Patent GB-746047-A (GB)
Title: New ox-diazole compounds and process for their manufacture
Filed: 1953-05-20
Abstract: The invention comprises oxadiazoles of the formula <FORM:0746047/IV(a)/1> where R and R1 are aromatic, aliphatic or araliphatic residues and R2 is an aliphatic or aromatic residue, at least one of these groups containing a conjugated system of double bonds conjugated to the adjoining oxadiazole ring, and all these residues being free from groups imparting dyestuff characteristics; W1 and W2 are amino, carboxylic acid or sulphonic acid, m is 0, 1 or 2 and n is 0 or 1.  These compounds can be made in various ways: (1) an acid hydrazide W1-R-CO-NH-NH-CO-[(R2) n-CO-NH-NH-CO-]m-R1-W2 is treated with an inorganic dehydrating agent, e.g. oleum, chlorsulphonic acid, thionyl chloride or phosphorus pentachloride; (2) a product containing no groups W1 and W2 is treated to introduce such groups, e.g. direct sulphonation, hydrolysis of carboxylic ester, carboxylic amide or trichloromethyl groups or reduction of nitro groups; in this way a dyestuff-forming group can be simultaneously removed; (3) reactions (1) and (2) can be carried out simultaneously, e.g. the dehydrating agent may sulphonate at the same time; (4) further modification of the groups W1 and W2 may be effected, e.g. amino groups can be converted into salts with inorganic or organic acids and/or reacted with solubility-imparting compounds, e.g. aldehyde bisulphite compounds, bromethanesulphonic acid, chloracetic acid, benzyl chloride sulphonic acid or butane sultone; amino groups may also be alkylated or aralkylated; sulphonic and carboxylic acid groups can be converted into their alkali metal or ammonium salts.  The acid hydrazides used as starting materials may be prepared by reacting hydrazine simultaneously or successively with two mols. of carboxylic acid (same or different) or derivative thereof, the groups W1 and W2 (or precursors thereof-see (2) above) being present in the carboxylic acid molecule or introduced at the time of the condensation.  The products can be used as fluorescent brightening agents as in Specification 746,046, [Group III].  In the examples (1) cinnamic acid, hydrazine sulphate and oleum are condensed to give 2:5 - bis - (sulphostyryl) - 1:3:4 - oxadiazole; (2) the same product is obtained from chlorosulphonic acid and N:N1-dicinnamoyl-hydrazine, the latter prepared from cinnamoyl chloride and hydrazine hydrate; (3) 2:5-bis(sulpho-a -naphthyl)-1:3:4-oxadiazole is produced from a -naphthoic acid, hydrazine sulphate and oleum; (4) cinnamic acid, oxalic dihydrazide and oleum are condensed to bis-[5-sulphostyryl - 1:3:4 - oxadiazolyl - (2)]; (5) a :b  - bis - [5 - sulphostyryl - 1:3:4 - oxadiazolyl - (2)] - ethylene is obtained from cinnamic hydrazide, fumaric acid and oleum; (6) 4-phenylbenzoic acid, cinnamic hydrazide and oleum are reacted to give 2-sulphostyryl-5-sulphodiphenylyl - 1:3:4 - oxadiazole; (7) 2:5 - bis - (p - dimethylaminophenyl) - 1:3:4-oxadiazole is prepared from p-dimethylaminobenzoic acid, hydrazine sulphate and oleum; (8) p-nitrobenzoyl chloride (or p-nitrobenzoic acid) is reacted with hydrazine sulphate to give N:N1 - di - (p - nitrobenzoyl) - hydrazine and ring closed to 2:5-bis-(p-nitrophenyl)-1:3:4-oxadiazole; the nitro groups are then reduced to amino and condensed with formaldehyde sodium bisulphite yielding 2:5-bis-(p-sulphomethylamino - phenyl) - 1:3:4 - oxadiazole; (9) 2:5 - bis - (m - carboxyphenyl) - 1:3:4-oxadiazole is obtained from isophthalic acid, hydrazine sulphate and oleum; (10) N:N1-di-(p - carbethoxybenzoyl) - hydrazine (from terephthalic acid chloride monoethyl ester and terephthalic monohydrazide ethyl ester, or from hydrazine hydrate and 2 mols. of terephthalic acid chloride monoethyl ester) is ring closed with chlorsulphonic acid and the ester groups hydrolysed to give 2:5-bis-(p-carboxyphenyl)- 1:3:4 - oxadiazole; the bis - (m-carboxyphenyl) isomer and the mixed m- and p-isomer are prepared similarly; (11) hydrazine hydrate and p-trichloromethyl-benzoyl chloride are condensed together and the product treated with oleum to yield the product of (10); (12) 1:4 - bis - [51 - (m - carboxyphenyl) - 11:31:41-oxadiazolyl - 21] - benzene is prepared from terephthalic acid dihydrazide, isophthalic acid and oleum; (13) bis-[5-(m-carboxyphenyl)-1:3:4-oxadiazolyl-2] is similarly obtained from oxalic acid dihydrazide; (14) the p-carboxy isomer of (13) is prepared from N:N1-bis-(p-carbethoxybenzoyl)-oxalic dihydrazide (from terephthalic acid chloride monoethyl ester and oxalic dihydrazide or from terephthalic monohydrazide ethyl ester and oxalyl chloride) by ring-closure with chlorsulphonic acid and hydrolysis of the ester groups; (15) terephthalic monohydrazide ethyl ester is condensed with maleic anhydride to give N-(p-carbethoxybenzoylamino)-maleimide and the latter rearranged by chlorsulphonic acid to 2-(p-carbethoxyphenyl) - 5 - (b  - carboxyvinyl)-1:3:7 - oxadiazole, hydrolysed to the corresponding dicarboxylic acid; the m-substitutedphenyl isomer is made similarly; (16) 2:5-bis(p - carboxyphenyl) - 1:3:4 - oxadiazole is condensed with cinnamic hydrazide and oleum to form 2:5-bis-[p-(51-sulphostyryl-11:31:41 -oxadiazolyl - 21-) phenyl] - 1:3:4 - oxadiazole; (17) 2 - sulphostyryl - 5 - (p - diethylaminophenyl) - 1:3:4 - oxadiazole is prepared from cinnamic hydrazide, p-diethylaminobenzoic acid and oleum; (18) N:N1 - di - (p - trichloromethyl - benzoyl) - hydrazine is hydrolysed to the p-carboxybenzoyl compound and ring closed with chlorosulphonic acid to 2:5-bis-(p - carboxyphenyl) - 1:3:4 - oxadiazole.  Other substituted 1:3:4-oxadiazoles that can be made similarly are 2:5-bis-(sulpho-o-chlorostyryl), 2:5 - bis - (sulpho - p - chlorostyryl), 2:5 - bis - (sulpho - p - methylstyryl), 2:5 - bis-(sulpho - p - diphenylyl), 2:5 - bis - (p - diethylaminophenyl) and 2:5 - bis - (41 - carboxy - p-diphenylyl]; also 1:4 - bis - (51 - sulphostyryl11:31:41 - oxadiazolyl - 21) - benzene and 1:4 - bis - [51 - (p - carboxyphenyl) - 11:31:41-oxadiazolyl - 21) - benzene. Sulphobenzoic acid may also be used as a starting material.  The radicals R, R1 and R2 may carry non-dyestuff-forming substituents such as halogen, alkyl or alkoxy.