Abstract: Amines which are compounds of the formula I: ##STR1## where R is a C.sub.6-20 hydrocarbon;X is --NR.sub.1 -- or --O--;each R.sub.1 is independently H or --[(CH.sub.2).sub.1-4 ]COOH or a C.sub.6-20 hydrocarbon;n is 1, 2 or 3;and which contains at least one (CH.sub.2).sub.1-4 COOH group; or salt thereof are useful in inhibiting corrosion of metals in a marine or freshwater environment e.g. in oil- and gas-field applications since they show relatively low toxicity to marine organisms.

Abstract: A method of acidizing a subterranean formation with an acqueous acid solution wherein the acid solution contains corrosion inhibiting amounts of an amine derivative prepared by reacting an unsaturated carboxylic acid with (a) fatty amine or polyamine, or (b) a fatty amido amine or polyamine, or (c) a fatty imidazoline amine or polyamine. The derivative is characterized by the absence of primary amino groups, and preferably contains only tertiary amino groups.

Abstract: Amine derivatives which are compounds of the formula (I): ##STR1## in which R is a C.sub.6-20 hydrocarbon; Y is --CO--NH-- and n is an integer of 1 to 6; or ##STR2## in which X is an alkylene group of 2 to 6 carbon atoms and n is an integer of 0 to 6;each R.sub.1 is independently H, --(CH.sub.2).sub.1-4 COOH, a C.sub.6-20 hydrocarbon or C.sub.6-20 hydrocarbon-carbonyl;R.sub.2 is H, (CH.sub.2).sub.1-4 COOH or C.sub.6-20 hydrocarboncarbonyl;the compound containing at least one (CH.sub.2).sub.1-4 COOH group; or a salt thereof are useful in inhibiting corrosion of metals in oil- and gas-field applications, and also show low toxicity to marine organisms.