Heat exchanger fouling in organic chemical production processes may be reduced using an antifoulant additive. The antifoulant additive may have one component selected from the group consisting of an alkylphosphate ester, and an alpha olefin maleic anhydride copolymer; or it may have two components selected from the group consisting of a metallic overbase, an alkylphosphate ester, and an alpha olefin maleic anhydride copolymer, wherein at least one of the two components in not an overbase. An additive having three components: a metallic overbase, an alkylphosphate ester, and an alpha olefin maleic anhydride copolymer; is also within the scope of the disclosure.