DIMETHYL DICARBONATE

CAS Number: 4525-33-1
 Synonyms: DMDC; Dimethyl pyrocarbonate; Velcorin (brand name); E242; Dicarbonic acid dimethyl ester; Pyrocarbonic acid dimethyl ester; Methoxycarbonyl anhydride
Physical Properties:
Appearance: Clear, colorless liquid (sharp, pungent odor; similar to acetic anhydride).
Solubility: Miscible with most organic solvents (ethanol, propylene glycol, glycerol); moderately soluble in water (approx. 3.4% w/w at 20°C) but rapidly hydrolyzes.
Molecular weight: 134.09 g/mol.
Boiling point: 172°C (with decomposition; actual boiling under reduced pressure is ~ 70°C at 10 mmHg).
Melting point: 16–17°C (solidifies below 16°C; handled as warm liquid).
Density: 1.213 g/cm³ at 25°C.
Refractive index: n²⁰/D = 1.392.
Flash point: 80°C (closed cup; combustible but not highly flammable).
Hydrolysis half-life: In water at 20°C, pH 7: t½ = 0.5 hours (30 minutes). At pH 3: t½ = 4 hours. Rapidly decomposes to methanol and carbon dioxide.
Applications:
Cold sterilization of beverages ("cold aseptic filling"): Still and carbonated beverages – fruit juices (apple, orange, grape, pineapple), soft drinks (colas, lemonades, flavored waters), iced tea, isotonic sports drinks, flavored milks (UHT-style), wine, beer, cider, and liquid egg products.
Wine making: Antimicrobial stabilization of sweet wines (to prevent refermentation) without heating or excessive SO₂.
Fruit preparations: Fruit purees, concentrates, and syrups (before aseptic packaging).
Brewing: Non-alcoholic beers and malt beverages.
Pharmaceuticals: Sterilization of aqueous-based liquid medicines and nutritional supplements.
Cosmetics: Preservation of water-based emulsions and lotions (limited use due to methanol generation).
Description:
 Dimethyl dicarbonate (E242) is a potent antimicrobial ester that functions as a cold sterilant for liquid foods. Unlike traditional heat pasteurization, which alters flavor, vitamins, and texture, DMDC acts rapidly at ambient temperatures (15–30°C) without heat damage. The mechanism involves electrophilic attack by DMDC on nucleophilic sites of microbial enzymes and proteins – specifically, the carboxymethylation of histidine imidazole rings, lysine ε-amino groups, and tyrosine phenolic groups. The most critical target is the enzyme alcohol dehydrogenase (ADH) in yeasts and other microorganisms. By carboxymethylating the active-site histidine of ADH, DMDC irreversibly inhibits the enzyme, blocking energy metabolism and reproduction. At typical usage concentrations (200–500 ppm in beverages), DMDC achieves a 5-log reduction (99.999% kill) of vegetative bacteria, yeasts, and molds within 1–4 hours. However, it is ineffective against bacterial endospores (Bacillus, Clostridium) and certain bacterial spores of lactic acid bacteria (e.g., some Lactobacillus species). Therefore, DMDC is used in combination with other hurdles: low pH, mild heat (60°C), or prior filtration. A key safety feature of DMDC is its rapid hydrolysis in water: DMDC + H₂O → 2 CH₃OH (methanol) + 2 CO₂ (carbon dioxide). The methanol generated is identical to that naturally present in fruit juices (from pectin degradation) and fermented beverages (from fermentation). At the maximum permitted use level (200–250 ppm DMDC), the theoretical maximum methanol increase is approximately 60 mg/L (60 ppm). This is significantly lower than natural methanol levels in many fruit juices (e.g., apple juice contains 100–300 ppm methanol from pectin; red wine contains 100–200 ppm). The CO₂ generated is less than that from carbonated beverages. Toxicologically, DMDC itself is acutely toxic (oral LD₅₀ in rats ~ 600 mg/kg) and is a skin and eye irritant. However, because it decomposes completely within minutes to hours of addition to beverages, consumers are not exposed to the parent compound. Regulatory bodies (US FDA, EU EFSA, JECFA) have approved DMDC for beverage cold sterilization under stringent conditions: it must be added using specialized injection equipment (e.g., Velcorin® dosing unit) that ensures uniform distribution and complete decomposition before filling. The ADI for DMDC is 0–10 mg/kg bw/day expressed as DMDC itself (JECFA). Actual residues in packaged beverages are undetectable (<0.1 ppm). DMDC is not approved for use in beverages containing more than 50% milk solids (due to slower decomposition), nor for infant formula. In winemaking, DMDC is especially valued for sweet wines (residual sugar > 2 g/L) where refermentation by residual yeasts (e.g., Saccharomyces cerevisiae, Brettanomyces bruxellensis) can cause bottle bursting. Unlike SO₂ (which can cause allergies and off-flavors) or sorbic acid (which produces geranium-like off-flavor), DMDC leaves no taste or odor when properly used. Historically, DMDC was also evaluated for preserving bulk water, but this use was rejected due to methanol accumulation. The global shift toward "clean label" preservatives has increased DMDC adoption because it is classified as "processing aid" or "cold sterilant" rather than a preservative that remains in the final product. However, the high equipment cost (dosing pumps, safety enclosures) limits its use to large-scale beverage producers.

SAFETY INFORMATION ABOUT DIMETHYL DICARBONATE

First aid measures:
Description of first aid measures:
General advice:
Consult a physician. 
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
 
If inhaled:
If breathed in, move person into fresh air. 
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately. 
Wash off with soap and plenty of water.
Consult a physician.
 
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
 
If swallowed:
Do NOT induce vomiting. 
Never give anything by mouth to an unconscious person. 
Rinse mouth with water. 
Consult a physician.
 
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
 
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment. 
 
Avoid breathing vapours, mist or gas. 
Evacuate personnel to safe areas.
 
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste. 
Keep in suitable, closed containers for disposal.
 
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
 
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place. 
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
 
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
 
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles. 
Faceshield (8-inch minimum). 
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
 
Skin protection:
Handle with gloves. 
Gloves must be inspected prior to use. 
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product. 
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. 
Wash and dry hands.
 
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
 
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. 
 
If the respirator is the sole means of protection, use a full-face supplied air respirator. 
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so. 
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions. 
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
 
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company. 
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product