The extraction of 2-methylidenebutanedioic acid was investigated using N-methyl-N,N-dioctyloctan-1-ammonium chloride (trioctylmethyl ammonium chloride) (Aliquat 336) with different diluents having distinct functional groups. Nine diluents were used in the study, that is, octan-1-ol, nonan-1-ol, decan-1-ol, ethyl acetate, propyl acetate, heptan-2-one, octan-2-one, octane, and decane. The measurements were performed at temperature of 298.2 K. The experimental results of batch extractions were used to calculate distribution coefficients (K-D), loading factors (Z), and extraction efficiency (E). The maximum distribution coefficient (K-D = 13.01) was obtained with octan-1-ol, and its extraction efficiency was 92.86 %. Further, the maximum loading factor reached a value of 0.427 at a 0.440 mol.kg(-1) amine concentration.