Telomer Acids: Monocarboxylic acids with long‐chain branching; Their derivatives, properties and potential uses in lubricants

Abstract

AbstractTelomer acids are synthesized by addition of acetic anhydride to α‐olefins using managenese (III) acetate as a free radical initiator. The telomerization mechanism comprises initiation, propagation and termination steps. The reaction product consists of a mixture of acids having [xn+2] carbon atoms (n: number of carbon atoms of α‐olefin: x:1, 2, 3, 4, …). The “first telomer” (x=1) is a linear fatty acid. Under appropriate conditions, mainly telomer acid (x:2, 3, 4, …) are obtained, being α‐ and γ‐branched monocarboxylic acids, characterized by long‐chain branches. Telomer acids derived from α‐olefins up to n=14 are liquids at room temperature, despite the high molecular weight. Esters of telomer acids show interesting properties in lubricant applications: low pour point, high viscosity index, low viscosity as a function of molecular weight, good thermo‐oxidative stability and a remarkably low elastomer swell. In amino amide derivatives, the telomer acid structure gives low viscosity properties, as is, for instance, found in significant viscosity reductions by using telomer acid as coreactant in polyisobutenyl succinic anhydride—tetraethylene pentamine condensation products. Dispersancy properties of these products are retained. Telomer acid metal salts exhibit quite different solubility characteristics and rheological properties than do fatty acid salts. Calcium salts of telomer acids are readily soluble in mineral oil: the rheology of these low viscosity solutions exhibits Newtonian behavior. Solvent‐free magnesium salts which are liquid can be obtained. Neutral and overbased calcium salts show pour point depressing activity in paraffinic oils. For overbased calcium salts, decrease of coefficient of friction with increasing temperature has been observed.