Propylene glycol Chemical Properties
- Melting point:
- -60 °C
- Boiling point:
- 187 °C(lit.)
- 1.036 g/mL at 25 °C(lit.)
- vapor density
- 2.62 (vs air)
- vapor pressure
- 0.08 mm Hg ( 20 °C)
- 2940 | PROPYLENE GLYCOL
- refractive index
- Flash point:
- 225 °F
- storage temp.
- Store at RT.
- Viscous Liquid
- APHA: ≤10
- Specific Gravity
- 1.038 (20/20℃)1.036～1.040
- 6-8 (100g/l, H2O, 20℃)
- explosive limit
- Water Solubility
- JECFA Number
- CAS DataBase Reference
- 57-55-6(CAS DataBase Reference)
- NIST Chemistry Reference
- Propylene glycol(57-55-6)
- EPA Substance Registry System
- Propylene glycol (57-55-6)
Propylene glycol Usage And Synthesis
Physical and Chemical Properties
Propylene glycol is scientifically named as “1,2-propanediol”, and has a chemical formula of CH3CHOHCH2OH and a molecular weight of 76.10. There is a chiral carbon atom in the molecule. Its racemate is a hygroscopic viscous liquid and is slightly spicy. It has a specific gravity of 1.036 (25/4 °C), a freezing point of-59 °C, and a boiling point of 188.2 °C, respectively 83.2 °C (1,333 Pa). It is miscible with water, acetone, ethyl acetate and chloroform, and is soluble in ether. It is soluble in many essential oils, but is not miscible with petroleum ether and paraffin oil. It is relatively stable to heat and light, and is more stable at low temperatures. Its L-isomer has a boiling point of 187 to 189 °C and a specific optical rotation [α] of D20-15.0°. It can be oxidized at high temperatures to propionaldehyde, lactic acid, pyruvic acid and acetic acid.
Figure 1 the molecular structure of propylene glycol.
Propylene glycol is a diol having the general nature of the alcohol. It can react with inorganic and organic acids to generate mono-or di-esters. It reacts with propylene oxide to generate ether, with hydrogen halide to generate halohydrin, and with acetaldehyde to generate methyl dioxolane.
Medicinal property and application
Propylene glycol has good solubility and less toxicity and irritation, and is widely used as solvents, extraction solvents and preservatives for injections (eg. intramuscular injections, intravenous injections) and non-injectable pharmaceutical preparations (such as oral liquid, ophthalmic preparations, otic preparations, dental preparations, rectovaginal preparations, transdermal preparations, etc.). It is better than glycerol solvent and can dissolve many substances such as corticosteroids (sex hormone), chloramphenicol, sulfonamides, barbiturate, reserpine, quinidine, corticosterone acetate, tetrahydropalmatine sulfate, mechlorethamine hydrochloride, vitamin A, vitamin D, many volatile oils, most of the alkaloids and many local anesthetics.
Propylene glycol is similar to ethanol when used as a bacteriostatic agent, and its efficacy to inhibit mold is similar to glycerin and is slightly lower than that of ethanol. Propylene glycol is commonly used as a plasticizer for the aqueous film coating materials. Its mixture with equal amounts of water can delay the hydrolysis of certain drugs, and increase the stability of the preparation product. It is used as an antimicrobial preservative in 15% to 30% propylene glycol solution and semi-solid formulation, as humectants in about 15% propylene glycol topical formulation, and as solvent and co-solvent in 10% to 30% propylene glycol aerosol solvent, 10% to 25 % propylene glycol oral solution, 10% to 60% injectable formulation and 5% to 80% topical formulation.
[Stability and storage condition] It is very stable at room temperature, but is oxidized when left open at high temperatures (above 280 °C); has a chemical stability after mixing with 95% ethanol or water; can be sterilized by autoclaving or sterile filtration. Propylene glycol has hygroscopicity, and should be positioned at cool and dry place and stored in dark airtight container.
[Incompatibility] It has incompatibility with some oxidants (such as potassium permanganate).
The above information is edited by the Chemicalbook of Jin Yinxue.
A 10μl sample is injected into the gas chromatograph, which has a thermal conductivity detector. The column is 1m × 6.35mm stainless steel column. The filler is polyethylene glycol 20M (Carbowax compound 20M) 4%, and the carrier is a 40/60 mesh sieved polytetrafluoroethylene (Chromosorb T) or similar material. Helium carrier gas has a flow rate of 75ml/min. Injector temperature is 240 °C; column temperature is 120 to 200 °C, temperature increment is 5 °C/min; final temperature is 250 °C. Under specified conditions, the residence time of propylene glycol is about 5.7 minutes, the residence time of three kinds of glycol isomers are respectively 8.2, 9.0 and 10.2 minutes. The area of each peak is determined using any proper method, and then the percentage of propylene glycol area is calculated and transformed into mass percentage.
FAO/WHO (2000): ADI is 0 to 25mg/kg.
LD50 is 22 to 23.9 mg/kg (mouse, oral).
GRAS (FDA, §184.1666, 2000).
FAO/WHO (1984): Cottage cheese, the cream mixture amount of 5g/kg (used alone or in combination with other carriers and stabilizers).
Japan (1998): Raw noodles, raw stuffing and cuttlefish smoked products ≤2%; skins for dumplings, steamed dumplings, spring rolls and wonton ≤1.2%; other food ≤0.6%.
GB 2760-96: pastry 3.0g/kg, chewing gum.
FDA, §184.1666 (2000): Alcoholic beverages 5%; frosting and candy 24%; frozen dairy 2.5%; flavoring agents, flavor enhancers 97%; nuts and nut products 5%; other food 2.0%.
It is a colorless, stable and viscous hydroscopic liquid, and is almost odorless and tasteless. It is miscible with water, ethanol and various organic solvents.
1. It is used as a resin, a plasticizer, a surfactant, and materials for emulsifier and demulsifier. It is also used as antifreeze and heat carrier.
2. It is used as gas chromatography stationary phase, solvents, antifreeze, a plasticizer and a dehydrating agent.
3. A carrier solvent; wetting agents; moisturizing agents; anti-caking agents; antioxidants; texturizing agents; surfactant; stabilizer; a thickener; dough modifiers; emulsifiers; flavoring agents; excipient; processing aids.GB2760-96 lists it as food processing aids.
It is mainly used as solvents for a variety of flavors, colors and preservatives, and as extraction solvents for vanilla beans, roasted coffee grains and natural spices. It is used as moisturizing agents and softeners for candy, bread, packaged meats and cheese. It is also used as mildew agents for noodles and sandwiches class. Addition of 0.006% in soymilk enables the flavor not to change upon heating and produces white glossy packaging tofu, which undergoes volume expansion when fried.
4. Propylene glycol is an intermediate for fungicide difenoconazole.
5. It is used a solvent. Preservatives, colorings, antioxidants and other poorly water-soluble food additives can be dissolved therein, which is then added into food; it is strongly hygroscopic and has food moisturizing and anti-freeze effect. China stipulates its use for pastry, and the maximum usage is 3.0g/kg.
6. Propylene glycol is an important raw material for unsaturated polyester, epoxy resin, and polyurethane resin. The use amount in this area accounts for about 45% of the total consumption of propylene glycol. Such unsaturated polyester is used extensively for reinforced plastics and surface coatings. Propylene glycol is excellent in viscosity and hygroscopicity and is non-toxic, and thus is widely used as hygroscopic agent, antifreeze, lubricants and solvents in the food, pharmaceutical and cosmetic industry. In the food industry, propylene glycol reacts with fatty acid to give propylene ester of fatty acids, and is mainly used as food emulsifier; Propylene glycol is a good solvent for flavorings and pigments. Propylene glycol is commonly used as solvents, softeners and excipients, etc. in the pharmaceutical industry for the manufacture of various types of ointments and salves. Propylene glycol is also used as a solvent and a softener for cosmetic since it has good mutual solubility with various spices. Propylene glycol is also used as tobacco moisturizing agents, antifungal agents, food processing equipment lubricants and solvents for food marking ink. Aqueous solution of propylene glycol is an effective anti-freeze agent.
7. It is used as a drug carrier, and agents for drug particles. It can be used as humectants, softeners, solvents and the like in cosmetics. It can be used as tobacco flavor, tobacco moisturizing agents, preservatives and the like in the tobacco industry. It can be used as flavor, food coloring solvents, food packaging softeners, food release agent and the like in food industry. It can also be used for the production of unsaturated polyester resins, and is also raw materials for plasticizers, dehydrating agents, surfactants, curing agents and binders. It can also be used in paints, pesticides, coatings and other industries.
8. It is used in aviation de-icing fluid, refrigerant and antifreeze, food and spices, fragrances, cosmetics and personal care products, heat transfer fluids, hydraulic and brake fluids, paints and coatings, pet food/animal feeding stuffs, medicines, polyurethane, unsaturated polyester resin and the like.
It can be obtained by hydrolysis of Propylene oxide:
Propylene oxide and water are fed in a molar ratio of 1: 15, and react at 150-2000 °C, a pressure of 1.2-1.4 MPa for 30 minutes to obtain 16% aqueous solution of propylene glycol, which is subjected to evaporation to obtain the finished product.
The reaction is performed under catalyzation of sulfuric acid or hydrochloric acid. 0.5% to 1.0% dilute sulfuric acid is added into 10% to 15% aqueous solution of propylene oxide, the mixture is hydrolyzed at 50 to 70 °C; the hydrolysate is neutralized and concentrated under reduced pressure, and refined to obtain the finished products.
The preparation method is a method in which propylene oxide is hydrolyzed to propylene glycol, and which can be carried out in the liquid phase. There are catalytic and non-catalytic processes in industry. Catalytic method is a method in which hydrolysis is carried out in the presence of 0.5% to 1% sulfuric acid at 50 to 70 °C. Non-catalytic process is carried out under high temperature and pressure (150 to 300℃, 980 to 2940kPa), and is used for production in domestic.
Oral-rat LD50: 20000 mg/kg; Oral-Mouse LD50: 32000 mg/kg
Eyes-rabbit 100 mg mild
Explosive hazardous characteristics
explosive when mixed with air
Flammability hazard characteristics
Flammable; generate irritating smoke upon combustion
Ventilated warehouse and low-temperature drying.
Dry powder, foam, sand, water.
clear viscous liquid
Propylene glycol is a colorless, odorless, syrupy liquid.
Propylene glycol has a slight, characteristic taste. It is practically odorless. It absorbs moisture when exposed to moist air.
Reported found in several varieties of mushrooms, roasted sesame seed, oat groats, parmesan cheese, cocoa, pecans and truffle.
Next to water, propylene glycol is the most common moisturecarrying vehicle used in cosmetic formulations. It has better skin permeation than glycerin, and it also gives a pleasant feel with less greasiness than glycerin. Propylene glycol is used as a humectant because it absorbs water from the air. It also serves as a solvent for anti-oxidants and preservatives. In addition, it has preservative properties against bacteria and fungi when used in concentrations of 16 percent or higher. There is a concern that propylene glycol is an irritant at high concentrations, though it appears to be quite safe at usage levels under 5 percent.
Propylene Glycol is a humectant and flavor solvent that is a polyhy- dric alcohol (polyol). it is a clear, viscous liquid with complete solu- bility in water at 20°c and good oil solvency. it functions as a humectant, as do glycerol and sorbitol, in maintaining the desired moisture content and texture in foods such as shredded coconut and icings. it functions as a solvent for flavors and colors that are insoluble in water. it is also used in beverages and candy.
Used as a solvent.
Propylene glycol generally is synthesized commercially by starting with propylene, converting to the chlorohydrin, and hydrolyzing to propylene oxide, which is then hydrolyzed to propylene glycol. It can also be prepared by other methods.
An alcohol in which the hydroxyl groups are attached to a carbon atom of a branched or straight-chain aliphatic hydrocarbon.
Manufactured by treating propylene with chlorinated water to form the chlorohydrin, which is converted to the glycol by treatment with sodium carbonate solution. It is also prepared by heating glycerol with sodium hydroxide.
Sentry Propylene Glycol (Union Carbide); Sirlene (Dow Chemical).
Aroma threshold values
Detection: 340 ppm
Thick odorless colorless liquid. Mixes with water.
Air & Water Reactions
1,2-Propanediol is hygroscopic. 1,2-Propanediol is sensitive to excessive heat (tends to oxidize at high temperatures). 1,2-Propanediol can react with oxidizing materials. 1,2-Propanediol is incompatible with acid chlorides, acid anhydrides, chloroformates, and reducing agents. 1,2-Propanediol dissolves many essential oils. A mixture of 1,2-Propanediol with hydrofluoric acid and silver nitrate was put in a glass bottle which burst 30 minutes later.
Liquid may irritate eyes.
1,2-Propanediol is combustible.
Propylene glycol is used as a solvent, a vehicle for topical medicaments such as corticosteroids or aciclovir, an emulsifier and humectant in food and cosmetics, and as antifreeze in breweries, in the manufactures of resins. It was present as an occupational sensitizer in the color film developer Flexicolor?. Patch tests in aqua are sometimes irritant.
Slightly toxic by ingestion, skin contact, intraperitoneal, intravenous, subcutaneous, and intramuscular routes. Human systemic effects by ingestion: general anesthesia, convulsions, changes in surface EEG. Experimental teratogenic and reproductive effects. An eye and human skin irritant. Mutation data reported. Combustible liquid when exposed to heat or flame; can react with oxidizing materials. Explosive in the form of vapor when exposed to heat or flame. May react with hydrofluoric acid + nitric acid + silver nitrate to form the explosive silver fulminate. To fight fire, use alcohol foam. When heated to decomposition it emits acrid smoke and irritating fumes.
Propylene glycol is used as a solvent; emulsifying agent; food and feed additive; flavor, in manu- facture of plastics; as a plasticizer, surface-active agent; antifreeze, solvent, disinfectant, hydroscopic agent; coolant in refrigeration systems; pharmaceutical, brake fluid; and many others.
Dewhurst et al. and
Baldwin et al. in studies on the carcinogenicity of
other chemicals used propylene glycol as the solvent. As a
result they tested propylene glycol alone for carcinogenic
activity in rats and mice. Dewhurst et al. used a single
injection of 0.2 mL, whereas Baldwin et al. gave rats
and mice three to five subcutaneous injections, amount not
specified. In neither case were tumors observed during a
period of about a year or 2 years .
Wallenious and Lecholm applied propylene glycol to the skin of rats three times a week for 14 months but found no tumor formation. Stenback and Shubik confirmed these findings when they applied propylene glycol at undiluted strength and as a 50 and 10% solution in acetone to the skin of mice during their lifetimes.
No tumors have been reported in the lifetime dietary feeding studies . In fact, Gaunt et al. specifically state that no tumors were found in the rats.
Dry the diol with Na2SO4, decant and distil it under reduced pressure. [Beilstein 1 IV 2468.]
Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explo- sions. Keep away from alkaline materials, strong acids (especially nitric acid), strong bases, permanganates, dichromates; may cause a violent reaction.
Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber.All federal, state, and local environmental regulations must be observed.
Propylene glycol Preparation Products And Raw materials
- Epoxidized soya bean oil
- Poly[dimethylsiloxane-co-methyl(3-hydroxypropyl)siloxane]-graft-poly(ethylene/propylene glycol) methyl ether
- 3-Chloro-1,2-propylene glycol
- alpha-Propylene glycol monomethyl ether,Methoxy ether of propylene glycol,Propylene glycol 1-methyl ether,1,2-PROPYLENE GLYCOL 1-MONOMETHYL ETHER
- beta-Propylene glycol,Propanediol-(1,3)-(1,3-propylene glycol)
- Propylene glycol
- Di(propylene glycol) methyl ether, mixture of isomers
- Hexylene Glycol
- Ethylene glycol diacetate
- Ethylene glycol
- Propylene oxide
- Diethylene glycol
- Products Intro:
- Product Name:1,2-Propanediol
Purity:standard for GC, >=99.5% (GC) Package:69RMB/5ML
- Products Intro:
- Purity:AR Package:500 毫升
- 025-58369808- ;025-58369808-
- Products Intro:
- Product Name:Propanediol
Purity:China Standardization Package:500ml;25kg;200kg
- Products Intro:
- Products Intro:
- Product Name:1,2-Propanediol
Purity:99% min Package:210kg drum Remarks:Pharm grade