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Comparatively Speaking Compound vs. Composition
By: Anthony J. O'Lenick Jr., Siltech LLC
Posted: October 4, 2011
Compounds are single chemical entities. Examples include sodium chloride (NaCl) and glucose. These materials cannot be separated into components using analytical techniques. Compounds are pure chemical substance consisting of two or more different chemical elements. Chemical compounds have a unique and defined chemical structure. They are comprised of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds. This makes compounds fundamentally different from compositions.
Compositions are mixtures of compounds rather than one single compound. Formulations are always complex compositions, and raw materials are commonly complex compositions. Formulations made from raw materials that are compositions themselves are complex and can be difficult to analyze and duplicate.
Raw materials can be mixtures for a variety of reasons, including the following.
- The raw materials used in the preparation of the compositions are themselves compositions, i.e., coconut oil, which is a mixture of a variety of carbon chain lengths ranging from C12 to C20.
- The process under which the raw materials were made provides an oligomer distribution of compounds rather than a single compound (like ethoxylation).
- The raw materials are not used in stiochiometric ratios, leaving an excess of one raw material present after the reaction is complete (like alkanolamides, which are run with an excess of amine).
- Some by-products are produced during the reaction (like chlorosulfonic sulfation).
- Additives are placed in the product as processing aides to alter viscosity, or change salt response in a formulation.
- Bleaches, antioxidants or related materials are added.
The ability to evaluate raw materials and pick one to replace another in a formulation requires an understanding of all these issues, making substitution difficult under many conditions. Certainly, one cannot rely upon INCI names for anything other than their intended use, namely providing label names.