Comparatively Speaking: Naming Cosmetic Raw Materials

In the following excerpt adapted from an article featured on the Chemist's Corner, Tony O'Lenick looks to Perry Romanowski to illustrate how names are assigned to cosmetic raw materials for the benefit of novice formulators. The cosmetics industry does not use the International Union for Pure and Applied Chemistry (IUPAC) naming system. Instead, it follows its own system as laid out in the International Nomenclature of Cosmetic Ingredients (INCI) dictionary. This dictionary is recognized worldwide by the cosmetics R&D industry, and is produced by a cosmetic industry trade group known as the Personal Care Products Council (PCPC).

List of Ingredients
The first thing to know about cosmetic ingredients is the ingredient list. In the United States, every personal care and cosmetic product is supposed to have its ingredients listed. In the business, this is referred to as the list of ingredients (LOI). Any ingredient above 1% is required to be listed in order of concentration by weight. At 1% or below, the ingredients can be listed in any order. Typically, preservatives and dyes are listed at the end. To be proper, companies should follow the naming conventions as laid out in the INCI dictionary.

Cosmetic Ingredient Naming Conventions
While many chemical names in the INCI seem arbitrary, there are some standard rules. The following conventions will help the reader make heads or tails of the ingredients on most LOIs. While all the conventions are not listed here, the major ones are, in addition to examples.

Common Names
When the PCPC first developed the INCI dictionary, originally called the CTFA Cosmetic Ingredient Dictionary, in 1973, many cosmetic ingredients already had names. These common names were incorporated into the dictionary even though they did not follow specific naming rules. Therefore, the term glycerin is used rather than the more accurate glycerol, and menthol rather than (1R, 2S, 5R)-2-isopropyl-5-methylcyclohexanol. Common names are also used for various natural ingredients like lanolin and beeswax.

Stem Names
Probably one of the most important basics to learn about naming cosmetic ingredients is the list of hydrocarbon stem names. This is a bit different than the IUPAC. For example, in the case of a 16-carbon alcohol, it is called cetyl alcohol instead of hexadecanol. For an 18-carbon acid, stearic acid is used instead of octadecanoic acid.

The cosmetic chemist will also run into names like cocamidopropyl betaine that do not match any of the stem names. This is because the raw material uses coconut oil as a starting raw material. In these cases, an abbreviation of that starting material is used. Other names that chemists will encounter include palm kernel oil, soybean oil and sunflower oil.

The INCI dictionary attempts to follow established conventions from other systems. For example, when naming an ether, the chemist takes the stem names from both fatty acids and adds the term ether. Thus, a molecule made with a 14-carbon and 16-carbon chains connected by an oxygen would be called cetyl myristyl ether. An ester of the same molecules would be cetyl myristate.

Hydrocarbons that contain nitrogen are amides and have the phrase included in their name. Therefore, lauramide is used to describe a 12-carbon molecule (lauryl) that has an NH2 group on its end. If the nitrogen has other hydrocarbons attached, those are also named. So, lauramide DEA would be that same 12-carbon molecule attached to a nitrogen, which also has ethyl groups attached to it. When these nitrogen-containing compounds are turned into salts, the suffix -monium is added. So, a 16-carbon attached to a nitrogen with three methyl groups is cetrimonium chloride.

A variety of conventions are used to name polymers. For nitrogen-containing polymers, the term polyquaternium is used. There is also a number associated with the ingredient but this does not refer to anything chemically, it just happens to be the order in which the material was registered. Other polymers use common abbreviations. PEG is polyethylene glycol; PPG is polypropylene glycol, etc.; these are followed by a number to refer to the moles of ethoxylation in the polymer.

For silicone-containing materials, terms like dimethicone, cyclomethicone and amodimethicone are used. Whenever some form of these words appears in a chemical name, the chemist knows there is some silicone in it.

Ten years ago, the abbreviation FD&C appeared in front of many chemical colorants. Today, however, the INCI dictionary has adopted a simplified method for naming colors: the color is simply listed followed by a number (e.g., Yellow 5). This does not tell the chemist anything about the chemical composition but the structure of it can be found in the INCI dictionary. An alternative naming system is the EU one, in which each colorant is assigned a 5-digit chemical index (CI) number. For example, Yellow 5 in the EU is called CI 19140.

Miscellaneous Rules
There are many other naming rules that are learned over time; here are just a few.
1. Water is called water, not deionized, purified or anything else—just water.
2. Fragrance is called fragrance no matter what compounds are used to make it. This is changing, but for now it’s correct.
3. Botanicals use the Latin name of the plant or part plus the term extract. So, if an ingredient taken from the leaf of a lemon is used, the ingredient is called Citrus medica limonum (lemon) leaf extract.

The naming conventions of cosmetic raw materials share some characteristics with the IUPAC system taught in organic chemistry courses. However, there are many differences and for some things, it is impossible to determine the chemical structure from just the name. For more information, the best bet is for chemists to access their company's or city's library to take a look at the latest version of the INCI dictionary. (Editor's note: In addition, there are online INCI and trade name directories available, such as the free Cosmetic Bench Reference (CBR), which provide some if not all of this information via the Internet.)

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