1070-4272/03/7611-1764$25.00 2003 MAIK Nauka/Interperiodica Russian Journal of Applied Chemistry, Vol. 76, No. 11, 2003, pp. 1764 1768. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 11, 2003, pp. 1814 1818. Original Russian Text Copyright 2003 by Yurchenko, Pogrebova, Pilipenko, Kras’ko. APPLIED ELECTROCHEMISTRY AND CORROSION PROTECTION OF METALS Corrosion-Protective Properties of N-Phenacylmethylpyridinium Bromides R. I. Yurchenko, I. S. Pogrebova, T. N. Pilipenko, and E. M. Kras’ko Kiev Polytechnic Institute, National Technical University of Ukraine, Kiev, Ukraine Received July 1, 2003 Abstract The inhibiting action of N-phenacylmethylpyridinium bromides on corrosion of carbon steel in a 3 M sulfuric acid solution was studied. A relationship between the structure of the compounds under study and their corrosion-protective properties was revealed. Compounds ensuring high degree of corrosion protec- tion of steel in acid media were found. Despite that the relationship between the structure of organic compounds and their corrosion-protective properties have been studied for a relatively long time [1 3], this problem still remains topical. Particularly promising is a search for effective corrosion inhibitors among substances exhibiting the so-called intra- molecular synergism [4 6]. This effect consists in that the presence of functional groups of varied nature in the inhibitor molecule enables multidimensional action on the corrosion process and ensures effective protection by the inhibitor. As objects of study were chosen phenacylmethyl- pyridinium bromides I XI, which are of interest in that they are simultaneously quaternary pyridinium salts and aromatic carbonyl compounds, i.e., belong to such types of organic compounds whose inhibiting action is well known [1, 2, 7]. Compounds I XI were synthesized by alkylation of 2-substituted pyridines with the corresponding -bromoacetophenones: R O R N Br I XI 1 N R + Br O R 1 + R O R N Br I XI 1 N R + Br O R 1 + where R = H, CH 3 , NH 2 , COCH 3 ;R 1 = H, CH 3 , OCH 3 , Br, Cl, NO 2 . The presence in these compounds of a methylene bridge separating the pyridinium and benzoyl moieties makes it possible to act upon each of them separately by varying the substituents R and R 1 and to reveal factors positively affecting the inhibiting action of the molecule as a whole. EXPERIMENTAL Compounds I IV were synthesized by published procedures; compounds V XI were uknown previous- ly, and their structure was confirmed by IR and 1 H NMR spectroscopy. 2-Amino-1-phenacylmethylpyridinium bromide V, 2-amino-1-(4-methylphenacyl)methylpyridinium bromide VII, 2-amino-1-(4-methoxyphenacyl)meth- ylpyridinium bromide VIII, 2-amino-1-(4-bromo- phenacyl)methylpyridinium bromide IX, 2-amino- 1-(4-chlorophenacyl)methylpyridinium bromide X, and 2-amino-1-(4-nitrophenacyl)methylpyridinium bromide XI. Solutions of equimolar amounts (0.02 M) of 2-aminopyridine and appropriate -bromoaceto- phenone in ethyl acetate were mixed. The reaction mixture was refluxed for 3 h for V and VII and for 5 h for IX XI. The next day, the reaction mixture was treated with ether, and the precipitate formed was separated and recrystallized from ethanol ether. For pyridium bromides V and VII XI, the yields (%) and melting points ( C) are as follows: V, 82, 218 220; VII, 75, 191 193; VIII, 80, 232 234; IX, 77, 215 217; X, 82, 220 222; and XI, 60, 252 254. 2-Acetyl-1-phenacylmethylpyridinium bromide VI. A mixture of equimolar amounts (0.02 M) of 2-acetylpyridine and -bromoacetophenone was heated to 125 130 C for 20 min and treated with a minor