A guide to C9–11 alcohol ethoxylate with 6 moles EO — what it is, how formulators use it, and how it compares with NPE and its sister grades — from a US-based distributor.
91-6 alcohol ethoxylate is a nonionic surfactant made by adding about six moles of ethylene oxide to a C9–11 synthetic alcohol. With an HLB near 12.4, it is a workhorse wetting agent and detergent for laundry, hard-surface, and I&I cleaners. Stratus Chemical supplies it in drums and bulk, with COA and SDS.
| Chemical name | Alcohols, C9–11, ethoxylated (avg. 6 mol EO) |
|---|---|
| CAS number | 68439-46-3 |
| Structure | CH3(CH2)n–O(CH2CH2O)yH, n = 8–10, y ≈ 6 |
| Type | Nonionic surfactant |
| Synonyms | C9–11 alcohol ethoxylate 6EO, C9–11 pareth-6, 91-6 AE, linear alcohol ethoxylate 6 mole |
| Grades supplied | 99.5% min actives; Kosher-certified material available |
| Packaging | Drums, bulk |
91-6 is a nonionic surfactant built from two parts: a C9–11 synthetic alcohol that dissolves grease and oil, and a chain of about six ethylene oxide units that makes the molecule water-soluble. The name encodes both. “91” is the C9–11 carbon range; “6” is the average moles of ethylene oxide.
That balance is why formulators use it. The short C9–11 chain makes it a fast, aggressive wetting agent that penetrates soils quickly, while six moles of EO give an HLB of about 12.4 — right in the detergent and oil-in-water emulsifier range. It is stable in both acidic and alkaline solutions, so the same surfactant works in an acid descaler and a caustic degreaser. It is compatible with anionic, amphoteric, and cationic surfactants and with common solvents, produces moderate foam, and is readily biodegradable.
| Appearance at 25 °C | Clear to slightly hazy liquid |
|---|---|
| Average moles EO | 6.0–6.5 |
| HLB | 12.4 |
| Actives | 99.5% min |
| pH, 1% aqueous | 6.0 |
| Density | 0.990 g/mL (8.25 lb/US gal) |
| Color, APHA | 50 max |
| Cloud point, 1% aqueous | 47–58 °C (116–136 °F) |
| Pour point | 6 °C (43 °F) |
| Viscosity at 38 °C (100 °F) | 22 cP |
| Flash point, PMCC | >94 °C (>201 °F) |
| RVOC (US EPA) | 0% |
| Preservative | Not required |
Typical values. The Certificate of Analysis for each lot governs.
This is the largest use. 91-6 is the primary nonionic in many all-purpose, glass, floor, and bathroom cleaners because it wets quickly, lifts oily soil, and rinses clean. It is commonly paired with an anionic such as DDBSA/LABSA or SLES for extra detergency, and with builders and chelants such as sodium gluconate or citric acid for hard-water performance. Because it stays stable at low and high pH, it also goes into acid bathroom cleaners and alkaline degreasers built on caustic soda.
In liquid laundry detergents, 91-6 removes oily and greasy soils that anionics alone handle poorly, and it holds performance in cold water. Its moderate foam profile suits both conventional and high-efficiency formulas when balanced with the rest of the surfactant system.
Janitorial concentrates, food-plant sanitation cleaners, vehicle washes, and parts washers use 91-6 as a concentrated, high-active wetting agent. Its 0% RVOC helps formulators meet VOC limits on cleaning products.
Pesticide and adjuvant formulators use 91-6 as an emulsifier and wetting agent, helping spray solutions spread across and penetrate waxy leaf surfaces.
In textile processing it is used for scouring and wetting ahead of dyeing, often as a replacement for NPE. In water-based paints and coatings it serves as a wetting agent and emulsion stabilizer.
The degree of ethoxylation sets the behavior. Fewer moles of EO make the surfactant more oil-soluble; more moles make it more water-soluble and raise the cloud point.
| 91-2.5 | 91-6 | 91-8 | |
|---|---|---|---|
| Average moles EO | 2.5 | 6.0–6.5 | 8.3 |
| HLB | 8.5 | 12.4 | 13.9 |
| Cloud point, 1% aq. | N/A (not water-soluble) | 47–58 °C | 78–85 °C |
| Pour point | −13 °C (9 °F) | 6 °C (43 °F) | 15 °C (59 °F) |
| Density, g/mL | 0.925 | 0.990 | 1.008 |
| Best fit | Oil-based systems, low-foam machine cleaning | General-purpose wetting and detergency | Hot-wash, higher-temperature, and more water-soluble systems |
How to choose: 91-6 is the default for most cleaners because its cloud point sits above normal use temperatures and its HLB favors oily soil removal. Move to 91-8 if the product is used hot or needs more solubility in high-electrolyte formulas — 91-6 will cloud out above roughly 50 °C. Move to 91-2.5 for solvent- or oil-based products and low-foam machine cleaning, where water solubility is not wanted.
Nonylphenol ethoxylates such as NPE 9 were the standard nonionic for decades, but they break down into nonylphenol, which is persistent and toxic to aquatic life. NPEs are restricted in the EU and are excluded from the US EPA Safer Choice program, and many brand owners have removed them from their supply chains. C9–11 alcohol ethoxylates with 6 to 8 moles of EO are among the most common drop-in candidates.
| 91-6 alcohol ethoxylate | Nonylphenol ethoxylate (NPE 9) | |
|---|---|---|
| Biodegradability | Readily biodegradable | Degrades to persistent nonylphenol |
| Regulatory direction | Widely accepted in “green” formulations | Restricted in the EU; excluded from EPA Safer Choice |
| Wetting speed | Very fast (short C9–11 chain) | Fast |
| Oily soil removal | Comparable | Strong |
| Handling | Can gel on dilution; pour point 43 °F | Similar gel behavior |
The trade-off: 91-6 is not always a one-for-one swap. NPEs have a slightly different foam and cloud-point profile, so a reformulated product may need a blend of 91-6 and 91-8, or a small adjustment to the anionic, to match the original. The right ratio is established by bench testing against the existing formula.
Gelling on dilution. Like all alcohol ethoxylates, 91-6 forms a thick gel at intermediate concentrations in water. Add the surfactant to the full batch of water under agitation rather than the reverse, and use warm water where possible. Heating reduces or eliminates the gel.
Cold weather. With a pour point of 6 °C (43 °F), 91-6 thickens and can solidify in an unheated warehouse or tank. If the product freezes, warm it gently and stir until it is uniform before use. Store in sealed containers in a cool, dry place.
Personal protection. Undiluted, 91-6 is a severe eye and skin irritant; a 1% dilution typically causes only slight to mild skin irritation. Wear gloves and safety goggles when handling the concentrate.
COA and SDS are provided with every shipment.
91-6 alcohol ethoxylate is a nonionic surfactant used as the main wetting agent and detergent in laundry liquids, hard-surface and all-purpose cleaners, and industrial & institutional (I&I) cleaners. It is also used as an emulsifier in agricultural pesticide formulations, a wetting and scouring agent in textile processing, and a surfactant in water-based paints. Stratus Chemical supplies it in drums and bulk.
The CAS number for 91-6 alcohol ethoxylate is 68439-46-3, which covers C9–11 alcohols, ethoxylated. The “91” refers to the C9–11 alcohol range and the “6” to an average of about six moles of ethylene oxide per molecule.
In 91-6 alcohol ethoxylate, the “91” means the hydrophobe is a C9–11 synthetic alcohol and the “6” means it carries an average of about 6 moles of ethylene oxide (6.0–6.5 typical). The same naming is used for sister grades such as 91-2.5 and 91-8, which carry less and more ethylene oxide.
91-6 alcohol ethoxylate has an HLB of about 12.4, which places it in the oil-in-water emulsifier and detergent range. Its 1% aqueous cloud point is typically 47–58 °C (116–136 °F).
Yes. 91-6 alcohol ethoxylate is one of the most common replacements for nonylphenol ethoxylates (NPE 9) in cleaners and textile processing. It gives similar wetting and detergency, is readily biodegradable, and avoids the alkylphenol chemistry that is restricted in the EU and excluded from the US EPA Safer Choice program. Some reformulation is usually needed to match foam and cloud point.
Like all alcohol ethoxylates, 91-6 passes through a thick gel phase at intermediate concentrations in water. To avoid it, add the surfactant to the full volume of water with good agitation rather than adding water to the surfactant, and use warm water where possible. Heating reduces or eliminates gel formation.
Yes. 91-6 alcohol ethoxylate is readily biodegradable, has 0% RVOC (reactive volatile organic compounds, US EPA), and needs no preservative because it is supplied at 99.5% minimum actives.
Stratus Chemical supplies 91-6 alcohol ethoxylate in drums and in bulk, with a Certificate of Analysis and Safety Data Sheet on every shipment. Kosher-certified material is available. To get pricing, send Stratus Chemical the volume and delivery location through the quote form and you will receive a response within one business day.
Looking for related products? See SLES, DDBSA / LABSA, cocamidopropyl betaine, and sodium gluconate, the full product range, or request a quote.
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