Patent GB-922383-A (GB)
Title: New substituted azobenzenes and their use in fungicidal compositions
Inventor: GEOGHEGAN MICHAEL JOSEPH AUGUS
IPC: C09B43/08
Filed: 1959-10-26
Abstract: The invention comprises monoazo compounds of formula H2N-R-N=N-R1-OH wherein R is a benzene residue substituted by one or more halogen atoms or alkyl or alkoxy radicals of 1-4 carbon atoms, R1 is a benzene residue which may be substituted by one or more hydroxy groups, halogen atoms or alkyl or alkoxy radicals of 1-4 carbon atoms, the amino and hydroxy groups being linked in paraposition to the azo group; and salts thereof.  They are prepared by coupling a diazonium compound of a para-nitroamine O2N-R-NH2 with a phenol R1-OH and reducing the nitro-azo compound to an aminoazo compound.  The compounds are used in fungicidal seed-dressing compositions (see Groups I and VI).  In an example the monoazo compound 2-methyl-4-nitroaniline--> phenol is prepared and refluxed with aqueous sodium sulphide to give 4-amino-41-hydroxy-2-methyl-azobenzene: the following derivatives of 4-amino-41-hydroxyazobenzene are also prepared:-2-methoxy-, 2-chloro-, 3-methyl-, 3-methoxy-, 2,21- or 2,31-dimethyl-, 21 or 31-methoxy-2-methyl-, 31-chloro-2-methyl-, 2,31,51-trimethyl-, 3,31,51-trimethyl-, 2-chloro-31,51-dimethyl-, 2-chloro-31-methoxy-, 2,31-dichloro-, 3,31-dimethoxy-, 2,5-dimethyl-31methoxy-, 2,5,31,51-tetramethyl-, 2-ethyl-31-methoxy-, 31,51-dimethyl-3-methoxy-, 31-ethoxy-2-methyl-, 31-ethyl-2-methyl- and 21-hydroxy-2-methyl-.  The preparation of the following salts is described:-hydrochloride, hydrobromide and p-toluenesulphonate of 4-amino-41-hydroxy-2,31,51-trimethyl-azobenzene and hydrochloride of 4-amino-41-hydroxy-31-methoxy -2-methylazobenzene; solutions in aqueous methanol of the sodium and potassium salts of 4-amino-41-hydroxy-2,3151-trimethylazobenzene.ALSO:Seed is treated before sowing with fungicidal compositions (see Group VI) which contain, as active ingredient, an azo compound of formula: H2N-R-N=N-R1-OH wherein R is a benzene residue substituted by one or more halogen atoms or alkyl or alkoxy radicals of 1-4 carbon atoms, R1 is a benzene residue which may be substituted by one or more halogen atoms, hydroxy groups or alkyl or akoxy radicals of 1-4 carbonaatoms, the amono and hydroxy group being linked in p-position to the azo group; or a salt thereof (see Group IV(c)).  Specified seeds are wheat, cotton and pea seeds.  The compositions may be in powder or liquid form.  In examples pea seeds are treated with powder compositions wherein china clay is the diluent or with solutions of alkali metal salts of the compounds dissolved in aqueous methanol. The treated seeds are tested for resistance to Pythium ultimum and compared with seeds treated with tetramethylthiuram disulphide. Other suitable diluents for powdered compositions are: talc, gypsum, basic slag, kieselguhr and bentonite.  The active ingredient may also be dissolved or suspended in water, acetone, diacetone alcohol or dimethylformamide.ALSO:Fungicidal compositions used for treating seeds (see Group I) contain as active ingredient a compound of formula H2N-R-N=N-R1-OH wherein R is a benzene residue substituted by one or more halogen atoms or alkyl or alkoxy radicals of 1-4 carbon atoms, R1 is a benzene residue which may be substituted by one or more hydroxy groups, halogen atoms or alkyl or alkoxy radicals of 1-4 carbon atoms, the amino and hydroxy groups being linked in p-position to the azo group 1 or a salt thereof (see Group IV (c)).  The compositions may be in powder form wherein the active ingredient is admixed with a diluent such as talc, china clay, gypsum, basic slag, kieselguhr or bentonite and possibly with other ingredients such as mineral oil and sticking, binding or wetting agents.  The compositions may also be liquid, the active ingredient being dissolved or suspended in water or an organic solvent e.g. acetone, diacetone alcohol or formamide.  In examples the compounds are compounded with china clay or used as solutions of their alkali metal salts in aqueous methanol.