Chemical Nomenclature and GCI

The process of generating a GCI is to some extent a creative one but it should be based on the principles of good chemical nomenclature. The two most common approaches to systematic nomenclature are those of the International Union of Pure and Applied Chemistry (IUPAC) and the Chemical Abstracts Service (CAS). Before these organizations existed, many chemicals were already known by names which are now referred to as “trivial names”. These names were generally based on the natural source of the chemical at the time of discovery and, especially in the case of organic chemicals, were often coined before anything was known about their molecular structure. Many trivial names, (e.g., choline, aniline and toluene), have been approved by IUPAC, whereas they have been systematized by CAS to names based on the parent structure (e.g. 2-hydroxy N,N,N trimethylethanaminium, benzenamine and methylbenzene, respectively). Some trivial or common names of inorganic chemicals such as muriatic acid, slaked lime or soda ash are still used today in industry and popular literature but are more properly referred to by their chemical names — hydrochloric acid, calcium hydroxide and sodium carbonate, respectively.

When discussing GCIs, it is useful to differentiate between the two major groups of chemicals—inorganic and organic. In the following discussion, the words in bold-face are acceptable as a GCI or as part of a GCI. Because of the sheer number of chemicals in the group and the nature of products in commerce, it is not surprising that organic chemicals are more commonly the subject of claims for exemption from disclosure of a chemical identity.

The simplest organic chemicals are saturated acyclic or straight-chain hydrocarbons, referred to generically as alkanes. Unsaturated hydrocarbons are alkenes (also referred to as olefins) or alkynes (or acetylenes), depending on whether there are double or triple bonds present in the parent structure. When these hydrocarbons exist as radicals (i.e. side groups on a parent structure), the prefixes alkyl-(or alkan-), alkenyl-(or alken-), and alkynyl-(or alkyn-) may be used. The descriptor aliphatic applies to the whole group of straight-chain and branched hydrocarbons, regardless of whether the structure is saturated or unsaturated. The term alicyclic describes both saturated and unsaturated cyclic hydrocarbons (but not aromatics). Aliphatic and alicyclic are very general names and should only be used as part of a GCI if a more specific name would reveal the CBI. Benzene and other related unsaturated, ringed hydrocarbons may be referred to as aromatic or aryl (generally if they are a radical) or as arene, if they are the parent structure. The use of the term carbocyclic, which includes alicyclic and aromatic structures, should be avoided. Carbocyclic structures with more than two fused rings may include the term polycyclic in the GCI.

It is somewhat more difficult to generate a GCI for heterocyclic organic chemicals or heterocycles, i.e. rings consisting of carbon and another atom(s) such as oxygen, nitrogen or sulphur. The simplest examples of rings which include oxygen are oxirane (ethylene oxide) and methyloxirane (propylene oxide). When these chemicals are used to alkoxylate other chemicals, such as amines or alcohols, the reaction products are referred to as alkanolamines and alkoxylates, respectively. Rings containing oxygen may be known by their trivial name (e.g. furan) or by the more generic name cyclic ethers. Rings containing nitrogen may be named based on their trivial name (e.g. imidazoline, lactam) or, for example, cyclic (di)amine and cyclic amide; whereas those with sulphur (e.g. thiophene) could be referred to as cyclic thioethers. When the hydroxyl of the carboxyl group of an acid has been replaced (e.g. acetyl chloride), the acid group may be referred to as acyl (e.g. acyl halide). Other trivial names such as glycol and terpene may be used to generate GCI such as alkylene glycol ether (for comparison, this would be equivalent to the GCI based on its systematic name, alkoxyalkanol) and cyclic terpene. Some trivial names may be used directly as GCI where the basic linkage is known but the precise structure of the reaction product(s) is not known (e.g. Schiff base from condensation of ketones or aldehydes with primary amines). The use of terms such as dibasic acid, polyhydric alcohol, tertiary amine, etc. should be avoided unless a more specific name would reveal the CBI.

Petroleum-based complex mixtures may have a GCI such as naphtha (generally with a descriptor such as light or heavy) or petroleum distillate. For complex mixtures involving long-chain carboxylic acids derived from animal or vegetable fats and oils, a GCI such as fatty acids (and the related derivatives fatty alcohol, fatty amine, fatty ester, etc.) may be used. Petroleum-based fatty acids are generally referred to as naphthenic acids. Generic terms and phrases such as (per)fluorocarbon, siloxane, phenolic epoxy resin, acrylate resins (which could include methacrylates), etc. are acceptable for a GCI, whereas organophosphorus, organosulphur, epoxy resin, etc. are not acceptable.

The approach used to designate the presence of certain functional groups or radicals on a chemical structure may vary, depending on whether they are a terminal group or occur within the structure (see Example 1). A terminal group may be identified generically as a term (e.g. ester, alcohol, aldehyde, salt) or as an appropriate syllable (-oate or alkoxy-, -ol, -al, -ate). If a radical is not a terminal group, the appropriate term may be used (e.g. ketone, azide, ether, halide, oxide, alcohol, amine) or the respective syllable (e.g. keto- or oxo-, azo-, oxa-, halo-, epoxy-, hydroxyl-, amino-) with the actual position on the straight chain or ringed parent structure masked. Not all groups or radicals have a suitable prefix or suffix syllable (e.g. oxime, acid anhydride). If there are more than two of the same radical, then the addition of the prefix poly- should be considered. The fact is that many of the organic CBI ingredients are reaction products, so the chemistry that must be reflected by a GCI is often much more complex. It is likely, in some cases, that even if the precursor ingredients were disclosed, it would be very difficult—if not impossible—for a competitor to reproduce the precise reaction products because of the complexity and secrecy of the manufacturing process itself. Nevertheless, if a GCI must be generated for such an ingredient, where the precise structure of the reaction product is not known, the best approach is to provide a GCI for the precursor ingredients (see Example 4 below).

Because of the relative ease of qualitative analysis of inorganics, it would normally be a simple matter to determine, for example, which cation(s) and anion(s) are in a mixture. Nevertheless, when the claim for CBI does involve inorganic chemicals, it is clear that there is not very much flexibility or many alternative choices for a GCI. The GCI of simple inorganic substances, such as those used in the example of trivial names at the beginning of this section would be inorganic or mineral acid, inorganic base and either sodium salt or carbonate salt. The metal portion of an inorganic chemical could be masked by using the term alkali, alkali earth, rare earth or transition metal (or, in some cases, just metal). In the case of non-metals present in the ingredient (e.g. boron, silicon, sulphur, etc.), most should probably be unmasked but the position or precise linkage could be masked. The other two major groups of non-metals could be masked in a GCI as halides and noble or inert gases.

Date Modified: 2010-12-15

Top of Page

Important Notices