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57-55-6

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Identification

Name
1,2-Propanediol
CAS
57-55-6
Synonyms
1,2-DIHYDROXYPROPANE
(+/-)-1,2-PROPANEDIOL
1,2-PROPANEDIOL
1,2-PROPYLENE GLYCOL
ARCOPLUS(R)
ARCTIC PLUS(R)
DOWFROST(TM)
FEMA 2940
GLYCOL-PROPYLENE
METHYL GLYCOL
Methylglyeol
MONO PROPYLENE GLYCOL
PG
PG-AAF
PG-ADF
PGI
PROPANE-1,2-DIOL
PROPYLENGLYCOLUM
SAFEWING MP IV 2001
1,2-Propandiol
EINECS(EC#)
200-338-0
Molecular Formula
C3H8O2
MDL Number
MFCD00064272
Molecular Weight
76.09
MOL File
57-55-6.mol

Chemical Properties

Appearance
clear viscous liquid
Appearance
Propylene glycol is a colorless, odorless, syrupy liquid.
Melting point 
-60 °C
mp 
-60 °C
Boiling point 
187 °C(lit.)

bp 
187 °C(lit.)

density 
1.036 g/mL at 25 °C(lit.)

vapor density 
2.62 (vs air)

vapor pressure 
0.08 mm Hg ( 20 °C)

refractive index 
n20/D 1.432(lit.)

FEMA 
2940
Fp 
225 °F

storage temp. 
Store at RT.
form 
Viscous Liquid
pka
14.49±0.20(Predicted)
color 
APHA: ≤10
Specific Gravity
1.038 (20/20℃)1.036~1.040
PH
6-8 (100g/l, H2O, 20℃)
explosive limit
2.4-17.4%(V)
Water Solubility 
miscible
Sensitive 
Hygroscopic
JECFA Number
925
Merck 
14,7855
BRN 
1340498
InChIKey
DNIAPMSPPWPWGF-UHFFFAOYSA-N
Contact allergens
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.
Uses
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.
Uses
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.
CAS DataBase Reference
57-55-6(CAS DataBase Reference)
NIST Chemistry Reference
Propylene glycol(57-55-6)
EPA Substance Registry System
57-55-6(EPA Substance)

Hazard Information

Chemical Properties
clear viscous liquid
General Description
Thick odorless colorless liquid. Mixes with water.
Reactivity Profile
PROPYLENE GLYCOL(57-55-6) is hygroscopic. PROPYLENE GLYCOL(57-55-6) is sensitive to excessive heat (tends to oxidize at high temperatures). This compound can react with oxidizing materials. PROPYLENE GLYCOL(57-55-6) is incompatible with acid chlorides, acid anhydrides, chloroformates, and reducing agents. PROPYLENE GLYCOL(57-55-6) dissolves many essential oils. A mixture of this compound with hydrofluoric acid and silver nitrate was put in a glass bottle which burst 30 minutes later.
Air & Water Reactions
Water soluble.
Health Hazard
Liquid may irritate eyes.
Potential Exposure
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.
Fire Hazard
This chemical is combustible.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, includ- ing resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medi- cal attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.
Incompatibilities
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.
Description
Propylene glycol is used as antifreeze in breweries and diaries, in the manufacture of resins, as a solvent, and as an emulsifier in food. It was present as an occupational sensitizer in the color-film developer Flexicolor.
Waste Disposal
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.
Occurrence
Reported found in several varieties of mushrooms, roasted sesame seed, oat groats, parmesan cheese, cocoa, pecans and truffle.
Indications
Propylene glycol solution (40% to 60%, v/vCH2CH[OH]CH2OH, propylene glycol) applied to the skin under plastic occlusion hydrates the skin and causes desquamation of scales. Propylene glycol, isotonic in 2% concentration, is a widely used vehicle in dermatologic preparations. Hydroalcoholic gels containing propylene glycol or other substances augment the keratolytic action of salicylic acid. Keralyt gel consists of 6% salicylic acid, 19.4% alcohol, hydroxypropylcellulose, propylene glycol, and water and is an extremely effective keratolytic agent. Overnight occlusion is used nightly until improvement is evident, at which time the frequency of therapy can be decreased to every third night or once weekly. This therapy is well tolerated, is usually nonirritating, and has been most successful in patients with X-linked ichthyosis vulgaris. Burning and stinging may occur when applied to damaged skin. Patients with other abnormalities of keratinization with hyperkeratosis, scaling, and dryness may also benefit.
Production Methods
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.
Preparation
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.
Definition
An alcohol in which the hydroxyl groups are attached to a carbon atom of a branched or straight-chain aliphatic hydrocarbon.
Brand name
Sentry Propylene Glycol (Union Carbide); Sirlene (Dow Chemical).
Aroma threshold values
Detection: 340 ppm
Hazard
Toxic.
Carcinogenicity
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.
Environmental Fate
Propylene glycol can be released into the environment via industrial releases or by disposal of consumer products. Propylene glycol is readily soluble in water and has a low sorption partition coefficient (KOC), so has the ability to move through soil and to leach into ground water. Because of low vapor pressure (0.1 mmHg at 25°C) and high water solubility, there is minimal volatilization to the atmosphere from surface water releases as well as substantial removal of its vapors by wet deposition. Its low octanol/water partition coefficient (KOW) indicates that bioconcentration and biomagnification should not happen. Propylene glycol is readily degraded in surface water and soil, by chemical oxidation and microbial digestion, with a short half-life (1–5 days) in aerobic or anaerobic conditions. It is also rapidly degraded in the atmosphere by photochemical oxidation, with a half-life about 1 day. Although environmental releases can and do occur (airports must monitor storm water runoff of deicing solutions), human health effects are likely to be minor, at least in comparison to effects from potential exposures in clinical scenarios.
Purification Methods
Dry the diol with Na2SO4, decant and distil it under reduced pressure. [Beilstein 1 IV 2468.]
Toxicity evaluation
Propylene glycol has a low degree of toxicity in animals as well as humans, such that very high doses are needed to elicit effects in acute toxicity studies. The toxic effects of propylene glycol appear to be similar in animals and in humans. Central nervous system (CNS) depression, hematologic toxicity, hyperosmolarity, metabolic acidosis, cardiovascular effects, and renal toxicity encompass the main acute and subacute syndromes for propylene glycol. Most of the effects of propylene glycol can be ascribed to high concentrations of the parent molecule or to the accumulation of D,L-lactate in the blood. Due to its alcohol moiety, propylene glycol at very high concentrations is the most likely reason for the CNS depression. Also, because high concentrations of propylene glycol will increase the osmolarity of the blood, the hyperosmotic effects are likely due to the parent molecule. The cardiovascular and renal effects may be a result of the hyperosmolarity in combination with the metabolic acidosis. The acidosis itself results from the accumulation of lactate (both D- and L-forms), which has been well documented in both animals and humans.

Safety Data

Safety Statements 
S24/25:Avoid contact with skin and eyes .
WGK Germany 
1

RTECS 
TY2000000

Autoignition Temperature
779 °F
TSCA 
Yes
HS Code 
29053200
Safety Profile
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.
Hazardous Substances Data
57-55-6(Hazardous Substances Data)

Raw materials And Preparation Products

Material Safety Data Sheet(MSDS)

Questions And Answer

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.
 the molecular structure of propylene glycol
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.
Content analysis
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.
Toxicity
FAO/WHO (2000): ADI is 0 to 25mg/kg.
LD50 is 22 to 23.9 mg/kg (mouse, oral).
GRAS (FDA, §184.1666, 2000).
Use limitation
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%.
Uses
Propylene glycol is used for similar applications as other glycols.
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.
Synthesis method
It can be obtained by hydrolysis of Propylene oxide:
CH3CHCH2+H2O[H+]→CH3CH(OH)CH2OH
Direct hydration
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.
Catalyzed hydrolysis
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.
Acute toxicity
Oral-rat LD50: 20000 mg/kg; Oral-Mouse LD50: 32000 mg/kg
Irritation data
Eyes-rabbit 100 mg mild
Extinguishing agent
Dry powder, foam, sand, water.

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