A likely impurity is the benzoic acid. Check the IR for the presence of OH from CO2H, and the CO frequencies. If the acid is present, then dissolve the aldehyde in Et2O, wash it with 10% NaHCO3 until effervescence ceases, then with brine, dry over CaCl2, evaporate and distil the residual oil, preferably under vacuum. It is almost insoluble in H2O, but soluble in EtOH and Et2O. The thiosemicarbazone has m 147o after recrystallisation from aqueous EtOH, MeOH or *C6H6. [Crounse J Am Chem Soc 71 1263 1949, Bernstein et al. J Am Chem Soc 73 906 1951, Gensler & Berman J Am Chem Soc 80 4949 1958, Beilstein 7 H 318, 7 II 347, 7 III 1095, 7 IV 723.]
ChEBI: A member of the class of benzaldehydes that is benzaldehyde substituted by an isopropyl group at position 4. It is a component of essential oils from Cumin and exhibits insecticidal activities.
clear colorless to yellow liquid