Is Propylene Glycol n-Butyl Ether a VOC?

Yes. Propylene Glycol n-Butyl Ether is classified as a volatile organic compound (VOC).

Is Propylene Glycol n-Butyl Ether on California's Proposition 65 list?

No. Propylene Glycol n-Butyl Ether is not on California's Proposition 65 list.

Is Propylene Glycol n-Butyl Ether biodegradable?

Yes. Propylene Glycol n-Butyl Ether has a confirmed biodegradable profile.

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Propylene Glycol n-Butyl Ether

Q: What is Propylene Glycol n-Butyl Ether used for in car care?

Glycol-ether solvent used to dissolve oily soils and improve surfactant penetration into greasy films; common replacement for 2-butoxyethanol in modern cleaner reformulations

Glycol ether solvents
CAS 5131-66-8
IUPAC: 1-Butoxy-2-propanol

Propylene Glycol n-Butyl Ether (CAS 5131-66-8) appears in 1 of the 2,122 car-care products CarCareTruth tracks (as of August 2026). It is classified as a VOC.

H319 (eye irritation) and H336 (drowsiness/dizziness) ingredient-level classifications at high concentrations. Does NOT carry the reproductive-toxicity (H361) or repeated-dose target-organ-toxicity (H373) hazard codes that 2-butoxyethanol does — the propylene-glycol ether family is generally regarded as a less hazardous substitute. At <5% in finished consumer products and water-dilution working strength, ingredient-level hazards are not typically retained at the mixture-level GHS classification.

Propylene glycol n-butyl ether (PnB, sometimes labeled as 1-butoxy-2-propanol or Dowanol PnB) is a glycol-ether solvent commonly used in heavy-duty cleaners and degreasers to dissolve oily soils and help surfactants penetrate greasy films. It is part of the propylene-glycol-ether family, which the cleaning-products industry has broadly adopted as a replacement for ethylene-glycol-ether solvents — most notably 2-butoxyethanol — because the propylene-glycol variants carry a meaningfully cleaner toxicology profile (no H361 reproductive flag, no H373 organ-toxicity flag).

It is a VOC under EPA and CARB definitions, so its contribution to total product VOC is tracked. In finished cleaners it typically appears at 1–5% as the active solvent.

Health & environment profile

VOC: yes
Prop 65 listed: no
Asthmagen: no
EPA Safer Choice: no
Aquatic toxicity: no
Biodegradable: yes
Bioaccumulative: no
Persistent: no
Ozone depleting: no
Microplastic: no
PFAS: no
Env. score: 3/5

Purpose: Glycol-ether solvent used to dissolve oily soils and improve surfactant penetration into greasy films; common replacement for 2-butoxyethanol in modern cleaner reformulations

Common questions about Propylene Glycol n-Butyl Ether

What is Propylene Glycol n-Butyl Ether used for in car care?: Glycol-ether solvent used to dissolve oily soils and improve surfactant penetration into greasy films; common replacement for 2-butoxyethanol in modern cleaner reformulations
Is Propylene Glycol n-Butyl Ether a VOC?: Yes. Propylene Glycol n-Butyl Ether is classified as a volatile organic compound (VOC).
Is Propylene Glycol n-Butyl Ether on California's Proposition 65 list?: No. Propylene Glycol n-Butyl Ether is not on California's Proposition 65 list.
Is Propylene Glycol n-Butyl Ether biodegradable?: Yes. Propylene Glycol n-Butyl Ether has a confirmed biodegradable profile.

1 product contain this

Simple Green Pro HD Heavy-Duty Cleaner & Degreaser
engine-degreaser
Prop 65

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.