Tocopherol (Vitamin E) as an Antioxidant: INCI and CAS Basics

If you have ever squinted at two ingredient lists that both say "vitamin E" and wondered why one calls it Tocopherol and the other Tocopheryl Acetate, you are not missing anything. They are related but chemically distinct, and mixing them up on a formula sheet is a common way to get a filing kicked back for review.

Two molecules, one vitamin

Tocopherol is the free alcohol form of vitamin E. It has a reactive hydroxyl group, which is exactly what makes it useful as an antioxidant. That hydroxyl group donates a hydrogen to neutralize free radicals, which is why formulators add small amounts of tocopherol to oils and emulsions to slow rancidity. It is doing a job for the formula, not for the skin, even though it happens to be gentle on skin too.

Tocopheryl Acetate is tocopherol with an acetate group attached to that same hydroxyl. The acetate makes the molecule more stable in a formula and less prone to oxidizing on the shelf, but it also blocks the reactive site. Tocopheryl Acetate does not act as an antioxidant in the finished product the way free tocopherol does. It is more commonly used as a skin conditioning ingredient and often shows up in formulas that carry an antioxidant, moisturizing, or anti-aging type claim.

That difference matters for how you describe the ingredient's function on a notification, and it matters if you are making any claim about protecting the formula or the skin from oxidative stress.

CAS numbers to know

INCI Name	CAS Number	Typical Function	Notes
Tocopherol	59-02-9	Antioxidant (formula stabilizer)	Also listed sometimes under mixed tocopherol CAS numbers depending on source
Tocopheryl Acetate	7695-91-2	Skin conditioning agent	Acetate ester, more oxidatively stable
Tocopherol (natural, mixed)	1406-18-4	Antioxidant	Used when sourced as a natural mixed-tocopherol blend rather than a single isomer

A quick note on the mixed tocopherol CAS number: natural vitamin E sources like soybean or sunflower oil often yield a blend of tocopherol isomers rather than pure alpha-tocopherol, and suppliers sometimes register that blend under its own CAS number. If your supplier documentation lists a CAS other than 59-02-9 for what they call tocopherol, that is usually why. Check the supplier's certificate of analysis or safety data sheet, since section 3 will list the actual composition.

Where formulators get tripped up

A few patterns show up again and again in ingredient lists sent for review:

• Listing "Vitamin E" as the INCI name. Trade and common names never go on a filing. It has to be mapped to Tocopherol or Tocopheryl Acetate, whichever is actually in the formula.
• Assuming a blend labeled "Vitamin E oil" is pure tocopherol. Many commercial "vitamin E oil" products are actually tocopherol diluted in a carrier like sunflower or safflower oil. If you're using one of these, you need to know the percentage of actual tocopherol in the blend, then multiply that by your use level to get the true concentration of tocopherol in your finished product, not the blend's whole percentage.
• Confusing an antioxidant ingredient with an antioxidant claim. Adding 0.1% tocopherol to protect your oil phase from going rancid is a formulation choice. Claiming your product "fights free radicals on skin" is a marketing claim, and claims are evaluated separately from ingredient function when a regulator or a retail buyer looks at your file.

Concentration ranges in practice

Tocopherol used purely as an antioxidant stabilizer is typically added at low levels, often well under 1%, just enough to protect the oil phase. Tocopheryl Acetate used for skin conditioning or as a headline ingredient in a serum or cream tends to appear at higher, more visible concentrations since it is often part of the product's positioning rather than a behind-the-scenes stabilizer.

Either way, when you're filling out a Cosmetic Notification Form in Canada, the ingredient goes in by its correct INCI name with its concentration or concentration range, and the function should reflect what the ingredient is actually doing in your specific formula, not what vitamin E does in general.

A practical way to keep this straight

Keep a running note next to your master formula that lists, for every supplier ingredient, the actual INCI name, the CAS number from the supplier's documentation, and whether it is the free tocopherol or the acetate ester. It sounds tedious the first time, but it saves you from re-deriving the same answer every time you file a new SKU or amend an existing one.

This is the kind of small, repeatable mapping problem that Cosmetic Comply was built to handle. Feed it your formula and supplier blend details, and it matches each ingredient to its correct INCI name and CAS number, carries blend percentages through the math, and flags anything that needs a second look before you file.