During the last 25 years, a great deal of work has been done to develop surface-active agents that contain phosphorous. This is due in part to the natural occurrence of phospholipids, a chemical necessary for life as we know it. Synthetic phosphorous-based surface-active agents can provide a number of properties to formulations including wetting, emulsifi cation, foaming, conditioning and having antimicrobial properties.
While there is no single compound with all of these various properties, the properties are a direct consequence of the structure of the compounds. There are three very different classes of phosphorus-based compounds with different properties. These include the mild, high-foaming, detergent molecules called phosphobetaines; the emollient conditioning compounds, which have become known as phospholipids; and the antimicrobial super conditioning agents called phosphoquats.
This article offers a review of the chemistry of natural phospholipids, synthetic phospholipids, phosphobetaines and phosphoquats. Naturally occurring lipids are actually triglycerides made by the reaction of a fatty acid and glycerin. These materials can be made in the laboratory with catalyst at a high temperature (180-200°C). However, the reaction occurs in living cells at low temperatures using specifi c enzyme systems (Figure 1).