Patent EA-001708-B1 (EA)
Title: Preparation of substituted aromatic amines
Inventor: WHEELER EDWARD L
IPC: C01C3/12
Filed: 1997-03-13
Abstract: 1. A method for preparation of substituted aromatic amines of formula (I) comprising the steps of: (a) oxidizing a solution of an aromatic amine of formula (II) in the presence of an oxidizing agent and a metal pentacyanoferrate (II) complex to form an arylenediaminpentacyanoferrate complex, said metal being selected from the group consisting of potassium and sodium; and (b) catalytically reducing said arylenediaminpentacyanoferrate complex with hydrogen using a heterogeneous metal catalyst, producing the corresponding substituted aromatic amines of formula (I)   wherein n equals 2 to 5, and R1 and R2 are as set forth below;   R1 and R2 may be the same or different, must be ortho or meta to the amino group, and may be hydrogen, C1-C4alkyl, C1-C4alkoxy, halogen, cyano, COO ions, forming salts and amides or mixtures thereof. 2. The method of Claim 1 wherein the oxidizing agent is oxygen or hydrogen peroxide. 3. The method of Claim 2 wherein the oxidizing agent is oxygen and a heterogeneous metal catalyst is present during said oxidizing step. 4. The method of Claim 2 wherein the oxygen used is under pressure ranging from about 1 to 100 atmospheres. 5. The method of Claim 2 wherein the oxygen in the oxidizing step and the hydrogen in the reducing step are used under pressures independently selected and ranging from about 2 to about 75 atmospheres. 6. The method of Claim 1 wherein the metal pentacyanoferrate (II) complex is a trisodiumpentacyanoferrate (II) complex containing water soluble ligands selected from the group consisting of ammonia, monoalkyl-amines, dialkylamines, trialkylamines, N,N-dimethylaminoethanol, N,N,N',N'-tetramethylethylenediamine and pyridine. 7. The method of Claim 6 wherein the trisodiumpentacyanoferrate (II) complex has the structure Na3[Fe(CN)5NH3.xH2O], or its dimer. 8. The method of Claim 1 wherein the heterogeneous metal catalyst is a supported catalyst selected from the group consisting of palladium, platinum, ruthenium, rhodium, or nickel. 9. The method of Claim 8 wherein the catalyst is platinum or palladium. 10. A method for producing N-phenyl-p-phenylenediamine comprising the steps of: a) oxidizing aniline in the presence of an oxidizing agent trisodiumpentacyanoferrate (II) complex to form an N-phenyl-p-phenylenediaminopentacyanoferrate complex; and b) catalytically reducing the N-phenyl-p-phenylenediaminpentacyanoferrate complex with hydrogen using a heterogeneous metal catalyst to yield N-phenyl-p-phenylenediamine. 11. The method of Claim 10 wherein a water-miscible organic solvent is added to solubilize the aniline and is selected from the group consisting of ethyleneglycol, propyleneglycol, diethyleneglycol, triethyleneglycol and mixtures thereof. 12. The method of Claim 10 wherein the N-phenyl-p-phenylenediaminpentacyanoferrate complex is subjected to hydrogenation in the presence of a heterogeneous metal catalyst in the presence of a water-immiscible solvent selected from the group consisting of butylacetate, hexanol, 2-ethyl-1-butanol, hexyl-acetate, ethyl butylacetate, amylacetate and substituted or unsubstituted aniline. 13. The method of Claim 1 further comprising the steps of: (c) recovering the metal pentacyanoferrate (II) complex which was reformed during the reducing step; and (c) recycling said complex by repeating said oxidizing step (a) using the metal pentacyanoferrate (II) complex. 14. The method of Claim 1 wherein said oxidizing step is conducted in an aqueous medium. 15. The method of Claim 1 wherein said oxidizing step (a) is carried out at temperatures range from 40 degree C to 55 degree C and said reducing stage (b) has reaction temperatures range from about 5 degree C to about 60 degree C for reacting with hydrogen. 16. The method of Claim 1 wherein reaction pH is from 10 to 12. 17. The method of Claim 1 wherein reaction pH is maintained mainly under rate, equal pH of water-solution metal pentacyanoferrate (II) complex.