Patent GB-345985-A (GB)
Title: Bleaching agents and method of producing same
IPC: A21D2/08
Filed: 1929-11-28
Abstract: Bleaching compounds are prepared by interaction of aldehydes, substituted aldehydes or material containing or setting free aldehydes, with acid halogenides in the absence of water.  The reaction mixture may be introduced into a finely-powdered mixture of a base adapted to facilitate the reaction: salts of weak acids or acids decomposed under the conditions of the process, metals such as powdered zinc, magnesium, aluminium or calcium may be used instead of the base.  Halogenating agents such as phosphorus pentachloride, phosphorus pentabromide, phosphorus trichloride, phosphorus oxychloride, aluminium chloride, thionylchloride, bleaching powder, chloramine-T, dichloramine-T, potassium chlorate or potassium perchlorate may be added.  Catalysts or diluents may be added before, during, or after the reaction.  The reaction may be carried out at an elevated temperature.  Aldehydes specified are acetaldehyde, propaldehyde, chloracetaldehyde, benzaldehyde, o-, m- and p-chlorbenzaldehyde, o-, m- and p-toluylaldehyde and ethylbenzaldehyde; as acid halides, acetyl chloride and bromide, chloracetyl chloride, benzoyl chloride, bromide and iodide, o-, m- and p-toluyl chloride and phenylacetyl chloride are mentioned. Examples are given of the interaction of benzaldehyde with benzoyl chloride and acetyl chloride, and of o-chlorbenzaldehyde with benzoyl chloride.ALSO:Flour, other milling products, and starches are bleached by intimately mixing aldehydes, substituted aldehydes or materials containing or setting free aldehydes with acid halogenides in absence of water and introducing the mixture into the flour or other material to be bleached.  The mixture may be introduced into a finely powdered mixture of a base adapted to facilitate the reaction: salts of weak acids or acids decomposed under the conditions of the process, metals such as powdered zinc, magnesium, aluminium or calcium may be used instead of the base. Halogenating agents such as phosphorus pentachloride, phosphorus pentabromide, phosphorus trichloride, phosphorus oxychloride, aluminium chloride, thionyl chloride, bleaching powder, chloramine-T, dichloramine-T, potassium chlorate or potassium perchlorate may be added.  Catalysts or diluents may be added before, during, or after the reaction.  The reaction may be carried out at an elevated temperature.ALSO:Starches are bleached by intimately mixing aldehydes, substituted aldehydes or material containing or setting free aldehydes with acid halogenides in absence of water and introducing the mixture into the material to be bleached.  The mixture may be introduced into a finely-powdered mixture of a base adapted to facilitate the reaction; salts of weak acids or acids decomposed under the conditions of the process, metals such as powdered zinc, magnesium, aluminium, or calcium may be used instead of the base.  Halogenating agents such as phosphorus pentachloride, phosphorus pentabromide, phosphorus trichloride, phosphorus oxychloride, aluminium chloride, thionylchloride, bleaching powder, chloramine-T, dichloramine-T, potassium chlorate, or potassium perchlorate may be added.  Catalysts or diluents may be added before, during, or after the reaction.  The reaction may be carried out at an elevated temperature.