(57) New composition comprises a functional fluid in contact with ferrous metal and a corrosion inhibiting amount of at least one compound of formula (I)
or a derivative thereof in which R1, R2 and R3 are, independently, hydrogen, a C1 -C15 straight or branched chain alkyl residue, a C5 -C12 cycloalkyl residue, a C6 -C15 aryl residue or C7 -C12 alkaryl residue, and R4 and R5 are, independently, hydrogen, 2-hydroxyethyl or 2-hydroxypropyl with the provisos that a) R4 and R5 are not simultaneously hydrogen, b) when R4 and R5 are each -CH2 -CH2 -OH, R1 and R2 are not simultaneously hydrogen and R3 is not a pentyl residue and c) that polyalkylene phenol or polycarboxylic ester co-additives are absent:
as well as salts thereof. Some of the compounds of formula I are new.
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