Uracil readily undergoes regular reactions including oxidation, nitration, and alkylation. However, electrophilic substitution is relatively facile at the 5-position, including nitration and halogenation. Another route of DNP synthesis is by nitration of phenol with nitric acid. Electrophiles attack the ring, illustrated by acid-catalysed nitration with nitric acid to give methyl 3-nitrobenzoate. Nitroglycerin can be produced by acid-catalyzed nitration of glycerol (glycerin). Another route of picric acid synthesis is direct nitration of 2,4-Dinitrophenol with nitric acid. Aromatic nitro compounds are typically synthesized by nitration. Together with other isomers, 4-nitrotoluene is prepared by nitration of toluene. It is produced from phenol by nitration followed by reduction with iron. Direct nitration of aniline is inefficient since anilinium is produced instead. An example of this is the nitration of toluene during the production of trinitrotoluene (TNT). The first step is transforming raw cellulose into nitrocellulose by conducting a nitration reaction. The nitronium ion, , is the active reagent in aromatic nitration reactions. They often are prepared by nitration of the substituted aromatic compounds followed by reduction. Ways include chemokine CCL nitration, which traps T cells in the stroma.