The esterification reaction of natural petroleum acids with allyl alcohol in the presence of N-methylpyrrolidone hydrogen sulfate, an ionic liquid, has been studied. An allyl ester of natural petroleum acid has been obtained, on the basis of which nitro derivatives as well as salts and complexes of petroleum acids have been synthesized and tested as inhibitors of acid corrosion. It has been shown that a potassium salt and a monoethanolamine complex obtained on the basis of the nitroproduct of natural petroleum acid have the highest protective effect (98.4 and 98.9%, respectively) at a concentration of 300 ppm and can be proposed as CO2 corrosion inhibitors.