GB885852A - Process for reduction with boron compounds - Google Patents

Abstract

Example 1 describes the preparation of a copper sol by adding pearl glue solution to aqueous or ammoniacal copper sulphate solution and then reducing with potassium borohydride. Example 4 describes the preparation in an analogous manner of a silver sol from silver nitrate solution.ALSO:Example 23 describes the preparation of asymmetrical dimethyl hydrazine by reducing nitrosodimethyl amine with sodium borohydride in the presence of a catalyst comprising an ammoniacal copper sol, a complex of copper chloride and aminoacetic acid or a complex potassium nickel cyanide together with pearl glue solution. Example 26 describes the reduction of nitrobenzene with sodium borohydride in the presence of a copper sol as catalyst to yield aniline together with small amounts of azobenzene and azoxybenzene, or when the catalyst is a complex potassium nickel cyanide or sodium anthraquinone-2-sulphonate, to yield azo benzene together with a small amount of azoxybenzene. In an analagous manner, nitrobenzene sulphonic acid may be reduced to the corresponding aminosulphonic acid, as also may benzyl cyanide to yield phenyl ethyl amine, or adipic acid diamide to yield hexamethylene diamine, or acetamide to yield ethyl amine.ALSO:In effecting reduction reactions, such as the vatting of vat dyestuffs or the removal of vat dyestuffs from textile materials, employing as the reducing agent an alkali metal or alkaline earth metal borohydride, or a borazane, borazene, or borazine, or a compound of the formula Na[B(OC2H5)3H] or BH3NH2.NH2.BH3, improved results are obtained by effecting the reaction in the presence of a catalyst comprising one or more of the following: (a) a metal sol of a metal possessing a solution potential more electropositive than -1.5 volts at a pH>7, such as a sol of Sn, As, Cu, Mo, Ni or Pt; (b) a metal complex compound the metal of which can be separated in the presence of a reducing agent at a redox potential between 0 volts and -1.5 volts at a pH of 8-15, such as a complex compound of Cu, Co, Ni, Sb, Mo, Sn or Cr with glycol, ethanolamine, ethylenediamine, b -diketones, a -hydroxycarboxylic acids or with ammonia or hydroxyl or halogen ions; (c) an inorganic compound which is a component of an inorganic redox system the potential of which lies between 0 volts and -1.5 volts at a pH of 8-15, such as the complex alkali metal cyanides of bivalent Ni, Co, Cr, or Mn, or an alkali metal stannate; and (d) an organic compound which is a component of an organic redox system the potential of which lies between 0 volts and -1.5 volts at a pH of 8-15, and where the reduction of this organic redox system involves hydrogenation, or where its oxidation involves dehydrogenation, such as anthraquinone-2-sulphonic acid, 1-amino-anthraquinone-8-sulphonic acid, 1-amino-4-bromoanthraquinone-2-sulphonic acid, 4-aminoanthraquinone-6-sulphonic acid, N,N1-dihydro-anthraquinone-azine-3,31-disulphonic acid, naphthol, indigo-trisulphonic acid and di - [anthraquinonyl - (1)] - amine, although many other substances are listed in Example 12. Improved results may further be obtained by the addition to the catalyst of a compound of tetravalent sulphur, such as sodium bisulphite or sodium sulphite, or a compound yielding the sulphite or bisulphite ion in water, such as sulphur dioxide, a metabisulphite, a dithionate or a dithionite. Numerous examples describe the vatting of various vat dyes followed by dyeing of textiles therewith, and Example 25 describes the removal of a vat dye from a fabric. Specifications 773,794, 818,790, 872,998 and 885,851 are referred to.