RU2805657C2 - Composition for corrosion inhibition containing 2-substituted benzimidazole and method of corrosion inhibition using 2-substituted benzimidazole - Google Patents

Abstract

FIELD: corrosion inhibitor.

SUBSTANCE: invention is related to a composition for inhibiting corrosion containing a compound or its salt of formula (I), an acid and a polar aprotic solvent, which can be used for inhibiting corrosion of a metal surface in contact with an aqueous system and for providing improved protection of metals against corrosion in the specified aqueous system. In formula (I), X independently represents hydrogen, halogen or an unsubstituted C_1-5 alkyl group; m is 1, 2, 3 or 4; R¹ is hydrogen; R² is absent; R³ represents a bond or CHR⁴; R⁴ is OR⁵; R⁵ represents hydrogen; Z independently represents nitrogen or CX. In this case, the concentration of a compound or salt of formula (I) in the composition ranges from 1 to 50 wt.%; the acid concentration in the composition is from 5 to 60 wt.% and the polar aprotic solvent concentration in the composition is from 0.001 to 30 wt.%. The invention is also related to a method for inhibiting corrosion, including adding the specified composition, and a composition for inhibiting corrosion containing a compound of formula (I), an acid and a sulpholane.
EFFECT: corrosion inhibiting composition and method are proposed.

13 cl, 2 tbl, 6 ex

Description

State of the art

1. Technical field

This invention relates generally to the synthesis of 2-substituted benzimidazoles and to compositions thereof. More particularly, the present invention relates to a homogeneous process for the synthesis of 2-substituted benzimidazoles and their use, for example, as corrosion inhibitors.

2. Description of the technical field

Benzimidazoles can be prepared by various synthetic routes. One traditional method is a condensation reaction between a diamine and a carboxylic acid over an acid catalyst. This method is mainly aimed at obtaining solid benzimidazoles as isolated final products in average to good yield.

Such benzimidazoles are synthesized mainly in inorganic acids, and the final product is precipitated by changing the pH to 7 or 8 with a base. The precipitated product is isolated by filtration and dried in an oven. Synthesis methods known from the prior art have several disadvantages, such as: 1) increased reaction time and processing time, leading to low productivity per batch; 2) loss of yield due to the stages of refinement and product isolation; 3) separation and subsequent drying stages require the installation of special equipment, which entails significant capital investments; 4) working with a solid product, both in the form of a wet filter cake and in the form of a dry powder, implies significant difficulties when working with the material, which leads to a decrease in yield; and 5) the final solid product must be dried before being redissolved in a solvent for certain applications such as anti-corrosion treatment.

Other uses of benzimidazoles include pharmaceuticals and agricultural chemicals. Polybenzimidazoles are known for their high strength and high temperature characteristics. Polybenzimidazoles find applications in semiconductors, contact sealants, wafer cartridges, insulating sleeves, thermal insulation materials, light-emitting diodes, solar cells, fuel cells and high-performance protective clothing. Other applications include those in the petrochemical and aerospace industries.

SUMMARY OF THE INVENTION

In some embodiments, a composition is described that contains a compound or a salt thereof of formula (I), an acid, and a polar aprotic solvent;

where X independently represents hydrogen, halogen or a substituted or unsubstituted C _1-5 alkyl group, and m is 1, 2, 3 or 4; R ¹ represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ² is absent, represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ³ represents a bond or CHR ⁴ ; R ⁴ is hydrogen, halogen, NR ⁵ R ⁶ or OR ⁵ ; and R ⁵ and R ⁶ are each independently hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; and Z is independently nitrogen, CX or N ^{+ R5} .

In some embodiments, the composition may contain water.

In some embodiments, the composition may be a homogeneous liquid.

In some embodiments, X is independently hydrogen or halogen, R ¹ is hydrogen, R ² is absent, and R ³ is CHR ⁴ .

In some embodiments, at least one Z is nitrogen.

In some embodiments, R ³ is a bond and at least one Z is nitrogen.

In some embodiments, the compound or salt thereof has formula (II)

where Y independently represents hydrogen, halogen or a C _1-5 alkyl group; and n is 1, 2, 3, 4 or 5.

In some embodiments, the acid may be a strong inorganic acid, a strong organic acid, or any combination thereof.

In some embodiments, the acid may be selected from sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, phosphoric acid, sulfamic acid, aminomethylphosphonic acid, p-toluenesulfonic acid, and any combination thereof.

In some embodiments, the polar aprotic solvent may be selected from acetonitrile, N,N -dimethylformamide, acetone, dimethyl sulfoxide, sulfolane, N-methylpyrrolidinone, methylsulfonylmethane, chlorobenzene, o-dichlorobenzene, nitromethane, ionic liquid, and any combination thereof.

In some embodiments, the composition may contain a phase transfer catalyst that is stable at high temperature.

In some embodiments, the high temperature stable phase transfer catalyst may be selected from the group consisting of an alkylguanidinium salt, an arylguanidinium salt, an alkylphosphonium salt, an arylphosphonium salt, a peralkylated phosphazenium salt, and any combination thereof.

In other embodiments, a method for preparing a compound or salt thereof of formula (V) is described.

The proposed method may include heating a mixture containing a compound or salt thereof of formula (III), a compound or salt thereof of formula (IV), an acid, a polar aprotic solvent and a high temperature stable phase transfer catalyst

where X independently represents hydrogen, halogen or a C _1-5 alkyl group, and m is 1, 2, 3 or 4; R ¹ represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ² is absent, represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ⁴ is hydrogen, halogen, NR ⁵ R ⁶ or OR ⁵ ; and R ⁵ and R ⁶ are each independently hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; and R ⁸ is hydrogen, halogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, a substituted or unsubstituted C ₅ -C ₆ heteroaryl group, a substituted or unsubstituted C ₄ -C ₆ aryl group, or a substituted or unsubstituted C ₃ -C ₁₂ cycloalkyl group.

In some embodiments, the mixture can be heated to a temperature of from about 80°C to about 160°C.

In some embodiments, the mixture may be heated for a period of time ranging from about 30 minutes to about 12 hours.

In some embodiments, the mixture may have a concentration of active compounds from about 1 to about 50% by weight.

In some embodiments, the proposed method may include adding a carboxylic acid to the mixture.

In some embodiments, this document describes the use of any composition described herein for inhibiting corrosion.

In some embodiments, a composition is described that can be prepared by any method described herein.

In other embodiments, a method for producing polybenzimidazole is described. The proposed method may involve heating a mixture containing diphenyl isophthalate and 3,3',4,4'-tetraaminodiphenyl, an acid, a polar aprotic solvent and a high temperature stable phase transfer catalyst.

In other embodiments, a method of inhibiting corrosion is described, which may include adding any composition described herein to an industrial water supply system that contains a metal surface.

The above description is intended to broadly highlight the features and technical advantages of the present invention in order to better understand the detailed description set forth below. Additional features and advantages of this invention are described below herein and are the subject of the claims of this application. Those skilled in the art will understand that the concept and specific embodiments of the invention described can readily be used as a basis for modifying or developing other embodiments to achieve the same objectives of the present invention. It will also be understood by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the present invention as set forth below in the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments are described below. The relationship and operation of the various elements of the described embodiments can be better understood with reference to the following detailed description. However, the embodiments are not limited to those given below. In some cases, details may be omitted that are not necessary to understand the embodiments described herein.

"Alkyl" refers to a straight or branched alkyl substituent. Examples of such substituents include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, isoamyl, hexyl and the like.

"Aryl" refers to an unsubstituted or substituted aromatic carbocyclic substituent as commonly understood in the art, and the term "C ₆ -C ₁₀ aryl" includes phenyl and naphthyl. It should be understood that the term aryl refers to cyclic substituents that are planar and contain 4n+2n electrons, according to Hückel's rule.

“Cycloalkyl” refers to a cyclic alkyl substituent containing, for example, from about 3 to about 8 carbon atoms, preferably from about 4 to about 7 carbon atoms, and more preferably from about 4 to about 6 carbon atoms. Examples of such substituents include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and the like. The cyclic alkyl groups may be unsubstituted or further substituted by alkyl groups such as methyl groups, ethyl groups and the like.

"Halogen" or "halo" refers to F, Cl, Br and I.

"Heteroaryl" refers to a monocyclic or bicyclic 5- or 6-membered ring system, the heteroaryl group being unsaturated and following Huckel's rule. Non-limiting examples of heteroaryl groups include furanyl, thiophenyl, pyrrolyl, pyrazolyl, imidazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, isoxazolyl, oxazolyl, isothiazolyl, thiazolyl, 1,3,4-oxadiazol-2-yl , 1,2,4-oxadiazol-2-yl, 5-methyl-1,3,4-oxadiazole, 3-methyl-1,2,4-oxadiazole, pyridinyl, pyrimidinyl, pyrazinyl, triazinyl, benzofuranyl, benzothiophenyl, indolyl , quinolinyl, isoquinolinyl, benzimidazolyl, benzoxazolinyl, benzothiazolinyl, quinazolinyl, etc.

"Oxo" refers to an oxygen atom bonded to a carbon atom by a double bond.

The compounds of this invention may be substituted with suitable substituents. The term "suitable substituent" in this context means a chemically acceptable functional group, preferably a moiety, that does not impair the activity of the compounds of the invention. Such suitable substituents include, but are not limited to, halogen groups, perfluoroalkyl groups, perfluoroalkoxy groups, alkyl groups, alkenyl groups, alkynyl groups, hydroxy groups, oxo groups, mercapto groups, alkylthio groups, alkoxy groups, aryl groups or heteroaryl groups, aryloxy or heteroaryloxy groups, aralkyl or heteroaralkyl groups, aralkoxy or heteroaralkoxy groups, OH-(C=O) groups, heterocyclic groups, cycloalkyl groups, amino groups, alkyl and dialkylamino groups, carbamoyl groups, alkylcarbonyl groups groups, alkoxycarbonyl groups, alkylaminocarbonyl groups, dialkylaminocarbonyl groups, arylcarbonyl groups, aryloxycarbonyl groups, alkylsulfonyl groups and arylsulfonyl groups. In some embodiments, suitable substituents may include halogen, an unsubstituted C ₁ -C ₁₂ alkyl group, an unsubstituted C ₄ -C ₆ aryl group, or an unsubstituted C ₁ -C ₁₀ alkoxy group. Those skilled in the art will appreciate that many substituents can be substituted with additional substituents.

In some embodiments, a composition is described that may contain a compound or salt thereof of Formula (I), an acid, and a polar aprotic solvent. The compound of formula (I) has the formula shown below

In some embodiments, X is independently hydrogen, halogen, or a substituted or unsubstituted C _1-5 alkyl group, and m can be 1, 2, 3, or 4. In some embodiments, R ¹ can be hydrogen, substituted or unsubstituted C _{a 1} -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group. In some embodiments, R ² may be absent, may be hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group. In some embodiments, R ³ may be a bond or CHR ⁴ . In some embodiments, R ⁴ may be hydrogen, halogen, NR ⁵ R ⁶ or OR ⁵ . In some embodiments, R ⁵ and R ⁶ are each independently hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group.

The substituent or substituents X may occupy any available position on the benzimidazole ring. Thus, in some embodiments, the X substituent or substituents may be located at the 4-position, 5-position, 6-position, and/or 7-position of the benzimidazole. In some embodiments, the X substituent is at the 5-position.

The number of substituents X equal to m can be 1, 2, 3 or 4. If m is 2, 3 or 4, then the substituents X can occupy any open position and can be located in the ortho, meta or para position relative to each other friend.

In some embodiments, the salt of the compound of formula (I) may be any salt, such as a chloride salt, bromide salt, iodide salt, sulfate salt, fluoride salt, perchlorate salt, acetate salt, trifluoroacetate salt, phosphate salt, nitrate salt, carbonate salt , bicarbonate salt, formate salt, chlorate salt, bromate salt, chlorite salt, thiosulfate salt, oxalate salt, cyanide salt, cyanate salt, tetrafluoroborate salt, etc. In some embodiments, the salt of the compound of formula (I) may be a hydrochloride or sulfate salt.

In some embodiments, Z is independently nitrogen, CX, or N ^{+ R5} .

In some embodiments, Z is CX.

In some embodiments, X is hydrogen and m is 4.

In some embodiments, R ¹ is hydrogen.

In some embodiments, R ² is omitted.

In some embodiments, R ³ is a bond.

In some embodiments, R ³ is CHR ⁴ .

In some embodiments, R ⁴ is hydrogen.

In some embodiments, R ⁴ is halogen.

In some embodiments, R ⁴ is NR ⁵ R ⁶ .

In some embodiments, R ⁴ is OR ⁵ .

In some embodiments, R ⁵ represents a substituted or unsubstituted C ₁ -C ₁₂ alkyl group.

In some embodiments, R ⁵ is hydrogen.

In some embodiments, R ⁵ is a substituted or unsubstituted C ₄ -C ₆ aryl group.

In some embodiments, one Z is nitrogen and the others are CX.

In some embodiments, at least two Zs are nitrogen and the remainder are CX.

In some embodiments, R ³ is a bond and at least one Z is nitrogen.

In some embodiments, X is independently hydrogen or halogen, R ¹ is hydrogen, R ² is absent, and R ³ is CHR ⁴ .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the compound or salt thereof of formula (I) is .

In some embodiments, the proposed composition may contain a compound or a salt thereof of formula (Ia),

where X independently represents hydrogen, halogen or a substituted or unsubstituted C _1-5 alkyl group, and m is 1, 2, 3 or 4; R ¹ represents hydrogen, or a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ² is absent, represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; and R ³ represents a bond or CHR ⁴ .

In some embodiments, the compound or a salt thereof has formula (II),

where X, m and R ³ , X independently represents hydrogen, halogen or a substituted or unsubstituted C _1-5 alkyl group; m is equal to 1, 2, 3 or 4; R ³ represents a bond or CHR ⁴ ; Y independently represents hydrogen, halogen or a C _1-5 alkyl group; and n is 1, 2, 3, 4 or 5.

In some embodiments, Y is hydrogen.

In some embodiments, Y is independently hydrogen and halogen.

As described herein, m can be 1, 2, 3 or 4. If m is 2, 3 or 4, then the X substituents can occupy any open position and can be located in the ortho, meta or para position relative to each other. The number of Y substituents n can be 1, 2, 3 or 4. If n is 2, 3 or 4, then the Y substituents can occupy any open position and can be located in the ortho, meta or para position relative to each other friend.

In some embodiments, the concentration of a compound or a salt thereof of formula (I), formula (Ia) or formula (II) in the composition can range from about 1% wt. to about 50% wt., from about 5% wt. to about 50% wt., from about 10% wt. to about 50% wt., from about 15% wt. to about 50% wt., from about 20% wt. to about 50% wt., from about 20% wt. to about 45% wt., from about 25% wt. up to about 45% wt. or from about 25% wt. up to about 40% wt.

In some embodiments, the acid may be a strong inorganic acid, a strong organic acid, or any combination thereof. In some embodiments, the acid may be a strong inorganic acid. In some embodiments, the acid may be a strong organic acid. As used herein, “strong” refers to acids having a pKa of less than about 1. In some embodiments, the acid may be selected from sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, phosphoric acid, sulfamic acid, aminomethylphosphonic acid, p- toluenesulfonic acid and any combination thereof.

In some embodiments, the acid may be sulfuric acid.

In some embodiments, the acid may be hydrochloric acid.

In some embodiments, the acid may be nitric acid.

In some embodiments, the acid may be methanesulfonic acid.

In some embodiments, the acid may be phosphoric acid.

In some embodiments, the acid may be sulfamic acid.

In some embodiments, the acid may be aminomethylphosphonic acid.

In some embodiments, the acid may be p-toluenesulfonic acid.

In some embodiments, the polar aprotic solvent may be selected from acetonitrile, N,N -dimethylformamide, acetone, dimethyl sulfoxide, sulfolane, N-methylpyrrolidinone, methylsulfonylmethane, chlorobenzene, o-dichlorobenzene, nitromethane, ionic liquid, and any combination thereof.

In some embodiments, the polar aprotic solvent may be acetonitrile.

In some embodiments, the polar aprotic solvent may be N,N -dimethylformamide.

In some embodiments, the polar aprotic solvent may be acetone.

In some embodiments, the polar aprotic solvent may be dimethyl sulfoxide.

In some embodiments, the polar aprotic solvent may be a sulfolane.

In some embodiments, the polar aprotic solvent may be N-methylpyrrolidinone .

In some embodiments, the polar aprotic solvent may be methylsulfonylmethane.

In some embodiments, the polar aprotic solvent may be chlorobenzene.

In some embodiments, the polar aprotic solvent may be o-dichlorobenzene .

In some embodiments, the polar aprotic solvent may be nitromethane.

In some embodiments, the polar aprotic solvent may be an ionic liquid.

In some embodiments, the composition may comprise a high temperature stable phase transfer catalyst.

In some embodiments, the high temperature stable phase transfer catalyst is selected from the group consisting of an alkylguanidinium salt, an arylguanidinium salt, an alkylphosphonium salt, an arylphosphonium salt, a peralkylated phosphazenium salt, and any combination thereof. Examples of high temperature stable phase transfer catalysts include, but are not limited to, hexaethylguanidinium chloride, tetraphenylphosphonium bromide, hexaalkylphosphonium salts, hexadecyltributylphosphonium bromide, or any combination thereof.

In some embodiments, the composition may contain water.

In some embodiments, the composition may be a homogeneous mixture. In some embodiments, the composition may be a solution.

In some embodiments, the composition may contain a phenylenediamine compound. In some embodiments, the composition may contain a phenylenediamine compound. If the composition contains a phenylenediamine compound, it is present in said composition in an amount of about 0.0001% wt. up to about 0.1% wt. In some embodiments, the amount of the phenylenediamine compound in the composition may be less than about 0.1% by weight. In some embodiments, the amount of the phenylenediamine compound in the composition may be less than about 0.9% by weight, about 0.8% by weight, about 0.7% by weight, about 0.6% by weight, about 0. 5% wt., about 0.4% wt. or about 0.3% wt.

In other embodiments, a method for preparing a compound or salt thereof of formula (V) is described.

The proposed method may include heating a mixture containing a compound or salt thereof of formula (III), a compound or salt thereof of formula (IV), an acid, a polar aprotic solvent and a high temperature stable phase transfer catalyst.

For formulas (III-V), X independently represents hydrogen, halogen, or a substituted or unsubstituted C _1-5 alkyl group, and m is 1, 2, 3 or 4; R ¹ represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ² is absent, represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ⁴ is hydrogen, halogen, NR ⁵ R ⁶ or OR ⁵ ; and R ⁸ may be hydrogen, halogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, a substituted or unsubstituted C ₅ -C ₆ heteroaryl group, a substituted or unsubstituted C ₄ -C ₆ aryl group, or a substituted or unsubstituted C ₃ - C ₁₂ cycloalkyl group. R ⁵ and R ⁶ each independently represent hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group.

In some embodiments, R ⁸ is a substituted or unsubstituted C ₅ -C ₆ heteroaryl group.

In some embodiments, R ⁸ is a substituted or unsubstituted C ₅ -C ₆ heteroaryl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group.

In some embodiments, R ⁸ is a substituted or unsubstituted C ₄ -C ₆ aryl group.

In some embodiments, R ⁸ is a substituted or unsubstituted C ₆ heteroaryl group.

In some embodiments, R ⁸ is a substituted or unsubstituted C ₆ aryl group.

In some embodiments, the reaction product of compounds of formulas (III) and (IV) may be further reacted in a post-modification step to introduce non-hydrogen substituents for R ¹ and substituents for R ² .

The synthesis methods described herein have many advantages relative to the prior art. The final product can be obtained in higher yield compared to conventional synthesis methods. In addition, the finished product can be in the form of a homogeneous liquid, which facilitates product transportation and formulation while minimizing loss of product yield. Since the final product can be in the form of a homogeneous liquid, there is no need to use solids separation methods and equipment, resulting in significant cost savings.

In some embodiments, a method for preparing a compound or salt thereof of formula (I) is described.

The proposed method may involve heating a mixture containing a compound or salt thereof of formula (III), a compound or salt thereof of formula (VI), an acid, a polar aprotic solvent and a high temperature stable phase transfer catalyst.

For formulas (I), (III) and (VI), X independently represents hydrogen, halogen, or a substituted or unsubstituted C _1-5 alkyl group, and m is 1, 2, 3 or 4; R ¹ represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ² is absent, represents hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; R ³ represents a bond or CHR ⁴ ; R ⁴ is hydrogen, halogen, NR ⁵ R ⁶ or OR ⁵ ; wherein R ⁵ and R ⁶ are each independently hydrogen, a substituted or unsubstituted C ₁ -C ₁₂ alkyl group, or a substituted or unsubstituted C ₄ -C ₆ aryl group; and Z is independently nitrogen, CX or N ^{+ R5} . In some embodiments, R ⁷ is oxo or COOH.

In some embodiments, R ⁷ is COOH.

In some embodiments, R ⁷ is oxo.

Any acid described herein and any equivalents may be used in the process for preparing the compounds or salts of formula (I) and (V).

In some embodiments, the concentration of acid in the mixture or composition can be from about 1% wt. up to about 70% wt. In some embodiments, the concentration of acid in the mixture or composition can be from about 1% wt. to about 60% wt., from about 1% wt. to about 50% wt., from about 1% wt. to about 40% wt., from about 1% wt. to about 30% wt., from about 5% wt. to about 60% wt., from about 5% wt. to about 50% wt., from about 5% wt. up to about 40% wt. or from about 5% wt. up to about 30% wt.

The process for preparing the compounds or salts of formula (I) and (V) may use any polar aprotic solvent described herein and any equivalents.

In some embodiments, the concentration of the polar aprotic solvent in the mixture or composition can be from about 0.001% wt. up to about 30% wt. In some embodiments, the concentration of polar aprotic solvent in the mixture can range from about 0.001 wt.%. to about 25% wt., from about 0.001% wt. to about 20% wt., from about 0.01% wt. to about 25% wt., from about 0.1% wt. to about 25% wt., from about 0.5% wt. to about 25% wt., from about 1% wt. to about 25% wt., from about 1% wt. up to about 20% wt. or from about 1% wt. up to about 25% wt. In some embodiments, the concentration of the polar aprotic solvent in the mixture may be 1% wt., 5% wt. or 10% wt.

The process for preparing the compounds or salts of formula (I) and (V) may use any high temperature stable phase transfer catalyst described herein and any equivalents.

In some embodiments, the concentration of the high temperature stable phase transfer catalyst in the mixture or composition may range from about 0.001 wt.%. up to about 30% wt. In some embodiments, the concentration of the high temperature stable phase transfer catalyst in the mixture or composition may range from about 0.001 wt.%. to about 25% wt., from about 0.001% wt. to about 20% wt., from about 0.01% wt. to about 25% wt., from about 0.1% wt. to about 25% wt., from about 0.5% wt. to about 25% wt., from about 1% wt. to about 25% wt., from about 1% wt. up to about 20% wt. or from about 1% wt. up to about 25% wt. In some embodiments, the concentration of the polar aprotic solvent in the mixture may be 1% wt., 5% wt. or 10% wt.

In some embodiments, a method for preparing a compound or salt thereof of formula (I) or (V) may involve heating the mixture to a temperature of from about 80°C to about 160°C. In some embodiments, the mixture can be heated to a temperature of from about 80°C to about 120°C, from about 90°C to about 120°C, or from about 90°C to about 110°C. The mixture can be heated using any device suitable for raising the temperature to an appropriate value. Heating systems can be powered by fuel, electricity or steam. For example, steam can be passed through tubes brought into contact with said mixture.

In some embodiments, the mixture may be heated for a period of time ranging from about 30 minutes to about 12 hours. In some embodiments, the mixture may be heated for a period of time ranging from about 1 hour to about 12 hours, from about 2 hours to about 12 hours, from about 2 hours to about 10 hours, from about 4 hours to about 10 hours, or from about 5 o'clock to about 10 o'clock.

In some embodiments, the mixture may have an active ingredient concentration of from about 1 to about 50% by weight, wherein "active ingredient concentration" refers to the concentration of the compounds of Formula (III) and Formula (IV) or the compounds of Formula (III) and Formula (VI) . In some embodiments, the mixture may have a concentration of active substances of about 10% wt. to about 50% wt., from about 20% wt. to about 50% wt., from about 20% wt. to about 45% wt., from about 25% wt. up to about 45% wt. or from about 25% wt. up to about 40% wt.

In some embodiments, the methods described herein may include adding a carboxylic acid to the mixture after the heating step. As used herein, "carboxylic acid" refers to an organic compound containing a carboxyl group. In some embodiments, the carboxylic acid may be a substituted or unsubstituted C ₁ -C ₃₂ alkyl carboxylic acid. In some embodiments, the carboxylic acid is reacted with unreacted compounds of formula (III). In some embodiments, the carboxylic acid may be acetic acid or formic acid. Other carboxylic acids that can be used include, but are not limited to, butanoic acid, carbonic acid, propionic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, glycolic acid, and the like. The amount of carboxylic acid added to the mixture can range from about 0.01% wt. up to about 10% wt. In some embodiments, the amount of carboxylic acid added to the mixture can be from about 0.1% wt. to about 5% wt., from about 1% wt. up to about 5% wt. or from about 1% wt. up to about 4% wt. In some embodiments, the amount of carboxylic acid added to the mixture may be about 1 wt%, about 2 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 6 wt%. about 7% wt., about 8% wt., about 9% wt. or about 10% wt.

In some embodiments, a composition prepared in accordance with the methods described herein is described. Methods for preparing a compound or salt of formula (I) or (V) can provide a uniform composition that can be used for corrosion inhibition without further purification.

In some embodiments, the compositions of this invention can be used in pharmaceutical preparations. In some embodiments, the compositions of this invention can be used in agricultural chemicals. In some embodiments, the compositions of this invention can be used to inhibit corrosion.

In some embodiments, a method for preventing corrosion is provided.

The present invention provides methods of using heterocyclic compounds and compositions containing heterocyclic compounds that are particularly useful for inhibiting the corrosion of metallic elements in industrial water supply systems. The addition of benzimidazole, which can chelate with metal, to the water supply provides excellent corrosion resistance to the metal. In particular, the addition of benzimidazoles substituted with 2-pyridyl or benzyl alcohol to a water supply that is in contact with a metal surface provides excellent corrosion inhibition of metals such as copper. In addition, while benzotriazoles and benzimidazoles are generally unstable in the presence of oxidizing halogen compounds, the compounds of this invention can 1,2-chelate with the metal to provide exemplary protection of the metal in the presence of oxidizing halogen compounds. In particular, 2-(2-pyridyl)benzimidazoles provide more effective corrosion protection than benzimidazole, 2-phenylbenzimidazole and tolyltriazole in the presence of oxidizing halogen compounds. Without being limited to any particular theory, it is believed that the compounds of this invention form a protective film that is substantially impermeable to conventional oxidizing halogen compounds due to the bidentate chelation of the corrosion inhibitor with the metal surface. Thus, in some embodiments, the methods of this invention provide protection against metal corrosion in water systems that use oxidizing halogen compounds as biocides.

In some embodiments of the present invention, a method is provided for inhibiting corrosion of a metal surface that is brought into contact with an aqueous system. The proposed method may include adding to the water supply any composition described in this invention. For example, the proposed composition may contain a compound of formula (I), an acid and a polar aprotic solvent.

"Industrial water supply system" means any system that circulates water as a major component. Non-limiting examples of "industrial water systems" include refrigeration systems, boiler systems, heating systems, membrane systems, papermaking systems, or any other system that circulates water.

The compounds of formulas (I), (Ia) and (II) can provide corrosion protection to any metal or metal alloy, including, but not limited to, copper, iron, silver, steel (eg, galvanized steel) and aluminum. In some embodiments, a compound of formula (I), (Ia) or (II) is added to an aqueous system brought into contact with a metal surface that contains copper to inhibit corrosion of the metal. In some embodiments, a compound of formula (I), (Ia) or (II) is added to an aqueous system brought into contact with a metal surface that contains a copper alloy to inhibit corrosion of the metal. In some embodiments, copper is complexed with one or more heteroatoms in a compound of formula (I), (Ia), or (II). In some embodiments, copper is complexed with one or more heteroatoms in a compound of formula (I), (Ia), or (II). Copper has many uses, including use as copper pipes and tubing in plumbing fixtures and industrial equipment. Copper and copper alloys are widely known for their use in cooling water systems and boiler water systems.

The compounds of formulas (I), (Ia) and (II) can be used to protect any copper alloy, including bronze and brass. Bronze typically contains copper and tin, but may contain other elements including aluminum, manganese, silicon, arsenic and phosphorus. Brass contains copper and zinc and is commonly used in piping for boiler water systems. In some embodiments, a compound of formula (I), (Ia) or (II) is added to an aqueous system brought into contact with a metal surface that contains bronze to inhibit corrosion of the metal. In some embodiments, a compound of formula (I), (Ia), or (II) is added to an aqueous system brought into contact with a metal surface that contains brass, such as Admiralty brass, to inhibit corrosion of the metal. In some embodiments, a compound of formula (I), (Ia) or (II) is added to an aqueous system brought into contact with a metal surface that contains a copper-nickel alloy to inhibit corrosion of the metal.

In some embodiments, a compound of formula (I), (Ia), or (II) inhibits corrosion of mild steel. In some embodiments, a compound of formula (I), (Ia), or (II) inhibits corrosion of metal alloys, including, but not limited to, galvanized steel, stainless steel, cast iron, nickel, and combinations thereof. Without being limited to any particular theory, it is postulated that compounds of formulas (I), (Ia) and (II) inactivate Cu(II) in solution, preventing the formation of galvanic cells on the surface of the steel. Thus, in some embodiments, a compound of formula (I), (Ia), or (II) inhibits pitting corrosion of mild steel.

Although the compounds of formula (I), (Ia) and (II) can be added to the water supply in any amount, the compounds of formula (I), (Ia) and (II) are typically added to the water supply in an amount of about 0 .01 ppm up to about 500 ppm In some embodiments, a compound of formula (I), (Ia), or (II) is added to the aqueous system in an amount of about 0.01 ppm. up to about 100 ppm In some embodiments, a compound of formula (I), (Ia), and (II) is added to the water supply in an amount of about 0.01 ppm. to about 100 ppm, from about 0.01 ppm to about 75 ppm, from about 0.01 ppm to about 50 ppm, from about 0.01 ppm to about 25 ppm, from about 0.01 ppm to about 10 ppm, from about 0.01 ppm to about 5 ppm, from about 0.1 ppm to about 100 ppm, from about 0.1 ppm to about 75 ppm, from about 0.1 ppm to about 50 ppm, from about 0.1 ppm to about 25 ppm, from about 0.1 ppm to about 10 ppm, from about 0.1 ppm to about 5 ppm, from about 1 ppm to about 100 ppm, from about 1 ppm to about 75 ppm, from about 1 ppm to about 50 ppm, from about 1 ppm to about 25 ppm, from about 1 ppm to about 10 ppm, from about 5 ppm to about 100 ppm, from about 10 ppm to about 100 ppm, from about 25 ppm to about 100 ppm, from about 50 ppm up to about 100 ppm or from about 80 ppm up to about 100 ppm

In some embodiments, the water supply system is a water cooling system. The cooling water system may be a closed loop cooling water system or an open loop cooling water system. In some embodiments, a compound of Formula (I), (Ia), or (II) is added to the closed loop cooling water system in an amount of about 0.01 ppm. up to about 200 ppm In some embodiments, a compound of Formula (I), (Ia), or (II) is added to the open loop cooling water system in an amount of about 0.01 ppm. up to about 20 ppm

The compounds of formula (I), (Ia) and (II) are brought into contact with a metal surface by any suitable method. In some embodiments, a solution of a compound of formula (I), (Ia), or (II) is brought into contact with a metal surface through dipping, spraying, or other coating techniques. In some embodiments, a solution of a compound of formula (I), (Ia), or (II) is introduced into the water supply system in any convenient manner and supplied to the water supply system on an intermittent or continuous basis.

In some embodiments, the compositions described herein may contain a fluorescent organic compound. In some embodiments, the fluorescent organic compound may be selected from rhodamine or derivatives thereof, acridine dyes, fluorescein or derivatives thereof, and combinations thereof. In some embodiments, the compositions described herein may contain a fluorescently tagged polymer.

Those skilled in the art will appreciate that compounds of formula (I), (Ia) or (II) can be added to a water supply alone or in combination with other corrosion inhibitors or water treatment agents. Multiple corrosion inhibitors may be added as a combined corrosion inhibitor composition, or each corrosion inhibitor may be added separately, including two or more compounds of formula (I), (Ia), and/or formula (II). In addition, a compound of formula (I), (Ia) or (II) can be added to the water supply in combination with many additional corrosion inhibitors, including, but not limited to, triazoles, benzotriazoles (e.g., benzotriazole or tolyltriazole), benzimidazoles, orthophosphates , polyphosphates, phosphonates, molybdates, silicates, oximes and nitrites. The compounds of formula (I), (Ia) and (II) can also be added to the water supply in combination with various additional additives such as treatment polymers, antimicrobial agents, anti-scaling agents, coloring agents, fillers, buffers, surfactants substances, viscosity modifiers, chelating agents, dispersants, deodorants, masking agents, oxygen neutralizers and indicator dyes.

In other embodiments, a method for preparing polybenzimidazoles may include heating a mixture containing diphenyl isophthalate and 3,3',4,4'-tetraaminodiphenyl, an acid, a polar aprotic solvent, and a high temperature stable phase transfer catalyst. The acid, polar aprotic solvent and high temperature stable phase transfer catalyst are as described herein.

Polybenzimidazoles are known for their high strength and high temperature characteristics. Polybenzimidazoles synthesized in accordance with the methods described herein can be used, for example, in semiconductors, contact sealants, wafer cartridges, insulating sleeves, thermal insulation materials, light emitting diodes, solar cells, fuel cells and high performance protective clothing. Other applications include those in the petrochemical and aerospace industries.

Examples

Example 1

Several condensation reactions were carried out between 1,2-phenylenediamine (OPD) and DL-mandelic acid at 100-110° C. for about 6 to about 8 hours and at an active concentration of about 30 to about 35 wt.% to obtain ( 1H -benzo[ d ]imidazol-2-yl)(phenyl)methanol. The effect of various additives such as high temperature stable catalysts and cosolvents on the homogeneity of the reaction mixture was studied and the results are presented in Table 1.

Table 1: Various additives used in the experiment

Additive Solvent Additive (% wt.) Active substances (% wt.) Uniformity No _{H2SO4 _} 0 20-30 No HEG-Cl* _{H2SO4 _} 10 thirty No HEG-Cl Methanesulfonic acid 10 35 Yes (1 week**) Sulfolane _{H2SO4 _} 15 thirty No Sulfolane Methanesulfonic acid 15 35 Yes

*HEG-Cl=Hexaethyleneguanidinium chloride

**room temperature

Example 2

Several experiments were carried out using about 5% wt. sulfolane and about 3% wt. acetic acid at the additional processing stage. The results of the HPLC analysis are presented in Table 2. The results obtained clearly demonstrate a reduction in the residual concentration of OPD to less than about 0.1 wt.%, and the resulting materials meet the standards. The content of active substances refers to the mass percentage concentration of OPD and DL-mandelic acid at the beginning of the reaction.

Methanesulfonic acid, sulfolane and water were loaded into a round-bottomed flask equipped with a magnetic stirrer, reflux condenser and temperature sensor. To this mixture were added DL-mandelic acid (1 eq.) and 1,2-phenylenediamine (1 eq.) and the contents of the flask were refluxed at about 100-110° C. for about 6-8 hours. After completion of the reaction, glacial acetic acid (3 wt.%) was added and reflux was continued for another 1-3 hours. After further processing, additional water was added so that the content of active substances was about 20% wt. Purity and residual OPD analysis was carried out using NMR and HPLC.

Table 2. Uniformity and degree of conversion under various reaction conditions

Experiment Sulfolane (% wt.) Acetic acid (wt.%) Active substances (% wt.) OPD (wt.%) Conversion rate (wt.%) Uniformity 1 5 3 20 0.02 97 Yes 2 2 3 20 0.02 97 Yes 3 5 3 20 0.09 91 Yes 4 5 3 20 0.04 97 Yes 5 5 3 20 0.05 96 Yes 6 5 3 20 0.02 97 Yes

Example 3: Synthesis of ( 1H -benzo[ d ]imidazol-2-yl)(phenyl)methanol

Methanesulfonic acid, sulfolane and water were loaded into a flask equipped with a magnetic stirrer, reflux condenser and temperature sensor. O-phenylenediamine (about 12.96 g, 1 eq.) and DL-mandelic acid (about 19.15, 1.05 eq.) were added to the resulting mixture and the contents of the flask were refluxed to about 110°C. After about 8 hours of heating, about 3 g of acetic acid was added and reflux was continued for about 3 hours to give the title compound in about 97% yield.

Example 4: Synthesis of (5-chloro-1H-benzo[d]imidazol-2-yl)(phenyl)methanol

Methanesulfonic acid, sulfolane and water were loaded into a flask equipped with a magnetic stirrer, reflux condenser and temperature sensor. 4-chlorobenzene-1,2-diamine (21.85 g, 1 eq.) and DL-mandelic acid (24.45, 1.05 eq.) were added to the resulting mixture and the contents of the flask were heated to reflux at about 110° WITH. After about 8 hours of heating, about 3 g of acetic acid was added and reflux was continued for about 3 hours to give the title compound in about 93% yield.

Example 5: (5-bromo-1H-benzo[d]imidazol-2-yl)(phenyl)methanol

Methanesulfonic acid, sulfolane and water were loaded into a flask equipped with a magnetic stirrer, reflux condenser and temperature sensor. 4-bromobenzene-1,2-diamine (22.08 g, 1 eq.) and DL-mandelic acid (19.15, 1.05 eq.) were added to the resulting mixture and the contents of the flask were heated to reflux at about 110° WITH. After about 8 hours of heating, about 3 g of acetic acid was added and reflux was continued for about 3 hours to give the title compound in about 94% yield.

Example 6: (5-methyl-1H-benzo[d]imidazol-2-yl)(phenyl)methanol

Methanesulfonic acid, sulfolane and water were loaded into a flask equipped with a magnetic stirrer, reflux condenser and temperature sensor. O-toluenediamine (18.3 g, 1 eq.) and DL-mandelic acid (23.94, 1.05 eq.) were added to the resulting mixture and the contents of the flask were refluxed to about 110°C. After about 8 hours of heating, about 3 g of acetic acid was added and reflux was continued for about 3 hours to give the title compound in about 95% yield.

Possible example 1: 2-(pyridin-2-yl)-1H-benzo[d]imidazole

Methanesulfonic acid, sulfolane and water are loaded into a flask equipped with a magnetic stirrer, reflux condenser and temperature sensor. To the resulting mixture add o-phenylenediamine (12.96 g, 1 eq.) and picolinic acid (15.51, 1.05 eq.) and reflux the contents of the flask at about 110°C. After 8 hours of reflux, add acetic acid (2 g) and continue refluxing for another 3 hours to give the title compound.

Possible example 2: 2-pentyl-1H-benzo[d]imidazole

Methanesulfonic acid, sulfolane and water are loaded into a flask equipped with a magnetic stirrer, reflux condenser and temperature sensor. To the resulting mixture add o-phenylenediamine (12.96 g, 1 eq.) and hexanoic acid (15, 1.05 eq.) and reflux the contents of the flask at about 110°C. After 8 hours of reflux, add acetic acid (2 g) and continue refluxing for another 3 hours to give the title compound.

Possible example 3: 2-phenyl-1H-benzo[d]imidazole

Methanesulfonic acid, sulfolane and water are loaded into a flask equipped with a magnetic stirrer, reflux condenser and temperature sensor. To the resulting mixture add o-phenylenediamine (15.66 g, 1 eq.) and benzoic acid (19 g, 1.05 eq.) and reflux the contents of the flask at about 110°C. After 8 hours of reflux, add acetic acid (2 g) and continue refluxing for another 3 hours to give the title compound.

Compound structures and chemical names were compiled and determined using ChemDraw Professional version 15.1.

Any composition described herein may contain, consist of, or consist essentially of any of the compounds/components described herein. In accordance with this invention, the expressions “consisting essentially of” or “consisting essentially of”, “consisting essentially of” and similar expressions limit the scope of the claims to the specified materials or steps and to those materials or steps that do not cause significant impact on the main and new characteristics of the claimed object of invention.

In this context, the term "about" refers to the specified value within the error due to the standard deviation inherent in the relevant test measurements, and if such errors cannot be determined, then "about" means within 10% of the specified value.

All compositions and methods described and claimed in this invention can be obtained and carried out without undue experimentation in the light of this description. Although the present invention may be embodied in many different forms, certain preferred embodiments of the present invention are described in detail herein. This description illustrates the principles of the present invention and is not intended to limit the invention to the specific embodiments presented. In addition, unless specifically stated otherwise, use of the term in the singular includes “at least one” or “one or more.” For example, “connection” includes “at least one connection” or “one or more connections.”

Any ranges given in absolute values or approximate values are inclusive of both, and any definitions used in this context are intended to provide clarity and not to be limiting. Although the numerical ranges and parameters presented above in the broad description of this invention are approximations, the numerical values presented above in the specific examples are written as accurately as possible. However, any numerical value inherently contains certain errors that inevitably arise from the standard deviations contained in their respective test measurements. In addition, all ranges described herein should be understood to include any and all subranges (including any fractional or integer values) included within them.

Moreover, the present invention includes any and all possible combinations of some or all of the various embodiments described herein. It should also be understood that various changes and modifications to the currently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention or without diminishing the intended benefits. It is therefore intended that such changes and modifications be included within the scope of the appended claims.

Claims (39)

1. A composition for inhibiting corrosion, containing a compound or a salt thereof of formula (I), an acid and a polar aprotic solvent , where X independently represents hydrogen, halogen or an unsubstituted C _1-5 alkyl group; and m is 1, 2, 3 or 4; R ¹ represents hydrogen; R ² is missing; R ³ represents a bond or CHR ⁴ ; R ⁴ represents OR ⁵ ; where R ⁵ represents hydrogen; And Z independently represents nitrogen or CX, where the concentration of the compound or salt of formula (I) in the composition is from 1 to 50 wt.%; the acid concentration in the composition ranges from 5 to 60 wt.%; And the concentration of the polar aprotic solvent in the composition ranges from 0.001 to 30 wt.%. 2. The composition according to claim 1, additionally containing water. 3. The composition according to claim 1, characterized in that X independently represents hydrogen or halogen; R ¹ represents hydrogen; R ² is missing; And R ³ is CHR ⁴ . 4. Composition according to claim 1, characterized in that at least one Z is nitrogen. 5. Composition according to claim 1, characterized in that R ³ represents a bond and at least one Z represents nitrogen. 6. Composition according to claim 1, characterized in that said compound or its salt has formula (II) , Where Y independently represents hydrogen; and n is 1, 2, 3, 4 or 5. 7. The composition according to claim 1, characterized in that said acid is selected from sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, phosphoric acid, sulfamic acid, aminomethylphosphonic acid, p-toluenesulfonic acid and any combination thereof. 8. The composition according to claim 1, characterized in that the polar aprotic solvent is selected from acetonitrile, N,N-dimethylformamide, acetone, dimethyl sulfoxide, sulfolane, N-methylpyrrolidinone, methylsulfonylmethane, chlorobenzene, o-dichlorobenzene, nitromethane, ionic liquid and any of them combinations. 9. The composition according to claim 1, characterized in that said composition is a homogeneous liquid. 10. The composition according to claim 1, additionally containing a high-temperature stable phase-transfer catalyst. 11. The composition according to claim 10, characterized in that said phase transfer catalyst, stable at high temperature, is selected from the group consisting of an alkylguanidinium salt, an arylguanidinium salt, an alkylphosphonium salt, an arylphosphonium salt, a peralkylated phosphazenium salt, and any combination thereof. 12. A method of inhibiting corrosion, comprising adding the composition according to claim 1 to an industrial water supply system containing a metal surface. 13. A composition for inhibiting corrosion, containing a compound or a salt thereof of formula (I), an acid and a sulfolane; , Where X independently represents hydrogen, halogen or an unsubstituted C _1-5 alkyl group; and m is 1, 2, 3 or 4; R ¹ represents hydrogen; R ² is missing; R ³ represents a bond or CHR ⁴ ; R ⁴ represents OR ⁵ ; where R ⁵ represents hydrogen; And Z independently represents nitrogen or CX.