Abstract: Compounds of the formula ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4, independently of one another, represent hydrogen, hydroxy or halogen or are alkyl, alkoxy, alkanoyloxy, or alkanoylamino groups which are unsubstituted or substituted by alkoxy, hydroxyl, halogen, aryl, cycloalkyl, azacycloalkyl, cyano or by polyalkyleneoxy, or two or more of adjacent R.sub.1 -R.sub.4 together form one or more fused rings of 5-8 members each; R is alkylene of up to 16 carbon atoms which is unsubstituted or substituted by hydroxy, lower alkoxy, or halo and which may be interrupted by oxygen, sulfur, carboxamido, sulfonamido, aminosulfonyl, aminocarbonyl, carbonyloxy, sulfinyl, or sulfonyl; and R.sub.f is perfluoroalkyl or perfluoroalkoxyalkyl of 4 to 16 carbon atoms; or mixtures thereof. Such compounds are useful as oil soluble corrosion inhibitors.