A compound is a condensate of 1,2,3-trihydroxybenzene with an aldehyde. The condensate is a macrocyclic compound such as a cyclic tetramer. The aldehyde is preferably a long-chain aldehyde such as hexanal, dodecanal or tetradecanal. The condensate can be used as an anti-wear additive in hydrocarbon liquids such as liquid paraffin or as an anti-corrosion additive. The condensate can be prepared by reacting 1,2,3-trihydroxybenzene with an equimolar quantity of an aldehyde in the presence of an acid.
