Process for preparation of n-substituted-2-oxazolidinones

Abstract

A process for the preparation of an N-substituted-2-oxazolidinone in which a cyclic carbonate is reacted with an N-substituted ethanolamine in the presence of an alkali metal carbonate catalyst, thereby forming the N-substituted-2-oxazolidinone.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 436,897, filed January 4, 2023. Said application is incorporated herein by reference. Technical Field

[0003] The present invention generally relates to a process for preparing N-substituted-2-oxazolidinones from cyclic carbonates and N-substituted ethanolamines using an alkali metal carbonate catalyst and their subsequent use in various applications, such as as solvents in lithium ion battery manufacturing and electrode preparation. Background Art

[0004] N-Methyl-2-pyrrolidone (NMP) is widely used in various industries, especially in the semiconductor, battery and other electronics industries. NMP is a polar organic chemical with a unique combination of properties, such as low vapor pressure, relatively high flash point, low freezing point and high boiling point. NMP's molecular structure provides a specific combination of dispersibility, polarity and hydrogen bonding, which gives it unique solubility. However, due to its reproductive toxicity, the European Chemicals Agency (ECHA) has classified NMP as a "substance of very high concern". Therefore, there is an urgent need to replace NMP with low-toxicity alternatives with similar performance characteristics.

[0005] One possible alternative includes N-substituted-2-oxazolidinones. Various methods for producing such 2-oxazolidinone derivatives are known, for example, by reacting a β-amino alcohol with phosgene, a dialkyl carbonate, carbon dioxide, urea, an isocyanate, ethyl chloride carbonate, or carbon disulfide; by reacting an epoxide with cyanuric acid, urea, or a cyanamide; by reacting an aziridine compound with carbon dioxide; or by reacting acrolein with an isocyanate.

[0006] However, these traditional methods have several disadvantages, including high initial raw material costs, complex processes, high reactant toxicity, and low overall yield of the desired product. Therefore, it is necessary to develop a relatively simple and efficient method for preparing N-substituted-2-oxazolidinones without the above disadvantages. Summary of the Invention

[0007] The present invention generally provides the method for preparing N-substituted-2-oxazolidinone.Said method is included in the step of reacting cyclic carbonate and N-substituted ethanolamine in the presence of an alkali metal carbonate catalyst, thereby forming the reaction product that comprises N-substituted-2-oxazolidinone.In some embodiments, said reaction product can further experience separation step, so that N-substituted-2-oxazolidinone is separated from one or more by products existing in the reaction product.

[0008] The N-substituted-2-oxazolidinones produced according to the process of the present invention can be used in various applications, for example, as solvents in batteries, semiconductors and other electrochemical processing applications, or as intermediates in the preparation of polymers, pharmaceuticals and agricultural chemicals. DETAILED DESCRIPTION

[0009] Before explaining various aspects of the present invention in detail, it should be understood that the present invention is not limited in its application to the structural details and the arrangement of components, steps, or methods described in the following description. The present invention may also have other embodiments or be practiced or implemented in various ways. In addition, it should be understood that the phraseology and terminology used herein are for descriptive purposes only and should not be construed as limiting.

[0010] Unless otherwise defined herein, technical terms related to the present invention should have the meanings commonly understood by those of ordinary skill in the art. In addition, unless otherwise required by context, singular terms should include plural terms and plural terms should include the singular.

[0011] As used in the present invention, unless otherwise specified, the following terms shall be understood to have the following meanings.

[0012] When used with the terms "comprising," "including," "containing," or "having," the indefinite article can mean "a," but is also consistent with "one or more," "at least one," and "one or more."

[0013] The term "or" is used to mean "and / or" unless it is expressly stated that only alternatives are referred to and the alternatives are mutually exclusive.

[0014] If the specification indicates that a component or feature "may," "could," "could," or "might" be included or have a certain feature, that particular component or feature is not required to be included or have that feature.

[0015] Throughout this disclosure, the term "about" is used to indicate that a value includes inherent variations in error for a quantifying device, mechanism, or method, or inherent variations between the objects being measured. For example, and without limitation, when the term "about" is used, the specified value may vary by ±10%, or 9%, or 8%, or 7%, or 6%, or 5%, or 4%, or 3%, or 2%, or 1%, or one or more fractions therebetween.

[0016] As used herein, the phrases "comprises" (and any form thereof as present tense), "has" (and any form thereof as present tense), "includes" (and any form thereof as present tense), or "contains" (and any form thereof as present tense) are inclusive or open-ended and do not exclude additional unrecited elements or method steps.

[0017] The phrases "in one embodiment," "in an embodiment," "according to an embodiment," and similar terms generally mean that the specified features, structures, or characteristics following the phrase are included in at least one embodiment of the present invention, and may be included in multiple embodiments of the present invention. Importantly, such phrases are non-limiting and do not necessarily refer to the same embodiment, but they can certainly refer to one or more preceding and / or subsequent embodiments. For example, in the appended claims, any of the claimed embodiments may apply in any combination.

[0018] In the methods described herein, the steps may be performed in any order without departing from the principles of the invention, unless a temporal or operational sequence is explicitly described.

[0019] Additionally, unless explicit claim language specifies that specific steps are to be performed separately, such steps may be performed simultaneously. For example, a step requiring to do X and a step requiring to do Y may be performed simultaneously in a single operation, and the resulting method would be within the literal scope of the claimed method.

[0020] Numerical values expressed in ranges should be interpreted in a flexible manner to include not only the numerical values explicitly stated as limits of the range, but also all individual numerical values or subranges contained within that range, as if those numerical values and subranges were explicitly stated. For example, a range such as 1-6 should be considered to include the specifically disclosed subranges such as 1-3, 2-4, 3-6, etc., as well as individual numerical values within that range, such as 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0021] The terms "preferred" and "preferably" refer to embodiments that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the present invention.

[0022] The terms "optional" or "optionally" mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0023] The present invention generally relates to a process for preparing N-substituted-2-oxazolidinones comprising the step of 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.

[0024] According to one embodiment, the cyclic carbonate is a compound having the general formula (I):

[0025]

[0026] wherein R1, R2, R3, R4, R5 and R6 are independently selected from hydrogen, hydroxyalkyl and hydrocarbon groups 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 hydrocarbon groups having 1 to 4 carbon atoms, and more preferably independently selected from hydrogen, methyl, ethyl and propyl.

[0027] In other embodiments, the cyclic carbonate of using in the present invention is those of above-mentioned general formula I, and when n is 0, R wherein , R , R , R , R 4 and R 6 be hydrogen and R 5 be hydrogen, methyl, ethyl or methylol.In another embodiment, when n is 1, R , R , R , R 5 and R 6 be hydrogen, methyl or ethyl independently.Most preferred cyclic carbonate is ethylene carbonate, propylene carbonate and butylene carbonate defined hereinafter.

[0028] The following are examples of cyclic carbonates used in the present invention and mixtures thereof: 1,3-dioxolane-2-one (also known as ethylene carbonate); 4-methyl-1,3-dioxolane-2-one (also known as propylene carbonate); 4-hydroxymethyl-1,3-dioxolane-2-one; 4,5-dimethyl-1,3-dioxolane-2-one; 4-ethyl-1,3-dioxolane-2-one; 4,4-dimethyl-1,3-dioxolane-2-one (the first three are also known as butylene carbonate); 4-methyl-5-ethyl-1,3-dioxolane-2-one; 4,5-diethyl-1,3-dioxolane-2-one; 4,4-diethyl-1,3-dioxolane-2-one; 1,3-dioxolane-2-one. Heterocyclohexane-2-one; 4,4-dimethyl-1,3-dioxane-2-one; 5,5-dimethyl-1,3-dioxane-2-one; 5,5-dihydroxymethyl-1,3-dioxane-2-one; 5-methyl-1,3-dioxane-2-one; 4-methyl-1,3-dioxane-2-one; 5-hydroxy-1,3-dioxane-2-one Heterocyclohexane-2-one; 5-hydroxymethyl-5-methyl-1,3-dioxane-2-one; 5,5-diethyl-1,3-dioxane-2-one; 5-methyl-5-propyl-1,3-dioxane-2-one; 4,6-dimethyl-1,3-dioxane-2-one and 4,4,6-trimethyl-1,3-dioxane-2-one.

[0029] In one embodiment, the N-substituted ethanolamine reacted with the cyclic carbonate is a compound having the general formula (II):

[0030] HO-(C2H4)-NHR(II)

[0031] wherein R is a hydrocarbon group, a cycloalkyl group, an aralkyl group or a hydroxyalkyl group having 1 to 10 carbon atoms.

[0032] In some embodiments, R is a hydrocarbon group having 1-6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, or butyl. In other embodiments, R is a cycloalkyl group, such as cyclohexyl or methylcyclohexyl. In other embodiments, R is an aralkyl group, such as benzyl. In still other embodiments, R is a hydroxyalkyl group, such as hydroxymethyl, hydroxyethyl, or hydroxypropyl.

[0033] In a 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.

[0034] The reaction between cyclic carbonate and the ethanolamine that N-replaces occurs in the presence of an alkali metal carbonate catalyst.The example of an alkali metal carbonate catalyst comprises salt of wormwood, sodium carbonate, rubidium carbonate, cesium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, manganese carbonate, barium carbonate, sodium bicarbonate, saleratus, lithium bicarbonate, calcium bicarbonate, barium bicarbonate, magnesium bicarbonate, strontium bicarbonate and their combination.In one embodiment, the alkali metal carbonate catalyst is selected from salt of wormwood, sodium carbonate, calcium carbonate and saleratus, and in a preferred embodiment, the alkali metal carbonate catalyst is salt of wormwood.

[0035] The reaction between the cyclic carbonate and the N-substituted ethanolamine can be carried out without a solvent or with a solvent, and the solvent does not participate in the reaction. Preferably, no solvent is used.

[0036] In some embodiments, the molar ratio of the cyclic carbonate to the N-substituted ethanolamine present during the reaction can be from about 0.8: 1 to about 1: 1.2, or from about 0.9: 1 to about 1.1: 1. In other embodiments, the molar ratio of the cyclic carbonate to the N-substituted ethanolamine present during the reaction can be from about 0.95: 1 to about 1.05: 1, or from about 0.97: 1 to about 1.03: 1, or from about 0.99: 1 to about 1.01: 1. There is no particular limitation on the order in which the cyclic carbonate and the N-substituted ethanolamine are added as raw materials, and the cyclic carbonate can be added to the N-substituted ethanolamine, or the N-substituted ethanolamine can be added to the cyclic carbonate, or the N-substituted ethanolamine and the cyclic carbonate can be added simultaneously.

[0037] In one embodiment, the gross weight (i.e., " gross weight of reaction mixture") based on cyclic carbonate, N-substituted ethanolamine and alkali metal carbonate catalyst, the amount of the alkali metal carbonate catalyst present in the reaction process can be less than about 2wt%, or less than about 1.5wt%, or less than about 1wt%, or less than about 0.5wt%. In other embodiments, the gross weight based on the reaction mixture, the amount of the alkali metal carbonate catalyst present in the reaction process can be about 0.001-1wt%, or about 0.01-0.75wt%, or about 0.02-0.1wt%.

[0038] In some embodiments, the reaction between the ethanolamine that cyclic carbonate and N-replace can occur at about 40-150 ℃ or about 50-130 ℃ temperature.The reaction between the ethanolamine that cyclic carbonate and N-replace can occur under pressure or under reduced pressure, but preferably implements under normal pressure.The time that reaction reaches completion can be about 0.5-10 hour, or about 2-5 hour.Except required N-replaces-2-oxazolidinone, in the reaction product obtained, there may be one or more by products (for example one or more by product dihydroxyamines, unreacted N-replaces-ethanolamine, unreacted cyclic carbonate, by product dialkylene glycol, by product trialkylene glycol and other impurity).By making reaction product experience separation technology such as concentration, crystallization, recrystallization, distillation, fractionation or chromatographic technique, N-replaces-2-oxazolidinone can be separated from at least a portion of one or more by products and be purified.

[0039] The percent yield of N-substituted-2-oxazolidinone obtained by the process of the present invention (i.e., 100 x ([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 can be produced by the process of the present invention 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.

[0040] According to one embodiment, the cyclic carbonate of approximately equimolar (i.e. 0.99: 1-1.01: 1) amount and the ethanolamine that N-replaces are combined, and it is initially reacted less than the time of about 1 hour at about 50-70 ℃ temperature and normal pressure.Then add alkali metal carbonate catalyst, and at about 120-140 ℃ and normal pressure, the ethanolamine that N-replaces of cyclic carbonate is further reacted, until reaction is finished (can be confirmed by gas chromatography).Then remove at least a portion of one or more by-products present in the obtained product by distillation, thereby produce purity and be at least about 90% or at least about 95% or at least about 99% N-replace-2-oxazolidinone.

[0041] The N-substituted-2-oxazolidinones obtained by the method of the present invention can be used in a variety of applications, such as in the preparation of lithium-ion batteries, as solvents for photochemical reactions, as solvents for photoelectrochemical display elements, in electrolyte solvents, in electrolyte solvents for batteries, as solvents for electrolytic reactions, as solvents for electrolytic polymerization, as electroplating solvents, as electropolishing solvents, as aprotic polar solvents in organic synthesis reactions, as polymerization or extraction solvents, as low-toxic high-boiling-point solvents, as industrial cleaning agents, as solvents for coating stripping, as pigment dispersants, and as intermediates for the preparation of polymer materials, pharmaceuticals, and agricultural chemicals. For example, the N-substituted-2-oxazolidinones can be used as intermediates for the production of fibers, tablet coatings, lubricant additives, rust inhibitors, and dyeing auxiliaries.

[0042] Provide the embodiment of the method for preparing N-substituted-2-oxazolidinone of the present invention below.But should be understood that purposes of the present invention is not limited to concrete experiment, result and experimental procedure disclosed hereinafter.On the contrary, these embodiments only provide simply as one of multiple embodiment, and are exemplary rather than exhaustive.

[0043] Example

[0044] Example 1 Method for preparing N-methyl-2-oxazolidinone

[0045] 400 grams of propylene carbonate were added to a 1-liter three-necked round-bottom flask equipped with a stirrer, an addition funnel, a nitrogen inlet, a condenser, and a 1-inch internal diameter distillation column. Propylene carbonate was then heated to 50-70°C. 294 grams of 2-(methylamino)ethanol were then slowly added to the flask via an addition funnel, and the reaction temperature was maintained at 50-70°C for approximately 0.5 hour. 0.14 grams of potassium carbonate were then added to the flask, and the reaction temperature was slowly adjusted to 130°C and maintained at this temperature for approximately 3 hours. The crude distillation reaction product was 99% pure N-methyl-2-oxazolidinone and by-product propylene glycol. Based on gas chromatographic measurements, the percentage yield of 3-methyl-2-oxazolidinone was higher (>93%).

[0046] Example 2 Method for preparing N-ethyl-2-oxazolidinone

[0047] 1030 grams of propylene carbonate are added to a 1 liter three-necked round-bottom flask equipped with a stirrer, an addition funnel, a nitrogen inlet, a condenser and a 1 inch internal diameter distillation column. Propylene carbonate is then heated to 50-70°C. Then 899 grams of 2-(ethylamino)ethanol are slowly added to the flask through an addition funnel, and the reaction temperature is maintained at 50-70°C for approximately 0.5 hour. Then 0.58 grams of potassium carbonate are added to the flask, and the reaction temperature is slowly adjusted to 130°C and maintained at this temperature for approximately 3 hours. The crude distillation reaction product is 99% pure 3-ethyl-2-oxazolidinone and by-product propylene glycol. Based on gas chromatographic measurement values, the percentage yield of 3-ethyl-2-oxazolidinone is higher (>93%).

[0048] Example 3 Method for preparing N-butyl-2-oxazolidinone

[0049] 1481 grams of propylene carbonate are added to a 1 liter three-necked round-bottom flask equipped with a stirrer, an addition funnel, a nitrogen inlet, a condenser and a 1 inch internal diameter distillation column. Propylene carbonate is then heated to 50-70°C. 1700 grams of 2-(butylamino)ethanol are then slowly added to the flask via an addition funnel, and the reaction temperature is maintained at 50-70°C for approximately 0.5 hour. 0.95 grams of potassium carbonate are then added to the flask, and the reaction temperature is slowly adjusted to 130°C and maintained at this temperature for approximately 3 hours. The crude distillation reaction product is 99% pure 3-butyl-2-oxazolidinone and the by-product propylene glycol. Based on gas chromatographic measurement values, the percentage yield of 3-butyl-2-oxazolidinone is higher (>95%).

[0050] As will be apparent from the foregoing description, the present invention is well adapted to carry out the objects and to obtain the advantages mentioned herein as well as those inherent therein. While exemplary embodiments of the invention have been described for the purposes of the present invention, it will be appreciated that numerous changes can be made therein without departing from the scope of the invention and the appended claims, and such changes will be readily apparent to those skilled in the art.

Claims

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

2. The method of claim 1, wherein the cyclic carbonate is a compound having the general formula (I): wherein R1, R2, R3, R4, R5 and R6 are independently selected from hydrogen, hydroxyalkyl and hydrocarbon groups having 1 to 8 carbon atoms; and n is an integer from 0 to 1.

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

4. The method of claim 3, wherein R1, R2, R3, R4, R5 and R6 are independently selected from hydrogen and a hydrocarbon group having 1 to 4 carbon atoms.

5. The method of claim 4, wherein R1, R2, R3, R4, R5 and R6 are independently selected from hydrogen, methyl, ethyl and propyl.

6. The method of claim 1, wherein the N-substituted ethanolamine is a compound having the general formula (II): HO-(C2H4)-NHR(II) wherein R is a hydrocarbon group, a cycloalkyl group, an aralkyl group or a hydroxyalkyl group having 1 to 10 carbon atoms.

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

8. The method of claim 7, wherein R is methyl, ethyl, propyl, isopropyl or butyl.

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

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

11. A method for preparing an N-substituted-2-oxazolidinone comprising reacting a cyclic carbonate with an N-substituted ethanolamine in the presence of an alkali metal 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. The method of claim 11, wherein the cyclic carbonate and the N-substituted ethanolamine are present in a molar ratio of about 0.99:1 to about 1.01:1 during the reaction.

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

14. The method of claim 11, wherein the reaction is carried out at a temperature of about 50-130°C.

15. The method of claim 11, wherein the separation technique is concentration, crystallization, recrystallization, distillation, fractionation or chromatography.

16. The method of claim 11, wherein the N-substituted-2-oxazolidinone 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. 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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