WO2024231553A1 - Method for manufacturing alkoxy boron and aluminium compounds - Google Patents

Abstract

A method of forming a compound of formula (I) wherein X is A1 or B; R1 in each occurrence is independently a monovalent substituent; R2 is a divalent organic group; and M+ is a cation, the method comprising: forming an intermediate compound by reaction of a compound of formula MXH4 with a compound selected from formula (IVa) and (IVb) and forming a compound of formula (I) by reaction of the intermediate compound with a compound of formula (Va), (Vb) or (Vc).

Description

METHOD FOR MANUFACTURING ALKOXY BORON AND ALUMINIUM COMPOUNDS

BACKGROUND

Lithium borate and aluminate salts have been extensively studied for use as electrolytes, for example for use in rechargeable batteries

WO 2011/024420 discloses compounds of formula (lb):

WO 00/53611 discloses a compound comprising a monoanion of formula (II):

SUMMARY

The present disclosure provides a method of forming a compound of formula (I):

wherein X is Al or B; R¹ in each occurrence is independently a monovalent substituent; R² is a divalent organic group; and M⁺ is a cation, the method comprising: forming an intermediate compound by reaction of a compound of formula MXH4 with a compound selected from formula (IV a) and (IVb): R¹— OH R¹=0

(IVa) (IVb) and forming a compound of formula (I) by reaction of the intermediate compound with a compound of formula (Va), (Vb) or (Vc):

(Va) (Vb) (Vc)

Optionally, R² is a group of formula (II):

wherein R³ in each occurrence is independently H or a substituent and Ar¹ is a C6-20 arylene group or a 5-20 membered heteroarylene group.

Optionally, Ar¹ is unsubstituted or substituted 1,2-phenylene.

Optionally, each R¹ is independently selected from C1-40 alkyl, optionally C1-20 alkyl, wherein one or more C atoms other than the C atom bound to O of OR¹ or a terminal C atom may be replaced with O, and one or more H atoms may be replaced by F.

Optionally, X is B.

Optionally, M⁺ is a lithium ion. Optionally, following formation of the compound of formula (I), at least one of a solvent and a polymer is added to the reaction mixture. Optionally, the solvent is selected from C2-10 alkylene carbonates; di(Ci-io alkyl) carbonates; linear, branched or cyclic compounds containing two or more ether groups; and mixtures thereof.

The present disclosure provides use of a method as described herein for reducing formation of products other than a product of formula (I).

DESCRIPTION OF DRAWINGS

Figure I is a ¹ H NMR spectrum of Compound 1 made by a method according to an embodiment of the present disclosure;

Figure 2 is a ¹ H NMR spectrum of Compound 1 made by a comparative method;

Figure 3A is a comparison of the

NMR spectra of Figures 1 and 2;

Figure 3B shows magnification of the aromatic region of the

NMR spectrum of Figure 3A; and

Figure 4 is a ¹ H NMR spectrum of Compound 2 made by a method according to an embodiment of the present disclosure;

DETAILED DESCRIPTION

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. References to a layer “over” another layer when used in this application means that the layers may be in direct contact or one or more intervening layers may be present. References to a layer “on” another layer when used in this application means that the layers are in direct contact. References to an element of the Periodic Table include any isotopes of that element.

The teachings of the technology provided herein can be applied to other systems, not necessarily the system described below. The elements and acts of the various examples described below can be combined to provide further implementations of the technology. Some alternative implementations of the technology may include not only additional elements to those implementations noted below, but also may include fewer elements.

These and other changes can be made to the technology in light of the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, the technology can be practiced in many ways. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms.

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of implementations of the disclosed technology. It will be apparent, however, to one skilled in the art that embodiments of the disclosed technology may be practiced without some of these specific details.

Compounds of Formula (I)

The present inventors have surprisingly found that compounds of formula (I) may possess both high electrochemical stability as well as high ionic conductivity and / or a high lithium transference number when used in a secondary metal battery or secondary metal ion battery:

X is Al or B.

R¹ in each occurrence is independently a monovalent substituent wherein R¹ is bound to O of OR¹ by a carbon atom of R¹.

Preferably, each R¹ is independently selected from linear, branched or cyclic C1-40 alkyl, optionally C1-20 alkyl, in which one or more C atoms of the alkyl, other than the C atom bound to O of OR¹ or a terminal C atom of the C1-40 alkyl may be replaced with O, and one or more H atoms may be replaced by F.

By “terminal C atom” of an alkyl group as used herein is meant the methyl C atom of an n- alkyl chain or the methyl C atoms of a branched alkyl chain.

Preferred groups R¹ are:

-(CH2CH2O)n-R⁵ wherein R⁵ is a C1-4 alkyl and n is 1-15, and wherein one or more H atoms may be replaced with F; and

C1-12 alkyl wherein one or more H atoms may be replaced by F.

In some embodiments, the R¹ groups are the same.

In some embodiments, the R¹ groups are different.

R² is a divalent organic group wherein each O of 0-R²-0 is bound to a carbon atom of R². Preferably, R² is a group of formula (II):

wherein R³ in each occurrence is independently H or a substituent and Ar¹ is a C6-20 arylene group or a 5-20 membered heteroarylene group.

Preferably, Ar¹ is unsubstituted or substituted 1,2-phenylene or an unsubstituted or substituted

5- or 6-membered hetero aromatic ring. A particularly preferred heteroaromatic group Ar¹ is a

6-membered heteroaromatic ring in which the ring atoms consist of C and N atoms only, for example pyridine or pyrimidine.

Where present, substituents of Ar¹ are preferably and independently selected from F and C1-12 alkyl wherein one or more non-adjacent, non-terminal C atoms of the C1-12 alkyl may be replaced with O, S, NR⁴, CO, COO or CONR⁴ wherein R⁴ in each occurrence is independently a Ci-n hydrocarbyl group, and one or more H atoms of the C1-12 alkyl group may be replaced with F.

A Ci-nhydrocarbyl group as described anywhere herein is preferably selected from C1-12 alkyl; phenyl; and phenyl substituted with one or more C1-6 alkyl groups.

Preferably, R³ in each occurrence is independently H, F or a C1-12 alkyl group in which one or more H atoms may be replaced with F and one or more non-terminal C atoms may be replaced with O. In a preferred embodiment, at least one R³, optionally each R³, is a Ci-6perfluoroalkyl group.

M⁺ is a cation. M⁺ is preferably an alkali metal cation, more preferably Li⁺.

Exemplary compounds of formula (I) include, without limitation:

Synthesis of compounds of formula (I) The present inventors have surprisingly found that higher purity of the compound of formula (I) may be achieved by forming the monodentate ligands -OR¹ of the compound of formula (I) before forming the bidentate ligand -O-R²-O-.

Accordingly, formation of the compound of formula (I) comprises a first stage of reacting a compound of formula (III) with a compound selected from formulae (IVa) and (IVb) to form an intermediate compound and a second stage comprising reaction of the intermediate compound with a compound selected from formulae (Va), (Vb) and (Vc):

XH₄- M⁺

(III)

R¹— OH R¹=0

(IVa) (IVb)

(Va) (Vb) (Vc)

The compound of formula (IV a) may be a primary, secondary or tertiary alcohol.

The compound of formula (IVb) may be an aldehyde or a ketone.

Exemplary compounds of formula (III) include, without limitation, lithium aluminium hydride (Li AIH4) and lithium borohydride (LiBLL).

Suitable solvents for the reaction include, without limitation, benzene substituted with one or more C1-4 alkyl or C1-4 alkoxy groups, for example toluene; polar, aprotic solvents for example tetrahydrofuran and ethers such as dialkyl ethers for example diethyl ether; 1,2- dimethoxy ethane; glymes; and mixtures thereof.

Preferably, no compound of formula (Va), (Vb) or (Vc) is present in the reaction mixture during the first stage. In some embodiments, the first and second stages are consecutive. According to these embodiments, the second stage does not commence until all the compound of formula (IVa) or (IVb) has been consumed.

In some embodiments, the commencement of the second stage can be concurrent with some, but not all, of the first stage. According to these embodiments, the second stage may commence when some, preferably a majority, but not all the compound of formula (IVa) or (IVb) has been consumed.

The reaction temperature preferably remains below 100°C for both the first and second stages.

Preferably, there is no purification of the reaction mixture between the first and second stages.

Preferably, the reaction temperature of the first stage remains below 30°C.

Electrolyte

An electrolyte comprising a compound of formula (I) suitably further comprises at least one of a polymer and a solvent. If a polymer and solvent are both present, the electrolyte may be a gel.

To form the electrolyte, solvent and / or polymer may be added to the reaction mixture upon completion of the reaction. Preferably, the reaction mixture does not undergo any purification steps before addition of the solvent and / or polymer.

The polymer may be selected from any known ion-conducting polymers including, without limitation: poly(alkylene oxide), for example poly(ethylene oxide) and poly(propylene oxide); and fluorinated polymers such as PVDF, PVDF-HFP; PMMA; polyacrylonitrile; polycarbonate; polyethylene; polypropylene; poly(vinyl methyl ketone); polyvinylpyrrolidone; polyether ether ketone; polyisoprene; polybutadiene; polystyrene-block-polyisoprene-block- polystyrene; poly(l-vinylpyrrolidone-co-vinyl acetate); polystyrene-block-polybutadiene- block-polystyrene; polystyrene-block-poly(ethylene oxide)-block-polystyrene; co-polymer and mixtures thereof.

The polymer is suitably a neutral polymer, i.e., not a polymer substituted with ionic groups, and in particular is suitably not a single-ion conducting polymer comprising anionic groups. The electrolyte may comprise one or more solvents. Solvents are preferably selected from C2- 10 alkylene carbonates, di(Ci-io alkyl) carbonates, for example propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate; linear, branched or cyclic compounds containing two or more ether groups, for example 1,3-dioxolane, 2,5-dimethoxy tetrahydrofuran, glyme (dimethoxy ethane), diglyme, triglyme and tetraglyme; cyclic lactones and mixtures thereof.

The compound of formula (I) may comprise a solvated M⁺ cation.

EXAMPLES

Synthesis Example 1

Compound 1 was prepared according to the following reaction scheme:

Compound 1

To a solution of lithium borohydride (7.9 mL, 3.84 mmol, 0.5M) in tetrahydrofuran was added dropwise a solution of 1,1, 1,3, 3, 3 hexafluoropropan-2-ol (HFIP) (0.8 mL, 7.68 mmol) in 7 mL of anhydrous tetrahydrofuran at -70°C.The mixture was stirred for 1 hour between -70°C and - 60°C, then allowed to warm to 0°C. A solution of hexafluoro-2-(2-hydroxyphenyl)propan-2-ol (HPP) (1 g, 3.84 mmol) in 7 mL of anhydrous tetrahydrofuran was added drop wise to the reaction mixture at room temperature. The mixture was stirred at 65°C for 4 hours and overnight at room temperature. ^!H NMR analysis of the reaction mixture identified unreacted HFIP, so additional LiBH4 (0.23 mL, 0.46 mmol) and HPP (0.1 g, 0.38 mmol) were added with a view to the remaining HFIP and added HPP and LiBH4 reacting to form Compound 1, and the reaction mixture was stirred at 65°C. No free alcohol was observed after 2 hours (monitored by NMR). Propylene carbonate (0.96 mL, 11.5 mmol) was added. Additional propylene carbonate was added to obtain a stable transparent liquid. ^!H NMR (600 MHz) in deuterated THF: 5 (ppm), 1.38 (d, CH3, from propylene carbonate 15.6H), 3.97 (m, CH, from propylene carbonate, 5.1H), 4.52 (t, CH, from propylene carbonate and CH from HFIP ligand, 6.8H), 4.81 (m, CH, from propylene carbonate 4.7H), 6.67 (m, 2H), 7.12 (td, J= 7.7Hz, J=1.6 Hz, 1H), 7.29 (d, J=7.9Hz, 1H).

The ¹ H NMR for the compound obtained by this method is shown in Figure 1. From integration of NMR peaks, it was calculated that for one molecule of hexafluoro-2-(2- hydroxyphenyl)propan-2-ol and two molecules of 1,1, 1,3, 3, 3 hexafluoropropan-2-ol in the product, which correspond to one lithium cation, 5.1 molecules of propylene carbonate are present as residual solvent.

Comparative Synthesis 1

To a solution of lithium borohydride (15.4 mL, 7.68 mmol, 0.5M) in tetrahydrofuran was added drop wise a solution of hexafluoro-2-(2-hydroxyphenyl)propan-2-ol (HPP) (2 g, 7.68 mmol) in 15 mL of anhydrous tetrahydrofuran at -70°C.The mixture was then stirred for 1 hour between -70°C and -60°C, then allowed to warm to 0°C. A solution of 1,1, 1,3, 3, 3 hexafluoropropan-2- ol (HFIP) (1.61 mL, 15.3 mmol) in 15 mL of tetrahydrofuran was added drop wise to the reaction mixture at room temperature. The mixture was stirred at 65°C for 4 hours and overnight at room temperature. ¹ H NMR of the reaction mixture identified unreacted starting alcohols HPP and HFIP so additional LiBH4 (1 mL, 2 mmol) was added, and the reaction mixture was stirred at 65 °C. No free alcohol was observed after 2 hours (monitored by NMR). Propylene carbonate (1.9 mL, 10.9 mmol) was added. Additional propylene carbonate was added to obtain a stable transparent liquid.

' H NMR (600 MHz) in deuterated THF: 5 (ppm), 1.38 (d, CH3, from propylene carbonate 14.4H), 3.97 (m, CH, from propylene carbonate 4.8H), 4.51 (t, CH, from propylene carbonate and CH, from HIFP ligand, 6.1H), 4.80 (m, CH, from propylene carbonate 4.2H), 6.73-6.63 (m, 2H), 7.08-7.12 (m, 1H), 7.17-7.19 (m, 0.1H), 7.28-7.34 (m, 1H).

The ¹ H NMR for the compound obtained by this method is shown in Figure 2. From integration of NMR peaks, it was calculated that for one molecule of hexafluoro-2-(2- hydroxyphenyl)propan-2-ol and two molecules of 1,1, 1,3, 3, 3 hexafluoropropan-2-ol in the product, which correspond to one lithium cation, 4.6 molecules of propylene carbonate are present as residual solvent. A comparison of the NMR spectra for the compound obtained by Synthesis Example 1 and Synthesis Example 2 is provided in Figure 3A, with the aromatic region expanded in Figure 3B.

With reference to Figure 3B and Table 1, the multiplet with chemical shift of 7.33 ppm corresponding to the formation of EiB(HPP)2 is almost entirely suppressed in Synthesis Example 1. Impurity peaks with chemical shifts of 4.43, 4.67 and 4.74 ppm are also significantly reduced.

Table 1

Synthesis Example 2

Compound 2 was prepared according to the following reaction scheme:

Compound 2

To a solution of lithium borohydride (7.9 mL, 3.84 mmol, 0.5M) in tetrahydrofuran was added drop wise a solution of 2,2,3,3-tetrafluoropropan-l-ol (0.68 mL, 7.68 mmol) in 7 mL of anhydrous tetrahydrofuran at -70°C.The mixture was then stirred for 1 hour between -70°C and -60°C, then allowed to warm to 0°C. A solution of hexafluoro-2-(2-hydroxyphenyl)propan-2- ol (HPP) (1 g, 3.84 mmol) in 7 mL of anhydrous tetrahydrofuran was added drop wise to the reaction mixture at room temperature. The mixture was stirred at 65°C for 4 hours and overnight at room temperature. Additional LiBPU (0.1 mL, 0.2 mmol) and HPP (0.06 g, 0.23 mmol) was added, and the reaction mixture was stirred at 65°C. No free alcohol was observed after 1 hour (monitored by NMR). Propylene carbonate (0.96 mL, 11.5 mmol) was added. Additional propylene carbonate was added to obtain a stable transparent liquid.

' H NMR (600 MHz) in deuterated THF: 5 (ppm), 1.38 (d, CH3, from propylene carbonate 11.6H), 3.77 (m, 4.2H), 3.97 (m, CH, from propylene carbonate 3.7H), 4.52 (t, CH, from propylene carbonate, 3.7H), 4.80 (m, CH, from propylene carbonate 3.3H), 6.10 (tt, J=53.51 Hz, J= 5.97 Hz, 2H), 6.70(m, 2H), 7.14 (td, J= 7.7 Hz, J=1.6 Hz, 1H), 7.31 (d, J=8.0 Hz, 1H).

The ¹ H NMR for the compound obtained by this method is shown in Figure 4. From integration of NMR peaks, it was calculated that for one molecule of hexafluoro-2-(2- hydroxyphenyl)propan-2-ol and two molecules of 2,2,3,3-tetrafluoropropan-l-ol in the product, which correspond to one lithium cation there is 3.70 molecules of propylene carbonate present as residual solvent.

Claims

A method of forming a compound of formula (I):

wherein X is Al or B; R¹ in each occurrence is independently a monovalent substituent;

R² is a divalent organic group; and M⁺ is a cation, the method comprising: forming an intermediate compound by reaction of a compound of formula MXH4 with a compound selected from formula (IVa) and (IVb):

R¹— OH R¹=O

(IVa) (IVb) and forming a compound of formula (I) by reaction of the intermediate compound with a compound of formula (Va), (Vb) or (Vc):

(Va) (Vb) (Vc)

2. The method according to claim 1 wherein R² is a group of formula (II):

wherein R³ in each occurrence is independently H or a substituent and Ar¹ is a C6-20 arylene group or a 5-20 membered heteroarylene group.

3. The method according to claim 2 wherein Ar¹ is unsubstituted or substituted 1,2- phenylene.

4. The method according to any one of the preceding claims wherein each R¹ is independently selected from C1-40 alkyl wherein one or more C atoms other than the C atom bound to O of OR¹ or a terminal C atom may be replaced with O, and one or more H atoms may be replaced by F.

5. The method according to any one of the preceding claims wherein X is B.

6. The method according to any one of the preceding claims wherein M⁺ is a lithium ion.

7. The method according to any one of the preceding claims wherein, following formation of the compound of formula (I), at least one of a solvent and a polymer is added to the reaction mixture.

8. The method according to claim 7 wherein the solvent is selected from C2-10 alkylene carbonates; di(Ci-io alkyl) carbonates; linear, branched or cyclic compounds containing two or more ether groups; and mixtures thereof.

9. Use of a method according to any one of the preceding claims for reducing formation of products other than a product of formula (I).