2,923,731 United States Patent Office Patented Feb. 2, 1960

2 methanol by crystallization or by evaporation of the solvent. - 2,923,731 The invention is operable if a solution of lithium chlo PREPARATION OF LITHIUM TETRAMETHOXY ride in methanol is mixed with a solution of alkali metal BORATE tetramethoxyborate in methanol, or if solid lithium chlo George Lewis Cunningham and Frank Pretka, Cleve ride is mixed with a solution of alkali metal tetramethoxy land, Ohio, assignors to Callery Chemical Company, borate in methanol, or if solid alkali metal tetramethoxy Pittsburgh, Pa., a corporation of Pennsylvania borate is mixed with a solution of lithium chloride in methanol, or if methanol is added to a mixture of solid No Drawing. Application March 19, 1956 10 lithium chloride and solid alkali metal tetramethoxyborate. Serial No. 572,202 In one experiment 157.82 parts of sodium tetramethoxy borate dissolved in 864 parts of anhydrous methyl alco 7 Claims. (C. 260-462) hol was added to 42.4 parts of anhydrous lithium chloride. The resultant slurry was stirred for approximately 4 hours. This invention relates to a method of preparing lithium 5 The slurry was then filtered to remove 43.88 parts of solid tetramethoxyborate LiB(OCH3)41 from other alkali sodium chloride. The filtrate was evaporated to dryness metal tetramethoxyborates and more particularly to its to give a product containing approximately 91% lithium preparation by metathetic reaction of anhydrous lithium tetramethoxyborate. chloride and another alkali metal tetramethoxyborate in In another experiment 149 parts of potassium tetra solvent alcohol. 20 methoxyborate is dissolved in 800 parts of methanol and Sodium borohydride can be prepared from sodium hy is added to 39 parts of anhydrous lithium chloride. The dride and methyl borate in solvent systems at low tem resultant slurry is stirred for approximately 4 hours and peratures according to the equation then filtered to remove 60 parts of solid potassium chlo ride. The filtrate is a solution containing 120 parts of 25 lithium tetramethoxyborate and about 8 parts KCl. The It is economically imperative that methyl borate be re solvent is evaporated leaving solid lithium tetramethoxy covered from the by-product sodium tetramethoxyborate. borate, Since tetramethoxyborates dissociate thermally to yield While we have described several embodiments of our methyl borate and the corresponding metal methoxide, invention it is to be understood that within the scope of the methyl borate can be recovered from the byproduct 30 the claims appended hereto this information may be by heating to cause thermal decomposition. Sodium practiced otherwise than as specifically described. tetramethoxyborate, however, is relatively stable and has Having thus described our invention and the manner in at 280 C. a dissociation pressure of only about 31 milli which it is to be performed, what we desire to claim and meters of mercury. At a temperature sufficiently high to secure by Letters Patent of the United States is: dissociate the sodium tetramethoxyborate to methyl bo 35 1. A method of preparing lithium tetramethoxyborate rate other side reactions occur reducing the yield of which consists of reacting a lithium halide and a salt of methyl borate and contaminating the product. In con the class consisting of NaB(OCH3)4 and KB(OCH3)4 in trast, lithium tetramethoxyborate has a dissociation pres methanol, separating the solid alkali halide by-product, sure of 100 millimeters of mercury at only about 260' C. and recovering the lithium tetramethoxyborate from meth and dissociates cleanly to methyl borate without any side 40 anol solution. reactions. 2. A method according to claim 1 in which the alkali Also, since lithium tetramethoxyborate decomposes tetramethoxyborate is sodium tetramethoxyborate. without side reactions to lithium methoxide and methyl 3. A method according to claim 1 in which the alkali borate, it is possible to produce high purity lithium tetramethoxyborate is potassium tetramethoxyborate. methylate from lithium tetramethoxyborate rather than 45 4. A method according to claim 1 in which a solution of LiCl, in methanol and a solution of the alkali metal from the old and more expensive reaction of lithium metal tetramethoxyborate in methanol are reacted. and methanol. 5. A method according to claim 1 in which a solution It is an object of this invention to provide a method of of the alkali metal tetramethoxyborate is reacted with sol preparing lithium tetramethoxyborate by a metathetic 50 id LiCl, reaction of a lithium halide such as lithium chloride and 6. A method according to claim 1 in which a solution another alkali metal tetramethoxyborate in solvent of LiCl, in methanol is reacted with the solid alkali metal methanol. tetramethoxyborate. Other objects of this invention will become apparent 7. A method according to claim 1 in which methanol as described in the specification and the claims hereinafter 55 is added to a mixture of solid LiCl and the solid alkali related. metal tetramethoxyborate. This invention is based upon our discovery that a lith ium halide such as lithium chloride and a tetramethoxy References Cited in the file of this patent borate salt of an alkali metal other than lithium will react Brown et al.: "American Chemical Society Journal,” in methanol solution to produce a solid alkali metal halide 60 vol. 75 (1953), page 192. and a solution of lithium tetramethoxyborate. Lithium Schlesinger et al.: "American Chemical Society Jour tetramethoxyborate may be recovered from the solvent nal vol. 75 (1953), page 190,