Isotopically-enriched boranes and methods of preparing them

A method of synthesizing B18H22 comprising the steps of

• (a) providing a salt of (B20H18)2−,
• (b) dissolving the (B20H18)2− salt in a fluid comprising at least one non-aqueous solvent;
• (c) contacting the (B20H18)2− salt solution with an acid to generate a hydronium salt of (B20H18)2−;
• (d) removing volatile components of the solution in vacuo under conditions conducive to formation of B18H22 by degradation of at least a portion of the hydronium salt of (B20H18)2−,
• (e) extracting the residue with water and at least one water immiscible solvent;
• (f) contacting the aqueous solution with an alkyl amine or an alkyl ammonium salt to precipitate (B20H18)2− salts;
• (g) repeating steps (b)-(f) at least once;
• and
• (h) concentrating the combined non-aqueous solutions generated in step (e) to obtain B18H22.

A method of synthesizing B18H22 comprising the steps of

• (a) providing a salt of (B20H18)2−,
• (b) dissolving the (B28H18)2− salt in a fluid comprising at least one non-aqueous solvent;
• (c) contacting the (B20H18)2− salt solution with an acid to generate a hydronium salt of (B20H18)2−;
• (d) removing volatile components of the solution in vacuo under conditions conducive to formation of B18H22 by degradation of at least a portion of the hydronium salt of (B20H18)2−,
• (e) extracting the residue with hydrocarbon solvent;
• (f) contacting the remaining residues with acetonitrile to dissolve (B20H18)2− salts;
• (g) repeating steps (b)-(f) at least once;
• and
• (h) concentrating the combined non-aqueous solutions generated in step (e) to obtain B18H22.