The band at 2925 cm corresponds to methylene groups CH2 The band at 1739 cm is assigned to C=O of a carboxylic acid, this is corroborated with bands at 1558 and 1419 cm with the group COO of carboxylic acids.
La banda en 1739 cm-1 se asigna al C = O, de un ácido carboxílico, mismo que se corrobora con las bandas en 1558 y 1419 cm-1 con el grupo COOde ácidos carboxílicos.