What is Propylene Glycol CAS 57-55-6?

Propylene Glycol, also called 1,2-propanediol or monopropylene glycol, is a clear, nearly odorless, hygroscopic liquid with the molecular formula C₃H₈O₂. It is widely used as a solvent, humectant, heat-transfer fluid, and chemical intermediate.

How is Propylene Glycol different from Ethylene Glycol?

Propylene Glycol has an additional methyl group compared with ethylene glycol and is much less acutely toxic. For this reason, food, pharmaceutical, cosmetic, and low-toxicity antifreeze applications use propylene glycol rather than ethylene glycol.

What grades of Propylene Glycol are available?

Industrial, food and USP requirements call for different specifications and supporting documents. The CAS number alone does not establish a grade. State the intended use, required standard, assay and impurity limits, quantity and destination; we will check current sourcing and the offered documents before confirming availability.

What are the main applications of Propylene Glycol?

It is used in unsaturated polyester resin production, antifreeze and heat-transfer fluids, food additives, flavors, fragrances, cosmetics, personal care products, and pharmaceutical formulations. It also acts as a carrier or solvent for many active ingredients and colorants.

Why is Propylene Glycol used in unsaturated polyester resins?

Propylene Glycol is one of the glycol monomers used in polyester polycondensation. The choice and ratio of glycol affect resin flexibility, hardness, water resistance, reactivity, and processing behavior, making PG important for balancing resin performance.

How should Propylene Glycol be stored and handled?

Keep it in tightly closed, compatible containers in a cool, dry, well-ventilated area away from strong oxidizers and ignition sources. Use liquid-chemical handling controls, suitable PPE, and protect material from moisture contamination.

Propylene Glycol CAS 57-55-6

Propylene Glycol (PG), CAS 57-55-6, is a hygroscopic diol used as a solvent, humectant and heat-transfer fluid. Its CAS number does not establish industrial, food, USP or cosmetic grade. Send your intended use, required standard, specification, quantity and destination; we will check the current sourced offer and available documents before quoting.

CAS: 57-55-6
Synonyms: 1,2-propanediol, 1,2-dihydroxypropane, methylethyl glycol, alpha-propylene glycol, monopropylene glycol
Einecs: 200-338-0
Molecular Formula: C₃H₈O₂
Grade: Confirm required grade and current specification for the sourced offer
Package: Confirm packaging for the actual sourced offer and destination

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Product Description

Propylene Glycol, CAS 57-55-6, also known as 1,2-propanediol or monopropylene glycol, is a clear hygroscopic diol; the EC/EINECS number is 200-338-0.

Synonyms: 1,2-propanediol; 1,2-dihydroxypropane; methylethyl glycol; alpha-propylene glycol; monopropylene glycol.

CAS: 57-55-6.

Molecular formula: C₃H₈O₂.

Molecular weight: 76.09 g/mol.

EC number: 200-338-0.

It is a colorless, transparent, almost odorless viscous liquid, hygroscopic and miscible with water, ethanol and acetone.

Assay, water, color and impurity limits depend on the current offered grade and specification; this page does not define a shipped-lot specification.

Density at 20 °C is 1.035–1.040 g/cm³; boiling point 188–189 °C, melting point about −59 °C and flash point about 99 °C.

Food, flavor and fragrance applications require a compliant, application-specific grade and current supporting documents; CAS identity alone does not establish suitability.

Pharmaceutical and personal-care uses require their own grade, impurity limits and regulatory review; no USP or cosmetic grade is confirmed on this page.

It is used as an intermediate for unsaturated polyester resins, plasticizers and surfactants, and as a low-volatility solvent in coatings, inks and cleaners.

It is used in aircraft deicing fluids, low-toxicity antifreeze and heat-transfer media where lower toxicity than ethylene glycol is required.

State the intended application, required grade or standard, assay, water and impurity limits, quantity and destination. We will check a current sourced offer against those requirements.

Store in tightly closed, compatible containers in a cool, dry, well-ventilated area away from strong oxidizers, strong acids and ignition sources.

Confirm packaging with the requested quantity and destination requirements.

Document requirements should be confirmed from the current specification, SDS, COA or other product-specific files.

The page is an RFQ entry point and does not state stock, price, MOQ or fixed lead time.

For an RFQ, state the intended use, required grade, specification, quantity, packaging, destination and document needs.

FAQ - Technical & Supply Chain

Q:
What is Propylene Glycol CAS 57-55-6?

A: Propylene Glycol, also called 1,2-propanediol or monopropylene glycol, is a clear, nearly odorless, hygroscopic liquid with the molecular formula C₃H₈O₂. It is widely used as a solvent, humectant, heat-transfer fluid, and chemical intermediate.
Q:
How is Propylene Glycol different from Ethylene Glycol?

A: Propylene Glycol has an additional methyl group compared with ethylene glycol and is much less acutely toxic. For this reason, food, pharmaceutical, cosmetic, and low-toxicity antifreeze applications use propylene glycol rather than ethylene glycol.
Q:
What grades of Propylene Glycol are available?

A: Industrial, food and USP requirements call for different specifications and supporting documents. The CAS number alone does not establish a grade. State the intended use, required standard, assay and impurity limits, quantity and destination; we will check current sourcing and the offered documents before confirming availability.
Q:
What are the main applications of Propylene Glycol?

A: It is used in unsaturated polyester resin production, antifreeze and heat-transfer fluids, food additives, flavors, fragrances, cosmetics, personal care products, and pharmaceutical formulations. It also acts as a carrier or solvent for many active ingredients and colorants.
Q:
Why is Propylene Glycol used in unsaturated polyester resins?

A: Propylene Glycol is one of the glycol monomers used in polyester polycondensation. The choice and ratio of glycol affect resin flexibility, hardness, water resistance, reactivity, and processing behavior, making PG important for balancing resin performance.
Q:
How should Propylene Glycol be stored and handled?

A: Keep it in tightly closed, compatible containers in a cool, dry, well-ventilated area away from strong oxidizers and ignition sources. Use liquid-chemical handling controls, suitable PPE, and protect material from moisture contamination.

Ordering & Documentation

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