Alphabetical general formula index

The simplest kind of formula is a compositional formula or empirical formula, which lists the constituent elements in the atomic proportions in which they are present in the compound. For such a formula to be useful in lists or indexes, an order of citation of symbols (hierarchy) must be agreed. Such hierarchies, often designated seniorities or priorities, are commonly used in nomenclature. For lists and indexes, the order is now generally recommended to be the alphabetical order of symbols, with one very important exception. Because carbon and hydrogen are always present in organic compounds, C is always cited first, H second and then the rest, in alphabetical order. In non-carbon-containing compounds, strict alphabetical order is adhered to. 

Classification of polymers by functional type is not generally suitable because some of the classes would be excessively large and the reader might have to search several classes to find a particular compound. Indexing by formula requires too much time and effort in searching for common polymers. The best solution is a simple alphabetical listing. To make an alphabetical listing practical it is necessary to define a set of rules of nomenclature. 

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