This work investigates the phase transfer catalytic replacement of ethyl-2-bromoisobutyrate (EtOBuBr) with phenol in the synthesis of ethyl-2-phenoxyisobutyrate (R1OR2COOR3, ester-ether compound) in an alkaline aqueous solution of KOH/organic solvent two-phase medium. In this substitution, tetrabutylammonium bromide (TBAB) acts as the phase transfer catalyst. Based on the solubility of (EtOBuBr) in aqueous solution and in an organic solvent, a mechanism for the reaction on the interface between the organic and aqueous phases is proposed. The concentration of each component in the reaction solution was determined experimentally from the material balance. Hydrolysis of EtOBuBr (reactant) and R1OR2COOR3 (ether-ester product) accompanied by the above substitution are both considered in the kinetic model. This work also investigates the kinetics of the reaction, such as the effects of the agitation speed, organic solvents, concentration of phenol (aqueous-phase reactant) and amount of TBAB catalyst on the conversion of hydrolysis, the replacement of EtOBuBr, and the yield of R1OR2COOR3.