Preparation of fluorosulfonate esters and onium salts derived therefrom
The present invention is directed to methods for preparing a fluorosulfonate ester or a salt thereof, through a reaction of a dissolved sulfonyl fluoride (R F SO 2 F) with alkoxide anion (RO − ) optionally in the presence of an aprotic base (B), where R F is fluorine or a C 1 -C 8 perfluoroalkyl group, and R is a primary alkyl or alkoxyalkyl. Alkoxide anion (RO − ) can be generated from a precursor such as an alcohol or silyl ester.
1. A method for preparing a fluorosulfonate salt, comprising:
reacting dissolved sulfuryl fluoride (SO 2 F 2 ) with an alkoxide anion (RO − ) precursor in the presence of an aprotic base (B) without addition of water, wherein R is a primary alkyl or alkoxyalkyl group; and
isolating a resulting onium salt [RB + ] [FSO 3 − ].
2. The method of claim 1 , wherein the alkoxide anion (RO − ) precursor is a primary alcohol (ROH).
3. The method of claim 1 , wherein the alkoxide anion (RO − ) precursor is a silyl ether having a formula ROSiR″ 3 , (RO) 2 SiR″ 2 , (RO) 3 SiR″ or (RO) 4 Si, and R″ is an alkyl group.
4. The method of claim 1 , wherein the aprotic base (B) is a tertiary amine (R′ 3 N), wherein each R′ is independently a C 1 -C 6 alkyl or alkoxyalkyl, a cycloalkyl, morpholinyl, or bicycloalkyl group.
5. The method of claim 1 , wherein the aprotic base is a heteroaromatic tertiary amine.
6. The method of claim 1 , wherein the reaction is conducted at or below atmospheric pressure.
7. The method of claim 1 , further comprising: isolating a resulting fluorosulfonate ester ROSO 2 F.
8. The method of claim 7 , wherein the alkoxide anion (RO − ) precursor is a hindered primary alkoxide.
9. The method of claim 7 , wherein the aprotic base is a hindered base.
10. The method of claim 1 , wherein the onium salt [RB + ] [FSO 3 − ] is obtained by reacting a resulting fluorosulfonate ester ROSO 2 F with the aprotic base in situ or added subsequently.
11. The method of claim 1 , wherein the onium salt [RB + ] [FSO 3 − ] is a quaternary ammonium salt [F SO 3 ] − [RR′ 3 N] + , or a quaternary heteroaromatic salt [FSO 3 ] − [RNAr] + , wherein each R′ is independently a C 1 -C 6 alkyl or alkoxyalkyl, a cycloalkyl, morpholinyl, or bicycloalkyl group, and NAr is a heteroaromatic group.
12. A method for preparing a fluorosulfonate salt, comprising:
reacting dissolved sulfuryl fluoride (SO 2 F 2 ) with an alcohol (ROH) in the presence of an aprotic base (B) under anhydrous condition, wherein R is a primary alkyl or alkoxyalkyl group; and
isolating a resulting onium salt [RB + ] [FSO 3 − ].
13. The method of claim 12 , wherein the alcohol (ROH) is a linear primary alcohol or alkoxyalcohol having from 1 to 20 carbon atoms.
14. The method of claim 12 , wherein the alcohol (ROH) is selected from the group consisting of methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, 2-methoxyethanol, 3-methoxypropanol, 2-ethoxyethanol, and 3-ethoxypropanol, benzyl alcohol, a ring-substituted benzyl alcohol, 2-ethylhexanol and neopentanol.
15. The method of claim 12 , wherein the alcohol (ROH) is partially or wholly fluorinated, except for the hydroxyl carbon.
16. The method of claim 12 , wherein reacting sulfuryl fluoride (SO 2 F 2 ) with an alcohol (ROH) is performed in a solvent, and the solvent is selected from the group consisting of dichloromethane, 1,1,1-trichloroethane, chloroform, tetrahydrofuran, acetonitrile, ethyl ether, chlorobenzene, fluorobenzene, 1,2-difluorobenzene, toluene, n-propyl ether, isopropyl ether, di-n-butyl ether and methyl tert-butyl ether.
17. The method of claim 12 , wherein the molar ratio of the aprotic base (B) to the alcohol (ROH) is 2:1 or greater, and the molar ratio of SO 2 F 2 to ROH is 1:1 or greater.
18. The method of claim 12 , further comprising isolating a resulting fluorosulfonate ester (ROSO 2 F), and where the alcohol (ROH) is a hindered primary alcohol, or the aprotic base is a hindered base.
19. The method of claim 12 , wherein the aprotic base comprises a tertiary amine (R′ 3 N) or a heteroaromatic tertiary amine (:NAr), wherein each R′ is independently a C 1 -C 6 alkyl or alkoxyalkyl, a cycloalkyl, morpholinyl, or bicycloalkyl group.
20. The method of claim 12 , wherein the resulting onium salt [RB + ] [FSO 3 − ] is a quaternary ammonium salt [F SO 3 ] − [RR′ 3 N] + , or a quaternary heteroaromatic salt [FSO 3 ] − [RNAr] + , wherein each R′ is independently a C 1 -C 6 alkyl or alkoxyalkyl, a cycloalkyl, morpholinyl, or bicycloalkyl.
21. The method of claim 12 , wherein the aprotic base comprises a tertiary amine (R′ 3 N), and the resulting onium salt is a quaternary ammonium salt [FSO 3 ] − [RR′ 3 N] + .
22. A method for preparing a fluorosulfonate salt, comprising:
reacting dissolved sulfuryl fluoride (SO 2 F 2 ) with a silyl ether, optionally in the presence of an aprotic base (B), wherein the sily ether has a formula ROSiR″ 3 or (RO) 2 SiR″ 2 , (RO) 3 SiR″ or (RO) 4 Si, R is a primary alkyl or alkoxyalkyl group and R″ is an alkyl group; and
isolating a resulting onium salt [RB + ] [FSO 3 − ].
23. The method of claim 22 , wherein R″ is methyl or ethyl group.
24. The method of claim 22 , wherein the aprotic base comprises a tertiary amine (R′ 3 N), and the resulting onium salt is a quaternary ammonium salt [FSO 3 ] − [RR′ 3 N] + , wherein each R′ is independently a C 1 -C 6 alkyl or alkoxyalkyl, a cycloalkyl, morpholinyl, or bicycloalkyl group.
25. The method of claim 22 , further comprising isolating a resulting fluorosulfonate ester (ROSO 2 F).
26. The method of claim 22 , wherein the resulting onium salt [RB + ] [FSO 3 − ] is obtained by reacting a resulting fluorosulfonate ester (ROSO 2 F) with the aprotic base in situ or added subsequently.
27. The method of any of claims 1 , 12 and 22 , comprising adding a protic amine to generate fluoride ion by reaction with SO 2 F 2 .
28. The method of any of claims 1 , 12 and 22 , wherein a fluorosulfonate ester is produced as a stable ester, and is treated with a protic amine to provide the resulting onium salt.