# US 11,306,400 B2 · 2-substituted imidazole and benzimidazole corrosion inhibitors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,306,400 B2 - Document ID: US11306400B2 - Status: Granted - Kind: B2 - Application number: 16/225,293 - Filed: 2018-12-19 - Published: 2019-05-09 - Granted: 2022-04-19 - Earliest claimed: 2015-05-28 - Assignees: Ecolab USA Inc. - Applicants: Ecolab USA Inc. - Inventors: Deepak Rane; Jothibasu Seetharaman; Jeffery M. Atkins; Anand Harbindu; Piyush Anant; Vaideeswaran Sivaswamy; Pradeep Cheruku - Web page: https://patentgrep.com/patent/US11306400B2 ## CPC - C23F 11/149: {Heterocyclic compounds containing nitrogen as hetero atom} - C07D 231/12: with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to ring carbon atoms - C07D 235/12: Radicals substituted by oxygen atoms - C07D 235/30: Nitrogen atoms not forming part of a nitro radical - C07D 401/04: directly linked by a ring-member-to-ring-member bond - C23F 11/10: using organic inhibitors - C23F 11/184: {Phosphorous, arsenic, antimony or bismuth containing compounds} - C02F 2103/023: {Water in cooling circuits} - C02F 2303/08: Corrosion inhibition - C23F 11/124: {Carboxylic acids} - C23F 11/141: {Amines; Quaternary ammonium compounds} - C23F 11/173: Macromolecular compounds - C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25 - C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08) - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) ## Abstract Disclosed are methods of using nitrogen-containing compounds as corrosion inhibitors. The present method is used to inhibit corrosion of a metal surface in contact with an aqueous system using 2-substituted imidazoles and 2-substituted benzimidazoles, and provides enhanced protection against corrosion of metals in the aqueous system. The method comprises the use of corrosion inhibitors that are generally resistant to halogen attack and provide good corrosion resistance in the presence of oxidizing halogen-based biocides. Formulations comprising 2-substituted imidazoles and 2-substituted benzimidazoles are also disclosed. ## Claims ### Claim 1 A formulation for inhibiting corrosion of a metal surface, the formulation comprising one or more phosphorus-containing compounds and a compound of formula (I) or (II); wherein formula (I) is wherein each X is the same or different, and each is selected from the group consisting of hydrogen, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, halosubstituted alkyl, amino, aminoalkyl, cyano, alkoxy, hydroxyl, thiol, alkylthio, carbonyl, nitro, phosphoryl, phosphonyl, and sulfonyl; Y is selected from the group consisting of hydroxyl, halogen, oxo, alkoxy, thiol, alkylthio, amino, hydrogen, and aminoalkyl; Z is selected from the group consisting of carbon and nitrogen; R1 is selected from the group consisting of hydrogen, deuterium, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, hydroxyl, and carbonyl; R2 and R3 are selected from the group consisting of hydrogen, halogen, hydroxyl, aryl, phenyl, heteroaryl, benzyl, alkylheteroaryl, carbonyl, C2-C16 alkenyl, C2-C16 alkynyl, C3-C8 cycloalkyl, and C1-C16 alkyl; and m is 1, 2, 3, or 4; or a salt thereof; and formula (II) is wherein each of X and Y is the same or different, and each is selected from the group consisting of hydrogen, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, halosubstituted alkyl, amino, aminoalkyl, cyano, alkoxy, hydroxyl, thiol, alkylthio, carbonyl, nitro, phosphoryl, phosphonyl, and sulfonyl; R is selected from the group consisting of hydrogen, deuterium, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, hydroxyl, and carbonyl; m is 1, 2, 3, or 4; and n is 1, 2, 3, or 4; or a salt thereof; with the proviso that when the imidazole is benzimidazole and X and R are both hydrogen, then the pyridine ring is 2-pyridyl. ### Claim 2 (depends on 1) The formulation of claim 1, wherein the one or more phosphorus-containing compounds is selected from phosphoric acid, polyposphoric acid, phosphorus pentoxide, and a phosphinosuccinic oligomer. ### Claim 3 (depends on 2) The formulation of claim 2, wherein the one or more phosphorus-containing compounds is polyposphoric acid. ### Claim 4 (depends on 1) The formulation of claim 1, wherein the formulation has a pH of from about 2 to about 5. ### Claim 5 (depends on 4) The formulation of claim 4, wherein the formulation has a pH of from about 2 to about 4. ### Claim 6 (depends on 5) The formulation of claim 5, wherein the formulation has a pH of from about 2 to about 3. ### Claim 7 (depends on 1) The formulation of claim 1, wherein the formulation comprises a compound of formula (I), wherein the compound of formula (I) is wherein each X is the same or different, and each is selected from the group consisting of hydrogen, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, halosubstituted alkyl, amino, aminoalkyl, cyano, alkoxy, hydroxyl, thiol, alkylthio, carbonyl, nitro, phosphoryl, phosphonyl, and sulfonyl; Y is selected from the group consisting of hydroxyl, halogen, oxo, alkoxy, thiol, alkylthio, amino, hydrogen, and aminoalkyl; R1 is selected from the group consisting of hydrogen, deuterium, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, hydroxyl, and carbonyl; R2 and R3 are the same or different, and each is selected from the group consisting of hydrogen, halogen, hydroxyl, aryl, phenyl, heteroaryl, benzyl, alkylheteroaryl, carbonyl, C2-C16 alkenyl, C2-C16 alkynyl, C3-C8 cycloalkyl, and C1-C16 alkyl; and m is 1, 2, 3, or 4; or a salt thereof. ### Claim 8 (depends on 7) The formulation of claim 7, wherein the compound of formula (I) is wherein each X is the same or different, and each is selected from the group consisting of hydrogen, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, halosubstituted alkyl, amino, aminoalkyl, cyano, alkoxy, hydroxyl, thiol, alkylthio, carbonyl, nitro, phosphoryl, phosphonyl, and sulfonyl; R2 and R3 are the same or different, and each is selected from the group consisting of hydrogen, halogen, hydroxyl, aryl, phenyl, heteroaryl, benzyl, alkylheteroaryl, carbonyl, C2-C16 alkenyl, C2-C16 alkynyl, C3-C8 cycloalkyl, and C1-C16 alkyl; and m is 1, 2, 3, or 4; or a salt thereof. ### Claim 9 (depends on 8) The formulation of claim 8, wherein the compound of formula (I) is wherein each X is the same or different, and each is selected from the group consisting of hydrogen, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, halosubstituted alkyl, amino, aminoalkyl, cyano, alkoxy, hydroxyl, thiol, alkylthio, carbonyl, nitro, phosphoryl, phosphonyl, and sulfonyl; and m is 1, 2, 3, or 4; or a salt thereof. ### Claim 10 (depends on 9) The formulation of claim 9, wherein the compound of formula (I) is or a salt thereof. ### Claim 11 (depends on 1) The formulation of claim 1, wherein the formulation comprises a compound of formula (II), wherein the compound of formula (II) is wherein each of X and Y is the same or different, and each is selected from the group consisting of hydrogen, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, halosubstituted alkyl, amino, aminoalkyl, cyano, alkoxy, hydroxyl, thiol, alkylthio, carbonyl, nitro, phosphoryl, phosphonyl, and sulfonyl; m is 1, 2, 3, or 4; and n is 1, 2, 3, or 4; or a salt thereof, with the proviso that when X is hydrogen, then the pyridine ring is 2-pyridyl. ### Claim 12 (depends on 11) The formulation of claim 11, wherein the compound of formula (II) is wherein each X is the same or different, and each is selected from the group consisting of hydrogen, C1-C16 alkyl, aryl, C2-C16 alkenyl, C2-C16 alkynyl, heteroaryl, C3-C8 cycloalkyl, benzyl, alkylheteroaryl, halogen, halosubstituted alkyl, amino, aminoalkyl, cyano, alkoxy, hydroxyl, thiol, alkylthio, carbonyl, nitro, phosphoryl, phosphonyl, and sulfonyl; and m is 1, 2, 3, or 4; or a salt thereof, with the proviso that when X is hydrogen, then the pyridine ring is 2-pyridyl. ### Claim 13 (depends on 12) The formulation of claim 12, wherein the compound of formula (II) is or a salt thereof. ### Claim 14 (depends on 1) The formulation of claim 1, wherein the formulation further comprises a fluorescent organic compound. ### Claim 15 (depends on 14) The formulation of claim 14, wherein the fluorescent organic compound is selected from the group consisting of Rhodamine, a derivative of Rhodamine, an acridine dye, fluorescein, a derivative of fluorescein, and combinations thereof. ### Claim 16 (depends on 1) The formulation of claim 1, wherein the formulation further comprises one or more additives selected from treatment polymers, anti-microbial agents, anti-scaling agents, colorants, fillers, buffers, surfactants, viscosity modifiers, chelating agents, dispersants, deodorants, masking agents, oxygen scavengers, and indicator dyes. ### Claim 17 (depends on 16) The formulation of claim 16, wherein the formulation further comprises one or more anti-scaling agents. ### Claim 18 (depends on 16) The formulation of claim 16, wherein the formulation further comprises one or more treatment polymers. ### Claim 19 (depends on 16) The formulation of claim 16, wherein the formulation further comprises one or more dispersants. ### Claim 20 (depends on 1) The formulation of claim 1, wherein the formulation further comprises one or more additional corrosion inhibitors selected from triazoles, benzotriazoles, benzimidazoles, orthophosphate, polyphosphates, phosphonates, molybdates, silicates, oximes, and nitrites.