A process for the production of the monozinc salt of hydroxymethane sulphinic acid from the dizinc salt

摘要

The mono-zinc salt of hydroxy methane sulphinic acid is prepared by acting on an aqueous suspension of the di-zinc salt with sulphurous acid, separating the zinc sulphite formed and recovering the mono-zinc sulphinate from the solution. Preferably, sulphur dioxide is fed into the aqueous suspension with vigorous stirring at not above 25 DEG C. until the reducing power of a filtered sample of the solution no longer increases whereupon the solution is filtered to remove the zinc sulphite and the solution of mono-zinc sulphinate is evaporated down. An example is given.ALSO:Zinc sulphite is obtained in the production of mono-zinc hydroxy methane sulphinate (see Group IV(b)) and may be converted by means of formaldehyde into its formaldehyde compound and the latter reduced with zinc dust, or it may be converted into zinc bisulphite and the latter reduced with zinc dust to zinc hyposulphite.