Patent GB-817096-A (GB)
Title: New oxdiazoles and process for their manufacture
IPC: D06M13/35
Filed: 1955-07-06
Abstract: Colourless oxdiazoles which contain one oxdiazole ring and, directly bound to that ring, at least one aromatic nucleus containing an hydroxyl group are capable of absorbing ultraviolet rays, especially those of short wavelength, and may, therefore, be used to protect materials, especially organic materials such as textiles, foils and lacquers, from their harmful effects.  For the preparation of the oxdiazoles see Group IV (b).  In examples: (5) 2,5-bis-[21 - hydroxyphenyl - (11)] - 1,3,4 - oxdiazole is incorporated in a normal stabilized mixture of polyvinyl chloride with dioctyl phthalate as plasticiser and a foil obtained therefrom; (6) 2,5 - bis - [sulpho - 21 - oxyphenyl - (11)] - 1,3,4 - oxdiazole as its disodium salt is added to an aqueous solution of polyvinyl alcohol and a film obtained therefrom.  Specifications 746,046, 746,047 and 816,749 are referred to.ALSO:The invention comprises colourless oxdiazoles which contain one oxdiazole ring which has directly attached thereto at least one aromatic nucleus containing a hydroxyl group.  They may be made by treating a colourless N (1): N (2)-diacyl-hydrazine whose acyl groups are derived from carboxylic acids and in which at least one of the CO groups is bound to an aromatic nucleus containing a hydroxyl group, with thionyl chloride, anhydrous aluminium chloride, phosgene or a sulphonating agent.  The diacyl-hydrazines may be made by acylating hydrazine with agents such as methyl esters or acid halides of carboxylic acids advantageously in the presence of an organic solvent.  Acylating agents derived from dicarboxylic acids, e.g. maleic anhydride may be used in which case the diacyl hydrazine formed will contain a free carboxylic acid group which on ring closure with an agent such as thionyl chloride, yields an oxdiazole containing a carboxylic acid halide group so that condensation with arylamines may be effected. Preferred derivatives of carboxylic acids are those derived from acids of formula <FORM:0817096/IV (b)/1> where R1 is a cyclic residue e.g. 2-oxydiphenylene oxide-, -oxycarbazole-, -oxyanthracene- and -oxynaphthalene-3-carboxylic acids, the methyl ester of the latter being preferred. Advantageously the products contain no groups imparting water solubility.  Preferred ring-closing agents are those which do not yield a sulphonated product, e.g. thionyl chloride, which is preferred, and aluminium chloride or phosgene, the reaction being effected by heating the reactants in an organic solvent such as chloro- or nitro-benzene.  When oleum is used for ring closing, sulphonation of the aryl residue may result, as well as ring closure.  The oxdiazoles are dyestuff intermediates and protect organic materials such as textiles, foils, gelatine and lacquers from the harmful effects of ultra-violet rays.  Examples are provided of the preparation of the oxdiazoles by the methods outlined above, those made being (1) bis - 2,5 - [21 - hydroxynaphthyl - (31)]-, (2) and (3) 2 - [21 - naphthyl - (31)] - 5 - [411 - chloro - phenyl - (111)]-, (4) 2 - [21,41 - dihyoxyphenyl - (11)] - 5 - (phenyl)-, (5) 2,5 - bis - [21 - hydroxy - phenyl - (11)]-, (6) the sym. di-sodium sulphonates of 2,5-bis-[21- and 41-hydroxy-, 21,41-dihydroxy-and 21-hydroxy-41-methyl-phenyl-(11)]-, (7) the sym. di-sodium sulphonate of 2,5-bis - [21 - hydroxy - 31,51 - dichloro- and 21-hydroxy - 51 - chloro - phenyl - (11)]- and (8) the sodium salt of 2-[21-hydroxy-31,51-dichlorophenyl - (11)] - 5 - [311 - sulphophenyl-(111)]-1,3,4-oxdiazoles. Specifications 746,046, [Group IV (a)], 746,047 and 816,749, [Group IV (a)], are referred to.