Process for preparing N-substituted 2-oxazolidinones

Abstract

A process for preparing N-substituted 2-oxazolidinones by reacting a cyclic carbonate and an N-substituted ethanolamine in the presence of an alkali carbonate catalyst to form the N-substituted 2-oxazolidinone.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 436,897, filed January 4, 2023, which is incorporated herein by reference.

[0002] The present disclosure generally relates to processes for preparing N-substituted 2-oxazolidinones from cyclic carbonates and N-substituted ethanolamines and alkali carbonate catalysts, and their subsequent use in various applications, such as in lithium ion battery manufacturing and as a solvent for electrode preparation. [Background technology]

[0003] N-methyl-2-pyrrolidone (NMP) is widely used in various industries, particularly in the semiconductor, battery, and other electronics industries. NMP is a polar organic chemical with a unique combination of properties, including low vapor pressure, a relatively high flash point, a low freezing point, and a high boiling point. NMP's molecular structure confers a specific combination of dispersing, polar, and hydrogen-bonding forces that enable its unique solvency. However, the European Chemicals Agency (ECHA) has classified NMP as a "substance of very high concern" due to its reproductive and developmental toxicity. Therefore, there is an urgent need to replace NMP with less toxic alternatives that have similar performance characteristics.

[0004] One promising alternative includes N-substituted 2-oxazolidinones. Various processes are known for preparing such 2-oxazolidinone derivatives, such as by reacting a β-aminoalcohol with one of phosgene, dialkyl carbonates, carbon dioxide, urea, isocyanates, ethyl chloroformate, or carbon disulfides; by reacting an epoxide with cyanuric acid, urea, or cyanamide; by reacting an aziridine compound with carbon dioxide; or by reacting acrolein with an isocyanate.

[0005] However, such conventional processes have several disadvantages, including high costs of starting materials, complicated procedures, high toxicity of reactants, and low overall yields of the desired products. Therefore, there is a need to develop a relatively simple and efficient process for preparing N-substituted 2-oxazolidinones that does not suffer from such disadvantages. Summary of the Invention

[0006] The present disclosure generally provides a process for preparing an N-substituted 2-oxazolidinone. The process includes reacting a cyclic carbonate and an N-substituted ethanolamine in the presence of an alkali carbonate catalyst to form a reaction product comprising the N-substituted 2-oxazolidinone. In some embodiments, the reaction product can be further subjected to a separation step to isolate the N-substituted 2-oxazolidinone from one or more by-products present in the reaction product.

[0007] The N-substituted 2-oxazolidinones produced according to the processes of the present disclosure can be used in a variety of applications, such as as solvents in battery applications, semiconductor applications, and other electrochemical processing applications, or as intermediates in the preparation of polymers, pharmaceuticals, and agricultural chemicals. DETAILED DESCRIPTION OF THE INVENTION

[0008] Before describing aspects of the present disclosure in detail, it is to be understood that the present disclosure is not limited in its application to the details and arrangement of elements or steps or methodologies set forth in the following description. The present disclosure is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0009] Unless otherwise defined herein, terminology used in connection with this disclosure shall have the meanings commonly understood by those of ordinary skill in the art. Further, unless the context otherwise requires, singular terms shall include pluralities and plural terms shall include the singular.

[0010] As utilized in accordance with the present disclosure, the following terms, unless otherwise specified, shall be understood to have the following meanings:

[0011] The use of the words "a" or "an," when used in conjunction with the terms "comprising," "including," "having," or "containing" (or variations of such terms), can mean "one," but is also consistent with the meanings of "one or more," "at least one," and "one or more."

[0012] Use of the term "or" refers to closed alternatives only and is used to mean "and / or" unless otherwise clearly indicated that the alternatives are mutually exclusive.

[0013] When a statement appears in this specification that an element or feature "may," "can," "could," or "might" be included or have a characteristic, it does not require that the particular element or feature be included or have that characteristic.

[0014] Throughout this disclosure, the term "about" is used to indicate that a value includes the inherent variation of error in the quantification of a device, mechanism, or method, or that there is inherent variation among the object(s) being measured. For example, without limitation, when the term "about" is used, the specified value to which it refers can vary by ±10 percent, or 9 percent, or 8 percent, or 7 percent, or 6 percent, or 5 percent, or 4 percent, or 3 percent, or 2 percent, or 1 percent, or one or more intervening percentages therebetween.

[0015] As used herein, the word "comprising" (and any form of comprising, such as "comprise" and "comprises")), the word "having" (and any form of having, such as "have" and "has"), the word "including" (and any form of including, such as "includes" and "include"), or the word "containing" (and any form of containing, such as "contains" and "contain")) is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

[0016] The phrase "in one embodiment" and "in one embodiment" The phrases "in an embodiment," "according to one embodiment," and the like generally mean that the particular feature, structure, or characteristic that follows the phrase is included in at least one embodiment of the present disclosure and may be included in multiple embodiments of the present disclosure. Importantly, such phrases are open-ended and do not necessarily refer to the same embodiment, but may, of course, refer to one or more prior and / or subsequent embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.

[0017] In the processes described herein, steps may be performed in any order without departing from the principles of the invention, unless a temporal or operational order is explicitly stated.

[0018] Furthermore, specified steps may be performed simultaneously unless express claim language recites them as being performed separately. For example, a claimed step of performing X and a claimed step of performing Y may be performed simultaneously in a single operation, and the resulting process is included within the literal scope of the claimed process.

[0019] Values ​​expressed in range format should be interpreted in an open manner to include not only the numerical values ​​expressly recited as the limits of the range, but also all individual numerical values ​​or subranges subsumed within that range, as if each numerical value and subrange were expressly recited. For example, a range (such as 1 to 6) should be considered to specifically disclose subranges (such as 1 to 3, 2 to 4, 3 to 6, etc.) as well as individual numbers within that range (e.g., 1, 2, 3, 4, 5, and 6). This applies regardless of the breadth of the range.

[0020] The terms "preferred" and "preferably" refer to embodiments that may offer certain benefits, under certain circumstances, while other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure.

[0021] The term "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes cases where the event or circumstance occurs and cases where it does not occur.

[0022] The present disclosure is generally directed to a process for the preparation of N-substituted 2-oxazolidinones, comprising reacting a cyclic carbonate with an N-substituted ethanolamine in the presence of an alkali metal catalyst to form a reaction product comprising the N-substituted 2-oxazolidinone.

[0023] According to one embodiment, the cyclic carbonate has formula (I): [ka] is a compound having the formula wherein R1, R2, R3, R4, R5, and R6 are independently selected from hydrogen, a hydroxyalkyl group, and a hydrocarbyl group having 1 to 8 carbon atoms, and n is an integer from 0 to 1. In one embodiment, R1, R2, R3, R4, R5, and R6 are independently selected from hydrogen and a hydrocarbyl group having 1 to 4 carbon atoms, more preferably hydrogen, a methyl group, an ethyl group, and a propyl group.

[0024] In another embodiment, the cyclic carbonate for use in the present disclosure is of Formula I above, where n is 0, R1, R2, R3, R4, and R6 are hydrogen, and R5 is hydrogen, methyl, ethyl, or hydroxymethyl. A further embodiment is where n is 1, and R1, R2, R3, R4, R5, and R6 are independently hydrogen, methyl, or ethyl. The most preferred cyclic carbonates are ethylene carbonate, propylene carbonate, and butylene carbonate, as defined below.

[0025] The following are examples of cyclic carbonates for use in the present disclosure, including mixtures thereof: 1,3-dioxolan-2-one (also known as ethylene carbonate); 4-methyl-1,3-dioxolan-2-one (also known as propylene carbonate); 4-hydroxymethyl-1,3-dioxolan-2-one; 4,5-dimethyl-1,3-dioxolan-2-one; 4-ethyl-1,3-dioxolan-2-one; 4,4-dimethyl-1,3-dioxolan-2-one (the foregoing three are also known as butylene carbonate); 4-methyl-5-ethyl-1,3-dioxolan-2-one; 4,5-diethyl-1,3-dioxolan-2-one; 4,4-diethyl -1,3-Dioxolan-2-one; 1,3-Dioxan-2-one; 4,4-Dimethyl-1,3-dioxan-2-one; 5,5-Dimethyl-1,3-dioxan-2-one; 5,5-Dihydroxymethyl-1,3-dioxan-2-one; 5-Methyl-1,3-dioxan-2-one; 4-Methyl-1,3-dioxan-2-one; 5-Hydroxy-1,3-dioxan-2-one; 5-Hydroxymethyl-5-methyl-1,3-dioxan-2-one; 5,5-Diethyl-1,3-dioxan-2-one; 5-Methyl-5-propyl-1,3-dioxan-2-one; 4,6-Dimethyl-1,3-dioxan-2-one; and 4,4,6-Trimethyl-1,3-dioxan-2-one.

[0026] In one embodiment, the N-substituted ethanolamine reacted with the cyclic carbonate has the formula (II): HO-(C2H4)-NHR (II) is a compound having the formula In the formula, R is a hydrocarbyl group having 1 to 10 carbon atoms, a cycloalkyl group, an aramid group, or a cycloalkyl group. In some embodiments, R is a hydrocarbyl group having 1 to 6 carbon atoms, such as a methyl, ethyl, propyl, isopropyl, or butyl group. In other embodiments, R is a cycloalkyl group, such as a cyclohexyl or methylcyclohexyl group. In still other embodiments, R is an aralkyl group, such as a benzyl group. In still further embodiments, R is a hydroxyalkyl group, such as a hydroxymethyl, hydroxyethyl, or hydroxypropyl group.

[0027] In one particular embodiment, the N-substituted ethanolamine is selected from 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(butylamino)ethanol, 2-(benzylamino)ethanol, and 2-(cyclohexylamino)ethanol.

[0028] The reaction between the cyclic carbonate and the N-substituted ethanolamine is carried out in the presence of an alkali carbonate catalyst. Examples of alkali carbonate catalysts include potassium carbonate, sodium carbonate, rubidium carbonate, cesium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, manganese carbonate, barium carbonate, sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, calcium bicarbonate, barium bicarbonate, magnesium bicarbonate, strontium bicarbonate, and combinations thereof. In one embodiment, the alkali carbonate catalyst is selected from potassium carbonate, sodium carbonate, calcium carbonate, and potassium bicarbonate, and in a preferred embodiment, it is potassium carbonate.

[0029] The reaction between the cyclic carbonate and the N-substituted ethanolamine may be carried out in the absence or presence of a solvent, which does not participate in the reaction. Preferably, no solvent is used.

[0030] In some embodiments, the molar ratio of cyclic carbonate to N-substituted ethanolamine present during the reaction can be about 0.8:1 to about 1:1.2, or about 0.9:1 to about 1.1:1. In other embodiments, the molar ratio of cyclic carbonate to N-substituted ethanolamine present during the reaction can be about 0.95:1 to about 1.05:1, or about 0.97:1 to about 1.03:1, or about 0.99:1 to about 1.01:1. The order in which the cyclic carbonate and N-substituted ethanolamine are added as raw materials is not particularly limited; the cyclic carbonate can be added to the N-substituted ethanolamine, the N-substituted ethanolamine can be added to the cyclic carbonate, or the N-substituted ethanolamine and cyclic carbonate can be added all at once.

[0031] In one embodiment, the amount of alkali carbonate catalyst present during the reaction can be less than about 2 wt. %, or less than about 1.5 wt. %, or less than about 1 wt. %, or less than about 0.5 wt. %, based on the total weight of the cyclic carbonate, N-substituted ethanolamine, and alkali carbonate catalyst (i.e., the "total weight of the reaction mixture"). In other embodiments, the amount of alkali carbonate catalyst present during the reaction can be from about 0.001 wt. % to about 1 wt. %, or from about 0.01 wt. % to about 0.75 wt. %, or from about 0.02 wt. % to about 0.1 wt. %, based on the total weight of the reaction mixture.

[0032] In some embodiments, the reaction between the cyclic carbonate and the N-substituted ethanolamine may be carried out at a temperature of about 40°C to about 150°C or about 50°C to about 130°C. The reaction between the cyclic carbonate and the N-substituted ethanolamine may be carried out under pressure or under reduced pressure, but is preferably carried out at atmospheric pressure. The time required for the reaction to reach completion may be about 0.5 hours to about 10 hours or about 2 hours to about 5 hours. The resulting reaction product may contain, in addition to the desired N-substituted 2-oxazolidinone, one or more by-products (e.g., by-product dihydroxyamine, unreacted N-substituted ethanolamine, unreacted cyclic carbonate, etc.). , by-product dialkylene glycol, by-product trialkylene glycol, and other impurities) may be present. The N-substituted 2-oxazolidinone can be isolated from at least a portion of the one or more by-products and purified by subjecting the reaction product to a separation technique, such as concentration, crystallization, recrystallization, distillation, fractional distillation, or chromatographic techniques.

[0033] The percent yield of N-substituted 2-oxazolidinone obtained by the process of the present disclosure (i.e., 100×([measured amount of N-substituted 2-oxazolidinone] / [maximum amount of N-substituted 2-oxazolidinone that can be produced from a given amount of cyclic carbonate and N-substituted ethanolamine])) can be at least about 85%, or at least about 90%, or at least about 92%, or at least about 93%, or at least about 94%, or at least about 95%. Specific examples of N-substituted 2-oxazolidinones that may be produced according to the processes of the present disclosure include, but are not limited to, N-methyl-2-oxazolidinone, N-ethyl-2-oxazolidinone, N-propyl-2-oxazolidinone, N-isopropyl-2-oxazolidinone, N-butyl-2-oxazolidinone, N-hydroxyethyl-2-oxazolidinone, N-hydroxypropyl-2-oxazolidinone, N-cyclohexyl-2-oxazolidinone, and N-benzyl-2-oxazolidinone.

[0034] According to one embodiment, approximately equimolar (i.e., 0.99:1 to 1.01:1) amounts of cyclic carbonate and N-substituted ethanolamine are combined and first reacted at a temperature of about 50-70°C under atmospheric pressure for less than about one hour. An alkali carbonate catalyst is then added, and the cyclic carbonate and N-substituted ethanolamine are further reacted at a temperature of about 120-140°C under atmospheric pressure until the reaction is complete (which can be confirmed by gas chromatography). At least a portion of one or more by-products present in the resulting reaction product is then removed by distillation to yield an N-substituted 2-oxazolidinone having a purity of at least about 90%, or at least about 95%, or at least about 99%.

[0035] The N-substituted 2-oxazolidinone obtained by the process of the present disclosure can be used in various ways, such as in the preparation of lithium ion batteries, as a photochemical reaction solvent, as a solvent for photoelectrochemical display elements, in electrolyte solvents, in battery electrolyte solvents, as a solvent for electrolytic reactions, as a solvent for electropolymerization, as a solvent for electroplating, as a solvent for electropolishing, as an aprotic polar solvent in organic synthesis reactions, as a solvent for polymerization or extraction, as a low-toxicity high-boiling solvent, as an industrial cleaning agent, as a solvent for stripping coating films, as a pigment dispersant, and as an intermediate in the preparation of polymeric materials, pharmaceuticals, and agricultural chemicals. For example, N-substituted 2-oxazolidinone is useful as an intermediate in the production of fibers, tablet coatings, lubricant additives, rust inhibitors, and dyeing auxiliaries.

[0036] Below are examples of the process of the present invention for preparing N-substituted 2-oxazolidinones. However, it will be understood that the present disclosure is not limited in its application to the specific experiments, results, and experimental procedures disclosed herein below. Rather, the examples are merely presented as one of various embodiments and are intended to be illustrative, not exhaustive. [Example]

[0037] Example 1 - Process for preparing N-methyl-2-oxazolidinone To a 1-liter, three-necked round-bottom flask equipped with a stirrer, addition funnel, nitrogen inlet, refrigeration, and a 1-inch internal diameter distillation column, 400 grams of propylene carbonate was added. The propylene carbonate was then heated to 50-70°C. 2 propylene carbonate was then added via the addition funnel. 94 grams of 2-(methylamino)ethanol was slowly added to the flask, and the reaction temperature was maintained within the range of 50-70°C for approximately 0.5 hours. 0.14 grams of potassium carbonate was then added to the flask, and the reaction temperature was gradually adjusted to 130°C and maintained at 130°C for approximately 3 hours. The crude reaction product was distilled to yield 99% pure N-methyl-2-oxazolidinone and the co-product propylene glycol. The percent yield of 3-methyl-2-oxazolidinone was high (>93%) based on gas chromatography measurements.

[0038] Example 2 - Process for preparing N-ethyl-2-oxazolidinone 1030 grams of propylene carbonate was added to a 1-liter, three-necked round-bottom flask equipped with a stirrer, addition funnel, nitrogen inlet, chiller, and a 1-inch internal diameter distillation column. The propylene carbonate was then heated to 50-70°C. 899 grams of 2-(ethylamino)ethanol was then slowly added to the flask via the addition funnel, and the reaction temperature was maintained within the range of 50-70°C over approximately 0.5 hours. 0.58 grams of potassium carbonate was then added to the flask, and the reaction temperature was gradually adjusted to 130°C and maintained at 130°C for approximately 3 hours. The crude reaction product was distilled to yield 99% pure 3-ethyl-2-oxazolidinone and the co-product propylene glycol. The percent yield of 3-ethyl-2-oxazolidinone was high (>93%) based on gas chromatography measurements.

[0039] Example 3 - Process for preparing N-butyl-2-oxazolidinone 1481 grams of propylene carbonate was added to a 1-liter, three-necked round-bottom flask equipped with a stirrer, addition funnel, nitrogen inlet, chiller, and a 1-inch internal diameter distillation column. The propylene carbonate was then heated to 50-70°C. 1700 grams of 2-(butylamino)ethanol was then slowly added to the flask via the addition funnel, and the reaction temperature was maintained within the range of 50-70°C over approximately 0.5 hours. 0.95 grams of potassium carbonate was then added to the flask, and the reaction temperature was gradually adjusted to 130°C and maintained at 130°C for approximately 3 hours. The crude reaction product was distilled to yield 99% pure 3-butyl-2-oxazolidinone and the co-product propylene glycol. The percent yield of 3-butyl-2-oxazolidinone was high (>95%) based on gas chromatography measurements.

[0040] From the foregoing description, it is evident that the present disclosure is well adapted to carry out the objects and attain the advantages mentioned herein and those inherent therein. While exemplary embodiments of the present disclosure have been described for the purposes of this disclosure, it will be understood that numerous modifications, as will readily occur to those skilled in the art, may be made, and that such modifications can be effected without departing from the scope of the present disclosure and the appended claims.

Claims

1. A process for preparing an N-substituted 2-oxazolidinone, comprising reacting a cyclic carbonate with an N-substituted ethanolamine in the presence of an alkali carbonate catalyst to form a reaction product comprising said N-substituted 2-oxazolidinone.

2. The cyclic carbonate has the formula (I): 【Chemistry 1】 is a compound having the formula In the formula, R １ , R ２ , R ３ , R ４ , R ５ , and R ６ 10. The process of claim 1, wherein n is independently selected from hydrogen, hydroxyalkyl groups, and hydrocarbyl groups having 1 to 8 carbon atoms, and n is an integer from 0 to 1.

3. 3. The process of claim 2, wherein n is 0.

4. R １ , R ２ , R ３ , R ４ , R ５ , and R ６ The process of claim 3, wherein is independently selected from hydrogen and hydrocarbyl groups having 1 to 4 carbon atoms.

5. R １ , R ２ , R ３ , R ４ , R ５ , and R ６ 5. The process of claim 4, wherein is independently selected from hydrogen, a methyl group, an ethyl group, and a propyl group.

6. The N-substituted ethanolamine has the formula (II): HO-(C) ２ H ４ )-NHR (II) is a compound having the formula 2. The process of claim 1, wherein R is a hydrocarbyl group, a cycloalkyl group, an aralkyl group, or a hydroxyalkyl group having 1 to 10 carbon atoms.

7. 7. The process of claim 6, wherein R is a hydrocarbyl group having 1 to 6 carbon atoms.

8. 8. The process of claim 7, wherein R is a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group.

9. 2. The process of claim 1, wherein the alkali carbonate catalyst is selected from potassium carbonate, sodium carbonate, calcium carbonate, and potassium bicarbonate.

10. 10. The process of claim 9, wherein the alkali carbonate catalyst is potassium carbonate.

11. 1. A process for preparing an N-substituted 2-oxazolidinone, comprising: reacting a cyclic carbonate with an N-substituted ethanolamine in the presence of an alkali carbonate catalyst to form a reaction product comprising the N-substituted 2-oxazolidinone and one or more by-products; and subjecting the reaction product to a separation technique to remove at least a portion of the one or more by-products.

12. 12. The process of claim 11, wherein the cyclic carbonate and the N-substituted ethanolamine are present during the reaction in a molar ratio of from about 0.99:1 to about 1.01:

1.

13. 12. The process of claim 11, wherein the amount of the alkali carbonate catalyst present during the reaction is from about 0.005% to about 1% by weight, based on the total weight of the cyclic carbonate, the N-substituted ethanolamine, and the alkali carbonate catalyst.

14. 12. The process of claim 11, wherein the reaction is carried out at a temperature of from about 50°C to about 130°C.

15. 12. The process of claim 11, wherein the separation technique is a concentration, crystallization, recrystallization, distillation, fractional distillation, or chromatographic technique.

16. 12. The process of claim 11, wherein the N-substituted 2-oxazolidinine is N-methyl-2-oxazolidinone, N-ethyl-2-oxazolidinone, N-propyl-2-oxazolidinone, N-isopropyl-2-oxazolidinone, N-butyl-2-oxazolidinone, N-hydroxyethyl-2-oxazolidinone, N-hydroxypropyl-2-oxazolidinone, N-cyclohexyl-2-oxazolidinone, or N-benzyl-2-oxazolidinone.

17. 17. The process of claim 16, wherein the N-substituted 2-oxazolidinone is prepared in a percent yield of at least 85%.

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