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DESCRIPTION
Disodium phosphate (E450), or disodium hydrogen phosphate, or sodium phosphate dibasic, is an inorganic compound with the chemical formula Na2HPO4.
Disodium phosphate (E450) is one of several sodium phosphates.
CAS NUMBER
7758-16-9
SYONYMS
7758-16-9,Disodium diphosphate,Sodium acid pyrophosphate,Disodium dihydrogen pyrophosphate,DISODIUM PYROPHOSPHATE,Diphosphoric acid, disodium salt,Disodium acid pyrophosphate,Dinatriumpyrophosphat,Dinatriumpyrophosphat [German],Disodium dihydrogen diphosphate,HSDB 377,UNII-H5WVD9LZUD,Pyrophosphoric acid, disodium salt,Sodium pyrophosphate (Na2H2P2O7),EINECS 231-835-0,H5WVD9LZUD,disodium;[hydroxy(oxido)phosphoryl] hydrogen phosphate,EC 231-835-0,DISODIUM PYROPHOSPHATE [HSDB],DISODIUM PYROPHOSPHATE [VANDF],SODIUM ACID PYROPHOSPHATE [MI],SODIUM ACID PYROPHOSPHATE [FCC],SODIUM ACID PYROPHOSPHATE [VANDF],MFCD00014246,DINATRIUMPYROPHOSPHAT (GERMAN),Disodiumpytophosphate,Disodium dihydrogenpyrophosphate,Sodium diphosphate dibasic,disodium pyrophosphate 2-,disodium hydrogen (hydrogen phosphonatooxy)phosphonate,Grahamsches salz,Disodium Diphosphate; Pyrophosphoric Acid Disodium Salt; Diphosphoric Acid Disodium Salt; Disodium Pyrophosphate; Disodium Acid Pyrophosphate;,Glassy sodium phosphate,DSSTox_CID_8842,sodium dihydrogendiphosphate,UNII-P1BM4ZH95LDSSTox_RID_78658,P1BM4ZH95L,DSSTox_GSID_28842,Sodium pyrophosphate, dibasic,Sodium dihydrogen pyrophosphate,CHEMBL3184949,SODIUM PYROPHOSPHATE, ACID,EINECS 272-808-3,Tox21_200813,DISODIUM PYROPHOSPHATE [INCI],AKOS015916169,AKOS024418779,Diphosphoric acid, sodium salt (1:2),NCGC00258367-01,CAS-68915-31-1,di-sodium dihydrogen pyrophosphate anhydrous
Disodium diphosphate (Na₂P₂O₇), also known as disodium pyrophosphate, is a widely used chemical compound with diverse applications in food processing, pharmaceuticals, and industrial processes.
This review explores the chemical structure, properties, synthesis methods, applications, toxicology, regulatory standards, and environmental impact of disodium diphosphate.
Particular attention is given to its role as a food additive, including its functionality, benefits, and safety evaluation.
Disodium diphosphate is an inorganic compound classified as a pyrophosphate salt.
Its unique properties, including chemical stability, buffering capacity, and emulsifying potential, make it indispensable across numerous industries.
In the food industry, it serves as a key additive to enhance texture, flavor stability, and preservation.
In pharmaceuticals, it stabilizes drug formulations and optimizes delivery.
Additionally, its environmental role, particularly in water treatment and pollution control, highlights its broader significance.
This comprehensive review delves into the intricate characteristics, synthesis pathways, applications, and impacts of disodium diphosphate to shed light on its multifaceted utility.
CHEMİCAL STRUCTURE AND PROPERTIES
MOLECULAR FORMULA AND STRUCTURE
The molecular formula of disodium diphosphate is Na₂P₂O₇. Structurally, it features a backbone of two tetrahedral phosphate groups joined by a bridging oxygen atom.
This arrangement imparts a highly polar character to the molecule, with sodium ions serving as counterbalancing cations.
Its crystalline nature contributes to its stability, and it typically forms hydrates depending on storage conditions.
These hydrates influence its hygroscopic properties and solubility, critical for various applications.
PHYSICAL AND CHEMICAL PROPERTIES
Molecular weight:
221.94 g/mol
Solubility:
Highly soluble in water, forming clear solutions; insoluble in alcohol and other organic solvents.
The high solubility enables its use in aqueous formulations across industries.
pH:
Aqueous solutions exhibit a slightly alkaline pH, typically ranging between 7.0 and 9.0, facilitating its buffering capacity.
This pH range is ideal for stabilizing both acidic and basic environments.
Thermal stability:
Stable up to 200°C; decomposes at higher temperatures, releasing water and forming metaphosphates.
This property is exploited in high-temperature industrial processes.
Hygroscopic nature:
Strongly hygroscopic, necessitating airtight storage to maintain purity and prevent deliquescence.
Improper storage can lead to product degradation and reduced efficacy.
Reactivity:
Reacts with divalent and trivalent metal ions to form insoluble precipitates, which underpins its sequestrant properties.
This characteristic is essential in preventing undesirable metal-catalyzed reactions in food and industrial applications.
SYNTHESIS OF DISODIUM DIPHOSPHATE
INDUSTRIAL SYNTHESIS
Disodium diphosphate is industrially synthesized using thermal processes involving monosodium phosphate (NaH₂PO₄).
The reaction proceeds through dehydration and condensation:
This process is typically conducted at temperatures between 250°C and 350°C in rotary kilns or fluidized bed reactors to ensure efficient heat transfer and product uniformity.
The reaction is exothermic, and careful control of reaction conditions is necessary to prevent over-condensation into higher-order phosphates.
Catalysts may be employed to optimize yield and reduce energy consumption, making the process economically viable.
LABORATORY PREPARATION
Laboratory synthesis of disodium diphosphate often involves neutralizing pyrophosphoric acid with sodium hydroxide or sodium carbonate under controlled pH and temperature conditions.
The resulting solution is then crystallized and purified to yield the desired product.
Alternative methods include direct reaction of phosphoric acid with sodium salts under specific drying conditions to promote pyrophosphate formation.
APPLICATIONS
FOOD INDUSTRY
Disodium diphosphate is an essential ingredient in numerous food products due to its functional versatility:
Leavening agent:
As a component of baking powders, it reacts with sodium bicarbonate to release carbon dioxide, contributing to dough expansion and texture improvement.
Its controlled release properties ensure consistent baking performance.
Emulsifier:
Stabilizes emulsions in processed cheese, salad dressings, and whipped toppings, ensuring consistent texture and preventing phase separation.
It enhances product stability during storage and transportation.
Buffering agent:
Maintains pH stability in acidic or alkaline food environments, critical for flavor preservation and shelf life extension.
Its buffering action is particularly beneficial in dairy and beverage applications.
Chelating agent:
Binds with trace metal ions such as iron and copper to inhibit oxidative discoloration in beverages and canned foods.
This property extends the visual and nutritional quality of products.
Moisture retention:
Enhances water-binding capacity in processed meats, improving juiciness and yield.
This application is particularly valuable in ensuring consumer satisfaction and reducing product shrinkage.
PHARMACEUTICAL INDUSTRY
In pharmaceuticals, disodium diphosphate serves as:
A buffering agent:
Regulates pH in oral, injectable, and topical formulations, ensuring drug stability and bioavailability.
It helps maintain the structural integrity of sensitive active ingredients.
Stabilizer:
Prevents degradation of active pharmaceutical ingredients by chelating metal ions and controlling environmental pH.
This ensures extended shelf life and therapeutic efficacy.
Excipient:
Facilitates tablet disintegration and dissolution, enhancing drug delivery efficiency.
Its role as an excipient is vital in achieving consistent drug release profiles.
INDUSTRİAL APPLİCATİONS
Beyond food and pharmaceuticals, disodium diphosphate finds extensive use in industrial processes:
Water treatment:
Functions as a dispersant and scale inhibitor in cooling towers and boilers, preventing mineral deposition and corrosion.
Its effectiveness in controlling scale buildup enhances operational efficiency.
Ceramics and pigments:
Acts as a deflocculant, reducing viscosity and improving particle dispersion for uniform application.
This property is crucial in producing high-quality ceramics and coatings.
Detergents:
Enhances cleaning efficacy by sequestering calcium and magnesium ions, which mitigates water hardness.
It also improves detergent performance in low-temperature washing cycles.
Flame retardants:
Used in fire-resistant coatings and materials due to its thermal stability and ability to form protective char layers under heat.
This application contributes to safety in construction and textiles.
ACUTE AND CHRONIC TOXICITY
Studies on rodents have shown that disodium diphosphate has low acute toxicity.
However, chronic exposure to high levels can lead to gastrointestinal irritation and phosphate imbalance.
These effects underscore the importance of adhering to established usage limits in food and industrial applications.
ACCEPTABLE DAILY INTAKE (ADI)
The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has set an acceptable daily intake (ADI) for pyrophosphates, including disodium diphosphate, at 70 mg/kg body weight.
This threshold ensures safety for consumers while allowing functional use in food products.
SAFETY INFORMATION ABOUT DISODIUM DIPHOSPHATE
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
