Compounds inhibiting inorganic fouling and method of preparing same

Abstract

This description relates to compounds that inhibit inorganic fouling and corrosion, as well as to the production process for these inhibitor compounds, which are aminoalkyl phosphonates which can be obtained in their protonated chemical form or in their non-protonated chemical form.

Description

INORGANIC SCALE INHIBITOR COMPOUNDS AND METHOD OF PREPARING THE SAME DESCRIPTION FIELD

[0001] This description concerns the field of oilfield chemicals. This description also concerns compounds derived from phosphonic acids. DESCRIPTION BASIS

[0002] In oil and gas production, the formation of inorganic scale and corrosion are recurring problems. Scale causes loss of oil flow, limits heat exchange, and can lead to complete shutdown of the production line (Desalination 2008 220(1):345-352; Journal of Petroleum Science and Engineering 2014 118:126-139). Corrosion causes reductions in the mass and thickness of pipes, structural changes, and deterioration of their mechanical properties, such as strength and ductility, until the material becomes unsuitable for use and must be replaced (GENTIL, 2007, Corrosion, 3rd ed., LTC - Livros Técnicos e Científicos Editora SA). The most commonly used method to control these two problems is the use of chemical inhibitors, which prevent or delay the formation of these processes and, therefore, the premature abandonment of the well (Spe Journal, 2012, 17.02: 362-378).Corrosion inhibitors are natural or synthetic substances capable of preventing the reaction of metal with the corrosive medium (BELTRÃO et al., 2009; Int. J. Electrochem. Sci., 2013, 8:9317-9331; Arabian Journal for Science and Engineering, 2018, 43:1-22; Journal of Molecular Liquids, 2022, 364:119992). For saline scale, phosphonates are among the most widely used additives as chemical inhibitors (Revista Virtual de Química, 2011, 3(1):2-13; Journal of Water Process Engineering, 2018, 21:1-8).

[0003] Phosphonates such as aminoalkylphosphonic acid compounds have several applications, such as inhibiting scaling in wells and equipment used in oil and gas production, in the rocks themselves reservoirs, in cooling and water treatment systems, in sugarcane processing plants, in pulp and paper processing, mining and foliar fertilizer processes, anti-corrosion, offshore oil drilling support, detergent additives, and chelating agents. As oil fields develop, water production gradually increases. The composition of oilfield produced water is complex and generally contains a variety of scale-forming ions, such as calcium, barium, carbonates, hydrogen carbonates, sulfates, etc., making the oilfield more susceptible to salt scale formation.

[0004] When applying these inhibitors in oil fields, there are concerns about their stability in the face of high temperatures and pressure found in reservoirs. Another growing concern is environmental and concerns the use of toxic substances as inhibitors. Phosphonates can be toxic and cause eutrophication if used in excess. Therefore, the development of more efficient inhibitors, which allow for their use in smaller yet still effective quantities, or inhibitors with low phosphorus content, is of great interest and importance. Another relevant point is the process of obtaining inhibitors such as aminoalkylphosphonates, as they often involve the use of strong bases or acids as chemical catalysts, and these compounds contribute to environmental pollution. STATE OF THE TECHNIQUE

[0005] Compounds containing phosphonate groups have been used as corrosion and scale inhibitors in various applications, such as in oil and gas production fields and water and sewage cooling and treatment systems, in sugarcane processing plants, in pulp and paper processing processes, mining processes and foliar fertilizers, and may be part of the formulation of drilling fluids or varnishes and coating films for vessels, pipelines and other structures exposed to aqueous media containing inorganic foulants or corrosives.

[0006] Document US10094203B2 discloses corrosion-inhibiting fluids prepared from phosphonates and gluconic acid, or their respective salts, the phosphonate being a tertiary amine phosphonate with the general formula X—N—Y2. The document also discloses the method for inhibiting corrosion using combinations of these substances, which are added to drilling brine fluids. Among the molecules, which are aminoalkylphosphonates, are 2-(2-aminoethoxy)ethanol phosphonate and other products already marketed by the applicant.

[0007] Document CN103708637A discloses inhibitors formed from aminotrimethylene phosphonic acid. The synthesis of these aminotrimethylene phosphonic N-oxides uses organic acids or alkali metal hydroxides / oxides as catalysts. These scale and corrosion inhibitors are suitable for water systems containing algaecides and chlorine-containing compounds, such as sodium hypochlorite and organic chlorine.

[0008] Document US20190256762A1 discloses the use of compounds synthesized from the reaction between 4-aminomethyl-1,8-octanediamine (TAN), a commercial product, and phosphorous acid as descaling agents in fluid compositions used in drilling fields. The described synthesis method relies on the presence of a formylating agent, as well as reaction conditions that convert at least one hydrogen of the TAN amine into a methylphosphonate group. The degree of phosphonation is controlled by the relative concentration of phosphorous acid, formylating agent, and TAN used in the reaction mixture. Complete phosphonation of the amines of TAN (which is a commercial product) yields the product 4-aminomethyl-1,8-octanediamine hexaphosphonate. The embodiments describe the use of hydrochloric acid as a catalyst for the synthesis reaction. The inventors report that their high efficiency allows the use of between 0.1 ppm and 1000 ppm in fluids, depending on the concentration of scale-forming components present.

[0009] Document ES2356272T3 describes a process for producing scale-inhibiting polymers using barium and strontium salts. The inhibitors are produced from anhydrides of dicarboxylic acids containing between 4 and 6 carbon atoms, such as maleic acid, olefins, and phosphorus-containing amines. Primary or secondary amines contain at least one phosphoric or phosphonic radical. Among the compounds listed in the specification are 2-aminoethyl phosphonic acid and 2-hydroxyethylamino-N,N-bismethylene phosphonic acid.

[0010] CN113402548A describes a multifunctional scale inhibitor belonging to the phosphonate class that has high efficiency in oil fields and would be stable for this application, but its synthesis does not start from renewable materials, such as biomass derivatives, and uses toxic compounds.

[0011] Document CN105600955A discloses 2-phosphono-butane-1,2,4-tricarboxylic acid (PBTCA) as a corrosion and scale inhibitor with a low phosphorus content. The phosphorus content in the molecule is approximately 11.5% of the total mass of PBTCA, well below the 30.1% found in 1-hydroxyethylene-1,1-diphosphonic acid (HEDP) and 31.1% found in aminotri(methylenephosphonic) acid (ATMP), commonly used inhibitors. In contrast, the product presented in the present patent application contains 16.2% phosphorus in its protonated form (HBM) or 12.1% in the salt form (BM), levels well below those found in the commercial inhibitors HEDP and ATMP.

[0012] Document PI0720097-8 discloses alkylaminophosphonates that can be used as scale inhibitors. The specification provides very comprehensive descriptions that, therefore, would allow the construction of molecules similar to those described in this patent application. However, in the embodiments disclosed in this prior art, the synthesis is carried out starting from amino acids, dodecyl thiol, chloropropyl imino bis(methylene sulfonic acid), or thioglycolic acid, which generate products distinct from those presented in this patent application, in reactions that employ large amount of sodium hydroxide. Furthermore, the document does not demonstrate scale-inhibiting activity for any of the molecules obtained.

[0013] The above documents reveal efforts related to the importance of reducing inorganic scale and corrosion in waters containing inorganic salts, for example, in activities intrinsically related to oil and gas operations. However, few technologies reduce environmental impacts, particularly those inherent to the use of phosphonates. BRIEF DESCRIPTION OF THE INVENTION

[0014] It is an objective of the present description to disclose aminoalkylphosphonate-type compounds with inorganic scale-inhibiting and corrosion-inhibiting properties. It is also an objective of the present description to disclose a method for producing these scale-inhibiting compounds, obtained from the reaction between 2-((2-aminoethyl)thio)succinic acid, phosphorous acid, and formaldehyde.

[0015] The objectives of the present description are achieved by means of a compound called 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid in its non-protonated form, that is, in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid salt (BM). The method of preparation of this compound comprises the following steps:

[0016] i) mixing cysteamine hydrochloride with an acid selected from the group comprising maleic acid and fumaric acid, in a molar ratio of cysteamine:maleic acid between 0.75:1.25 and 1.25:0.75;

[0017] ii) stir the mixture at a temperature between 20 and 40 °C for an interval of between 2 and 4 hours;

[0018] iii) remove the solvent and wash the resulting oil, which is a 2-((2-aminoethyl)thio)succinic acid hydrochloride compound;

[0019] iv) mix 2-((2-aminoethyl)thio)succinic acid hydrochloride and phosphorous acid in a container, in a molar ratio between 0.75:2.75 and 1.25:1.75;

[0020] v) heat the mixture to a temperature between 90 and 130 °C;

[0021] vi) add to the mixture an aldehyde selected from the group comprising formaldehyde and paraformaldehyde, in a molar ratio aldehyde:phosphorous acid between 0.75:1.25 and 1.25:0.75;

[0022] vii) maintain agitation and heating for a period of between 2 and 30 hours;

[0023] viii) adjust the pH of the reaction medium to a value between 8 and 11;

[0024] ix) add a solution of methanol and acetone to the mixture;

[0025] x) remove the supernatant, obtaining a solid precipitate consisting of the inhibitor in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid salt (BM).

[0026] The objectives of the present description are also achieved by means of a compound called 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid in its protonated form, that is, in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid (HBM). The method of preparation of this compound comprises the following steps:

[0027] i) mixing cysteamine hydrochloride and an acid selected from the group comprising maleic acid and fumaric acid, in a cysteamine / maleic acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0028] ii) stir the mixture at a temperature between 20 and 40 °C for an interval between 2 and 4 hours, obtaining 2-((2-aminoethyl)thio)succinic acid hydrochloride;

[0029] iii) remove the solvent and wash the resulting oil, which is a 2-((2-aminoethyl)thio)succinic acid hydrochloride compound;

[0030] iv) mix 2-((2-aminoethyl)thio)succinic acid and phosphorous acid in a container, in a molar ratio between 0.75:2.75 and 1.25:1.75;

[0031] v) heat the mixture to a temperature between 90 and 130 °C;

[0032] vi) add to the mixture an aldehyde selected from the group comprising formaldehyde and paraformaldehyde, in an aldehyde / phosphorous acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0033] vii) maintain stirring and heating for a period of between 2 and 30 hours;

[0034] viii) remove the solvents, obtaining a compound in the protonated form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid.

[0035] The method of preparing the compound 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid in its protonated form (HBM) may also comprise the following steps:

[0036] i) mixing cysteamine hydrochloride with an acid selected from the group comprising maleic acid and fumaric acid, in a cysteamine / acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0037] ii) stir the mixture at a temperature between 20 and 40 °C for an interval between 2 and 4 hours, obtaining 2-((2-aminoethyl)thio)succinic acid hydrochloride, which is an intermediate product;

[0038] iii) adding an aldehyde selected from the group comprising formaldehyde and paraformaldehyde to the mixture of 2-((2-aminoethyl)thio)succinic acid and phosphorous acid after heating the mixture to between 90 and 130 °C, with a molar ratio of aldehyde:phosphorous acid between 0.75:1.25 and 1.25:0.75;

[0039] iv) maintain stirring and heating for a period of between 2 and 30 hours;

[0040] v) remove the solvents, obtaining a compound in the protonated form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid (HBM).

[0041] The compounds described in this patent application are capable of inhibiting inorganic fouling and corrosion, particularly those caused by carbonates, in activities such as oil and gas production in oil fields. Furthermore, the high efficiency achieved by these compounds allows them to be applied in low concentrations, thus reducing their toxicity and their contribution to the eutrophication of waterways. Furthermore, the synthesis processes described have a lower potential for environmental pollution, as they are synthetic routes that use green solvents, such as water, less aggressive reagents, and renewable sources. Maleic acid and fumaric acid can be obtained from biomass. BRIEF DESCRIPTION OF THE FIGURES

[0042] The present invention is illustrated in the embodiments represented in figures, as briefly described below.

[0043] Figure 1 shows the structural formula of the scale and corrosion inhibitor, 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid, in its protonated form (HBM), according to one embodiment of the present description.

[0044] Figure 2 shows the structural formula of the scale and corrosion inhibitor, 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid, in salt form (BM), where M x a cation, for example, Na + , K + , Mg 2+ , Ca 2+ , NH4 + , according to one embodiment of the present description.

[0045] Figure 3 shows the structural formula of an intermediate product of the synthesis of the scale and corrosion inhibitor, in the form of 2-((2-aminoethyl)thio)succinic acid, according to one embodiment of the present description.

[0046] Figure 4 shows the structural formula of an intermediate product of the synthesis of the scale and corrosion inhibitor, in the form of 2-((2-aminoethyl)thio)succinic acid hydrochloride, according to one embodiment of the present description.

[0047] Figure 5 is a general schematic of the production process of the scale and corrosion inhibitor compound showing the formation of the intermediate synthesis product, according to one embodiment of the present description.

[0048] Figure 6 is a general schematic of the production process of the scale and corrosion inhibitor compound, 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid, in its protonated form, according to one embodiment of the present description.

[0049] Figure 7 is a spectrum obtained by Hydrogen Nuclear Magnetic Resonance (NMR) 1H) of the intermediate synthesis product, in the form of 2-((2-aminoethyl)thio)succinic acid hydrochloride, according to one embodiment of the present description.

[0050] Figure 8 is a spectrum obtained by Carbon-13 Nuclear Magnetic Resonance (NMR) 13 C) of the intermediate synthesis product, in the form of 2-((2-aminoethyl)thio)succinic acid hydrochloride, according to one embodiment of the present description.

[0051] Figure 9 is a spectrum obtained by Hydrogen Nuclear Magnetic Resonance (NMR) 1 H) of the inhibitor compound in salt form (BM), according to an embodiment of the present description.

[0052] Figure 10 is a spectrum obtained by Carbon-13 Nuclear Magnetic Resonance (NMR). 13 C) of the inhibitor compound in salt form (BM), according to an embodiment of the present description.

[0053] Figure 11 is a spectrum obtained by Phosphorus-31 Nuclear Magnetic Resonance (NMR) 31P) of the inhibitor compound in salt form (BM), according to an embodiment of the present description.

[0054] Figure 12 is a spectrum obtained by Hydrogen Nuclear Magnetic Resonance (NMR) 1 H) of the inhibitor compound in protonated form (HBM), according to an embodiment of the present description.

[0055] Figure 13 is a spectrum obtained by Carbon-13 Nuclear Magnetic Resonance (NMR). 13 C) of the inhibitor compound in protonated form (HBM), according to an embodiment of the present description.

[0056] Figure 14 is a spectrum obtained by Phosphorus-31 Nuclear Magnetic Resonance (NMR) 31 P) of the inhibitor compound in protonated form (HBM), according to an embodiment of the present description.

[0057] Figure 15 is a bar graph showing the percentage of scale inhibition efficiency of the substances HBM and BM, according to an embodiment of the present description, compared to the inhibitory effect of other commercial products of the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0058] The present description discloses inorganic scale and corrosion inhibitor compounds consisting of the molecule 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid in the protonated form or in the form of a salt of the acid.

[0059] In one embodiment, the scale inhibitor consists of a derivative of maleic acid or its geometric isomer, which is fumaric acid, containing a tertiary amine, a sulfur atom, and one or two phosphonate groups.

[0060] In one embodiment of the present disclosure, the scale inhibitor compound is 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid in protonated form (HBM).

[0061] In one embodiment of the present description, the scale inhibitor compound is 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid in the non-protonated form, i.e., in the form of a salt, preferably in the form of the sodium salt of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid (BM).

[0062] One embodiment of the protonated form of the inhibitor compound (HBM) is illustrated by the structural formula of Figure 1, while one embodiment of the salt form of the inhibitor compound (BM) is illustrated by the structural formula of Figure 2.

[0063] In one embodiment, the scale inhibitor compound has a general formula:

[0064] where A is an atom selected from the group comprising O, N and S;

[0065] where R is a radical selected from a group comprising a linear, branched, cyclic or aromatic C2-C10 chain, OR”, NHR”, NR”R” and SR”, where R” is a radical selected from the group comprising H, linear, branched, cyclic or aromatic carbon chain, OH, COOH, NH2, SH;

[0066] where M is a radical selected from the group comprising H + , In the + , K + , Mg 2+ , Ca 2+ and NH4 + , where x = 1 or 2; and

[0067] where R' is a radical selected from the group comprising H, COOH or OH.

[0068] In one embodiment of the present disclosure, production of the inhibitor compound in the protonated form (HBM) is accomplished by a direct synthesis process.

[0069] In one embodiment of the present description, the process of producing the inhibitor compound in the non-protonated form (BM) comprises the following steps:

[0070] i) Mix cysteamine hydrochloride and maleic acid in a cysteamine:maleic acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0071] ii) Stir the mixture at a temperature between 20 and 40 °C for an interval of between 2 and 4 hours;

[0072] iii) Remove the solvent and wash the resulting oil, which is a 2-((2-aminoethyl)thio)succinic acid hydrochloride compound;

[0073] iv) Mix 2-((2-aminoethyl)thio)succinic acid hydrochloride and phosphorous acid in a container, in a molar ratio between 0.75:2.75 and 1.25:1.75;

[0074] v) Heat the mixture to a temperature between 90 and 130 °C;

[0075] vi) Add to the mixture an aldehyde selected from the group comprising formaldehyde and paraformaldehyde, in a molar ratio of aldehyde:phosphorous acid between 0.75:1.25 and 1.25:0.75;

[0076] vii) Keep stirring and heating for a period between 2 and 30 hours;

[0077] viii) Adjust the pH of the reaction medium to a value between 8 and 11;

[0078] ix) Add a solution of methanol and acetone to the mixture;

[0079] x) Remove the supernatant, obtaining a solid precipitate consisting of the inhibitor in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid salt (BM).

[0080] In one embodiment of the present description, the process of producing the inhibitor compound in protonated form (HBM) comprises following steps:

[0081] i) Mix cysteamine hydrochloride and maleic acid in a cysteamine / maleic acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0082] ii) Stir the mixture at a temperature between 20 and 40 °C for an interval of between 2 and 4 hours, obtaining 2-((2-aminoethyl)thio)succinic acid hydrochloride;

[0083] iii) Remove the solvent and wash the resulting oil, which is a 2-((2-aminoethyl)thio)succinic acid hydrochloride compound;

[0084] iv) Mix 2-((2-aminoethyl)thio)succinic acid and phosphorous acid in a container, in a molar ratio between 0.75:2.75 and 1.25:1.75;

[0085] v) Heat the mixture to a temperature between 90 and 130 °C;

[0086] vi) Add to the mixture an aldehyde selected from the group comprising formaldehyde and paraformaldehyde, in an aldehyde / phosphorous acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0087] vii) Keep stirring and heating for a period between 2 and 30 hours;

[0088] viii) Remove the solvents, obtaining a compound in the protonated form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid.

[0089] In any embodiment, the reagents are solubilized in a solvent selected from the group comprising water and organic solvents, such as ethanol, acetone, methanol and propanol.

[0090] Figure 5 shows a general scheme of the production process of the scale and corrosion inhibitor compound, illustrating the formation of 2-((2-aminoethyl)thio)succinic acid hydrochloride as an intermediate synthesis product.

[0091] In one embodiment, the production of the inhibitor compound in the protonated form (HBM) excludes the drying and washing step of the intermediate synthesis product called 2-((2-aminoethyl)thio)succinic acid, comprising the following steps:

[0092] i) Mix cysteamine hydrochloride and maleic acid in a cysteamine / maleic acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0093] ii) Stir the mixture at a temperature between 20 and 40 °C for an interval of between 2 and 4 hours, obtaining 2-((2-aminoethyl)thio)succinic acid hydrochloride, which is an intermediate product;

[0094] iii) Add formaldehyde to the mixture of 2-((2-aminoethyl)thio)succinic acid and phosphorous acid after heating it between 90 and 130 °C, with a formaldehyde:phosphorous acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0095] iv) Keep stirring and heating for a period of between 2 and 30 hours;

[0096] v) Remove the solvents, obtaining a compound in the protonated form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid.

[0097] Figure 6 is a general diagram of the production process of the scale and corrosion inhibitor compound in its protonated form (HBM) without the solvent removal and washing step of the intermediate product.

[0098] In one embodiment, the compound 2-((2-aminoethyl)thio)succinic acid in the form of a salt is obtained from maleic or fumaric acid, by a method comprising the following steps:

[0099] i) Mix cysteamine hydrochloride and maleic acid or fumaric acid in a cysteamine / dicarboxylic acid molar ratio between 0.75:1.25 and 1.25:0.75;

[0100] ii) Stir the mixture at a temperature between 20 and 40 °C for an interval between 2 and 4 hours, when maleic acid is the starting material, obtaining the intermediate product 2-((2-aminoethyl)thio)succinic acid hydrochloride. When the starting material is fumaric acid, stir the mixture between 40 and 120 °C for an interval between 4 and 30 hours.

[0101] In one embodiment of the present description, in the first step of producing the inhibitor compounds, maleic acid or fumaric acid is mixed with a substance of general formula HS(CH2) n NH x , preferably cysteamine (C2H7NS), and the reaction between the two molecules generates an intermediate product called acid 2-((2-aminoethyl)thio)succinic acid. The structural formula of this compound is seen in Figure 3.

[0102] In one embodiment of the present disclosure, in the first step of the process for producing the inhibitor compounds, maleic acid reacts with cysteamine in the form of cysteamine hydrochloride (C2H8CINS), generating 2-((2-aminoethyl)thio)succinic acid hydrochloride as the intermediate product. The structural formula of this compound is seen in Figure 4.

[0103] In one embodiment, in the step of washing the resulting oil, which consists of the compound called 2-((2-aminoethyl)thio)succinic acid in the form of 2-((2-aminoethyl)thio)succinic acid hydrochloride, it is washed three times with ethanol and dried in a high vacuum.

[0104] In one embodiment, in the step of washing the resulting oil, a solvent selected from the group comprising organic solvents such as ethanol, acetone, methanol and propanol is used.

[0105] In one embodiment, the intermediate compound in the form of 2-((2-aminoethyl)thio)succinic acid hydrochloride will be used in the second stage of inhibitor production, in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid sodium salt (BM).

[0106] In another embodiment of the present description, the intermediate compound in the form of 2-((2-aminoethyl)thio)succinic acid hydrochloride will be used in the second stage of the production of the inhibitor in the protonated form, that is, in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid (HBM).

[0107] In one embodiment, maleic acid or fumaric acid is obtained from renewable sources.

[0108] In one embodiment of the present description, the substance of general formula HS(CH2) n NH x is cysteamine (C2H7NS), preferably a cysteamine hydrochloride salt (C2H8CINS).

[0109] In one embodiment, the reaction between maleic acid and cysteamine occurs in an aqueous or alcoholic reaction medium, the alcohol being a short-chain alcohol, preferably ethanol.

[0110] In one embodiment, the container for carrying out the synthesis process is a sealed container, preferably a glass or borosilicate container.

[0111] In one embodiment, maleic acid and cysteamine salt are added to the reaction medium in a molar ratio between 0.75:1.25 and 1.25:0.75, with the equimolar ratio preferably being 1:1.

[0112] In one embodiment, the mixture of maleic acid and cysteamine is stirred at a temperature between 20 and 40 °C for a period of 2 to 4 hours, preferably for a period of 3 hours.

[0113] In one embodiment, phosphorous acid is added to 2-((2-aminoethyl)thio)succinic acid, in an aqueous or alcoholic reaction medium, and the resulting mixture is heated to a temperature between 90 and 130 °C, preferably at a temperature of 105 °C.

[0114] In one embodiment, 2-((2-aminoethyl)thio)succinic acid and phosphorous acid are added in a molar ratio between 0.75:2.75 and 1.25:1.75, with the molar ratio preferably being 1:2.2.

[0115] In one embodiment, formaldehyde or paraformaldehyde is added to the mixture of 2-((2-aminoethyl)thio)succinic acid hydrochloride and phosphorous acid immediately after heating the mixture, with a formaldehyde:phosphorous acid molar ratio between 0.75:1.25 and 1.25:0.75, preferably the equimolar ratio being 1:1, remaining under stirring and heating for a period of 2 to 30 hours, preferably for a period of 2.5 hours.

[0116] In another embodiment, to obtain the compound in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid salt (BM), the pH of the reaction medium is adjusted to a value between 8 and 11, preferably pH 9, preferably using a concentrated sodium hydroxide solution; then, this medium is poured into a solvent solution, preferably a solution containing methanol / acetone in a volumetric ratio of 3:1. The addition of solvents will generate a precipitate.

[0117] In one embodiment, the volumetric ratio between the medium reaction medium and the solvent solution is between 0.75:2.5 and 1.25:2.5, with a volumetric ratio of 1:2 of reaction medium / solvent solution being preferred.

[0118] In one embodiment, the precipitate is filtered, collected in a round-bottom flask and dried in high vacuum for an interval between 2 and 4 hours, preferably for 3 hours, to obtain a dry white solid, the structural formula of which can be seen in Figure 2, which corresponds to the inhibitor in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid salt (BM).

[0119] In one embodiment, the solution containing the inhibitor compound 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid in salt form (BM) or in protonated form (HBM) is used immediately after the synthesis step, without the need for a prior extraction or concentration step.

[0120] In one embodiment, the solution containing the inhibitor compound 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid in salt form or in protonated form undergoes a solvent removal step to obtain the inhibitor in a concentrated form.

[0121] In one embodiment, the solvent removal steps are accomplished by filtration or evaporation under reduced pressure.

[0122] In one embodiment, the corrosion and scale inhibitor compound is used in applications such as oil and gas production fields and water and sewage cooling and treatment systems, in sugarcane processing plants, in paper and cellulose processing processes, mining processes and foliar fertilizers, and may be part of the formulation of drilling fluids or varnishes and coating films for vessels, pipelines and other structures exposed to aqueous media containing incrustants or inorganic corrosives. EXAMPLES OF IMPLEMENTATION OF THE INVENTION

[0123] In what follows, exemplary realizations of the object described herein are presented, in a non-restrictive manner, illustrating results and advantages achieved by the same. Example 1. Two-step inhibitor synthesis:

[0124] In this example, a first step is performed, and the reaction results in the formation of an intermediate synthesis product. This product, once isolated, is used in a second step, in which the inhibitor is formed. Example 1.1. First step: production of intermediate product:

[0125] In this step, 2-((2-aminoethyl)thio)succinic acid hydrochloride, an intermediate in the synthesis of the scale and corrosion inhibitor 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid, is synthesized. In a reaction flask, 1.136 g (10 mmol) of cysteamine hydrochloride and 20 mL of water (concentration = 0.5 M) were added. To this solution was added a solution containing 1.161 g (10 mmol) of maleic or fumaric acid and 15 mL of water (concentration = 0.667 M). The mixture was stirred at room temperature for 3 h when maleic acid was used, or stirred at 100 °C for 24 h when fumaric acid was used. The solvent was removed under reduced pressure, resulting in 2.3 g of a colorless oil. The structure of the molecule in the form of 2-((2-aminoethyl)thio)succinic acid can be seen in Figure 3, while the hydrochloride salt form of 2-((2-aminoethyl)thio)succinic acid, which corresponds to the properly isolated intermediate form, can be seen in Figure 4.The intermediate in the form of hydrochloride was characterized by Hydrogen Nuclear Magnetic Resonance (NMR. 1 H), as shown in Figure 7, and Carbon-13 (NMR 13 C), as shown in Figure 8. The following are the spectroscopic data, showing the chemical shifts associated with the hydrogens and carbons of the structure, as numbered in the figures, where: NMR 1 H (400 MHz, D2O) õppm: õ 3.79 (1 H, q, H-C2); 3.27 (2H, t, H-C2); 3.08-2.83 (4H, m, H-C3e HC r ). NMR 13 C (100 MHz, D2O) õppm: õ 28.44 (C3); 35.98 (C r ); 38.41 (C2); 41.58 (C2); 174.60 (C4); 175.50 (CJ. Example 1.2. Second step: production of the inhibitor in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic salt (BM):

[0126] In a sealed 15 ml tube, 0.4581 g (2 mmol) of 2-((2-aminoethyl)thio)succinic acid hydrochloride, 0.3608 g (4.4 mmol) of phosphorous acid, and 5 ml of water were added. Thus, the molar concentrations of 2-((2-aminoethyl)thio)succinic acid and phosphorous acid were, respectively, 0.4 M and 0.88 M. This mixture was heated to 105 °C, and then 0.3670 g (4.4 mmol) of 36% (v / v) formaldehyde was added. The obtained mixture was left under heating and stirring for 24 hours. The pH of the reaction medium was adjusted to approximately 9 using a 3 M aqueous NaOH solution, and then it was poured into 40 ml of a methanol / acetone solution (3:1 v / v). The precipitate was filtered, collected in a flask and dried under high vacuum for 3 hours. 0.920 g of a dry white solid was obtained, whose structural formula can be seen in Figure 2. The product was also characterized by NMR 1 H (Figure 9), NMR 13 C (Figure 10) and NMR 31P (Figure 11). The following are the spectroscopic data, showing the chemical shifts associated with the hydrogens and carbons, as numbered in the figures, where: NMR 1 H (400 MHz, D2O) õppm: õ 3.59 (1 H, q, H-C2); 3.15 (2H, t, H-C2); 2.82 (4H, d, NCH,P): 2.88-2.40 (4H, m, H-C3e HC r ). NMR 13 C (100 MHz, D2O) õppm: õ 26.65 (C r ); 40.86 (C3); 47.63 (C2); 53.77 (d, C2); 55.30 (dd, NÇH2P); 179.51 (C4); 179.77 (C. NMR 31 P (100 MHz, D2O) õppm: õ 12.43 (NCH^C^HNa); 14.61 (NCH2PO3Na2). Example 1.3. Second step: production of the inhibitor in the form of protonated 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid (HBM):

[0127] In a sealed 15 ml tube were added 0.4581 g (2 mmol) of 2-((2-aminoethyl)thio)succinic acid hydrochloride, 0.3608 g (4.4 mmol) of phosphorous acid and 5 ml of water. Thus, the molar concentrations of 2-((2-aminoethyl)thio)succinic acid and phosphorous acid were, respectively, 0.4 M and 0.88 M. This mixture was heated to 105 °C and then 0.3670 g (4.4 mmol) of 36% (v / v) formaldehyde was added. The obtained mixture was left under heating and stirring for 24 h. The solvent was removed under reduced pressure, obtaining a yellow oil that was characterized by NMR 1 H (Figure 12), NMR 13 C (Figure 13) and NMR 31 P (Figure 14). The structural formula of the product in its protonated form (HBM) can be seen in Figure 1. What follows are the spectroscopic data, showing the chemical shifts associated with the hydrogens and carbons, as numbered in the figures, where: NMR 1H (400 MHz, D2O) õppm: õ 3.82 (1 H, q, H-C2); 3.75 (2H, t, H-C2); 3.56 (4H, d, NÇH2P); 3.23-2.81 (4H, m, H-C3e HC r ). NMR 13 C (100 MHz, D2O) õppm: õ 25.05 (C r ); 35.87 (C3); 41.42 (C2); 51.35 (dd, NÇH2P); 55.36 (t, C2); 174.49 (C4); 175.28 (C. NMR 31 P (100 MHz, D2O) õppm: õ 7.45 (NCH^O^).

[0128] The two-step inhibitor synthesis scheme (as per Example 1.1 followed by Example 1.2 or Example 1.3) is seen in Figure 5. Example 2. Direct synthesis of the inhibitor from maleic acid and cysteamine, without isolation step of the intermediate product:

[0129] In a sealed 15 mL tube, 1.136 g (10 mmol) of cysteamine hydrochloride and 20 mL of water (concentration = 0.5 M) were added. To this solution was added a solution containing 1.161 g (10 mmol) of maleic acid and 15 mL of water (concentration = 0.667 M). The mixture was stirred at room temperature for 3 h. Then, 1.804 g (22 mmol) of phosphorous acid was added. This mixture was heated to 105 °C, and then 1.835 g (22 mmol) of 36% formaldehyde was added. The mixture was allowed to heat and stir for 2.5 h. After this period, the solvent was removed under reduced pressure, obtaining the inhibitor product in the protonated form (HBM).

[0130] Figure 6 shows the scheme of the direct synthesis of the inhibitor, as in Example 2. Example 3. Inhibition effect of inorganic scale formed by calcium carbonate

[0131] The samples synthesized in Example 1 (BM and HBM) were evaluated for their effect on inhibiting calcium carbonate scale. The brine was prepared according to the standardized test in National Association of Corrosion Engineers (NACE) Standard TM0374-2007, item no. 21208. The calcium-containing brine had the following composition: 12.15 g L 1 CaCl2.2H2O; 3.68 g L' 1 MgCI2.6H2O; 33.0 g L' 1 of NaCI; and the composition of the brine containing bicarbonate was: 7.36 g L' 1 NaHCO3; 33.0 g L' 1 of NaCl. The test was performed over 24 hours at a temperature of 71 ± 1 °C. Changes in calcium ion concentration before and after precipitation were determined by titration with EDTA using the indicator Murexide (CAS 3051-09-0). The results show that 50 mg L' 1of the scale inhibitor, both in its protonated form (HBM) and in its salt form (BM), were sufficient to obtain a scale inhibition efficiency of 100%, as shown in Table 1, since it was not possible to observe calcium carbonate precipitation when using this inhibitor concentration in the test water. For a comparative evaluation, concentrations of 25 mg L -1 and 50 mg L -1 of the two forms of the inhibitor (HBM and BM) and other commercial inhibitors were tested. The results show that the commercial inhibitors performed worse than HBM and BM, as can be seen in Figure 15.

[0132] Table 1: Scale inhibitory effect of HBM and BM substances according to standardized test in Standard TM0374-2007 (NACE).

[0133] The results, as shown in Figure 15, show that the new inhibitor is more efficient than four other important commercial inhibitors: HEMPA, DTPMPA, DEQUEST2076 and DEQUEST2076A.

[0134] The sample synthesized in Example 2 was evaluated for its thermal stability at 4 °C for a period of 30 days and at 130 °C for a period 21 days. The product did not present turbidity, phase change, sludge formation or gelation in relation to the original sample. Table 2 presents the test results, with the captions “S” for positive formation results; “N” for negative formation results; and for untested conditions.

[0135] Table 2: Thermal stability test of the product of Example 2. [0136 Although exemplary embodiments of the processes and products described have been presented in this report, it is not intended that the scope of protection be limited to their literal meaning. Therefore, the description should be interpreted not as limitative, but merely as examples of particular embodiments that retain the inventive concept presented herein. A person skilled in the art may readily apply the teachings presented herein to analogous solutions arising therefrom, limited only by the scope of the claims of this application.

Claims

CLAIMS 1. Process for producing a scale inhibitor compound characterized by comprising a reaction between three compounds: (1) 2-((2-aminoethyl)thio)succinic acid; (2) phosphorous acid; and (3) formaldehyde or paraformaldehyde.

2. Process, according to claim 1, characterized by comprising the steps of: i) Mixing cysteamine hydrochloride with an acid selected from the group comprising maleic acid and fumaric acid, in a cysteamine:acid molar ratio between 0.75:1.25 and 1.25:0.75; ii) Stirring the mixture at a temperature between 20 and 120 °C for an interval between 2 and 30 hours; iii) Removing the solvent and washing the resulting oil, which is a compound of 2-((2-aminoethyl)thio)succinic acid hydrochloride; iv) Mixing 2-((2-aminoethyl)thio)succinic acid hydrochloride and phosphorous acid in a container, in a molar ratio between 0.75:2.75 and 1.25:1.75; v) Heat the mixture to a temperature between 90 and 130 °C; vi) Add to the mixture an aldehyde selected from the group comprising formaldehyde and paraformaldehyde, in a molar ratio of aldehyde:phosphorous acid between 0.75:1.25 and 1.25:0.75; vii) Maintain stirring and heating for a period between 2 and 30 hours; viii) Adjust the pH of the reaction medium to a value between 8 and 11;ix) Add a solution of methanol and acetone to the mixture; x) Remove the supernatant, obtaining a solid precipitate consisting of the inhibitor in the form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid salt.; 3. Process, according to claim 1, characterized by comprising the steps of: i) Mixing cysteamine hydrochloride with an acid selected from group comprising maleic acid and fumaric acid, in a cysteamine:acid molar ratio between 0.75:1.25 and 1.25:0.75; ii) Stir the mixture at a temperature between 20 and 120 °C for an interval between 2 and 30 hours; iii) Remove the solvent and wash the resulting oil, which is a compound of 2-((2-aminoethyl)thio)succinic acid hydrochloride; iv) Mix 2-((2-aminoethyl)thio)succinic acid and phosphorous acid in a container, in a molar ratio between 0.75:2.75 and 1.25:1.75; v) Heat the mixture to a temperature between 90 and 130 °C; vi) Add to the mixture an aldehyde selected from the group comprising formaldehyde and paraformaldehyde, in an aldehyde / phosphorous acid molar ratio between 0.75:1.25 and 1.25:0.75; vii) Keep stirring and heating for a period between 18 and 30 hours; viii) Remove the solvents, obtaining a compound in the protonated form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid.

4. Process, according to claim 1, characterized by comprising the steps of: i) Mixing cysteamine hydrochloride with an acid selected from the group comprising maleic acid and fumaric acid, in a cysteamine:acid molar ratio between 0.75:1.25 and 1.25:0.75; ii) Stirring the mixture at a temperature between 20 and 120 °C for an interval between 2 and 30 hours; iii) Adding to the mixture of 2-((2-aminoethyl)thio)succinic acid and phosphorous acid heated to a temperature between 90 and 130 °C, an aldehyde selected from the group comprising formaldehyde and paraformaldehyde, with an aldehyde:phosphorous acid molar ratio between 0.75:1.25 and 1.25:0.75; iv) Maintaining stirring and heating for a period between 2 and 30 hours; v) Remove the solvents, obtaining a compound in the protonated form of 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic acid.

5. Process according to any one of claims 1 to 4, characterized in that the acid mixed with the cysteamine hydrochloride is maleic acid; and that the mixture is stirred at a temperature between 20 and 40 °C for an interval between 2 and 4 hours.

6. Process according to any one of claims 1 to 4, characterized in that the acid mixed with the cysteamine hydrochloride is fumaric acid; and that the mixture is stirred at a temperature between 40 and 120 °C for an interval between 4 and 30 hours.

7. Process according to any one of claims 1 to 4, characterized in that the intermediate product 2-((2-aminoethyl)thio)succinic acid is obtained from the following steps: i) Mixing cysteamine hydrochloride and an acid selected from the group comprising maleic acid and fumaric acid, in a cysteamine:acid molar ratio between 0.75:1.25 and 1.25:0.75; ii) Stir the mixture at a temperature between 20 and 120 °C for an interval between 2 and 30 hours.

8. Process according to any one of claims 1 to 7, characterized in that the reagents are solubilized in a solvent selected from the group comprising water and organic solvents, such as ethanol, acetone, methanol and propanol.

9. Process according to any one of claims 1 to 8, characterized in that the washing steps employ an organic solvent selected from the group comprising ethanol, acetone, methanol and propanol.

10. Process according to any one of claims 1 to 9, characterized in that the solvent removal steps are carried out by filtration or evaporation under reduced pressure.

11. Scale inhibitor compound characterized in that it is obtained by the process of any one of claims 1 to 10 and has a formula: where A is an atom selected from the group comprising O, N and S, where R is a radical selected from a group comprising a linear, branched, cyclic or aromatic C2-C10 chain, OR”, NHR”, NR”R” and SR”, where R” is a radical selected from the group comprising H, linear, branched cyclic or aromatic carbon chain, OH, COOH, NH2, SH; where M is a radical selected from the group comprising H + , In the + , K + , Mg 2+ , Ca 2+ and NH4 + , where x = 1 or 2; and where R' is a radical selected from the group comprising H, COOH or OH.

12. Compound according to claim 11, characterized in that it is a 2-((2-(bis(phosphonomethyl)amino)ethyl)thio)succinic salt.

13. Use of the compound of any one of claims 11 to 12, characterized by inhibiting or delaying the formation of inorganic scale.

14. Use according to claim 13, characterized by preventing or delaying the formation of inorganic carbonate scale.

Images