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Sodium Benzoate, Antimol, Soda Benzoate, Sobanate, Benzoate, E211, 532-32-1

Sodium Benzoate, Antimol, Soda Benzoate, Sobanate, Benzoate, E211, 532-32-1

SODIUM BENZOATE (E211)

1. Chemical Identity and Material Classification

  • Chemical Name: Sodium Benzoate, Benzoic Acid Sodium Salt

  • Synonyms: Antimol, Benzoan Sondy, Soda Benzoat, Benzoat Sodyum, Sobanate, Benzoate

  • CAS Number: 532-32-1

  • EC Number (EINECS): 208-534-8

  • Molecular Formula: C₇H₅NaO₂

  • Molecular Weight: 144.11 g/mol

  • E Number: E211 (food additive)

  • Chemical Class: Aromatic carboxylic acid salt (preservative)

  • HS Code: 2916.31

  • UN Number: Not regulated (non-hazardous for transport)

2. Physical Properties

2.1 General Physical Properties

Property Value
Appearance White to off-white crystalline powder, granules, or flakes
Physical state (20°C) Solid (crystalline)
Odor Odorless or faint benzaldehyde-like odor
Taste Sweet, astringent (characteristic benzoate taste)
Density (20°C) 1.50 g/cm³
Bulk density (typical) 0.6–0.9 g/cm³
Melting point >300°C (decomposes before melting)
Decomposition temperature >300°C → decarboxylation, benzene formation
Boiling point Decomposes before boiling
Flash point Non-flammable
Vapor pressure Negligible
Refractive index (nD20) 1.515
Specific gravity 1.50

2.2 Solubility in Water

Temperature (°C) Solubility (g/100 mL water)
0°C 50.0
10°C 55.0
20°C 63.0
25°C 66.0
30°C 70.0
40°C 75.0
50°C 80.0
60°C 85.0
80°C 95.0
100°C 100.0

Note: Sodium benzoate is very soluble in water (63 g/100 mL at 20°C) – unlike benzoic acid which has low water solubility.

2.3 Solubility in Other Solvents

Solvent Solubility
Water Very soluble (63 g/100 mL at 20°C)
Ethanol Slightly soluble (2–3 g/100 mL)
Methanol Slightly soluble
Acetone Slightly soluble
Glycerol Soluble
Propylene glycol Soluble
Oils Insoluble

2.4 Aqueous Solution Properties

Parameter Value
pH (1% solution, 20°C) 7.0–8.5 (neutral to slightly alkaline)
pH (saturated solution, 20°C) 8.0–9.0
Heat of solution Endothermic (cools water slightly)
Dissociation NaC₆H₅COO → Na⁺ + C₆H₅COO⁻ (benzoate ion)

3. Chemical Properties

3.1 Molecular Structure

Structure: C₆H₅–COO⁻ Na⁺

  • Sodium salt of benzoic acid

  • Dissociates in water to form benzoate anion (C₆H₅COO⁻) and sodium cation (Na⁺)

  • Benzoate anion is the active antimicrobial species after protonation to benzoic acid (C₆H₅COOH)

3.2 Acid-Base Equilibrium (Critical for Antimicrobial Activity)

Equilibrium: C₆H₅COO⁻ + H⁺ ⇌ C₆H₅COOH

Parameter Value
pKa of benzoic acid (25°C) 4.20
Active species Benzoic acid (undissociated form) is antimicrobial
pH dependence Activity increases as pH decreases (more undissociated acid)

Proportion of active benzoic acid vs. pH:

pH % Undissociated Benzoic Acid Antimicrobial Activity
2.0 ~99% Very high
3.0 ~94% High
3.5 ~85% High
4.0 ~60% Moderate
4.5 ~35% Low
5.0 ~15% Very low
6.0 ~1.5% Negligible
7.0 ~0.1% None

3.3 Thermal Decomposition

Temperature Reaction Products
>300°C C₆H₅COONa → C₆H₆ + Na₂CO₃ + CO₂ Benzene, sodium carbonate, carbon dioxide
Combustion 2C₆H₅COONa + 15O₂ → 14CO₂ + 5H₂O + Na₂CO₃ Complete combustion products

3.4 Chemical Reactivity

Reaction Description
With strong acids C₆H₅COONa + HCl → C₆H₅COOH↓ + NaCl (precipitates benzoic acid)
With strong bases Stable (benzoate anion is basic)
With oxidizing agents May oxidize to phenol derivatives
With metal salts May form metal benzoates (some soluble, some insoluble)

3.5 Stability

Parameter Behavior
Stability in dry air Stable indefinitely
Stability in moist air Slightly hygroscopic (absorbs moisture slowly)
Light sensitivity Stable (no photodegradation)
Thermal stability Stable up to 300°C
Hydrolytic stability Stable (resistant to hydrolysis)

3.6 Incompatibilities

Substance Hazard
Strong acids (H₂SO₄, HCl, HNO₃) Precipitation of benzoic acid
Strong oxidizing agents Oxidation (may form phenol derivatives)
Ferric salts (Fe³⁺) May form colored complexes
Ascorbic acid (vitamin C) Under heat, may form benzene (trace amounts – health concern)
Caffeine (in beverages) Combined with ascorbic acid → trace benzene formation

4. Antimicrobial Mechanism (Preservative Action)

4.1 Mechanism of Action

Step Description
1 Sodium benzoate dissociates in water → benzoate ion (C₆H₅COO⁻)
2 Benzoate ion diffuses into microbial cell (yeast, bacteria, mold)
3 Inside the cell (pH ~5–6), benzoate protonates to form benzoic acid (C₆H₅COOH)
4 Benzoic acid disrupts cell membrane function
5 Inhibits enzymes involved in metabolism (especially Krebs cycle)
6 Prevents microbial growth and reproduction

4.2 Antimicrobial Spectrum

Microorganism Sensitivity Typical Inhibitory Concentration
Yeasts (Candida, Saccharomyces) High 0.05–0.1%
Molds (Aspergillus, Penicillium) High 0.05–0.1%
Bacteria (Gram-positive) (Bacillus, Staphylococcus) Moderate 0.1–0.2%
Bacteria (Gram-negative) (E. coli, Pseudomonas) Low 0.2–0.5%
Lactic acid bacteria Low May be resistant
Acetic acid bacteria Moderate 0.1–0.2%

4.3 pH Dependence

  • Optimal pH: 2.5–4.0 (most effective)

  • Effective range: pH 2.5–5.0

  • Ineffective above pH 5.5: <15% undissociated benzoic acid

5. Quality Specifications

5.1 Food Grade (FCC / USP / E211)

Parameter Specification Test Method
Assay (C₇H₅NaO₂, dried basis) 99.0–100.5% Titration
Loss on drying (105°C, 2 hours) ≤ 1.5% Gravimetric
Water (K. Fischer) ≤ 1.5% Karl Fischer
pH (1% solution) 7.0–8.5 pH meter
Chlorides (Cl) ≤ 0.02% Turbidimetric
Sulfates (SO₄) ≤ 0.03% Turbidimetric
Heavy metals (as Pb) ≤ 10 ppm Colorimetric
Lead (Pb) ≤ 2 mg/kg Atomic absorption
Arsenic (As) ≤ 3 ppm Atomic absorption
Mercury (Hg) ≤ 1 ppm Atomic absorption
Readily carbonizable substances Passes test Color comparison
Alkalinity Passes test Titration
Purity White crystalline powder Visual

5.2 Technical / Industrial Grade

Parameter Specification
Assay (C₇H₅NaO₂) ≥ 99.0%
Loss on drying ≤ 2.0%
Chlorides (Cl) ≤ 0.05%
Sulfates (SO₄) ≤ 0.1%
Heavy metals ≤ 50 ppm
Iron (Fe) ≤ 50 ppm
Appearance White to off-white powder

6. Production Methods

6.1 Neutralization of Benzoic Acid (Industrial Standard)

Reaction: C₆H₅COOH (benzoic acid) + NaOH (sodium hydroxide) → C₆H₅COONa + H₂O

Process:

  1. Benzoic acid is dissolved in water

  2. Neutralized with sodium hydroxide or sodium carbonate

  3. Solution filtered and crystallized

  4. Crystals dried and milled

Purity: 99.0–100.5% (food grade)

6.2 From Toluene Oxidation (Benzoic acid production)

Process:

  1. Toluene is oxidized with air (cobalt or manganese catalyst)

  2. Benzoic acid is produced

  3. Neutralized with NaOH → sodium benzoate

6.3 From Sodium Benzoate Solution (Crystallization)

Process:

  1. Sodium benzoate solution concentrated

  2. Cooled to crystallize

  3. Centrifuged and dried

7. Industrial Applications

7.1 Food and Beverage Industry (Primary Application – E211)

Application Function Typical Concentration (w/w)
Carbonated soft drinks (cola, fruit sodas) Preservative (prevents yeast/mold) 0.02–0.1%
Fruit juices and concentrates Preservative 0.05–0.1%
Pickles and relishes Preservative (mold inhibition) 0.05–0.1%
Jams, jellies, marmalades Preservative (mold inhibition) 0.05–0.1%
Margarine and spreads Preservative 0.05–0.1%
Salad dressings and sauces Preservative (with vinegar – pH 3–4) 0.05–0.1%
Maple syrup Preservative (mold prevention) 0.05–0.1%
Canned vegetables Preservative (with acidification) 0.05–0.1%
Chewing gum Preservative 0.05–0.1%
Alcoholic beverages (wine coolers) Preservative 0.05–0.1%

Maximum permitted levels (EU, US, Codex):

  • Soft drinks: 150–200 mg/kg (0.015–0.02%)

  • Jams, jellies: 500–1,000 mg/kg (0.05–0.1%)

  • Pickles: 500–1,000 mg/kg (0.05–0.1%)

  • Salad dressings: 500–1,000 mg/kg (0.05–0.1%)

Note: Sodium benzoate is often used in combination with potassium sorbate for synergistic preservative effect.

7.2 Pharmaceutical Applications

Application Function Typical Concentration
Oral liquid medications (syrups, suspensions) Preservative (prevents microbial growth) 0.1–0.2%
Cough syrups Preservative 0.1–0.2%
Liquid analgesics (acetaminophen) Preservative 0.1–0.2%
Topical creams and ointments Preservative 0.1–0.5%
Mouthwash and oral rinses Preservative, flavor enhancer 0.05–0.1%
Toothpaste Preservative, sweetener 0.1–0.5%
Antifungal preparations Active ingredient (limited) Variable
Ammonia metabolism disorder treatment (UCD) Urea cycle disorder treatment (sodium benzoate is used IV/orally to reduce ammonia) Variable

7.3 Personal Care and Cosmetics

Application Function Typical Concentration
Shampoos and conditioners Preservative, fragrance stabilizer 0.1–0.5%
Liquid hand soaps Preservative 0.1–0.5%
Body washes Preservative 0.1–0.5%
Facial cleansers Preservative 0.1–0.5%
Deodorants and antiperspirants Preservative, corrosion inhibitor 0.1–0.5%
Makeup (foundations, powders) Preservative 0.1–0.5%
Baby wipes Preservative 0.1–0.5%
Denture cleaners Active ingredient (antimicrobial) 1–5%

INCI Name: Sodium Benzoate

7.4 Industrial and Technical Applications

Application Function Typical Concentration
Antifreeze and engine coolants Corrosion inhibitor 0.1–1%
Metalworking fluids Corrosion inhibitor, preservative 0.1–1%
Cooling water treatment Corrosion inhibitor 0.05–0.5%
Paints and coatings Preservative (in-can) 0.05–0.2%
Latex emulsions Preservative 0.1–0.5%
Adhesives (starch-based, PVA) Preservative, corrosion inhibitor 0.1–0.5%
Printing inks Preservative, corrosion inhibitor 0.1–0.5%
Silicone rubber (mastic) Component in cleaning formulations Variable

7.5 Corrosion Inhibition (Metal Protection)

Application Mechanism Effectiveness
Aluminum corrosion inhibition Forms protective benzoate film on aluminum surface Moderate
Steel corrosion inhibition Adsorbs on metal surface Moderate
Engine coolants Protects aluminum radiators from corrosion Effective (in combination)

7.6 Tobacco Industry

Application Function
Cigarette tobacco treatment Preservative (prevents mold growth during processing)
Moisture retention aid Humectant (in combination with other agents)

7.7 Dye and Pigment Industry

Application Function
Dye intermediate Precursor for certain dye syntheses
Pigment dispersant Aids pigment dispersion in formulations

7.8 Plastic and Polymer Industry

Application Function
Polypropylene additive Improves clarity and strength (limited, newer application)

7.9 Animal Feed

Application Function Typical Concentration
Pet food (dry and wet) Antimycotic (prevents mold) 0.05–0.1%
Livestock feed Preservative 0.05–0.1%

7.10 Agriculture

Application Function
Crop protection Fungicide (acid form – benzoic acid, not sodium salt)
Post-harvest treatment Mold prevention on fruits and vegetables

8. Toxicology and Safety

8.1 Acute Toxicity

Parameter Value Classification
Oral LD₅₀ (rat) 2,500–4,000 mg/kg (low toxicity) Not classified
Dermal LD₅₀ (rabbit) >2,000 mg/kg Not classified
Inhalation LC₅₀ Not determined (dust may irritate) Not classified
Skin irritation Non-irritant Not classified
Eye irritation Mild irritant (dust) Not classified
Skin sensitization Non-sensitizer Not classified

8.2 Chronic Toxicity

Endpoint Classification
Carcinogenicity Not classified (non-carcinogenic)
Mutagenicity Negative
Reproductive toxicity Not classified
Target organ toxicity Not classified

8.3 Special Hazards – Benzene Formation

Concern: Sodium benzoate can form trace amounts of benzene when combined with ascorbic acid (vitamin C) under heat or light.

Reaction: Benzoate + Ascorbic acid (vitamin C) → Benzene (trace) + CO₂

Condition Risk Level
Soft drinks with vitamin C + sodium benzoate + heat/light Low (<10 ppb benzene)
Ambient temperature, no light Negligible
Food products without ascorbic acid No risk

Regulatory standards:

  • US EPA drinking water limit for benzene: 5 ppb

  • FDA: Soft drinks with >5 ppb benzene may be recalled (rare)

8.4 Hypersensitivity (Allergic Reactions)

Population Reactions
General population Very rare (0.01–0.1%)
Asthmatics Urticaria (hives), bronchospasm (rare)
Atopic individuals Contact urticaria (rare)

8.5 GHS Classification (Typical)

Classification Category
Signal word None (not classified as hazardous)
Hazard statements None (under normal conditions)
Precautionary statements P264, P280 (for dust – eye protection)

8.6 NFPA Rating

Health Flammability Reactivity
1 0 0

9. Safety Precautions and Personal Protective Equipment (PPE)

  • Hazards:

    • Low acute toxicity

    • Dust may cause mild eye and respiratory tract irritation

    • Non-flammable

    • Slightly hygroscopic (absorbs moisture)

  • PPE (recommended – industrial handling):

    • Safety glasses (EN 166) – optional (low hazard)

    • Dust mask (FFP1/FFP2) – for dusty operations

    • Chemical-resistant gloves (nitrile – optional)

    • Protective clothing (dust protection)

  • Engineering controls:

    • Local exhaust ventilation (LEV) for dust control

    • Eyewash stations

  • Storage conditions:

    • Keep tightly closed in original container (HDPE, PP, paper bags with liner)

    • Store in cool, dry, well-ventilated area

    • Protect from moisture (slightly hygroscopic)

  • First aid:

    • Inhalation: Move to fresh air

    • Eye contact: Rinse with water for 15 minutes; remove contact lenses; seek medical attention if irritation persists

    • Skin contact: Wash with soap and water

    • Ingestion: Rinse mouth; drink water (low toxicity)

10. Environmental Fate

Parameter Value
Biodegradability Readily biodegradable (>90% in 28 days, OECD 301)
Aquatic toxicity (fish, LC₅₀, 96 hours) 100–500 mg/L (low to moderate toxicity)
Daphnia magna (EC₅₀, 48 hours) 50–200 mg/L
Algal toxicity (EC₅₀, 72 hours) 10–100 mg/L
Bioaccumulation Low potential (log P < 1)
Soil mobility High (high water solubility)
WGK Germany 1 (low hazard to water)
Disposal method Dissolve in water, flush to wastewater treatment (check local regulations)

11. Storage and Shelf Life

11.1 Storage Conditions

Parameter Requirement
Storage temperature 5–30°C (room temperature)
Container Keep tightly closed (HDPE, PP, paper bags with liner)
Protect from Moisture (slightly hygroscopic – may cake)
Environment Cool, dry, well-ventilated area

11.2 Shelf Life

Parameter Value
Shelf life (sealed, dry) 24–36 months
Degradation indicators Caking (moisture absorption), loss of flowability

12. Transport Information

Regulation Classification
UN Number Not regulated (non-hazardous)
ADR/RID Not classified as dangerous goods
IMDG Not regulated
IATA Not regulated
Proper shipping name Sodium benzoate (non-hazardous)

13. Synonyms and Common Names

  • English: Sodium Benzoate, Benzoic Acid Sodium Salt, Antimol, Sobanate

  • Trade names: Benzoate, Benzoat Sodyum, Soda Benzoat

  • E number: E211

  • French: Benzoate de sodium

  • German: Natriumbenzoat

  • Spanish: Benzoato de sodio

  • Turkish: Sodyum Benzoat, Antimol

14. Regulatory Status

Regulation Status
REACH (EU) Registered (EC 208-534-8)
TSCA (US) Listed
FDA GRAS – food additive (E211) – 21 CFR § 184.1733
EFSA Permitted as food additive (E211) – with maximum residue limits
USP / Ph. Eur. Monographed for pharmaceutical use
EPA Not restricted

15. Why Choose Sodium Benzoate?

Advantage Description
Effective broad-spectrum preservative Effective against yeasts, molds, and some bacteria (especially in acidic pH)
Low cost One of the most economical food preservatives
GRAS status FDA-approved for food use (E211)
High water solubility 63 g/100 mL at 20°C – easy to incorporate
Synergistic with other preservatives Works well with potassium sorbate, parabens
Stable Long shelf life (24–36 months)
Non-toxic at use levels Very low acute toxicity (LD₅₀ >2,500 mg/kg)
Widely approved Permitted in food, pharma, cosmetics globally
pH indicator Weakly alkaline solution (pH 7–8)
Corrosion inhibitor Protects metal surfaces in coolants and industrial fluids

Limitations:

  • pH-dependent activity – Only effective at pH <4.5 (requires acidic environment)

  • Precipitates with strong acids – Forms insoluble benzoic acid

  • Potential benzene formation – With ascorbic acid (vitamin C) under heat/light

  • Not effective at neutral/alkaline pH – Above pH 5.5, activity negligible

  • Slight hygroscopicity – Absorbs moisture; may cake

16. Sodium Benzoate vs. Benzoic Acid – Comparison

Property Sodium Benzoate (C₇H₅NaO₂) Benzoic Acid (C₆H₅COOH)
Water solubility (20°C) 63 g/100 mL (very high) 0.34 g/100 mL (very low)
Form White powder White crystals/flakes
pH (1% solution) 7.0–8.5 (alkaline) 2.5–3.5 (acidic)
Active form Benzoic acid (after protonation) Benzoic acid (direct)
Optimal pH range 2.5–4.5 2.5–4.5
Dust hazard Low Higher (respiratory irritant)
Corrosivity Low Moderate
Food additive code E211 E210
Preferred use Liquid formulations (soluble) Dry mixes, low moisture foods

17. Sodium Benzoate vs. Potassium Sorbate – Comparison

Property Sodium Benzoate Potassium Sorbate
Optimal pH range 2.5–4.5 3.0–6.0
Primary target Yeasts, molds Molds, yeasts, bacteria
Water solubility (20°C) 63 g/100 mL 58 g/100 mL
Cost Lower Moderate
Flavor impact Slight bitter/sweet Minimal
Benzene formation risk With ascorbic acid None
Food additive code E211 E202
Common application Soft drinks, pickles Baked goods, cheese, wine

18. Sodium Benzoate – Recommended Usage Levels

Product Type Typical Concentration (%) Maximum Permitted (Regulatory)
Soft drinks (carbonated) 0.01–0.02% 0.015% (150 mg/kg)
Fruit juices 0.05–0.1% 0.1% (1,000 mg/kg)
Pickles, relishes 0.05–0.1% 0.1% (1,000 mg/kg)
Jams, jellies 0.05–0.1% 0.1% (1,000 mg/kg)
Salad dressings 0.05–0.1% 0.1% (1,000 mg/kg)
Pharmaceuticals (oral liquids) 0.1–0.2% 0.2% (2,000 mg/kg)
Cosmetics 0.1–0.5% 0.5% (5,000 mg/kg)
Mouthwash 0.05–0.1% 0.1% (1,000 mg/kg)

19. Sodium Benzoate – pH Dependence Chart

pH % Undissociated Benzoic Acid Antimicrobial Activity
2.0 99% Excellent
2.5 98% Excellent
3.0 94% Very good
3.5 85% Good
4.0 60% Moderate
4.2 50% Moderate
4.5 35% Low
5.0 15% Very low
5.5 5% Negligible
6.0 1.5% None
7.0 0.1% None

Conclusion: Sodium benzoate is most effective at pH <4.0.

20. Summary Table – Key Specifications at a Glance

Parameter Value
Product Name Sodium Benzoate (E211)
CAS Number 532-32-1
EC Number 208-534-8
Molecular Formula C₇H₅NaO₂
Molecular Weight 144.11 g/mol
Appearance White to off-white crystalline powder
Density 1.50 g/cm³
Melting Point >300°C (decomposes)
pH (1% solution) 7.0–8.5
Water Solubility (20°C) 63 g/100 mL
Assay (food grade) 99.0–100.5%
E Number E211
pKa (benzoic acid) 4.20
Optimal pH range 2.5–4.5
Primary Applications Food preservative (soft drinks, pickles, jams), pharmaceutical preservative, cosmetic preservative, corrosion inhibitor
GHS Signal Word None (non-hazardous)
Hazard Statements None
Oral LD₅₀ (rat) 2,500–4,000 mg/kg
Biodegradability Readily biodegradable
Shelf Life 24–36 months

This TDS is prepared in compliance with ISO 11014-1 format and is intended for food technologists, beverage formulators, pharmaceutical scientists, cosmetic chemists, industrial engineers, and procurement professionals. Certificates of Analysis (CoA), Safety Data Sheets (SDS), and sample validation reports are available upon request.

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