Patent GB-989293-A (GB)
Title: Boron compounds
Inventor: MILLER HENRY CHARLES
IPC: C01B35/18
Filed: 1961-06-07
Abstract: Polyhydropolyborates of the general formula M1a(BnHm)b, where M1 is an alkali or alkaline earth metal, (BnHm) is an anion in which n and m are respectively 3 and 8, 11 and 14, or 12 and 12, and a and b are 1 or 2 depending on the valencies of M1 and (BnHm), are prepared by contacting diborane at superatmospheric pressure with a compound of the formula M1(BH4)x where x is 1 or 2.  The process is especially useful for preparing alkali and alkaline earth metal compounds of the divalent anion B12H12 which has characteristic absorption bands in the infra-red absorption spectrum and a characteristic X-ray diffraction structure for the cesium salt; the sodium salt has a low solubility in 1,2-dimethoxyethane.  These compounds may be converted by metathetic reactions to compounds having different cations, e.g. metals; ammonium, amine or hydrazonium, which may be substituted with hydrocarbon groups; aryldiazonium, ammino-metal, substituted polyphosphonium, or substituted sulphonium.  Many specific cations are referred to.  The process according to the invention also produces salts of the monovalent anion B11H14 which has characteristic infra-red absorption, nuclear magnetic resonance, and ultra-violet absorption, and characteristic X-ray diffraction pattern for the cesium salt; the sodium salt is highly soluble in 1,2-dimethoxyethane. Both types of reaction products are mainly stable crystalline solids which are soluble in water or hydroxylated solvents and may contain water or solvent of crystallization. Examples describe reaction of NaBH4 with B2H6 in the presence of dry 1,2-dimethoxyethane at 25 DEG  or 60 DEG  C. to form NaB3H8, and conversion of this salt to (CH3)4N.B3H8 and CsB3H8; a similar reaction at 100 DEG  C. yields a product from which Na2B12H12 with solvent of crystallization is obtained from the 1,2-dimethoxyethane-insolubl part, and (CH3)4N.B11H14 from the soluble part.  Other examples use ethyl ether, triethylamine, benzene, tri-(n-butyl) phosphine, or dimethyl sulphide as the inert solvent and describe the preparation of NaB11H14; reaction temperatures of 120 DEG  C. and 180 DEG  C. are also used and in one example the reactant is KBH4.  An alkali metal or hydride thereof will react at above 100 DEG  C. with the diborane to form the hydroborate in situ.  Inert gases may be charged to the reaction vessel to provide the increased pressure. An acid having the B12H12 anion is obtained by treating a solution of the salt with a strong inorganic or organic acid, or by using an acidic ion exchange resin (see Specification 989,294).  The polyhydropolyborates are useful as sequestering agents, e.g. to remove copper from gasoline or aqueous media.ALSO:Polyhydropolyborate salts of the general formula Ma(B12H12)b are prepared by metathetic reactions from corresponding alkali or alkaline earth metal salts (see Division C1).  M may be substituted ammonium, hydrazonium, substituted hydrazonium, aryl diazonium, substituted polyphosphonium, substituted sulphonium, a polybasic nitrogenous cation, or (NH3)nY, where Y is Co, Ni, Cu, Zn, Cd, Hg, or Ag.  The compounds Zn(NH3)4B12H12 and (NH2-NH3)2B12H12 are specifically claimed. The preparation of (CH3)4NB3H8 and (CH3)4 NB11H14 from corresponding sodium salts is also described. Specification 989,294 is referred to.