A method for determining the amount of water in a sample using sulfonic acid.

Abstract

A first method for determining the amount of water in a sample includes providing a reagent including sulfur dioxide or a derivative thereof, a base, an optional hydrogen halide or hydrogen halide donor, a solvent, and a sulfonic acid, and titrating the sample with the reagent. A second method for determining the amount of water in a sample includes providing the reagent, combining the sample with the reagent, and adding an iodine source to the sample and / or the reagent. The reagent may alternatively consist essentially of sulfur dioxide or a derivative thereof, imidazole and / or a derivative thereof, an optional hydrogen halide or hydrogen halide donor, acetonitrile, methanesulfonic acid, and methanol and / or ethanol.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 107,233, filed Oct. 29, 2020, which is hereby incorporated by reference in its entirety.

[0002] (Field of the Invention) The present disclosure generally relates to methods for determining the amount of water in a sample using sulfonic acid. More specifically, the present disclosure relates to the use of sulfur dioxide or its derivatives, bases, solvents, and one or more types of sulfonic acids.

Background Art

[0003] The determination of water by the Karl Fischer method, i.e., via Karl Fischer titration, utilizes the following reactions, and the stoichiometry between iodine and water is 1:1. In an alcohol solution or a protic solution, it is as follows: (1) SO2 + ROH + B → BHSO3R, (2) BHSO3R + I2 + H2O + 2B → BHSO4R + 2BHI In a non - alcoholic or aprotic solution, it is as follows: (3) SO2 + I2 + H2O + 3B → BSO3 + 2BHI,

[0004] Undesirable side reactions such as the benzene reaction (4) and the hydrolysis reaction of SO3 (5) lead to a deviation from the required 1:1 stoichiometry, and the overall stoichiometry between iodine and water becomes 1:n (n = 1 - 2), resulting in a very low discovery of water. (4) 2H2O + SO2 + I2 → H2SO4 + 2HI (5) SO3 + H2O + 2B → BHSO4 + BH Where B is a base and ROH is an alcohol. This titration is performed in two basic forms, namely volumetric titration and coulometric titration.

[0005] In classical Karl Fischer titration, the reagent contains an alkyl sulfite, which is oxidized in the presence of water to form an alkyl sulfate. Karl Fischer titration is typically carried out in an alcohol solution (e.g., methanol). The use of a certain amount of alcohol helps to stabilize the stoichiometry of the Karl Fischer reaction by shifting the equilibrium towards reactions (1) and (2). However, unwanted side reactions (4) and (5) can still occur.

[0006] The use of a reagent containing an excess of pyridine to stabilize the stoichiometry has been described in the literature. However, in such systems, the determinable water equivalence strongly depends on the experimental conditions. For example, in such systems, pyridine-SO3 adducts are formed and are involved in water-consuming side reactions (5) that can change the titration results.

[0007] Furthermore, the difficulty in using non-alcoholic (aprotic) Karl Fischer reagents is a change in stoichiometry. Depending on the aprotic solvent and base used, the ratio of iodine to water in the Karl Fischer reaction is often 1:1 to 2 (not 1:1). When the hydrolysis of the base-SO3 adduct can be suppressed, the stoichiometry of I2:H2O remains 1:1.

[0008] Therefore, there remains an opportunity to develop a Karl Fischer reagent with a stabilized 1:1 stoichiometry that enables very accurate titrations in both alcoholic and non-alcoholic solvents. SUMMARY OF THE INVENTION

[0009] The present disclosure describes embodiments that utilize sulfonic acid to stabilize the Karl Fischer reaction stoichiometry (I2:H2O, 1:1) in both protic and aprotic solvents. In other words, by adding sulfonic acid to the Karl Fischer reagent, unwanted side reactions such as (4) and (5) above can be better suppressed.

[0010] This disclosure provides a first method for determining the amount of water in a sample, the first method comprising the steps of providing a reagent comprising sulfur dioxide or a derivative thereof, a base, an optional hydrogen halide or hydrogen halide donor, a solvent, and a sulfonic acid, and titrating the sample with the reagent.

[0011] The disclosure also provides a second method for determining the amount of water in a sample. This method includes the steps of preparing the aforementioned reagents, combining the sample with the reagents, and adding an iodine source to the sample and / or reagents.

[0012] The disclosure also provides reagents that may alternatively consist of essentially sulfur dioxide or its derivatives, imidazole and / or its derivatives, an optional hydrogen halide or hydrogen halide donor, methanesulfonic acid, acetonitrile and / or methanol and / or ethanol and / or 1-methoxy-2-propanol and / or propylene glycol. [Modes for carrying out the invention]

[0013] The following detailed description is, in effect, merely illustrative and is not intended to limit the methods or reagents. Furthermore, it is not intended to be constrained by any of the background art described above or any theory presented in the following detailed description.

[0014] Embodiments of this disclosure generally relate to methods of titration and solutions therefor. For the sake of brevity, prior art may not be described in detail herein. Furthermore, various tasks and process steps described herein may be incorporated into more comprehensive procedures or processes having additional steps or functions not described in detail herein. In particular, various steps in titration are well known, and therefore, for the sake of brevity, many conventional steps are either briefly mentioned herein or completely omitted without providing details of the well known steps. Various desirable features and characteristics of this disclosure will become apparent when the subsequent detailed description of this disclosure and the appended claims are combined with the accompanying drawings and the background art of this disclosure.

[0015] This disclosure provides a method for determining the amount of water in a sample. Typically, this method can be described as a form or variation of Karl Fischer titration used to determine the amount of water or moisture in a sample. Generally, there are two methods used to carry out Karl Fischer titration. The first is known as volumetric Karl Fischer titration. In this titration, the determination of the amount of water in the sample is based on the amount or volume of reagent used to replace the water. In this titration, the sample is dissolved in a solvent before the titration begins. Reagents are added until the water is removed.

[0016] The second method is known as coulometric Karl Fischer titration. In this titration, the reagent and solvent are combined in a titration cell. Once the sample is introduced into the titration cell and dissolved, iodine is released by induction of an electric current. The amount of current required to convert water is the determinant of the amount of water in the sample. The advantage of coulometric Karl Fischer titration is its ability to accurately measure small amounts of water, for example, as low as 0.1 micrograms (μg). Each titration is described in more detail below.

[0017] Referring here to the sample itself, the sample can be any type of sample containing water. The amount of water in the sample is not particularly limited and can be selected by those skilled in the art. For example, in coulometric titration, the amount of water in the sample is about 0.1 to about 10,000 μg, about 0.1 to about 3,000 μg, about 20 to about 3,000 μg, or about 1 to about 10,000 μg. In volumetric titration, the amount of water can greatly exceed 10,000 μg. In further other embodiments, the maximum amount of water is determined by the size of the container used for the amount of reagent required. The sample can be a liquid, a gas, or a solid, provided that the sample contains the amount of water present therein. Typically, the sample is a liquid containing the amount of water present therein. In various embodiments, the reagents of this disclosure are used with conventionally problematic samples that have side reactions with conventional reagents, such as solutions of ketones and / or aldehydes and unsaturated compounds such as vinylene carbonate.

[0018] This method includes the step of preparing a reagent. The reagent may be alternatively referred to as "Karl Fischer reagent." The reagent is used to titrate a sample containing an amount of water contained therein. For example, the reagent can be used in the Karl Fischer method described above, for example, by volumetric or coulometric titration. When used, for example, in coulometric titration, the reagent may be referred to as a titration solution. For example, in volumetric titration in one or two-component reagents, the reagent of this disclosure may act as a solvent. Additionally, a mixture of iodine and the reagent may act as a one-component reagent.

[0019] Reagents may be alcohol-free or may contain alcohol. Typically, the terms “free of” describe embodiments containing less than 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, or 0.01 weight percent of alcohol, based on the total weight of the reagent. In one embodiment, the reagent is completely alcohol-free (i.e., contains zero weight percent or an amount of alcohol below a typical detection limit). Alternatively, the reagent may contain any alcohol, but is not limited to methanol, ethanol, propanol, mono- and di-ethylene glycol monoalkyl ethers, and combinations thereof. In one embodiment, the reagent contains an alcohol selected from methanol, ethanol, propanol, 1-methoxypropan-2-ol, mono- and di-ethylene glycol monoalkyl ethers, and combinations thereof, or contains a solvent that is an alcohol.

[0020] The reagent comprises sulfur dioxide or a derivative thereof, a base, an optional hydrogen halide donor or hydrogen halide, a solvent, and a sulfonic acid, and comprises the step of titrating a sample with the reagent. The reagent may be the above compound, may essentially consist of the above compound, or may consist of the above compound. The term "essentially consisting of" may describe embodiments that do not include a hydrogen halide donor or a compound that is not a hydrogen halide. The term "essentially consisting of" may alternatively describe embodiments that include or do not include one or more soluble halides that are not hydrohalides of the above hydrogen halide donor or a second derivative of imidazole described below. For example, the reagent may include, or may not include, one or more of the following: sodium halide, or halides of organic cations such as tetrabutylammonium iodide, imidazole hydrogen iodide, or trimethylamine hydrogen iodide, and / or dissociated organic salts such as tetrabutylammonium chloride, diethanolamine hydrogen bromide, guanidinium salts such as guanidinium benzoate, and / or combinations thereof. The reagent may or may not contain imidazole itself. The reagent may also contain or may not contain nitrogen bases such as salts or carboxylic acids, such as buffering agents like tetramethylammonium acetate, trimethylammonium acetate, tetrabutylammonium benzoate, lithium propionate acetate, propionic acid, butyric acid, benzoic acid, diethanolammonium benzoate, or imidazolium acetate, or combinations thereof.

[0021] Throughout this description, whenever the word “halide” is used, it is conceivable that in various non-limiting embodiments, any halide, namely fluorine, chlorine, bromine, iodine, or a combination thereof, may be used. Furthermore, in other non-limiting embodiments, whenever the word “iodide” is used, it may be substituted with fluoride, chloride, or bromide.

[0022] Sulfur dioxide or its derivatives: To reiterate, the reagent contains sulfur dioxide (SO2) or its derivatives. The term “its derivatives” refers to compounds that act the same or substantially the same as sulfur dioxide in Karl Fischer titration and will be understood by those skilled in the art. For example, possible derivatives include, but are not limited to, sulfites such as dimethyl sulfite, ethyl sulfite, and combinations thereof, which are reducing agents.

[0023] In one additional embodiment, sulfur dioxide or its derivatives are present in an amount of about 0.05 to about 5 moles per liter of reagent. In other embodiments, sulfur dioxide or its derivatives are present in an amount of about 0.05 to about 1, about 0.1 to about 1, or about 0.1 to about 0.5 moles per liter of reagent. In various non-limiting embodiments, it is also conceivable that all values ​​and ranges of values, including those between and including these values ​​shown above, are specifically designed for use herein, in whole or in part.

[0024] base: Regarding the base, it may be any base known in the art that is suitable for Karl Fischer titration. For example, the base may be a nitrogen-containing base or a nitrogen-free base. For example, the base may be a primary, secondary, or tertiary amine. In another embodiment, the base may be pyridine or a derivative thereof. In another embodiment, the base may be a primary amine. Alternatively, the base may be imidazole, a derivative of imidazole, or a combination thereof. The base and the reagent itself may contain less than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, or 0.1 weight percent of pyridine, or may contain no pyridine at all.

[0025] In various embodiments, the reagent includes a base-to-sulfur dioxide or derivative molar ratio greater than 1:1 or less than 1:1. In various embodiments, the base-to-sulfur dioxide or derivative molar ratio is about 1.5:1, about 2:1, about 2.5:1, about 3:1, about 3.5:1, about 4:1, about 4.5:1, about 5:1, about 5.5:1, about 6:1, about 6.5:1, about 7:1, about 7.5:1, about 8:1, about 8.5:1, about 9:1, about 9.5:1, about 10:1, about The molar ratios are approximately 10.5:1, about 11:1, about 11.5:1, about 12:1, about 12.5:1, about 13:1, about 13.5:1, about 14:1, about 14.5:1, about 15:1, about 15.5:1, about 16:1, about 16.5:1, about 17:1, about 17.5:1, about 18:1, about 18.5:1, about 19:1, about 19.5:1, or about 20:1. Each of these molar ratios can be reversed, thereby indicating that the molar ratio of base to sulfur dioxide or its derivatives is less than 1:1. In various embodiments, when a liquid system is used, the molar ratio can be much higher than 20:1, for example, 30:1, 40:1, 50:1, or even higher. In one embodiment, the molar ratio of base to sulfur dioxide or its derivatives is greater than 2:1. In another embodiment, the molar ratio of base to sulfur dioxide or its derivative is greater than 5:1. In yet another embodiment, the molar ratio of base to sulfur dioxide or its derivative is about 14:1. Furthermore, the reagent may contain an amount "greater" than any of the aforementioned ratios, for example, an amount "greater" than about 2:1, an amount greater than about 2.5:1, etc. In other embodiments, the base is present in an amount of about 0.5 to about 5.5, or about 0.5 to about 5, or about 0.5 to about 2.5 moles per liter of reagent. In various non-limiting embodiments, all values ​​and ranges of values ​​between and including these values ​​shown above may be explicitly designed for use herein, in whole or in part.

[0026] When referring to derivatives of imidazole, particularly as described below, when the "second" derivative is used, this derivative can be described as the "first derivative" of imidazole. It should be understood that "derivatives of imidazole" and "the first derivatives of imidazole" can be used interchangeably throughout.

[0027] The first derivative of imidazole can have the following structure:

[0028]

Chemical formula

[0029] In various embodiments, the first derivative of imidazole is present in the reagent in the amounts described above, relative to the base and sulfur dioxide or its derivative. In other embodiments, the first derivative of imidazole is present in amounts of about 0.5 to about 5.5, or about 0.5 to about 5, or about 0.5 to about 2.5 moles per liter of reagent. In other embodiments, the first derivative of imidazole is present in an amount that reflects one or more of the above molar ratios of the first derivative of imidazole to sulfur dioxide or its derivative greater than 1:1. For example, if the above number of moles of sulfur dioxide or its derivative is present in the reagent, the first derivative of imidazole may be present in a number of moles greater than 1:1, for example, in one of the above ratios, or, if used in excess, for example, as a solvent. In various non-limiting embodiments, it is conceivable that all values ​​and ranges of values, including those between and including these values ​​shown above, are specifically designed for use herein, in whole or in part.

[0030] Hydrogen halide donors: The hydrogen halide donor can be any amine hydrogen halide. This amine can be any known in the art, and therefore the donor can be a hydrohalide of imidazole itself, such as hydroiodide, hydrogen chloride, or hydrobromide. Furthermore, this amine can be any of those described herein. In various embodiments, this amine can be an optionally substituted aliphatic, cyclic, heterocyclic, or aromatic amine such as pyridine and its derivatives, trimethylamine, trialkylamine such as triethylamine, tri-n-butylamine, N,N-dimethylethylamine, N,N-diethylmethylamine, imidazole, N-ethylmorpholine, N-methylmorpholine, 2-morpholinoethanol, 1-methylpiperidine, 1-ethylpiperidine, 1-methylpyrrolidine, 2-(dimethylamino)-2-methyl-1-propanol, diethanolamine, pyridine and its derivatives, and combinations thereof. Therefore, the hydrogen halide donor may be the iodide / bromide / hydrogen chloride of any of the above amines. The reagent may not contain any of the hydrogen halide donors described immediately before it, and instead may utilize the hydrogen halide donors described immediately after it.

[0031] In one embodiment, the hydrogen halide donor is a hydrohalide of a second derivative of imidazole, for example, a hydroiodide of a second derivative of imidazole. In another embodiment, the hydrogen halide donor is a hydrobromide of a second derivative of imidazole. In yet another embodiment, the hydrogen halide donor is hydrogen chloride of a second derivative of imidazole.

[0032] In one embodiment, the hydrogen halide donor is a second derivative of imidazole, such as hydroiodide, hydrobromide, or hydrogen chloride, or a combination thereof, and the second derivative of imidazole can have the following structure:

[0033] [ka] In the formula, R, R 1 , and R 2 Each of these is independently a hydrogen atom, a phenyl group, a substituted phenyl group, a first hydrocarbyl group having 1 to 6 carbon atoms, or a second hydrocarbyl group having 1 to 6 carbon atoms with a heteroatom interposed at at least one position. In one structure, R, R 1 , and R 2 Not all of them can be hydrogen atoms. In another embodiment, R, R 1 , and R 2 Each of these is a hydrogen atom. In various embodiments, the first hydrocarbyl group has 1, 2, 3, 4, 5, or 6 carbon atoms. The second hydrocarbyl group may also independently contain 1, 2, 3, 4, 5, or 6 carbon atoms, and at one or more positions in the group chain, the heteroatoms may include, but are not limited to, nitrogen, oxygen, phosphorus, chlorine, bromine, or iodine. Furthermore, R 1 and R 2 Each of them can be placed at any position on the ring. R, R 1 , and R 2 Each of these is the first derivative of imidazole, R, R 1 , and R 2 This may differ. Alternatively, R, R 1 , and R 2 Each of them is R 3 , R 4 , and R 5 It may be described as follows. In one further embodiment, R, R 1 , and R 2 Each of these is independently a hydrogen atom, or a methyl group, ethyl group, propyl group, or butyl group, provided that R, R 1 , and R 2 It is not the case that all of them are hydrogen atoms.

[0034] The hydrohalides may be hydroiodides, hydrogen chlorides, or hydrobromids of any of the above amines, or combinations thereof. In other words, the hydrohalides may be any of the above amines, or any of the above embodiments of, for example, the second derivative of imidazole, which will be recognized by those skilled in the art. The second derivative of imidazole and the first derivative of imidazole may have the same general structure except that the second derivative of imidazole is a hydrohalide. In other words, the only difference between the first and second derivatives of imidazole may be that the five-membered ring structure and substituents are the same or nearly the same, but the first may not be a hydrohalide while the second is.

[0035] The hydrogen halide donor may be any of the above compounds alone, a hydrohalide of a second derivative of imidazole alone, or a combination thereof. The hydrogen halide may be a hydroiodide, hydrochloride, or hydrobromide salt, or a combination thereof, without an amine donor.

[0036] The hydrogen halide donor may be present in any amount selected by those skilled in the art, for example, in amounts of about 0.01 to about 5, about 0.1 to about 2, about 0.2 to about 1.5, or about 0.2 to about 1 mole per liter of reagent. In various non-limiting embodiments, all values ​​and ranges of values, including those between and including these values ​​shown above, may be specifically designed for use herein, in whole or in part.

[0037] The reagent also contains a hydrogen halide acceptor. This acceptor has a pK greater than 5. AThis receptor may have any of the following known in the art, but is not limited to, optionally substituted aliphatic, cyclic, heterocyclic, or aromatic amines such as pyridine and its derivatives, trialkylamines, including trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, N,N-dimethylethylamine, N,N-diethylmethylamine, N,N-dimethyl-n-butylamine, N,N,N',N'-tetramethylethylenediamine, imidazole, 1-methylpiperidine, 1-ethylpiperidine, 1,2-dimethylpyrrolidine, 2-(dimethylamino)-2-methyl-1-propanol, 1-methylpyrrolidine, N-ethylmorpholine, N-methylmorpholine, 2-morpholinoethanol, and combinations thereof. In various embodiments, the hydrogen halide acceptor is selected from 2-morpholinoethanol, 2-(dimethylamino)-2-methyl-1-propanol, diethanolamine, and combinations thereof. In various embodiments, the receptor is used in amounts ranging from 0.005 to 5 moles per liter of reagent. In various non-limiting embodiments, all values ​​and ranges of values, including those between and including those shown above, may be explicitly designed for use herein, in whole or in part.

[0038] solvent: With regard to the solvent, the solvent may be any solvent known in the art. The solvent may be a protic solvent, an aprotic solvent, or a combination thereof, may contain them, may consist essentially of them, or may consist of them. In one embodiment, the solvent may be a protic solvent, may contain a protic solvent, may consist essentially of a protic solvent, or may consist of a protic solvent. In another embodiment, the solvent may be an aprotic solvent, may contain an aprotic solvent, may consist essentially of an aprotic solvent, or may consist of an aprotic solvent. In yet another embodiment, the solvent may be an alcohol, a nitrile solvent, or a combination thereof, may contain them, may consist essentially of them, or may consist of them. In one embodiment, the solvent may be an alcohol, may contain an alcohol, may consist essentially of an alcohol, or may consist of an alcohol. In another embodiment, the solvent may be a nitrile solvent, may contain a nitrile solvent, may consist essentially of a nitrile solvent, or may consist of a nitrile solvent. The reagent may contain, based on the total weight of the reagent, one or more of the following: aprotic solvents, protic solvents, alcohols, or nitrile solvents, either none, or less than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, or 0.1 weight percent. The term “essentially consisting of” may describe one or more embodiments that, based on the total weight of the reagent, either contain none, or contain less than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, or 0.1 weight percent of the following: aprotic solvents, protic solvents, alcohols, or nitrile solvents, or any other solvent in the art. In various non-limiting embodiments, all values ​​and ranges of values ​​between and including these values ​​shown above may be explicitly designed for use herein, in whole or in part.

[0039] In one embodiment, the solvent may be a solvent selected from acetonitrile, propionitrile, and combinations thereof, may contain such solvent, may be essentially composed of such solvent, or may consist of such solvent. In another embodiment, the solvent may be acetonitrile, may contain such solvent, may be essentially composed of such solvent, or may consist of such solvent. In a further embodiment, the solvent may be an alcohol selected from methanol, ethanol, propanol, 1-methoxypropan-2-ol, mono- and di-ethylene glycol monoalkyl ethers, and combinations thereof, may contain such alcohol, may be essentially composed of such alcohol, or may consist of such alcohol.

[0040] When an aprotic solvent is used, the aprotic solvent may be any of the ones known in the art, but is not limited to, diisopropyl ether, dibutyl ether, dioxane, tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, nitriles such as acetonitrile, ethyl acetate, ethyl propionate, isobutyl acetate, n-butyl acetate, ethylene carbonate, propylene carbonate, esters such as butyrolactone, halogenated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, bromoform, dibromomethane, 1,2-dichloropropane, acid amides such as dimethylformamide, N-methylformamide, formamide, dimethylacetamide, 2-pyrrolidone, N-methylpyrrolidone, ketones such as acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, methylcyclohexanone, ethylene carbonate, acetylacetone, and other aprotic solvents such as dimethylacetal. In one embodiment, the aprotic solvent is selected from acetonitrile, propylene carbonate, ethyl acetate, tetrahydrofuran, dioxane, dimethylformamide, or methylene chloride, and combinations thereof. In a further embodiment, the aprotic solvent is selected from cyclic and acyclic carbonates, ethers, esters, halohydrocarbons, acid amides, nitriles, ketones, glycol ethers, and combinations thereof. In another embodiment, the aprotic solvent is selected from acetonitrile, ethylene carbonate, propylene carbonate, and combinations thereof. In yet another embodiment, the aprotic solvent is selected from acetonitrile, propylene carbonate, and combinations thereof. In one embodiment, the aprotic solvent is acetonitrile. In another embodiment, the aprotic solvent is propylene carbonate. In another embodiment, the aprotic solvent is dimethylformamide. In yet another embodiment, the aprotic solvent is selected from dimethylformamide, acetonitrile, and combinations thereof. In yet another embodiment, the aprotic solvent may be a pure (liquid) derivative of imidazole, such as any of those described herein.The reagent may be free of one or more of the above aprotic solvents, or may contain one or more of the above aprotic solvents in amounts less than 5, 4, 3, 2, 1, 0.5, or 0.1 weight percent, based on the total weight of the reagent. The aprotic solvent may be present in any amount selected by those skilled in the art, for example, in an amount that constitutes the “residue” of the compound such that the titration composition has a total volume of 100. In various non-limiting embodiments, it is also conceivable that all values ​​and ranges of values ​​between and including these values ​​shown above, in whole or in part, are specifically designed for use herein.

[0041] When a protic solvent is used, the protic solvent may be any known in the art. For example, the protic solvent may be an alcohol such as methanol, ethanol, propanol, mono- and / or diethylene glycol monoalkyl ethers, or combinations thereof, having 1, 2, 3, 4, 5, 6, 7, or 8 carbon atoms. The protic solvent may be used in any amount as described above relative to the aprotic solvent. In various non-limiting embodiments, it is also conceivable that all values ​​and ranges of values, including those between and including these values ​​shown above, are specifically designed for use herein, in whole or in part.

[0042] The solvent may be used in any amount determined by those skilled in the art. For example, the solvent may be used in an amount that "balances" all the other components of the reagent so that the total amount of all components of the reagent is 100 parts or 100% by weight. Alternatively, the solvent may be used in amounts of about 1 to about 99, about 5 to about 95, about 10 to about 90, about 15 to about 85, about 20 to about 80, about 25 to about 75, about 30 to about 70, about 35 to about 65, about 40 to about 60, about 45 to about 55, about 50 to about 55, about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, or about 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent by weight, based on the total weight of the reagent. In various non-limiting embodiments, it is conceivable that all values ​​and ranges of values, including those between and including these values, may be specifically designed for use herein, in whole or in part.

[0043] Sulfonic acid: The reagent also contains a sulfonic acid. The sulfonic acid may be any known in the art. Typically, the sulfonic acid is an alkyl sulfonic acid, an aryl sulfonic acid, or a combination thereof. For example, an alkyl sulfonic acid may contain an alkyl group having 1 to 8 carbon atoms, e.g., 1, 2, 3, 4, 5, 6, 7, or 8 carbon atoms. In various embodiments, the alkyl sulfonic acid is selected from methanesulfonic acid, ethanesulfonic acid, and combinations thereof. In other embodiments, the aryl sulfonic acid is selected from toluenesulfonic acid, alkylbenzenesulfonic acid, e.g., linear alkylbenzenesulfonic acid, and combinations thereof. In yet another embodiment, the sulfonic acid is selected from methanesulfonic acid, ethanesulfonic acid, toluenesulfonic acid, alkylbenzenesulfonic acid, and combinations thereof. In one embodiment, the sulfonic acid is methanesulfonic acid. In various non-limiting embodiments, it is conceivable that all values ​​and ranges of values, including those between and including these values, may be specifically designed for use herein, in whole or in part.

[0044] In various embodiments, sulfonic acid is present in amounts of about 0.1 to about 80, about 0.1 to about 1, about 0.2 to about 0.9, about 0.3 to about 0.8, about 0.4 to about 0.7, about 0.5 to about 0.6, about 5 to about 75, about 10 to about 70, about 15 to about 65, about 20 to about 60, about 25 to about 55, about 30 to about 50, about 35 to about 45, about 40 to about 45, about 8 to about 15, or about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 weight percent based on the total weight of the reagent. In other embodiments, sulfonic acid is present in amounts of about 0.01 to about 20, about 0.01 to about 0.1, about 0.02 to about 0.09, about 0.03 to about 0.08, about 0.04 to about 0.07, about 0.05 to about 0.06, about 1 to about 20, about 2 to about 19, about 3 to about 18, about 4 to about 17, about 5 to about 16, about 6 to about 15, about 7 to about 14, about 8 to about 13, about 9 to about 12, about 10 to about 11, about 0.5 to about 1.5, or about 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, or 1.5 moles per liter of reagent. In various non-limiting embodiments, it is conceivable that all values ​​and ranges of values, including those between and including these values, may be specifically designed for use herein, in whole or in part.

[0045] In one additional embodiment, sulfur dioxide or its derivative is present in an amount of about 0.05 to about 1 mole per liter of reagent, a base is present in an amount of about 0.5 to about 2.5 moles or about 0.5 to about 5 moles per liter of reagent, a hydrohalide donor or hydrogen halide is present in an amount of about 0.01 to about 2 moles per liter of reagent, and a sulfonic acid is present in an amount of about 0.5 to about 1.5 moles per liter of reagent. The solvent may constitute the residue of the reagent.

[0046] In another additional embodiment, sulfur dioxide or its derivative is present in an amount of about 0.10 to about 0.30 moles per liter of reagent, a base is present in an amount of about 0.5 to about 1 mole per liter of reagent, a hydrohalide donor or hydrogen halide is present in an amount of about 0.1 to about 1.5 moles per liter of reagent, and a sulfonic acid is present in an amount of about 0.5 to about 1.5 moles per liter of reagent. The solvent may contain the residue of the reagent.

[0047] In further embodiments, sulfur dioxide or its derivative is present in an amount of about 0.2 moles per liter of reagent, and the first derivative of imidazole is present in an amount of about 1.4 moles per liter of reagent, where R, R 1 , and R 2 Each of these is independently a hydrogen atom or a methyl group, ethyl group, propyl group, or butyl group, provided that R, R 1 , and R 2 It is not all hydrogen atoms, and the hydrohalide, a second derivative of imidazole, is present in an amount of approximately 0.2 moles per liter of reagent, with R, R 1 , and R 2 Each of these is independently a hydrogen atom, or a methyl group, ethyl group, propyl group, or butyl group, provided that R, R 1 , and R 2 Not all of it consists of hydrogen atoms; sulfonic acid is present in an amount of approximately 0.5 to 1.5 moles per liter of reagent. The solvent can constitute the residue of the reagent. In various non-limiting embodiments, it is also conceivable that all values ​​and ranges of values, including those between and including these values ​​shown above, are specifically designed for use herein.

[0048] In one additional embodiment, for example, in connection with the use of an alcoholic coulogenic reagent, sulfur dioxide or a derivative thereof is present in an amount of about 0.05 to about 1 mole per liter of reagent, a base is present in an amount of about 0.5 to about 2.5 or about 0.5 to about 5 moles per liter of reagent, a hydrohalide donor or hydrogen halide is present in an amount of about 0.01 to about 2 moles per liter of reagent, and a sulfonic acid is present in an amount of about 0.5 to about 1.5 moles per liter of reagent. The solvent may constitute the residue of the reagent.

[0049] In another additional embodiment, sulfur dioxide or its derivative is present in an amount of about 0.2 to about 1.0 mole per liter of reagent, a base is present in an amount of about 1.0 to about 1.7 moles per liter of reagent, a hydrohalide donor or hydrogen halide is present in an amount of about 0.1 to about 1.1 moles per liter of reagent, and a sulfonic acid is present in an amount of about 0.5 to about 1.5 moles per liter of reagent. The solvent may constitute the residue of the reagent.

[0050] In further embodiments, sulfur dioxide or its derivative is present in an amount of about 0.9 moles per liter of reagent, and the first derivative of imidazole is present in an amount of about 1.2 moles per liter of reagent, where R, R 1 , and R 2 Each of these is independently a hydrogen atom or a methyl group, ethyl group, propyl group, or butyl group, provided that R, R 1 , and R 2 It is not all hydrogen atoms, and the hydrohalide, a second derivative of imidazole, is present in an amount of approximately 0.9 moles per liter of reagent, with R, R 1 , and R 2 Each of these is independently a hydrogen atom, or a methyl group, ethyl group, propyl group, or butyl group, provided that R, R 1 , and R 2Not all of these are hydrogen atoms; sulfonic acid is present in an amount of approximately 0.5 to 1.5 moles per liter of reagent. The solvent may constitute the residue of the reagent. In various non-limiting embodiments, it is also conceivable that all values ​​and ranges of values, including those between and including these values ​​shown above, are specifically designed for use herein, in whole or in part.

[0051] In another additional embodiment, for example, in relation to the use of an alcoholic volume one-component reagent, sulfur dioxide or its derivative is present in an amount of about 0.01 to about 1 mole per liter of reagent, the base is present in an amount of about 0.5 to about 2.5 or about 0.5 to about 5 moles per liter of reagent, and the hydrohalide of a second derivative of imidazole is present in an amount of about 0.01 to about 2 moles, where R, R 1 , and R 2 Each of these is independently a hydrogen atom, or a methyl group, ethyl group, propyl group, or butyl group, provided that R, R 1 , and R 2 It is not the case that all of it consists of hydrogen atoms, or the hydrohalides of the second derivative of imidazole are present in amounts of approximately 0.3 to 1.0 moles per liter of reagent, and R, R 1 , and R 2 Each of these is independently a hydrogen atom, or a methyl group, ethyl group, propyl group, or butyl group, provided that R, R 1 and R 2 It is not entirely composed of hydrogen atoms; iodine is present in amounts of approximately 0.5 to 5 moles per liter of reagent, and sulfonic acid is present in amounts of approximately 0.5 to 1.5 moles per liter of reagent. The solvent may constitute the residue of the reagent. In various non-limiting embodiments, it is also conceivable that all values ​​and ranges of values, including those between and including these values ​​shown above, are specifically designed for use herein.

[0052] Specifically regarding the steps for preparing the reagents, the reagents can be produced / prepared using any order of addition. For example, any total or partial amount of any of the above components can be combined with any total or partial amount of any other component.

[0053] In one embodiment, for example, about 130 g of base is combined with about 130 g of a hydrohalide donor or hydrogen halide and dissolved in a solvent. Subsequently, about 8 g of sulfur dioxide or a derivative thereof is introduced into the solution.

[0054] In yet another example, the reagents can be used in the anode and / or cathode spaces of two coulometric chamber cells, or as a universal electrolyte in a single chamber cell. These reagents of the Disclosure can also be used as solvent components of one-component or two-component reagents. For example, when the reagents of the Disclosure are used as solvents, one-component or two-component reagents can be added thereto to titrate the volume of water in a sample. When iodine is added to these reagents of the Disclosure, the corresponding reagent can be used as a one-component reagent.

[0055] In other embodiments, the reagent solutions described herein can be used as anodelithe in a coulometric cell having only one chamber, or additionally, as cathodelithe in a coulometric cell having two separate chambers. Furthermore, the solutions can also be packed into a volumetric titration cell as a solvent component. The aqueous sample can be added to the titration cell and titrated using a commercially available iodine reagent (e.g., a one-component or two-component reagent).

[0056] In one embodiment, the method includes the step of titrating the sample with a reagent. This is typically described as a volumetric method. In another embodiment, the method includes the step of mixing the sample and the reagent so that the sample can be titrated. In this embodiment, the method typically includes the step of providing an iodine source (I2). The iodine source may be any of those known in the art, or, for example, solid I2 dissolved in any of the above-mentioned reagents. In various embodiments, the solution to which iodine is added may have about 1 to about 10 weight percent iodine after its addition. In the coulometric method, iodine can be produced by anodic oxidation of iodide so that no additional iodine or external source is required / used. The sample can be titrated to determine the amount of water in the sample by using one of the Karl Fischer methods described above. In various non-limiting embodiments, it is also conceivable that all values ​​and ranges of values, including those between and including these values ​​shown above, are specifically designed for use herein, in whole or in part.

[0057] For example, any required iodine can be added via the iodine solution described above, or produced by anodic oxidation from the added iodide. In this method, the added or produced iodine is typically reduced to iodide by the reaction of sulfur dioxide or its derivatives with water. If water is already absent, free iodine remains. Iodine excess can be used to indicate an endpoint, for example, for visual or photometric indication. Alternatively, the endpoint can be indicated electrochemically, for example, by potentiometric or dicurrent measurement.

[0058] Volumetric titration can be performed by introducing the reagent as a solvent component into the titration vessel. The sample may then be added to the titration vessel, thereby titrating water by introducing iodine containing a one-component or two-component reagent. Typically, titration using a one-component reagent, which is a solution of iodine, a base, and SO2, as in the conventional method, involves providing the solvent in the vessel, adding the sample to the vessel containing the solvent, and then adding the one-component reagent to the mixture of sample and solvent in the vessel. The reagents of this disclosure can be used as solvents in this titration. Titration using a two-component reagent typically involves providing a solvent containing a base and SO2, such as the reagents of this disclosure, in the vessel. The sample is then typically added to the vessel. Finally, the two-component reagent is typically added to the vessel so that the titration reaction can be initiated.

[0059] The reagents of this disclosure can also be used as one-component titration reagents in volumetric titration. To use them, it is necessary to add 1 to 10% by weight of iodine to the reagents.

[0060] Coulometric determination can be performed, for example, by introducing reagent components into a coulometric cell such as a divided cell, then adding the sample according to the cell structure, and switching the electrolytic current until the water present in the sample is converted.

[0061] Before determining the amount of water in the sample, water contained in the aprotic solvent can be removed by blank titration (e.g., by pre-decomposition in the case of coulometry). Typically, in coulometric titration, the first derivative of imidazole is combined with a hydrohalide of a second derivative of imidazole. In various embodiments, for example, if the coulometric cell requires a reagent with a conductivity of about 5 to about 20 mS / cm, it may be necessary to add an additional supporting electrolyte. These may be soluble inorganic salts such as tetrabutylammonium chloride or imidazolium hydrogen bromide.

[0062] To indicate endpoints, potentiometric or dual-current indices may be used in both volumetric analysis and coulometric titration. For example, reagents and / or samples may be supplemented with one or more known compounds having known, reproducible endpoints. These may be selected by those skilled in the art. Furthermore, one or more buffers may be used. In yet another embodiment, the method may or may not include one or more compounds, method steps, etc., described in U.S. Patent No. 5,401,662. That U.S. patent is expressly incorporated herein in whole by reference in various non-limiting embodiments.

[0063] In various embodiments, the methods of the present disclosure produce an initial drift of about 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or less than 1 μg / min, which is determined by those skilled in the art using any of the titration methods described above. In various non-limiting embodiments, it is also conceivable that all values ​​and ranges of values, including those between and including these values ​​shown above, are specifically designed for use herein, in whole or in part.

[0064] In additional embodiments of this disclosure, the reagent may be free of a hydrogen halide donor. In other embodiments, the reagent may be as follows, all figures being approximate amounts of the reagent in moles / liter:

[0065] [Table 1]

[0066] In various non-limiting embodiments, it is conceivable that all values ​​and ranges of values, including those between and including these values, may be specifically designed for use herein, in whole or in part.

[0067] In other embodiments, the reagent comprises sulfur dioxide, iodide (hydroiodide of imidazole or one of its aforementioned derivatives), one of the aforementioned imidazole derivatives, or a mixture thereof with one or more amines such as those described above. In related embodiments, the solvent is an anhydrous aprotic solvent such as propylene carbonate (PC) or acetonitrile (or a mixture of different aprotic solvents such as ethers, esters, halohydrocarbons, acid amides, and combinations thereof).

[0068] In various embodiments, it has been found that by using a mixture of sulfonic acid and acetonitrile as a solvent, it is possible to prepare Karl Fischer reagents that react in the same or similar manner as alcohol-containing reagents. For example, some reagents of this disclosure exhibit the same stoichiometric reaction 1:1, H2O:I2 as in many alcohol solutions. Furthermore, some reagents exhibit a series of additional advantages. For example, methanesulfonic acid significantly increases the conductivity of Karl Fischer reagents prepared from protic and aprotic solvents (see Example 3). High conductivity values ​​are particularly important in the coulometric Karl Fischer method. Therefore, Karl Fischer reagents based on methanesulfonic acid are remarkably suitable for the coulometry of water. Since sulfonic acid is a good proton donor, reagents containing sulfonic acid can be used as a universal anode reagent in a titration cell without a diaphragm, and also as a cathode in a titration cell with a diaphragm. In various embodiments, the reagent is prepared by dissolving a base (e.g., imidazole, 1-ethylimidazole, 2-ethylimidazole) in acetonitrile. Further solvents such as propylene carbonate or acid amides such as 2-pyrrolidone may also be added. Imidazolium hydroiodide, or hydroiodide of a substituted imidazolium derivative, or another source of hydroiodide may be added together with the sulfonic acid. Finally, sulfur dioxide can be passed through the solution.

[0069] In one embodiment, a one-component volume reagent is prepared. For example, the reagent can be prepared by dissolving a base (e.g., imidazole, 1-ethylimidazole) in acetonitrile. Further solvents such as propylene carbonate or acid amides such as 2-pyrrolidone can also be added. Imidazolium hydroiodide, or hydroiodide of a substituted imidazolium derivative, or another source of hydroiodide can be added together with the sulfonic acid. Sulfur dioxide can be passed through the solution. Finally, iodine is added to the solution.

[0070] In another embodiment, a two-component volumetric assay reagent is prepared. For example, the titrator can be prepared by dissolving iodine in acetonitrile. Further solvents such as propylene carbonate or acid amides such as 2-pyrrolidone can also be added. In addition, the solvent can be prepared by dissolving a base (e.g., imidazole, 1-ethylimidazole) in acetonitrile. Further solvents such as propylene carbonate or acid amides such as 2-pyrrolidone can also be added. Hydroiodide of hydrogen iodide or imidazolium hydroiodide or a substituted imidazolium derivative can also be added along with the sulfonic acid. Finally, sulfur dioxide is passed through the solution.

[0071] Acetonitrile can also be used in combination with other solvents such as acid amides, chloroform, xylene, alcohols, or alcoholic reagents, and as a result, the combination of acetonitrile with alcohols and / or other solvents can be adapted to the requirements of the sample. [Examples]

[0072] A series of titrations are performed as comparative examples in accordance with this disclosure.

[0073] Example 1: The first example involves titration of the water standard shown below using a Metrohm 852 Titrando apparatus. This example focuses on stabilizing the KF stoichiometry of a protic KF reagent, demonstrating that in the absence of methanesulfonic acid, the error is unacceptably high (approximately 86%). However, with the use of methanesulfonic acid, the error is reduced to almost zero.

[0074] [Table 2]

[0075] Example 2: The second example involves titration of the water standard shown below using a Metrohm 852 Titrando apparatus. This example focuses on stabilizing the KF stoichiometry of an aprotic KF reagent, where the error is approximately 7% in the absence of methanesulfonic acid. However, with the use of methanesulfonic acid, the error is reduced to almost 0.

[0076] [Table 3]

[0077] Example 3: A third example involves measuring the conductivity of protic solvents (e.g., methanol) and aprotic solvents (e.g., acetonitrile) with and without methanesulfonic acid. The conductivity may increase significantly by 2,500 to 8,000 times when methanesulfonic acid is added.

[0078] [Table 4]

[0079] In various non-limiting embodiments, any of the terms alcohol-free solvent, solution, and / or reagent may be substituted with aprotic solvent, solution, and / or reagent. Similarly, in various non-limiting embodiments, any of the terms alcohol solvent, solution, and / or reagent may be substituted with protic solvent, solution, and / or reagent.

[0080] While the above detailed description presents at least one exemplary embodiment, it should be understood that a vast number of variations exist. It should also be understood that the exemplary embodiments, or any of the exemplary embodiments, are illustrative only and are not intended to limit the scope, applicability, or configuration in any way. Rather, the above detailed description will provide a convenient roadmap for those skilled in the art to implement the exemplary embodiments. It should be understood that various modifications can be made to the function and configuration of the elements described in the exemplary embodiments without departing from the scope set forth in the attached claims. The present invention includes the following embodiments. [1] A method for determining the amount of water in a sample, wherein the method is A. (1) Sulfur dioxide or its derivatives, (2) Bases and (3) A hydrogen halide or hydrogen halide donor of any choice, (4) Solvent and, (5) Sulfonic acid and, The steps include preparing reagents containing, A method comprising the step of titrating the sample with the reagent. [2] The method according to [1], wherein the sulfonic acid is an alkyl or aryl sulfonic acid or a combination thereof. [3] The method according to [1], wherein the sulfonic acid is selected from methanesulfonic acid, ethanesulfonic acid, toluenesulfonic acid, alkylbenzenesulfonic acid, and combinations thereof. [4] The method according to [1], wherein the sulfonic acid is methanesulfonic acid. [5] The method according to any one of [1] to [4], wherein the solvent comprises an alcohol, a nitrile solvent, or a combination thereof. [6] The method according to any one of [1] to [4], wherein the solvent is selected from acetonitrile, propionitrile, and combinations thereof. [7] The method according to any one of [1] to [4], wherein the solvent comprises an alcohol selected from methanol, ethanol, propanol, 1-methoxypropan-2-ol, mono- and di-ethylene glycol monoalkyl ethers, and combinations thereof. [8] The base is an imidazole and / or a derivative thereof, and the imidazole derivative has the following structure:

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[10] A reagent for Karl Fischer titration, wherein the reagent is (1) Sulfur dioxide or its derivatives, (2) Imidazole and / or its derivatives, (3) A hydrogen halide or hydrogen halide donor of any choice, (4) Acetonitrile and (5) Methanesulfonic acid and (6) A reagent consisting of methanol and / or ethanol and / or 1-methoxy-2-propanol and / or propylene glycol.

Claims

1. A method for determining the amount of water in a sample, wherein the method is a. i. Sulfur dioxide or its sulfites, ii. Bases and, iv. Solvent and, v. A step of preparing a reagent containing sulfonic acid, b. A method comprising the step of titrating the sample with the reagent.

2. The base is an imidazole and / or a derivative thereof, and the imidazole derivative has the following structure: 【Chemistry 1】 In the formula, R, R １ , and R ２ Each of these is independently a hydrogen atom, a phenyl group, a substituted phenyl group, a first hydrocarbyl group having 1 to 6 carbon atoms, or a second hydrocarbyl group having 1 to 6 carbon atoms with a heteroatom interposed at at least one position, provided that R, R １ , and R ２ The method according to claim 1, wherein not all of the atoms are hydrogen atoms.

3. The reagent further comprises a hydrogen halide or a hydrogen halide donor, wherein the hydrogen halide donor is a hydrohalide of imidazole or a hydrohalide of a second derivative of imidazole, and the second derivative of imidazole has the following structure: 【Chemistry 2】 b. In the formula, R, R １ , and R ２ Each of these is independently a hydrogen atom, a phenyl group, a substituted phenyl group, a first hydrocarbyl group having 1 to 6 carbon atoms, or a second hydrocarbyl group having 1 to 6 carbon atoms with a heteroatom interposed at at least one position. c. The method according to claim 1, wherein the sulfur dioxide or its sulfite is present in an amount of 0.01 to 5 moles per liter of reagent, the base is present in an amount of 0.1 to 10 moles per liter of reagent, and the sulfonic acid is present in an amount of 0.5 to 1.5 moles per liter of reagent.

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