Synthesis of tetralin-1,4-dione, compositions and apparatuses thereof

Abstract

A method of tautomerizing tetralin-1,4-dione from 1,4-dihydroxynaphthalene is described, which comprises vaporizing a liquid feedstock composition comprising tetralin-1,4-dione and 1,4-dihydroxynaphthalene, then solidifying the vapor to form a solid crude composition with an increased tetralin-1,4-dione concentration relative to the liquid feedstock composition. An apparatus for tautomerizing 1,4-dihydroxynaphthalene into tetralin-1,4-dione is also described, which apparatus includes a reaction vessel comprising an internal chamber and a cold plate disposed within the internal chamber.

Description

SYNTHESIS OF TETRALIN-1, 4-DIONE, COMPOSITIONS AND APPARATUSESTHEREOFINCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATION

[0001] Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet or PCT Request as filed with the present application are hereby incorporated by reference under 37 CFR 1.57, and Rules 4.18 and 20.6. The present application claims the benefit of priority to U.S. Provisional App. No. 63 / 607,452, filed December 7, 2023, which is incorporated by reference.BACKGROUNDField

[0002] This disclosure relates generally to tautomerization of compounds, and more particularly to tautomerizing 1,4-dihydroxynaphthalene into tetralin- 1,4-dione.Description of the Related Art

[0003] Tetralin- 1,4-dione has been tautomerized from its tautomer 1,4- dihydroxynaphthalene by both thermal and acid-catalyzed methods. The thermal method comprised melting 1,4-dihydroxynaphthalene to induce a liquid-phase tautomerization, followed by rapidly cooling the liquid to freeze the equilibrium ratio of the tautomers, thereby enabling extraction of the tetralin- 1,4-dione with a solvent. The acid-catalyzed method comprised dissolving 1,4-dihydroxynaphthalene in a trifluoroacetic acid, adding a large amount of toluene, and evaporating the solvent before recrystallizing the solid in diisopropyl ether. Such methods provide low yields and / or low throughput.

[0004] As such, improved methods and apparatuses for tautomerization of tetralin- 1, 4-dione from 1,4-dihydroxynaphthalene may be beneficial.SUMMARY

[0005] For purposes of summarizing the disclosure and the advantages achieved over the prior art, certain objects and advantages of the disclosure are described herein. Not all such objects or advantages may be achieved in any particular embodiment. Thus, forexample, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0006] All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.

[0007] In one aspect, a method of tautomerizing 1,4-dihydroxynaphthalene into tetralin- 1,4-dione is described. The method includes: vaporizing a liquid feedstock composition to form a vapor composition, wherein the liquid feedstock composition comprises tetralin- 1,4-dione and 1,4-dihydroxynaphthalene at a first molar ratio of tetralin-1, 4-dione: 1,4- dihydroxynaphthalene; and solidifying the vapor composition to form a solid crude composition comprising tetralin- 1,4-dione and 1,4-dihydroxynaphthalene at a second molar ratio of tetralin-1, 4-dione: 1,4-dihydroxynaphthalene; wherein the second molar ratio is greater than the first molar ratio.

[0008] In some embodiments, the method further comprises melting a solid feedstock to form the liquid feedstock composition. In some embodiments, the melting comprises a pressure of at least 1 atm. In some embodiments, the melting is performed in a substantially inert gas environment. In some embodiments, the solid feedstock comprises at least about 90% 1,4-dihydroxynaphthalene. In some embodiments, the method further comprises continuously providing the solid feedstock to be melted. In some embodiments, the method further comprises synthesizing the solid feedstock comprising 1,4- dihydroxynaphthalene from 1,4-naphthoquinone.

[0009] In some embodiments, vaporizing comprises a pressure of at most 1 atm. In some embodiments, vaporizing is performed in a substantially inert gas environment. In some embodiments, the method further comprises collecting the solid crude composition. In some embodiments, the solid crude composition is continuously collected. In some embodiments, the first molar ratio of tetralin- 1,4-dione: 1,4-dihydroxynaphthalene is at most about 1 : 1.1. In some embodiments, the second molar ratio of tetralin-1, 4-dione: 1,4-dihydroxynaphthalene is at least about 2:1. In some embodiments, the second molar ratio of tetralin-1, 4-dione: 1,4-dihydroxynaphthalene is at least about 6:1.

[0010] In some embodiments, the method further comprises purifying the solid crude composition to form a purified product, wherein the purified product comprises tetralin- 1, 4-dione and 1,4-dihydroxynaphthalene at a third molar ratio of tetralin-1, 4-dione: 1,4- dihydroxynaphthalene, and wherein the third molar ratio is greater than the second molar ratio. In some embodiments, purifying is selected from the group consisting of sublimation, recrystallization, chromatography, and combinations thereof. In some embodiments, recrystallization comprises dissolving the solid crude composition in an organic, polar solvent. In some embodiments, the third molar ratio of tetralin-1, 4-dione: 1,4-dihydroxynaphthalene is at least about 14: 1. In some embodiments, the third molar ratio of tetralin-1, 4-dione: 1,4- dihydroxynaphthalene is at least about 30: 1. In some embodiments, purifying forms a waste product composition, and wherein the method further comprises combining the waste product composition with the liquid feedstock composition.

[0011] In another aspect, an apparatus for tautomerizing 1,4-dihydroxynaphthalene into tetralin- 1,4-dione is described. The apparatus includes: a reaction vessel comprising an internal chamber and a thermal transfer area, wherein the internal chamber comprises a chamber floor; a reaction vessel inlet in material communication with the internal chamber; and a cold plate disposed within the internal chamber.

[0012] In some embodiments, the cold plate overhangs the chamber floor. In some embodiments, the apparatus further comprises a heating element adjacent to the thermal transfer area.

[0013] In another aspect, a solid crude composition is described. The composition includes: tetralin- 1,4-dione; and 1,4-dihydroxynaphthalene; wherein the tetralin- 1,4- dione: 1,4-dihydroxynaphthalene molar ratio is about 5:1 to 7: 1; and wherein the composition is substantially free of solvents.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a flowchart of an example method for tautomerizing 1,4- dihydroxynaphthalene into tetralin- 1,4-dione in a crude composition, according to some embodiments.

[0015] FIG. 2 is a flowchart of an example method for tautomerizing 1,4- dihydroxynaphthalene into tetralin- 1,4-dione in a crude composition with additional optional steps, according to some embodiments.

[0016] FIG. 3 is an illustration of an example apparatus for tautomerizing 1,4- dihydroxynaphthalene into tetralin- 1,4-dione, according to some embodiments.

[0017] FIG. 4 is an H-NMR spectra of 1,4-naphthaquinone.

[0018] FIG. 5 is an H-NMR spectra of a solid feedstock comprising 1,4- dihydroxynaphthalene, according to some embodiments.

[0019] FIG. 6 is an H-NMR spectra of a solid crude composition comprising 1,4- dihydroxynaphthalene and tetralin- 1,4-dione, according to some embodiments.

[0020] FIG. 7 is an H-NMR spectra of a sublimation-purified product comprising 1,4-dihydroxynaphthalene and tetralin- 1,4-dione, according to some embodiments.

[0021] FIG. 8 is an H-NMR spectra of a recrystallization-purified product comprising tetralin- 1,4-dione, according to some embodiments.

[0022] FIG. 9 is an H-NMR spectra of tetralin- 1,4-diol.DETAILED DESCRIPTION

[0023] The foregoing and other aspects of the present disclosure will now be described in more detail with respect to the description and methodologies provided herein. This description is not intended to be a detailed catalogue of all the ways in which the embodiments of the present disclosure may be implemented, or of all the features that may be added to the present disclosure. For example, features illustrated with respect to one embodiment may be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from that embodiment. In addition, numerous variations and additions to the various embodiments suggested herein, which do not depart from the instant disclosure, will be apparent to those skilled in the art in light of the instant detailed description, figures and claims. Hence, the following specification is intended to illustrate some particular embodiments, and not to exhaustively specify all permutations, combinations and variations thereof.

[0024] Disclosed herein are methods of tautomerizing tetralin- 1,4-dione (apparatuses thereof, and compositions thereof. In liquid form, 1,4-dihydroxynaphthalene forms its tautomer tetralin- 1, 4-dione. The disclosed methods vaporize a liquid melt comprising tetralin- 1,4-dione and 1,4- dihydroxynaphthalene, wherein the vapor composition formed comprises an increased amount of the tautomer tetralin- 1,4-dione than the liquid-phase melt. By solidifying the vapor composition, the desired tetralin- 1,4-dione tautomer can be obtained in relatively high amounts and / or purity.Tautomerization Process

[0025] FIG. 1 is a flowchart of an example method 100 for tautomerizing 1,4- dihydroxynaphthalene into tetralin- 1,4-dione. The method 100 includes vaporizing 106 a liquid feedstock composition comprising tetralin- 1,4-dione and 1,4-dihydroxynaphthalene to form a vapor composition, and solidifying 108 the vapor composition to form a solid crude composition. In the liquid feedstock composition, tetralin- 1,4-dione and 1,4- dihydroxynaphthalene are present at a first molar ratio, and when the liquid feedstock composition is vaporized the vapor composition formed includes tetralin- 1,4-dione and 1,4- dihydroxynaphthalene at a vapor molar ratio, wherein the amount of tetralin- 1,4-dione is increased relative to the amount of 1,4-dihydroxynaphthalene. Once the vapor composition is solidified into a solid crude composition, the vapor molar ratio of tetralin- 1,4-dione and 1,4- dihydroxynaphthalene may be retained or substantially retained at a second molar ratio that is greater than the first molar ratio. Thus, a solid crude composition is formed comprising an increased concentration of tetralin- 1,4-dione than its tautomer, 1,4-dihydroxynaphthalene relative to a liquid feedstock composition.

[0026] FIG. 2 is a flowchart of an example method 200 for tautomerizing 1,4- dihydroxynaphthalene into tetralin- 1,4-dione in a crude composition. The method 200 includes vaporizing 206 a liquid feedstock composition comprising tetralin- 1,4-dione and 1,4- dihydroxynaphthalene to form a vapor composition and solidifying 208 the vapor compositionto form a solid crude composition, with additional optional steps relative to method 100. Blocks 202, 204, 210, and 212 are blocks illustrating optional steps in the method and are marked by dotted connecting lines. As blocks 202, 204, 210, and 212 are optional, in some embodiments method 200 may begin with block 202, block 204 or block 206, and may end with block 208, block 210 or block 212.

[0027] FIG. 2 depicts synthesizing 202 a solid feedstock comprising 1,4- dihydroxynaphthalene. In some embodiments, the solid feedstock can be synthesized from a 1,4-naphthaquinone starting material. A solid feedstock comprising 1,4- dihydroxynaphthalene is melted 204 to form the liquid feedstock composition. In some embodiments, the solid feedstock may be synthesized 202 and / or purchased. Subsequent to vaporizing the liquid feedstock composition to form a vapor composition 206 and solidifying the vapor composition to form a solid crude composition 208, the solid crude composition is purified 210 to form a purified product with an increased concentration or molar ratio of tetralin- 1,4-dione relative to the solid crude composition. In some embodiments, a waste product composition is produced as a by-product of the purification 210, and the waste product composition comprises 1,4-dihydroxynaphthalene. The waste product composition may be recycled 212 to tautomerize additional tetralin- 1,4-dione.

[0028] In some embodiments, at least one method step (e.g., all method steps) is performed by a solvent-free process. In some embodiments, at least one method step (e.g., all method steps) is performed continuously. In some embodiments, the melting is performed in or in a substantially inert gas environment. In some embodiments, the melting of the solid feedstock may be performed under pressure of, of about, of at least, or of at least about 0.8 atm, 0.9 atm, 1 atm, 1.5 atm, 2 atm, 2.5 atm, 3 atm or 5 atm, or any range of values therebetween. In some embodiments, increased pressure inhibits sublimation of the solid feedstock. In some embodiments, the melting of the solid feedstock may be performed at temperatures of, of about, of at least, or of at least about 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 320 °C or 350 °C, or any range of values therebetween.

[0029] In some embodiments, vaporizing is performed by reducing the pressure of the environment, increasing the temperature of the liquid feedstock composition, or a combination thereof. In some embodiments, the vaporizing is performed in or in a substantiallyinert gas environment. In some embodiments, vaporization is performed at a pressure of, of about, of at most, or of at most about 0.1 atm, 0.2 atm, 0.3 atm, 0.4 atm, 0.5 atm, 0.6 atm, 0.7 atm, 0.8 atm, 0.9 atm, 1 atm, 1.2 atm, 1.5 atm, 2 atm, or any range of values therebetween. In some embodiments, the vaporizing of the liquid feedstock composition may be performed at temperatures of, of about, of at least, or of at least about, 80 °C, 100 °C, 150 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 320 °C, 340 °C, 350 °C, 360 °C, 380 °C, 390 °C, 400 °C, 420 °C or 450 °C, or any range of values therebetween.

[0030] In some embodiments, solidifying the vapor composition is performed by cooling the vapor on a cool surface (e.g., finger and / or plate). In some embodiments, the solidifying of the vapor composition may be performed at temperatures of, of about, at most, or of at most about, -20 °C, -10 °C, -5 °C, 0 °C, 5 °C, 10 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 95 °C or 100 °C, or any range of values therebetween.

[0031] In some embodiments, purification may be performed by sublimation, recrystallization, chromatography, or combinations thereof. In some embodiments using at least recrystallization for purification, recrystallization may comprise dissolving the solid crude composition in an organic, polar solvent. In some embodiments, the organic, polar solvent is selected from methyl tert-butyl ether, diisopropyl ether, and combinations thereof. In some embodiments, purification may be performed or performed at least 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 times, or any range of values therebetween. In some embodiments, purifications forms a waste product composition in addition to the purified product. In some embodiments, the waste product composition comprises 1,4-dihydroxynaphthalene. In some embodiments, the waste product composition is a solution comprising a solvent.

[0032] In some embodiments, the waste product composition is recycled. In some embodiments, recycling is performed by combining the waste product composition with the solid feedstock and / or liquid feedstock composition. In some embodiments, recycling is performed prior to, subsequent to and / or concurrently with vaporizing the liquid feedstock composition. In some embodiments, recycling comprises melting the waste product composition.Feedstock

[0033] In some embodiments, the solid feedstock is, consists of, consists essentially of, or comprises, 1,4-dihydroxynaphthalene. In some embodiments, the solid feedstock comprises 1,4-dihydroxynaphthalene in, in about, in at least, or in at least about, 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 90 wt.%, 95 wt.%, 99% or 99.5 wt.%, or any range of values therebetween.

[0034] The liquid feedstock composition comprises tetralin- 1,4-dione and 1,4- dihydroxynaphthalene. In some embodiments, the liquid feedstock composition comprises a first molar ratio of tetralin- 1,4-dione: 1,4-dihydroxynaphthalene. In some embodiments, the first molar ratio is, is about, is at most, or is at most about, 1 : 10, 1:9, 1 :8, 1 :7, 1 :6, 1 :5, 1:4, 1 :3, 1:2, 1 : 1.1, 1 : 1, or any range of values therebetween.Solid Crude Composition

[0035] The solid crude composition comprises tetralin- 1,4-dione and 1,4- dihydroxynaphthalene. In some embodiments, the solid crude composition comprises a second molar ratio of tetralin-1, 4-dione: 1,4-dihydroxynaphthalene. In some embodiments the third molar ratio is, is about, is at least, or is at least about, 1: 1, 1.5:1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 6.5: 1, 7: 1, 8:1, 9: 1 or 10:1, or any range of values therebetween. In some embodiments, the solid crude composition is or is substantially free of solvents.Purified Product

[0036] In some embodiments, the purified product is, consists of, consists essentially of, or comprises, tetralin- 1,4-dione. In some embodiments, the purified product further comprises 1,4-dihydroxynaphthalene. In some embodiments, the purified product comprises a third molar ratio of tetralin-1, 4-dione: 1,4-dihydroxynaphthalene. In some embodiments, the third molar ratio is greater than the second molar ratio. In some embodiments, the third molar ratio is, is about, is at least, or is at least about, 10: 1, 11 : 1, 12:1, 13:1, 14: 1, 15:1, 16: 1, 17:1, 18: 1, 19:1, 20: 1, 25:1, 30: 1, 40: 1, 50: 1, 60:1, 70: 1, 80: 1, 90: 1, 95:1 or 100:1, or any range of values therebetween.Apparatus

[0037] The methods described herein may be performed in a suitable apparatus. FIG. 3 illustrates an example embodiment of an apparatus 300 for tautomerizing 1,4- dihydroxynaphthalene into tetralin- 1,4-dione. Apparatus 300 comprises a reaction vessel 302, wherein the reaction vessel 302 comprises an internal chamber 304 and a thermal transfer area. In some embodiments, the thermal transfer area may be disposed (e.g., exposed) on the bottom and / or one or more sides of reaction vessel 302. The internal chamber 304 comprises a chamber floor 306, and disposed (e g., exposed) within the internal chamber 304 and overhanging the chamber floor 306 is a cold plate 320. The height of the cold plate 320 is configured such that cold plate 320 is in contact with a vapor within the internal chamber 304 and such that cold plate 320 is disposed (e.g., exposed) above a material on the chamber floor 306. A lid 310 comprising a reaction vessel inlet 308 in material (e.g., solid, liquid and / or gaseous) communication (e.g., contact) with the internal chamber 304 is shown, and allows feedstock to be added to the internal chamber 304. Handles 314 are shown disposed outside reaction vessel 302. The cold plate 320 is configured to be cooled through coolant piping 322 that enters the internal chamber 304 through lid 310. In some embodiments, apparatus 300 further comprises a heating element adjacent to the thermal transfer area.

[0038] Apparatus 300 can be used to tautomerize 1,4-dihydroxynaphthalene into tetralin- 1,4-dione. For example, a feedstock composition (e.g., solid or liquid feedstock composition) is introduced into the internal chamber 304 through the reaction vessel inlet 308 and rests on the chamber floor 306, The internal chamber 304 may be sealed prior to the process beginning, and in some embodiments the pressure of the internal chamber may be modified (e.g., increased and / or decreased relative to atmospheric pressure). In some embodiments, an inert gas may be introduced within the internal chamber 304. In some embodiments, if the feedstock composition is in solid form, heat and / or pressure of the internal chamber 304 may be modified to melt the solid feedstock and form a liquid feedstock composition. This liquid feedstock may be vaporized to form a vapor composition in the internal chamber 304, and the vapor composition is deposited as a solid crude composition on the cool surface of cold plate 320. In some embodiments, the vaporization may continue until the liquid feedstock composition is exhausted. The solid crude composition deposited on cold plate 320 may be collected.

[0039] In some embodiments, the internal chamber is configured to maintain pressures at, below or above atmospheric pressure. In some embodiments, the internal chamber is configured to maintain pressures of, of about, of at least, of at least about, of at most, or of at most about, 0.1 atm, 0.2 atm, 0.3 atm, 0.4 atm, 0.5 atm, 0.6 atm, 0.7 atm, 0.8 atm, 0.9 atm, 1 atm, 1.2 atm, 1.5 atm, 2 atm , 2.5 atm, 3 atm or 5 atm, or any range of values therebetween. In some embodiments, the apparatus is configured to be at a temperature of, or about, of at least, or of at least about, -20 °C, -10 °C, -5 °C, 0 °C, 5 °C, 10 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 95 °C, 100 °C, 150 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 380 °C, 400 °C, 420 °C or 450 °C, or any range of values therebetween. In some embodiments, the cold plate is configured to be at a temperature of, of about, of at most, or of at most about, -20 °C, -10 °C, -5 °C, 0 °C, 5 °C, 10 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C 90 °C, 95 °C, or 100 °C, or any range of values therebetween.EXAMPLES

[0040] Some aspects of the embodiments discussed above are disclosed in further detail in the following examples, which are not in any way intended to limit the scope of the present disclosure. Those in the art will appreciate that many other embodiments also fall within the scope of the disclosure, as it is described herein above and in the claims.Example 1 - Synthesis of L4-dihydroxynaphthalene from L4-naphthaquinone

[0041] A 1,4-naphthaquinone precursor was dissolved in methanol and chilled over ice. An H-NMR spectra of this 1,4-naphthaquinone precursor is shown in FIG. 4. Sodium borohydride was then slowly added to the stirred reaction vessel in a 1: 1 molar ratio to 1,4- naphthaquinone. After the reduction reaction was complete, the reaction was quenched with water and the methanol was removed. The product, 1,4-dihydroxynaphthalene was extracted from the aqueous fraction using ethyl acetate. The organic solvent was then dried and removed to yield 1,4-dihydroxynaphthalene (i.e., the solid feedstock), as shown in the H-NMR spectra shown in FIG. 5.Example 2 - Tautomerization of E4-dihydroxynaphthalene to tetralin- 1,4-dione

[0042] The 1,4-dihydroxynaphthalene produced in Example 1 (i.e., the solid feedstock) was added to the reaction vessel of FIG. 3 and a vacuum was applied to remove air and residual moisture. The reaction vessel was then backfilled with nitrogen gas before heat was applied through the bottom. The cold plate of the reaction vessel was chilled with recirculating coolant. As soon as the 1,4-dihydroxynaphthalene was molten (i.e., the liquid feedstock composition), a vacuum was applied. This caused the liquid to rapidly boil and the vapor was condensed onto the cold plate. Once the reaction was complete, the reaction chamber was cooled, and the deposited vapor was removed from the cold plate. The “crude” material on the cold plate (i.e., the solid crude composition) contained 1,4-dihydroxynaphthalene and tetralin- 1,4-dione in approximately a 1 :6 molar ratio, as seen in the H-NMR spectra shown in FIG. 6. The un-evaporated material may be re-used indefinitely.Example 3 - Purification by Sublimation

[0043] The crude material of Example 2 was added to a vacuum chamber and heated to 60 °C below a chilled cold finger. The deposited sublimate (i.e., the purified product) contained 1,4-dihydroxynaphthalene and tetralin- 1,4-dione in a ratio greater than 1 : 14, as seen in the H-NMR spectra shown in FIG. 7. This process may be repeated to yield pure tetralin- 1, 4-dione. The non-sublimated material can be isolated and re-used in the internal chamber of the reaction vessel of FIG. 3 so that more of the material may be converted to the desired tautomer, tetralin- 1,4-dione.Example 4 - Purification by Recrystallization

[0044] The crude material of Example 2 was dissolved in a hot ether, then chilled to recrystallize pure tetralin- 1,4-dione (i.e., the purified product), as seen in the H-NMR spectra shown in FIG. 8. The non-crystalized material may be isolated and re-used in the internal chamber of the reaction vessel of FIG. 3 so that all of the material may be converted to the desired tautomer, tetralin- 1,4-dione.Example 5 - Synthesis of tetralin- 1,4-diol from tetralin- 1,4-dione

[0045] Tetralin- 1,4-diol is a useful material that can be synthesized from tetralin-1, 4-dione. The purified tetralin- 1,4-dione (i.e., the purified product) was dissolved in cold methanol, then sodium borohydride in a 1 :1 molar ratio was slowly added to the tetralin- 1,4- dione solution. After the reduction reaction was complete, the reaction was quenched with water and the methanol was removed. The product, tetralin- 1,4-diol, was extracted using methyl isobutyl ketone from the aqueous fraction. The organic solvent was then dried and removed to yield tetralin- 1,4-diol, as seen in the H-NMR spectra shown in FIG. 9.

[0046] While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the systems and methods described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure. Accordingly, the scope of the present inventions is defined only by reference to the appended claims.

[0047] Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0048] Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a singleimplementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination.

[0049] Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and / or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. For example, any of the components for an energy storage system described herein can be provided separately, or integrated together (e.g., packaged together, or attached together) to form an energy storage system.

[0050] For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0051] Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and / or steps. Thus, such conditional language is not generally intended to imply that features, elements, and / or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and / or steps are included or are to be performed in any particular embodiment.

[0052] Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

[0053] Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount, depending on the desired function or desired result.

[0054] The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.

Claims

WHAT IS CLAIMED IS:

1. A method of tautomerizing 1,4-dihydroxynaphthalene into tetralin- 1,4-dione, comprising: vaporizing a liquid feedstock composition to form a vapor composition, wherein the liquid feedstock composition comprises tetralin- 1,4-dione and 1,4- dihydroxynaphthalene at a first molar ratio of tetralin-1, 4-dione: 1,4- dihydroxynaphthalene; and solidifying the vapor composition to form a solid crude composition comprising tetralin- 1,4-dione and 1,4-dihydroxynaphthalene at a second molar ratio of tetralin- 1,4- dione: 1,4-dihydroxynaphthalene; wherein the second molar ratio is greater than the first molar ratio.

2. The method of claim 1, further comprising melting a solid feedstock to form the liquid feedstock composition.

3. The method of claim 2, wherein the melting comprises a pressure of at least 1 atm.

4. The method of claim 2 or 3, wherein the melting is performed in a substantially inert gas environment.

5. The method of any one of claims 2-4, wherein the solid feedstock comprises at least about 90% 1,4-dihydroxynaphthalene.

6. The method of any one of claims 2-5, further comprising continuously providing the solid feedstock to be melted.

7. The method of any one of claims 2-6, further comprising synthesizing the solid feedstock comprising 1,4-dihydroxynaphthalene from 1,4-naphthoquinone.

8. The method of any one of claims 1-7 wherein vaporizing comprises a pressure of at most 1 atm.

9. The method of any one of claims 1-8, wherein vaporizing is performed in a substantially inert gas environment.

10. The method of any one of claims 1-9, further comprising collecting the solid crude composition.

11. The method of claim 10, wherein the solid crude composition is continuously collected.

12. The method of any one of claims 1-11, wherein the first molar ratio of tetralin- 1,4- dione: 1,4-dihydroxynaphthalene is at most about 1 : 1.1.

13. The method of any one of claims 1-12, wherein the second molar ratio of tetralin-1.4-dione: 1,4-dihydroxynaphthalene is at least about 2:1.

14. The method of claim 13, wherein the second molar ratio of tetralin-1, 4-dione: 1,4- dihydroxynaphthalene is at least about 6:1.

15. The method of any one of claims 1-14, further comprising purifying the solid crude composition to form a purified product, wherein the purified product comprises tetralin- 1,4- dione and 1,4-dihydroxynaphthalene at a third molar ratio of tetralin-1, 4-dione: 1,4- dihydroxynaphthalene, and wherein the third molar ratio is greater than the second molar ratio.

16. The method of claim 14, wherein purifying is selected from the group consisting of sublimation, recrystallization, chromatography, and combinations thereof.

17. The method of claim 15, wherein recrystallization comprises dissolving the solid crude composition in an organic, polar solvent.

18. The method of any one of claims 15-17, wherein the third molar ratio of tetralin-1.4-dione:l,4-dihydroxynaphthalene is at least about 14:1.

19. The method of claim 18, wherein the third molar ratio of tetralin-1, 4-dione: 1,4- dihydroxynaphthalene is at least about 30: 1.

20. The method of any one of claims 15-19, wherein purifying forms a waste product composition, and wherein the method further comprises combining the waste product composition with the liquid feedstock composition.

21. An apparatus for tautomerizing 1,4-dihydroxynaphthalene into tetralin- 1,4-dione, comprising: a reaction vessel comprising an internal chamber and a thermal transfer area, wherein the internal chamber comprises a chamber floor; a reaction vessel inlet in material communication with the internal chamber; and a cold plate disposed within the internal chamber.

22. The apparatus of claim 21, wherein the cold plate overhangs the chamber floor.

23. The apparatus of claim 21 or 22, further comprising a heating element adjacent to the thermal transfer area.

4. A solid crude composition, comprising: tetralin- 1,4-dione; and1 ,4-dihydroxynaphthalene; wherein the tetralin-l,4-dione: l,4-dihydroxynaphthalene molar ratio is about: 1 to 7:1; and wherein the composition is substantially free of solvents.

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