmailPotassium Thioglycolate, Potassium Mercaptoacetate, Potassium Sulfanylacetate, 34452-51-2
POTASSIUM THIOGLYCOLATE
Potassium Mercaptoacetate / Potassium Sulfanylacetate / Thioglycolic Acid Potassium Salt
CAS Number: 34452-51-2
EC Number: 252-024-2
1. IDENTIFICATION
| Property | Information |
|---|---|
| Chemical Name | Potassium 2-sulfanylacetate (IUPAC) |
| Synonyms | Potassium thioglycolate, Potassium mercaptoacetate, Potassium sulfanylacetate, Thioglycolic acid potassium salt, Acetic acid, mercapto-, monopotassium salt |
| Chemical Formula | C₂H₃KO₂S |
| Molecular Weight | 130.21 g/mol |
| CAS Number | 34452-51-2 |
| EC Number (EINECS) | 252-024-2 |
| Appearance (Pure) | White to off-white crystalline powder (solid) |
| Appearance (Solution) | Colorless to pale pink clear to slightly hazy liquid |
| Odor | Characteristic pungent, unpleasant mercaptan (sulfur/rotten egg) odor |
2. CHEMICAL CLASSIFICATION & STRUCTURE
| Property | Information |
|---|---|
| Chemical Class | Organopotassium compound; Thiol (mercaptan) derivative |
| Related Compound | Thioglycolic acid (HS-CH₂-COOH) |
| Functional Group | Thiolate (-S⁻) – provides reducing activity |
| Ionic Character | Anionic (in aqueous solution) |
Dissociation in Water:
HS-CH₂-COOK + H₂O → K⁺ + ⁻S-CH₂-COO⁻
Mechanism of Action:
The thiolate group (-S⁻) reduces disulfide bonds (-S-S-) in keratin to thiol groups (-SH):
Keratin-S-S-Keratin + 2 ⁻S-CH₂-COO⁻ → 2 Keratin-S⁻ + ⁻OOC-CH₂-S-S-CH₂-COO⁻
This weakens the hair/fiber structure, allowing mechanical removal or reshaping.
3. PHYSICAL PROPERTIES
| Property | Pure Solid | 42% Solution (Typical Commercial) |
|---|---|---|
| Physical State (20°C) | Solid (crystalline powder) | Liquid |
| Appearance | White to off-white powder | Colorless to pale pink liquid |
| Odor | Strong mercaptan odor | Strong mercaptan odor |
| Melting Point | 226 – 229 °C (decomposes) | – |
| Density (20°C) | ~1.31 g/cm³ | ~1.311 g/cm³ (solution) |
| Solubility in Water | Very high (freely soluble) | Completely miscible |
| pH (solution) | – | Alkaline (basic) |
| Active Thioglycolic Acid Equivalent | ~100% | ~30% (in 42% solution) |
Commercial Solution Typical Specifications:
-
Concentration: 42% Potassium Thioglycolate in water
-
Active Thioglycolic Acid (TGA) Content: Approximately 30%
-
Color: Colorless to pale pink (pink indicates slight oxidation)
-
pH: 10 – 12 (alkaline)
4. CHEMICAL PROPERTIES
| Property | Information |
|---|---|
| Chemical Formula | C₂H₃KO₂S |
| Molecular Weight | 130.21 g/mol |
| Active Reducing Agent | Thiolate anion (⁻S-CH₂-COO⁻) |
| Redox Potential | Strong reducing agent |
| pH Stability | Stable in alkaline conditions; decomposes in strong acids (releases H₂S) |
| Oxidation Sensitivity | Oxidizes in air to form disulfide (dithiodiglycolate) |
| Light Sensitivity | Slightly sensitive; store in opaque containers |
| Incompatible Materials | Strong oxidizing agents, strong acids, metal ions (can form complexes) |
Oxidation Reaction:
text
2 HS-CH₂-COOK + [O] → KOOC-CH₂-S-S-CH₂-COOK + H₂O
5. PRODUCTION PROCESS
| Stage | Description |
|---|---|
| 1. Raw Materials | Thioglycolic acid (HS-CH₂-COOH) and potassium hydroxide (KOH) |
| 2. Neutralization Reaction | Thioglycolic acid is neutralized with potassium hydroxide in aqueous medium |
| 3. Reaction | HS-CH₂-COOH + KOH → HS-CH₂-COOK + H₂O |
| 4. Concentration | The solution is concentrated to desired strength (typically 42%) |
| 5. Filtration | The solution is filtered to remove impurities |
| 6. Stabilization | Antioxidants (e.g., sodium sulfite, EDTA) may be added to prevent oxidation |
| 7. Packaging | The solution is packaged under inert atmosphere (nitrogen) |
Note: Detailed industrial production information is typically proprietary.
6. COMPARISON: POTASSIUM vs CALCIUM THIOGLYCOLATE
| Property | Potassium Thioglycolate | Calcium Thioglycolate |
|---|---|---|
| Counter-ion | K⁺ | Ca²⁺ |
| CAS Number | 34452-51-2 | 814-71-1 |
| Solubility | Higher (more soluble in water) | Lower |
| Active TGA Equivalent (42% solution) | ~30% | ~35% (in 35% solution) |
| Cream Consistency | Generally thinner | Better (thicker, more stable cream) |
| Formulation Preference | Used in combination or for specific pH | Often preferred for creams |
| Typical Use | Depilatories, hair straighteners | Depilatories, hair straighteners |
| Odor | Strong mercaptan | Strong mercaptan |
Key Difference: Calcium thioglycolate is often preferred in cream formulations because it provides better consistency. Potassium thioglycolate has higher water solubility.
7. APPLICATIONS
7.1. Depilatory Products (Hair Removers) – Primary Use
| Product Type | Function |
|---|---|
| Depilatory Creams | Main active ingredient for removing unwanted body hair |
| Depilatory Aerosols | Foaming hair removal products |
| Depilatory Gels | Transparent hair removal products |
| Facial Depilatories | Gentle formulations for facial hair removal |
| Shower Depilatories | Hair removal products for use in shower |
Mechanism: The thioglycolate breaks disulfide bonds in keratin, weakening hair so it can be easily wiped or rinsed away.
Typical pH Range: 11 – 12.5
Typical Application Time: 5 – 15 minutes (never exceed recommended time)
7.2. Hair Straightening Products (Hair Relaxers)
| Product Type | Function |
|---|---|
| Hair Relaxer Creams | Chemically straightens curly hair |
| Professional Straightening Systems | Salon-use permanent straightening |
| At-home Straightening Kits | Consumer hair straightening products |
Process:
-
Apply thioglycolate cream to hair (breaks disulfide bonds)
-
Mechanically straighten hair (comb/flatten)
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Apply neutralizing agent (oxidizer – hydrogen peroxide or sodium bromate)
-
Disulfide bonds re-form in straight configuration
7.3. Dermatological Preparations
| Application | Function |
|---|---|
| Acne Treatments | Keratolytic agent – helps exfoliate dead skin cells, unclog pores |
| Chemical Peels | Removes outer layer of dead skin |
| Comedone Removers | Softens blackheads and whiteheads |
| Wart Removal | Keratolytic action on keratinized tissue |
Note: For dermatological applications, calcium thioglycolate is also commonly used as an alternative.
7.4. Combinations in Formulations
| Combination | Purpose |
|---|---|
| Calcium Thioglycolate + Potassium Thioglycolate | Optimizes efficacy and cream consistency |
| Lidocaine / Benzocaine | Reduces skin irritation during depilation |
| Aloe vera / Allantoin | Soothes skin after depilation |
| Sodium sulfite / Sodium bisulfite | Antioxidant – prevents oxidation |
| EDTA | Chelating agent – stabilizes formulation |
8. TYPICAL FORMULATION CONCENTRATIONS
| Product Type | Potassium Thioglycolate Concentration | Active TGA Equivalent |
|---|---|---|
| Body Depilatory Cream | 2 – 8% (as active) | 1.5 – 6% |
| Facial Depilatory Cream | 1 – 4% (as active) | 0.7 – 3% |
| Hair Straightening Cream | 5 – 10% (as active) | 3.5 – 7% |
| Professional Straightener | 8 – 12% (as active) | 6 – 9% |
Note: Commercial 42% potassium thioglycolate solution contains approximately 30% active thioglycolic acid (TGA). Adjust formulation calculations accordingly.
9. QUALITY SPECIFICATIONS (42% Solution – Typical)
| Parameter | Specification |
|---|---|
| Appearance | Colorless to pale pink clear to slightly hazy liquid |
| Potassium Thioglycolate Content | 42 ± 2% |
| Thioglycolic Acid (TGA) Equivalent | 30 ± 2% |
| pH (as is) | 10 – 12 |
| Density (20°C) | 1.30 – 1.32 g/cm³ |
| Chlorides (Cl) | ≤ 0.1% |
| Iron (Fe) | ≤ 0.001% |
| Heavy Metals (Pb) | ≤ 0.001% |
| Sulfate (SO₄) | ≤ 0.1% |
10. STORAGE & HANDLING
| Parameter | Information |
|---|---|
| Storage Conditions | Cool, dry, well-ventilated area; 5-25°C recommended |
| Container Requirements | Tightly closed, opaque (amber) HDPE or glass containers |
| Protect From | Air (oxidation), light, heat, strong acids, strong oxidizing agents |
| Shelf Life | 12-24 months (under inert atmosphere with antioxidants) |
| Oxidation Indicator | Pink to brown color indicates oxidation; discard if dark brown |
| Incompatible Materials | Strong oxidizing agents, strong acids, metal ions (Cu, Fe, etc.) |
| Packaging Options | 25 kg, 200 kg HDPE drums, 1000 kg IBC, flexibag |
Special Handling Notes:
-
Inert atmosphere recommended: Store under nitrogen to prevent oxidation
-
Antioxidants: Product typically contains stabilizers (sodium sulfite, EDTA)
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Avoid metal contact: Copper, iron, and other metals catalyze oxidation
-
Ventilation: Use with adequate ventilation due to strong odor
11. SAFETY & HEALTH INFORMATION
GHS Classification
| Hazard Class | Category |
|---|---|
| Skin Corrosion/Irritation | Category 1B (H314) |
| Serious Eye Damage | Category 1 (H318) |
| Acute Toxicity (Oral) | Category 4 (H302) |
| Acute Toxicity (Dermal) | Category 4 (H312) |
| Skin Sensitization | Category 1 (H317) |
| Specific Target Organ Toxicity (Inhalation) | Category 3 (H335) |
| Acute Aquatic Toxicity | Category 3 (H402) |
Hazard Statements (H-Codes)
| Code | Statement |
|---|---|
| H302 | Harmful if swallowed |
| H312 | Harmful in contact with skin |
| H314 | Causes severe skin burns and eye damage |
| H317 | May cause an allergic skin reaction |
| H318 | Causes serious eye damage |
| H335 | May cause respiratory irritation |
| H402 | Harmful to aquatic life |
Precautionary Statements (P-Codes)
| Code | Statement |
|---|---|
| P260 | Do not breathe dust/mist |
| P280 | Wear protective gloves, protective clothing, eye protection, face protection |
| P302+P352 | IF ON SKIN: Wash with plenty of water |
| P305+P351+P338 | IF IN EYES: Rinse cautiously with water for several minutes |
| P310 | Immediately call a POISON CENTER or doctor |
Toxicological Information
| Parameter | Value |
|---|---|
| Oral LD50 (rat) | ~1,000 – 2,000 mg/kg (estimated) |
| Dermal LD50 (rabbit) | ~2,000 mg/kg |
| Skin Irritation | Severe – causes burns |
| Eye Irritation | Severe – causes damage |
| Skin Sensitization | May cause allergic reactions |
| Inhalation | May cause respiratory tract irritation |
First Aid Measures
| Exposure Route | Action |
|---|---|
| Inhalation | Remove to fresh air. Seek medical attention if respiratory irritation occurs. |
| Skin Contact | Remove contaminated clothing. Wash with plenty of water for at least 15 minutes. Seek medical attention. |
| Eye Contact | Rinse immediately with plenty of water for at least 15 minutes. Seek immediate medical attention. |
| Ingestion | Do NOT induce vomiting. Rinse mouth. Drink water. Seek immediate medical attention. |
Personal Protective Equipment (PPE)
| Equipment | Recommendation |
|---|---|
| Respiratory Protection | Organic vapor respirator (if ventilation inadequate) |
| Hand Protection | Chemical-resistant gloves (nitrile, neoprene, butyl rubber) – avoid latex |
| Eye Protection | Chemical safety goggles + face shield |
| Body Protection | Chemical-resistant apron, lab coat, protective clothing |
NFPA 704
| Health (Blue) | Fire (Red) | Reactivity (Yellow) | Special (White) |
|---|---|---|---|
| 3 | 0 | 1 | None |
12. ENVIRONMENTAL INFORMATION
| Parameter | Information |
|---|---|
| Biodegradability | Readily biodegradable |
| Aquatic Toxicity | Harmful to aquatic life (H402) |
| Bioaccumulation | Low potential |
| Waste Disposal | Dispose according to local regulations. Neutralize before disposal. |
13. TRANSPORT INFORMATION
| Parameter | Information |
|---|---|
| UN Number | 3266 (Corrosive liquid, basic, organic, n.o.s.) |
| Hazard Class | 8 (Corrosive substance) |
| Packing Group | III |
| Proper Shipping Name | CORROSIVE LIQUID, BASIC, ORGANIC, N.O.S. (Potassium thioglycolate solution) |
| Marine Pollutant | No |
| ADR/RID Label | 8 |
14. REGULATORY INFORMATION
| Region | Status |
|---|---|
| EU | REACH registered; approved for cosmetic use under Cosmetics Regulation (EC) 1223/2009 |
| Turkey (KKDIK) | Mandatory compliance; requires registration |
| USA (TSCA) | Listed |
| Canada (DSL) | Listed |
| FDA | Approved for use in cosmetics (depilatories, hair straighteners) |
| Cosmetic Concentration Limit (EU) | Maximum concentration in ready-to-use depilatories: 5% (as thioglycolic acid equivalent) |
Cosmetic Restrictions (EU Cosmetics Regulation):
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Depilatories: Maximum 5% thioglycolic acid equivalent (pH 7-12.7)
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Hair straighteners: Maximum 8% thioglycolic acid equivalent (professional use), 5% (consumer use)
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Nail products: Maximum 5% thioglycolic acid equivalent
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Labeling: Must contain warning: "Contains thioglycolate. Follow instructions carefully."
15. SYNONYMS & OTHER NAMES
| Turkish Name | English Name |
|---|---|
| Potasyum Tiyoglikolat | Potassium Thioglycolate |
| Potasyum Merkaptoasetat | Potassium Mercaptoacetate |
| Tiyoglikolik Asit Potasyum Tuzu | Thioglycolic Acid Potassium Salt |
| Potasyum 2-sülfanilasetat | Potassium 2-sulfanylacetate |
Database Identifiers:
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CAS: 34452-51-2
-
EC: 252-024-2
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MDL: MFCD00043376
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PubChem CID: 23690406
-
UNII: 0QRK7H6N1B
16. COMPARISON WITH THIOGLYCOLIC ACID
| Property | Potassium Thioglycolate | Thioglycolic Acid |
|---|---|---|
| Form | Liquid (42% solution) or solid | Liquid |
| pH (as is) | 10-12 (alkaline) | ~2 (acidic) |
| Odor | Strong mercaptan | Strong mercaptan |
| Reactivity | Ready to use (already neutralized) | Requires neutralization |
| Cosmetic Use | Directly used in depilatories | Must be neutralized to active form |
| Handling | Corrosive (basic) | Corrosive (acidic) |
17. SUMMARY
Potassium Thioglycolate (Potassium Mercaptoacetate, CAS 34452-51-2) is the potassium salt of thioglycolic acid. It is a strong reducing agent that breaks disulfide bonds in keratin, making it the key active ingredient in depilatory (hair removal) creams and hair straightening products.
Key Features:
| Feature | Description |
|---|---|
| Appearance | Colorless to pale pink liquid (42% solution) |
| Active Component | Thiolate anion (⁻S-CH₂-COO⁻) |
| Mechanism | Reduces disulfide bonds in keratin |
| pH | Alkaline (10-12) |
| Odor | Strong characteristic mercaptan (sulfur) odor |
Main Application Areas:
| Sector | Applications |
|---|---|
| Cosmetics | Depilatory creams, gels, aerosols; hair straighteners (relaxers) |
| Dermatology | Acne treatments, chemical peels, keratolytic agents |
| Personal Care | Facial depilatories, shower depilatories |
Comparison with Calcium Thioglycolate:
| Feature | Potassium | Calcium |
|---|---|---|
| Solubility | Higher | Lower |
| Cream Consistency | Thinner | Better (preferred for creams) |
| Active TGA (42% sol.) | ~30% | ~35% (in 35% sol.) |
Key Safety Points:
-
CORROSIVE – Causes severe skin burns and eye damage
-
SKIN SENSITIZER – May cause allergic reactions
-
STRONG ODOR – Characteristic mercaptan (rotten egg/sulfur) smell
-
OXIDATION SENSITIVE – Store under inert atmosphere; do not use if dark brown
-
DO NOT EXCEED APPLICATION TIME – Typically 5-15 minutes maximum
-
PATCH TEST – Always perform on small skin area before first use
18. IMPORTANT NOTES
-
Active Concentration Understanding: Commercial 42% potassium thioglycolate solution contains approximately 30% active thioglycolic acid (TGA). Always calculate based on TGA equivalent, not the salt concentration.
-
Calcium vs Potassium: While both are used in depilatories, calcium thioglycolate is often preferred for cream formulations because it provides better consistency. Potassium thioglycolate is more water-soluble.
-
Oxidation Indicator: Fresh potassium thioglycolate solution is colorless to pale pink. If the solution turns dark brown, oxidation has occurred and the product should be discarded (reduced efficacy).
-
Odor Management: The strong mercaptan odor is inherent. In cosmetic products, fragrances are used to mask the odor. The odor itself does not indicate product degradation.
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Application Time Warning: Depilatory products should never exceed the recommended application time (typically 5-15 minutes). Prolonged exposure can cause chemical burns.
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pH Importance: The alkaline pH (10-12) is essential for the reducing activity. If pH drops below 9, the product becomes ineffective.
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Patch Test Required: Due to risk of allergic reactions, a patch test on a small skin area is recommended 24-48 hours before first use.
-
Contraindications: Do not use on damaged, irritated, sunburned skin, or on mucous membranes.
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Neutralization: After depilatory use, the skin should be rinsed thoroughly with water. An after-care cream (neutralizing or soothing) is recommended.
-
Storage: Store in opaque (amber) containers under inert atmosphere (nitrogen) to prevent oxidation. Keep tightly sealed when not in use.
Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS) provided by the manufacturer/supplier.
