Esters are a group of organic compounds consisting of a carbon atom that has three other atoms, including singly-bound oxygen. When exposed to nucleophiles, the carbonyl atom is attacked. The C-H bond adjacent to the carbonyl is weakly acidic and undergoes deprotonation with strong bases. The hydrocarbon group on the side of the ester chain is a carboxylic acid.
When combined with alcohol, esters are easily distinguishable from other molecules. Because they lack highly polarised hydrogens, the ester molecules are more prone to penetration in the gas phase. This means that a product containing an ester will be more effective and safer for consumers. In addition, esters can replace petroleum-based ingredients or other unsustainable substances. In the case of cosmetics, esters may improve the sensory experience for consumers.
In addition to phenoxyethanol, esters can be distinguished by their IR spectra. The IR spectra of esters show an intense sharp band in the range 1730-1750 cm-1. This peak is known as the nC-O peak. Depending on the type of functional groups attached to the carbonyl atom, the peak may decrease in wavelength. For instance, if a benzene ring is added to the alcohol, the nC-O peak is lowered to 30 cm-1. Recently, in October 2020, BASF announced to expand its ester base stocks production capacity in its Jinshan, China factory.