DE1061325B - Process for the preparation of water-soluble or water-dispersible substituted acidic aminocarboxamides or their salts as corrosion prevention agents - Google Patents

Description

Process for the preparation of water soluble or dispersible substituted acidic aminocarboxamides or their salts as corrosion inhibitors It has been found that valuable substituted aminocarboxamides are obtained, when amine salts are formed from polybasic aminocarboxylic acids and these are formed by splitting off water converted into the corresponding aminocarboxamides. These process products have a very good anti-corrosive effect against the attack of acids on metal objects, especially iron or steel. An excellent protective effect have the azninocarboxamides against attack by hydrochloric acid. So that will on the. Inhibitors closed a sensitive gap.

The starting materials used for the production of the substances according to the invention are those amines are used which contain at least one higher molecular weight lipophilic, aliphatic, cycloaliphatic or fatty aromatic hydrocarbon radical of at least 8 Contains carbon atoms in the molecule, optionally also by heteroatoms may be interrupted or contain substituents. Amines of this type are for example Dodecylamine, oleylamine, octadecylamine, alkylcyclohexylamine (alkyl radicals C3 to C12), Naphthenylamines, alkylanilines (alkyl radicals C3 to C "), also amine mixtures, such as B. coconut amine, also secondary amines such as methyloleylamine, ethyl-dodecylamine, Didodecylamine.

Suitable aminocarboxylic acids are nitrilotriacetic acid, ethylenediaminetetraacetic acid, Oxyalkyliminodiacetic acids, in particular oxyethyl-iminodiacetic acid, oxyethyl-ethylenediarnintriacetic acid.

The corresponding amine salts are formed in the customary manner in aqueous solution or organic solvents or by melting them together of the starting components.

The elimination of water from the amine salts takes place through dry heating of the salts at temperatures above 100 ° C., preferably at 180 to 200 ° C., and in vacuo. The substituted according to the invention are obtained by customary work-up methods Aminocarboxamides in good yields and in the form of light-colored, waxy, products soluble or dispersible in water.

If dodecylamine is reacted with nitrilotriacetic acid, the reaction proceeds according to the following scheme: In the case of the process products listed below, the following results were obtained when testing for inhibitory action against attack by 4N hydrochloric acid on sheet iron: Preparation% inhibition a) C "H" NHCOCH @ NCH, CO0Na (C H2) 2 96.00 / 0 Na00C - CH2 - N - CH2COONa b) C, H "NHCOCH2NCH2COONa (C H2) 2 99.20 /, C8H17NHCOCH2NCH2COONa c) CIH17NHCOCHZNCH2COONa (CH2) 2 99.70 / 0 Na00CCH2NCH2COONa CH2CH20H d) C8H17NHCOCH2N \ 99.4% CH2COONa Carrying out the tests The attack by 4N hydrochloric acid on sheet iron in the presence of the substance to be tested was measured. The hydrogen released was determined cathetometrically in a calibrated 1 cm3 burette and used to calculate the rate of dissolution of the iron. 0.05 g of the test substances were always weighed in. These amounts were added to each 50 cubic meters of acid. The measurements were carried out after 24 hours of exposure at room temperature.

The compounds according to the invention are superior to known anti-corrosive agents such as urotropine, diphenyl sulfone or the trithions, which have an inhibitory effect of about 90 to 95%. EXAMPLE 1 27.7 g of n-dodecylamine are dissolved in 300 czn3 of methanol and 28.1 g of oxyethyl-iminodiacetic acid are then added at 50 to 60 ° C. with stirring; After stirring for 1 hour at 65 ° C. and then allowing it to cool to 10 ° C., the precipitate obtained is filtered off with suction and dried. Yield 47 g of the monododecylamine salt of oxyethyl-iminodiacetic acid, which melts from methanol at 156 ° to 157 ° C. (after decomposition). The yield of this product can be increased to 50.5 g by concentrating the mother liquor. The salt is heated at 180 to 190 ° C./12 mm - if necessary in a stream of nitrogen - until no more water splitting off (formation of bubbles) can be observed. The residue is dissolved in methanol and converted into the corresponding sodium salt by adding a methanolic sodium hydroxide solution containing 5.8 g of sodium hydroxide dissolved in 100 cm3 of methanol. Methanol is stripped off in vacuo and the residue is dried at 70 ° C. in vacuo. Yield 52.5 g (93% of theory, based on n-dodecylamine). EXAMPLE 2 36.2 g of coconut amine (molecular weight 191) are dissolved in 400 cm3 of methanol and, as in Example 1, converted into the corresponding salt using 37.4 g of oxyethyl inünodiacetic acid. The salt is recrystallized from methanol. Yield 60.8g.

Dehydration also takes place at 180 to 190 ° C / 12 mm. Of the The residue is mixed with a methyl alcoholic sodium hydroxide solution containing 6.7 g of sodium hydroxide contains dissolved in 100 cm3 of methanol, as converted into the sodium salt above. yield 62.5 g (86% of theory, based on the amine).

Example 3 37 g of dodecylamine are dissolved in 500 cm3 of ethanol. at At 60 to 65 ° C., 38 g of nitrilotriacetic acid are added with stirring; after 2 hours Subsequent stirring is suctioned off while hot and a small amount of unreacted nitrilotriacetic acid get back. The monododecylamine salt of nitrilotriacetic acid crystallizes from the filtrate the end; the yield of salt can be increased by concentrating the mother liquor. yield 41 g. Melting point after recrystallization from water 200 to 202 ° C (after decomposition) -.

The salt is dehydrated as in Example 1 at 180 to 200 ° C / 12 mm. The residue is dissolved in methanol (with the exception of slight smearing) and with the calculated amount of methanolic sodium hydroxide solution into the disodium salt transferred, which one after distilling off the methanol and drying at 70 ° C / 12 mm receives. Yield 30 g (37% of theory). Example 4 76.4g coconut amine (molecular weight 191) were reacted with 75.2 g of nitrilotriacetic acid as in Example 13. There were with otherwise the same procedure, 83 g of the disodium salt of the compound were obtained. yield 50.5 0% of theory.

Claims (4)

PATENT CLAIMS: 1. Process for the preparation of water-soluble or dispersible substituted acidic aminocarboxamides or their salts as a corrosion prevention agent, characterized in that one has higher molecular weight primary or secondary amines with di- or polybasic aminocarboxylic acids to the . Reacts corresponding amine salts and subjects them to the elimination of water. 2. Process according to Claim 1, characterized in that the water is split off at temperatures above 100 ° C, preferably at 180 to 200 ° C carried out. 3. Procedure according to claim 1 and 2, characterized in that the elimination of water under carried out under reduced pressure. 4. The method according to claim 1 to 3, characterized in that the starting materials used are aminocarboxylic acids which contain oxyalkyl radicals on the nitrogen atom. Considered publications: Beilstein, Handbuch der Organic Chemistry, 4th edition, Ergw. 1I, Vol. 12, p. 291; U.S. Patent No. 2,695,270; French patent specification No. 1 102 391.