GB710716A - Improvements in or relating to the preparation of 1-phenyl-2-dihalogenacetylamino-1:3-propandiols and derivatives thereof substituted in the phenyl residue - Google Patents

Abstract

1-Phenyl- and 1-nitrophenyl-2-dihaloacetylamino-1 : 3-propanediols are manufactured by reacting the corresponding aminodiols with a trihaloacetaldehyde and simultaneously or subsequently with a metal cyanide, if desired in the presence of an acid-binding agent, or with hydrogen cyanide in the presence of an acid-binding agent. The metal cyanide is preferably an alkaline-earth metal or especially an alkali metal cyanide, and may be used in an amount of 1 mol. or more per mol. of aminodiol, or, when an acid-binding agent (preferably in excess) is present, in catalytic proportions, e.g. 0.01-0.1 mols. per mol. of aminodiol. The reaction may be carried out in a solvent, e.g. water, an alcohol such as methanol or ethanol, or a hydroxyl-free neutral solvent such as dioxan. In examples: (1), (2) and (4) DL-threo-1-(p-nitrophenyl)-2-amino-1 : 3-propanediol is suspended in water and warmed with chloral and sodium or barium cyanide; (3) the L-isomer is treated as in (2) to produce chloramphenicol; (5) and (6) the water in (1), when using sodium cyanide, is replaced by dioxan or methanol, in which the aminodiol dissolves; (7) the process of (2) is carried out in the presence of calcium carbonate and only a catalytic amount of sodium cyanide; (8) and (9) DL- or L-threo-1-(p-nitrophenyl)-2-amino-1 : 3-propanediol is allowed to stand with chloral in dioxan, and the resulting chloralamine of the formula <FORM:0710716/IV (b)/1> is isolated in crude form, dissolved in dioxan and refluxed with a suspension of sodium cyanide in methanol; (10) DL-erythro-1-phenyl-2-amino-1 : 3-propanediol is treated as in (1); (11) DL - threo - 1 - (p - nitrophenyl) - 2 - amino - 1 : 3 - propanediol is suspended in aqueous hydrocyanic acid and the suspension is stirred with chloral with the addition of caustic soda solution. Tribromoacetaldehyde is also specified as a reactant, and alkali metal carbonates and bicarbonates, magnesium oxide and magnesium carbonate as acid-binding agents.