Propyl 4-hydroxybenzoate (PHB), is a p-hydroxybenzoate derivative. It can be prepared by reacting p-hydroxybenzoic acid with n-propanol in the presence of an acidic ionic liquid.It crystallizes in the monoclinic space group P21/c.It is reported to be an endocrine disrupting compound.
It is hydrolyzed to p-hydroxybenzoic acid, conjugated and the conjugates are rapidly excreted in the urine. There is no evidence of accumulation. Acute toxicity studies in animals indicate that propyl paraben is relatively non-toxic by both oral and parenteral routes, although it is mildly irritating to the skin.
Propyl Hydroxybenzoate is soluble 1 in 2500 of water and 1 in 1.5 of alcohol. The solubility of both componds is increased in hot water.
Some research indicates they are safe as used in cosmetics and are preferred over other preservatives to keep a formula stable. These studies also showed parabens did not have any effect when compared to natural hormones in the body.
