초록 ▼

The invention provides new methods for synthesis of B9H9-, B10H102-, B11H14-, and B12H122- salts, particularly alkylammonium salts of B9H9-, B10H102-, B11H14-, and B12H122-. More particularly, the invention provides methods of preparing tetraalkylamronium salts of B9H9-, B10H102-, B11H14-, and B12H1

The invention provides new methods for synthesis of B9H9-, B10H102-, B11H14-, and B12H122- salts, particularly alkylammonium salts of B9H9-, B10H102-, B11H14-, and B12H122-. More particularly, the invention provides methods of preparing tetraalkylamronium salts of B9H9-, B10H102-, B11H14-, and B12H122- by pyrolysis of tetraalkylammonium borohydrides under controlled conditions. The invention additionally provides methods of preparing, in an atom efficient process, octadecaborane from the tetraalkylammonium salts of the invention. Preferred methods of the invention are suitable for preparation of isotopically enriched boranes, particularly isotopically enriched 10B18H22 and 11B18H22.

대표청구항 ▼

What is claimed is: 1. A method of preparing B18H22 from boric acid comprising the steps of: (a) preparation of borate ester from boric acid and a primary, secondary, or tertiary alcohol; (b) reducing the borate ester with NaAIH4 or NaH to form NaBH4; (c) preparing R4NBH4 from NaBH4 and R4NX either

What is claimed is: 1. A method of preparing B18H22 from boric acid comprising the steps of: (a) preparation of borate ester from boric acid and a primary, secondary, or tertiary alcohol; (b) reducing the borate ester with NaAIH4 or NaH to form NaBH4; (c) preparing R4NBH4 from NaBH4 and R4NX either in situ or after isolation of NaBH4, wherein R is a hydrocarbon and X is an anion; (d) pyrolysis of solid R4NBH4 at about 185 ° C. to form B10H102-; (e) oxidation of B10H102-to give B20H182-; (f) contacting a solution of B20H182-with acidic cation exchange resin; (g) decomposing the resultant acid to give B18H22; (h) extracting the residue with solvent in which boric acid byproduct is insoluble; (i) repeating steps (g) and (h) until no further B18H22 is produced; (j) contacting the residues with solvent to dissolve any B20H182-containing salts and excluding boric acid byproduct; (k) repeating steps with (f)-(j) at least once; and (l) concentrating the combined hydrocarbon solutions to afford B18H22. 2. The method of claim 1, wherein the boric acid is B-10 enriched boric acid. 3. The method of claim 1, wherein the boric acid is B-11 enriched boric acid. 4. The method of claim 1, wherein the step of preparing R4NBH4 comprises contacting about equal molar amounts of sodium borohydride and R4NX. 5. The method of claim 4, wherein the sodium borohydride is B-10 enriched sodium borohydride. 6. The method of claim 4, wherein the sodium borohydride is B-11 enriched sodium borohydride. 7. The method of claim 4, wherein the sodium borohydride prepared in step (b) is used in situ. 8. The method of claim 1, wherein the step of preparing NaBH4 comprises contacting the borate ester and NaAIH4 in an ethereal solvent at a temperature of from about 65° C. to about 135° C. 9. The method of claim 8, wherein the borate ester is a B-10 enriched borate ester. 10. The method of claim 8, wherein the borate ester is B-11 enriched borate ester. 11. The method of claim 8, wherein the ethereal solvent is tetrahydrofuran. 12. The method of claim 8, wherein the ethereal solvent further comprises toluene as a co-solvent. 13. The method of claim 11, wherein the ethereal solvent further comprises toluene as a co-solvent. 14. A method of preparing B18H22 from boric acid, comprising: (a) preparation of borate ester from boric acid and an alcohol; (b) reducing the borate ester to form NaBH4; (c) preparing R4NBH4 from NaBH4 and R4NX, wherein R is a hydrocarbon and X is an anion; (d) pyrolysis of solid R4NBH4 to form B10H102-; (e) oxidation of B10H102-to give B20H182-; (f) contacting a solution of B20H182-with acidic cation exchange resin; (g) decomposing the resultant acid to give B18H22; (h) extracting the residue with solvent in which boric acid byproduct is insoluble; (i) repeating steps (g) and (h) until substantially no further B18H22 is produced; (j) contacting the residues with solvent to dissolve any B20H182-containing salts and excluding boric acid byproduct. 15. The method of claim 14, wherein steps with (f)-(j) are repeated at least once.