Method of synthesizing enriched decaborane for use in generating boron neutron capture therapy pharmaceuticals

A method of preparing decaborane comprising the steps of:

• (a) contacting in an inert, non-aqueous solvent medium and at a temperature of from about 85.degree. C. to about 135.degree. C.:
• (i) a tetrahydroborate having the formula
• MBH.sub.4
• wherein M represents an ion selected from the group consisting of sodium, potassium, lithium, cesium, rubidium, and lower alkyl ammonium,
• (ii) an alkyl halide of the formula
• RX
• wherein R represents an alkyl group of from 1 to about 10 carbon atoms and X represents chloride, bromide, or iodide, and
• (iii) a catalyst selected from the group consisting of iodine, alkali metal iodides, ammonium iodide, bromine, alkali metal bromides, ammonium bromide, and mixtures thereof, resulting in formation of a mixture comprising tetradecahydroundecaborate ions,
• with the proviso that an additional amount of said catalyst is added to said inert, non-aqueous solvent medium over and above any of said catalyst that is formed in situ during said contacting process;
• (b) isolating said tetradecahydroundecaborate ions from said mixture;
• and
• (c) contacting and oxidizing said isolated tetradecahydroundecaborate ions at a temperature of about -10.degree. C. to about 50.degree. C. with an oxidizing agent having an electrode potential of at least +0.6 volts.

A method for preparing a tetradecahydroundecaborate ion comprising:

• (a) suspending in an inert, non-aqueous solvent medium and at a temperature of from about 85.degree. C. to about 135.degree. C. a tetrahydroborate having the formula
• MBH.sub.4
• wherein M represents an ion selected from the group consisting of sodium, potassium, lithium, cesium, rubidium, and lower alkyl ammonium forming a suspension;
• (b) adding to said suspension
• (i) an alkyl halide of the formula
• RX
• wherein R represents an alkyl group of from 1 to about 10 carbon atoms and X represents chloride, bromide, or iodide;
• and
• (ii) a catalyst selected from the group consisting of iodine, alkali metal iodides, ammonium iodide, bromine, alkali metal bromides, ammonium bromide, and mixtures thereof,
• such that said tetrahydroborate, said alkyl halide, and said catalyst come into contact thereby forming a tetradecahydroundecaborate ion.

A method of preparing decaborane comprising the steps of:

• (a) suspending in an inert, non-aqueous solvent medium and at a temperature of from about 85.degree. C. to about 135.degree. C. a tetrahydroborate having the formula
• MBH.sub.4
• wherein M represents an ion selected from the group consisting of sodium, potassium, lithium, cesium, rubidium, and lower alkyl ammonium forming a suspension,
• (b) adding to said suspension
• (i) an alkyl halide of the formula
• RX
• wherein R represents an alkyl group of from 1 to about 10 carbon atoms and X represents chloride, bromide, or iodide, and
• (ii) a catalyst selected from the group consisting of iodine, alkali metal iodides, ammonium iodide, bromine, alkali metal bromides, ammonium bromide, and mixtures thereof,
• such that said tetrahydroborate, said alkyl halide, and said catalyst come into contact forming a mixture comprising tetradecahydroundecaborate ions;
• (c) isolating said tetradecahydroundecaborate ions from said mixture;
• and
• (d) contacting and oxidizing said isolated tetradecahydroundecaborate ions at a temperature of about -10.degree. C. to about 50.degree. C. with an oxidizing agent having an electrode potential of at least +0.6 volts.