Preparation of difluoro chelato borate salts

Abstract

A process for preparing a difluoro chelato borate salt comprising an anion A of formula (I) ##STR00001##
wherein ##STR00002##
is a bidentate radical derived from a 1,2-, 1,3- or 1,4-diol, from a 1,2-, 1,3- or 1,4-dicarboxylic acid or from a 1,2-, 1,3- or 1,4-hydroxycarboxylic acid by abstracting the two H atoms of pairs of adjacent OH groups of the respective diol, hydroxycarboxylic acid or dicarboxylic acid. The process includes step (i) reacting (a) one or more BF3 sources; (b) a dihydric compound selected from 1,2-, 1,3- and 1,4-diols, 1,2-, 1,3- and 1,4-dicarboxylic acids, and 1,2-, 1,3- and 1,4-hydroxycarboxylic acids; (c) one or more second boron sources which do not contain F; and (d) one or more proton acceptors.

Claims

1. A process for preparing a difluoro chelato borate salt comprising an anion A of formula (I) ##STR00026## wherein ##STR00027## is a bidentate radical derived from a 1,2-, 1,3- or 1,4-diol, from a 1,2-, 1,3- or 1,4-dicarboxylic acid or from a 1,2-, 1,3- or 1,4-hydroxycarboxylic acid by abstracting the two H atoms of pairs of adjacent OH groups of the respective diol, hydroxycarboxylic acid or dicarboxylic acid; comprising, in the presence of an ammonium salt or a phosphonium salt, step (i) reacting (a) one or more BF.sub.3 sources selected from bortrifluorid-dihydrate and bortrifluorid-methanol; (b) a dihydric compound selected from 1,2-, 1,3- and 1,4-diols, 1,2-, 1,3- and 1,4-dicarboxylic acids, and 1,2-, 1,3- and 1,4-hydroxycarboxylic acids, wherein the dihydric compound (b) is selected from oxalic acid, salicylic acid, and phthalic acid; (c) one or more second boron sources which do not contain F; and (d) one or more proton acceptors; wherein the BF.sub.3 source (a) and the second boron source (c) are used in step (i) in a molar ratio ranging from 1.5:1 to 2.5:1, referred to boron; wherein the second boron source (c) is selected from boric acid, B(OC.sub.1-C.sub.6 alkyl).sub.3, B(OC.sub.5-C.sub.7 (hetero)aryl).sub.3, and ammonium and alkali metal salts of borate complexes of the dihydric compound used as component (b); wherein the proton acceptor (d) is selected from organic amines NR.sup.1R.sup.2R.sup.3, NH.sub.4OH, and organic ammonium hydroxides [NR.sup.1R.sup.2R.sup.3R.sup.4]OH wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are selected independently from each other from H, optionally substituted C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.20 alkenyl, C.sub.2-C.sub.20 alkynyl, C.sub.5-C.sub.12 (hetero)aryl, and C.sub.6-C.sub.30 (hetero)aralkyl, wherein one or more CH.sub.2 groups of alkyl, alkenyl, alkynyl and (hetero)aralkyl which are not directly bound to the N-atom may be replaced by O, 1,2-epoxyethylene, cyclopropylene, OSO.sub.2, SO.sub.2O, OC(O), C(O)O, OC(O)O, or OC(O)C(O)O; or wherein R.sup.1 and R.sup.2 are linked and jointly selected from a 4- to 5-membered hydrocarbon group forming together with the central N-atom a five- or six-membered heterocycle which may substituted by one or more substituents selected from C.sub.1-C.sub.10 alkyl, and wherein one or more members of the 4- to 5-membered hydrocarbon group may be replaced by one or more O, S or NR; R is selected from H, C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.10 alkenyl, C.sub.2-C.sub.10 alkynyl, C.sub.6-C.sub.12 aryl, and C.sub.7-C.sub.24 aralkyl, which may be substituted by one or more groups selected from F, cyclopropyl, 1,2-epoxyethyl, and sulfonate, and wherein one or more CH.sub.2 groups of alkyl, alkenyl, alkynyl and aralkyl which are not directly bound to the N-atom may be replaced by O, 1,2-epoxyethylene, cyclopropylene, OSO.sub.2 or SO.sub.2O; and wherein at least one of R.sup.1, R.sup.2, and R.sup.3 is not H.

2. The process according to claim 1, wherein the total content of additional sources for F-atoms is less than 50 mol.-% based on the total amount of BF.sub.3-source (a).

3. The process according to claim 1, wherein the volatile reaction products are removed during and/or after step (i).

4. The process according to claim 1, wherein the dihydric compound (b) is selected from 1,2-diols, 1,2-dicarboxylic acids, and 1,2-hydroxycarboxylic acids.

5. The process according to claim 1, wherein the proton acceptor (d) is selected from ammonia, organic amines, organic ammonium hydroxides, NH.sub.4OH, and nitrogen containing aromatic heterocycles.

6. The process according to claim 1, wherein the proton acceptor (d) is selected from organic amines NR.sup.1R.sup.2R.sup.3 and organic ammonium hydroxides [NR.sup.1R.sup.2R.sup.3R.sup.4]OH wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are selected independently from each other from H and optionally substituted C.sub.1-C.sub.20 alkyl or wherein R.sup.1 and R.sup.2 are linked and jointly selected from a 4- to 5-membered hydrocarbon group forming together with the central N-atom a five- or six-membered heterocycle which may substituted by one or more substituents selected from C.sub.1-C.sub.10 alkyl, and wherein one or more member of the 4- to 5-membered hydrocarbon group may be replaced by one or more O, S or NR; R is selected from H and C.sub.1-C.sub.10 alkyl; and wherein at least one of R.sup.1, R.sup.2, and R.sup.3 is not H.

7. The process according to claim 1, wherein the proton acceptor (d) is a nitrogen containing aromatic heterocycle selected from pyridine, pyrimidine, pyrrol, pyrazol, and imidazole.

8. The process according to claim 1, wherein the cation of the difluoro chelato borate salt comprising an anion A stems from the proton acceptor (d) used in step (i).

9. The process according to claim 1, wherein step (i) is carried out in the presence of a solvent or solvent mixture (e), wherein the ammonium salt or the phosphonium salt is a source of the cation of the difluoro chelato borate salt comprising an anion A.

Description

(1) The disclosure is illustrated by the examples which follow, which do not, however, restrict the invention.

I.) Preparation of triethylammonium difluoro(oxalatoborate)

(2) ##STR00018##

Example 1

(3) 38 g oxalic acid dihydrate, 6 g boric acid and 30 g triethylamine were mixed with 150 mL acetonitrile. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, triethylammonium difluoro(oxalatoborate) was obtained as colorless, solidified melt. Quantitative F-NMR showed a purity of 92%, together with the corresponding tetrafluoro borate salt (2%) and bis(oxalatoborate) salt in 6%.

Example 2

(4) 38 g oxalic acid dihydrate, 6 g boric acid and 30 g triethylamine were mixed with 150 mL acetone. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, triethylammonium difluoro(oxalatoborate) was obtained as colorless, solidified melt. Quantitative F-NMR showed a purity of 93%, together with the corresponding tetrafluoro borate salt (3%) and bis(oxalatoborate) salt in 4%.

Example 3

(5) 38 g oxalic acid dihydrate, 6 g boric acid and 30 g triethylamine were mixed with 150 mL methanol. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, triethylammonium difluoro(oxalatoborate) was obtained as colorless, solidified melt. Quantitative F-NMR showed a purity of 88%, together with the corresponding tetrafluoro borate salt (6%) and bis(oxalatoborate) salt in 6%.

Example 4

(6) Triethylammonium difluoro(oxalatoborate) was prepared according to example 3. Crystallization from a mixture of acetone and methyl-tert-butyl-ether resulted in isolation of colorless, crystalline material in 40% yield. Quantitative F-NMR showed a purity of 100%.

(7) .sup.1H NMR (CD.sub.3CN, 400 MHz) (ppm)=1.23 (t, 9H), 2.20 (br, s, 1H), 3.15 (quar, 6H). .sup.19F NMR (CD.sub.3CN, 376 MHz) =154 ppm. .sup.11B NMR (CD.sub.3CN, 128 MHz) =3.0 ppm. Melting Point: 55 C.

Example 5

(8) 38 g oxalic acid dihydrate, 6 g boric acid and 30 g triethylamine were mixed with 150 mL methanol. 26 g Bortrifluorid-methanol adduct was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, triethylammonium difluoro(oxalatoborate) was obtained as colorless, solidified melt. Quantitative F-NMR showed a purity of 84%, together with the corresponding tetrafluoro borate salt (7%) and bis(oxalatoborate) salt in 9%.

Example 6

(9) 19 g oxalic acid dihydrate, 43 g triethyammonium bis(oxalatoborate) and 30 g triethylamine were mixed with 150 mL acetonitrile. 31 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, triethylammonium difluoro(oxalatoborate) was obtained as colorless, solidified melt. Quantitative F-NMR showed a purity of 90%, together with the corresponding tetrafluoro borate salt (4%) and bis(oxalatoborate) salt in 6%. .sup.19F NMR (CD.sub.3CN, 376 MHz) (ppm)=154 (BF.sub.2), 150 (BF.sub.4). .sup.11B NMR (CD.sub.3CN, 128 MHz) (ppm)=1.2 (BF.sub.4), 3.0 (BF.sub.2), 7.5 (B).

II.) Preparation of ethyl-di(isopropyl)ammonium difluoro(oxalatoborate)

(10) ##STR00019##

Example 7

(11) 38 g oxalic acid dihydrate, 6 g boric acid and 38 g ethyl-di(isopropyl)amine were mixed with 150 mL methanol. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, ethyl-di(isopropyl)ammonium difluoro(oxalatoborate) was obtained as yellowish, solidified melt in 97% yield. Quantitative F-NMR showed a purity of 87%, together with the corresponding tetrafluoro borate salt (6%) and bis(oxalatoborate) salt in 7%.

(12) .sup.1H NMR (MeOD, 400 MHz) (ppm)=1.32-1.48 (m, 15H), 3.22 (quar, 2H), 3.60-3.71 (m, 2H). .sup.19F NMR (MeOD, 376 MHz) =154 ppm. .sup.11B NMR (MeOD, 128 MHz) =3.0 ppm. Melting Point: 229 C.

III.) Preparation of ethyl-di(methyl)ammonium difluoro(oxalatoborate)

(13) ##STR00020##

Example 8

(14) 38 g oxalic acid dihydrate, 6 g boric acid and 22 g ethyl-di(methyl)amine were mixed with 150 mL methanol. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, ethyl-di(methyl)ammonium difluoro(oxalatoborate) was obtained as yellowish, solidified melt in 96% yield. Quantitative F-NMR showed a purity of 89%, together with the corresponding tetrafluoro borate salt (4%) and bis(oxalatoborate) salt in 7%.

(15) .sup.1H NMR (MeOD, 400 MHz) (ppm)=1.36 (t, 3H), 2.87 (s, 6H), 3.18 (quar, 2H). .sup.19F NMR (MeOD, 376 MHz) =154 ppm. .sup.11B NMR (MeOD, 128 MHz) =3.0 ppm. Melting Point: 48 C.

IV.) Preparation of isopropylammonium difluoro(oxalatoborate)

(16) ##STR00021##

Example 9

(17) 38 g oxalic acid dihydrate, 6 g boric acid and 18 g isopropylamine were mixed with 150 mL methanol. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, isopropylammonium difluoro(oxalatoborate) was obtained as colorless, solidified melt in 89% yield. Quantitative F-NMR showed a purity of 90%, together with the corresponding tetrafluoro borate salt (2%) and bis(oxalatoborate) salt in 8%.

(18) 1H NMR (MeOD, 400 MHz) (ppm)=1.39 (d, 6H), 3.38-3.52 (m, 1H). 19F NMR (MeOD, 376 MHz) =154 ppm. 11B NMR (MeOD, 128 MHz) =3.0 ppm. Melting Point: 38 C.

V.) Preparation of tetraethylammonium difluoro(oxalatoborate)

(19) ##STR00022##

Example 10

(20) 38 g oxalic acid dihydrate, 6 g boric acid and 44 g tetraethylammonium hydroxide were mixed with 150 mL methanol. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, tetraethylammonium difluoro(oxalatoborate) was obtained as colorless, solidified melt in 75% yield. Quantitative F-NMR showed a purity of 92%, together with the corresponding tetrafluoro borate salt (4%) and bis(oxalatoborate) salt in 4%.

(21) .sup.1H NMR (MeOD, 400 MHz) (ppm)=1.20 (t, 12H), 3.17 (quar, 8H). .sup.19F NMR (MeOD, 376 MHz) =154 ppm. .sup.11B NMR (MeOD, 128 MHz) =3.0 ppm. Melting Point: 118 C.

VI.) Preparation of N-methylpyrrolidinium difluoro(oxalatoborate)

(22) ##STR00023##

Example 11

(23) 38 g oxalic acid dihydrate, 6 g boric acid and 26 g N-methylpyrrolidine were mixed with 150 mL methanol. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, N-methylpyrrolidinium difluoro(oxalatoborate) was obtained as dark red, solidified melt in 95% yield. Quantitative F-NMR showed a purity of 86%, together with the corresponding tetrafluoro borate salt (6%) and bis(oxalatoborate) salt in 8%.

(24) .sup.1H NMR (MeOD, 400 MHz) (ppm)=1.82-2.03 (m, 2H), 2.05-2.23 (m, 2H), 2.89 (d, 3H), 2.95-3.06 (m, 2H), 3.60-3.74 (m, 2H). .sup.19F NMR (MeOD, 376 MHz) =154 ppm. .sup.11B NMR (MeOD, 128 MHz) =3.0 ppm. Melting Point: 232 C.

VII.) Preparation of pyridinium difluoro(oxalatoborate)

(25) ##STR00024##

Example 12

(26) 38 g oxalic acid dihydrate, 6 g boric acid and 24 g pyridin were mixed with 150 mL methanol. 21 g Bortrifluorid-dihydrate was added and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. Upon cooling, pyridinium difluoro(oxalatoborate) was obtained as colorless, solidified melt in 85% yield. Quantitative F-NMR showed a purity of 90%, together with the corresponding tetrafluoro borate salt (3%) and bis(oxalatoborate) salt in 7%.

(27) .sup.1H NMR (MeOD, 400 MHz) (ppm)=8.02-8.14 (m, 2H), 8.58-8.69 (m, 1H), 8.82-8.90 (m, 2H). .sup.19F NMR (MeOD, 376 MHz) =154 ppm. .sup.11B NMR (MeOD, 128 MHz) =3.0 ppm. Melting Point: 90 C.

VIII.) Preparation of 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium difluoro(oxalatoborate)

(28) ##STR00025##

Example 13

(29) A solution of 346 g 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium methansulfonate in methanol was charged to a reactor at room temperature. 35 g Boric acid, 216 g oxalic acid dihydrate, 173 g triethylamine and 118 g bortrifluorid dihydrate were added under stirring and the reaction mixture was heated to 70 C. After cooling to 20 C., seed crystals of 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium difluoro(oxalatoborate) were added and stirring was continued for additional 12 h at 0 C. The suspension was filtered and the residue sequentially washed with portions of cold methanol. 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium difluoro(oxalatoborate) was obtained as colorless solid in 8% yield.

Example 14

(30) A solution of 346 g 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium methansulfonate in methanol was charged to a reactor at room temperature. 24 g Boric acid, 144 g oxalic acid dihydrate, 115 g triethylamine and 79 g bortrifluorid dihydrate were added under stirring and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. After cooling to 25 C., methanol was added, followed by seed crystals of 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium difluoro(oxalatoborate) and additional stirring for 12 h at 0 C. The suspension was filtered and the residue sequentially washed with portions of cold methanol. 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium difluoro(oxalatoborate) was obtained as colorless solid in 45% yield.

Example 15

(31) A solution of 346 g 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium methansulfonate in methanol was charged to a reactor at room temperature. 35 g Boric acid, 216 g oxalic acid dihydrate, 173 g triethylamine and 118 g bortrifluorid dihydrate were added under stirring and the reaction mixture was heated to 120-130 C., while volatile components were removed by distillation. The residue was further dried for 2 h at 120 C. and 10 mbar. After cooling to 25 C., methanol was added, followed by seed crystals of 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium difluoro(oxalatoborate) and additional stirring for 12 h at 0 C. The suspension was filtered and the residue sequentially washed with portions of cold methanol. 1-methyl-1-(2-((methylsulfonyl)oxy)ethyl)-pyrrolidinium difluoro(oxalatoborate) was obtained as colorless solid in 51% yield.