Tetraethylguanidine is a carbonyl compound that contains an alkylthio group, carbonyl group, and an arylalkyl group. It is used as an additive in liquid detergents to render them resistant to hard water and as a functional group in cosmetics. Tetraethylguanidine has been shown to cross-link proteins and bind with cationic surfactants. It is also used as a cross-linking agent for the production of polyurethane foam insulation. Tetraethylguanidine has been shown to have anti-aging properties by inhibiting lipid peroxidation, which may be due to its ability to form imines and alkali metal complexes.