Aqueous synthesis of 2-halo-4,6-dinitroresorcinol and 4,6-diaminoresorcinol

Abstract

The displacement of halogen from a 1,2,3-trihalo-4,6-dinitroresorcinol can be carried out in an aqueous medium using alkali metal hydroxide to form 2-halo-4,6-dinitroresorcinol. The product is a useful intermediate in the synthesis of 4,6-diaminoresorcinol, which is a monomer for polybenzoxazole polymers. The process from part of a useful aqueous process for synthesizing 4,6-diaminoresorcinol.

What is claimed is: 
     
       1. A process for synthesizing 2-halo-4,6-dinitroresorcinol, said process comprising the step of contacting a 1,2,3-trihalo-4,6-dinitrobenzene with .Iadd.at least about 6 moles of .Iaddend.hydroxide anions .Iadd.per mole of 1,2,3-trihalo-4,6-dinitrobenzene .Iaddend.in an aqueous solution or slurry containing essentially no alkanol under conditions such that a 2-halo-4,6-dinitroresorcinol is formed in yields of at least about 75 percent. 
     
     
       2. The process of claim 1 wherein each halogen on the 1,2,3-trihalo-4,6-dinitrobenzene is individually chlorine or bromine. 
     
     
       3. The process of claim 2 wherein each halogen on the 1,2,3-trihalo-4,6-dinitrobenzene is chlorine. 
     
     
       4. The process of claim 1 wherein the hydroxide anions are the product of an alkali metal hydroxide added to the reaction mixture or the aqueous solvent. 
     
     
       5. The process of claim 4 wherein the alkali metal hydroxide is lithium, sodium or potassium hydroxide. 
     
     
       6. The process of claim 4 wherein the alkali metal hydroxide is sodium hydroxide. .[.7. The process of claim 4 wherein the reaction mixture contains at least about 4 moles of alkali metal hydroxide per mole of 
     
     
        1,2,3-trihalo-4,6-dinitrobenzene..]. 8. The process of claim 4 wherein the reaction mixture contains .[.between about 4.5and.]. .Iadd.no more than about .Iaddend.8 moles of alkali metal hydroxide per mole of 
     
     
        1,2,3-trihalo-4,6-dinitrobenzene. 9. The process of claim 4 wherein the alkali metal hydroxide is added to a slurry containing water and 
     
     
        1,2,3-trihalo-4,6-dinitrobenzene. 10. The process of claim 1 wherein the reaction mixture contains at least about 80 moles of water per mole of 
     
     
        1,2,3-trihalo-4,6-dinitrobenzene. 11. The process of claim 1 wherein the reaction mixture contains at least about 100 moles of water per mole of 
     
     
        1,2,3-trihalo-4,6-dinitrobenzene. 12. The process of claim 1 wherein the temperature of the reaction is between about 60° C. and reflux. 
     
     
            A process for synthesizing 2-halo-4,6-dinitroresorcinol, said process comprising the step of contacting a 1,2,3-trihalo-4,6-dinitrobenzene with .Iadd.at least about 6 moles of .Iaddend.an alkali metal hydroxide .Iadd.per mole of 1,2,3-trihalo-4,6-dinitrobenzene .Iaddend.in an aqueous solution or slurry containing at least about 80 moles of water per mole of 1,2,3-trihalo-4,6-dinitrobenzene at a temperature of at least about 70° C. under conditions such that a 2-halo-4,6-dinitroresorcinol is 
     
     
        formed in yields of at least about 75 percent. 14. The process of claim 13 wherein the 1,2,3-trihalo-4,6-dinitrobenzene is 
     
     
        1,2,3-trichloro-4,6-dinitrobenzene. 15. The process of claim 14 wherein the reaction mixture contains .[.between 4 and.]. .Iadd.no more than about .Iaddend.8 moles of alkali metal hydroxide per mole of 
     
     
        1,2,3-trichloro-4,6-dinitrobenzene. 16. The process of claim 15 wherein the temperature of the reaction is between about 75° C. and 
     
     
        95° C. 17. The process of claim 16 wherein the reaction mixture contains between 100 and 200 moles of water per mole of 
     
     
        1,2,3-trihalo-4,6-dinitrobenzene. 18. The process of claim 17 wherein the alkali metal hydroxide is added to a slurry containing the water and the 
     
     
        1,2,3-trichloro-4,6-dinitrobenzene. 19. The process of claim 18 wherein the reaction mixture contains .[.between 4.5 and.]. .Iadd.no more than 
     
     
        about .Iaddend.7 moles of alkali metal hydroxide. 20. The process of claim 19 wherein the alkali metal hydroxide is lithium, sodium or potassium hydroxide.