FIELD OF THE INVENTION The present invention relates to the preparation of aromatic dia ines from phenol, dihydroxybenzenes or dihydroxynaphthalenes with a 10 bromoaniline using potassium carbonate and copper (I) chloride as catalyst.

BACKGROUND OF THE INVENTION U.S. Patent 4,222,962 discloses making

15 1,3-bis(3-aminophenoxy)benzene by reaction of

3-aminophenol with 1,3-dibromobenzene. This reference describes the making of 1,3-bis(3-nitrophenoxy)benzene by the reaction of 3-bromonitrobenzene with the sodium salt of resorcinol in pyridine with a copper catalyst.

20 U.S. Patent 4,692,554 discloses a two-step process for making 1,3-bis(3-aminophenoxy)benzene. The first step involves the condensation of an alkali metal salt of 3-aminophenol with tri- and tetrahalo- benzenes. The second step is removal of the remaining

25 halogens by reduction.

In the past, 3-(3-aminophenoxy)aniline has been prepared by reduction of 3-(3-nitrophenoxy)nitro¬ benzene or 3-(3-aminophenoxy)nitrobenzene.

30 SUMMARY OF THE INVENTION

The present invention relates to a process < for making aromatic diamines by the reaction of a potassium salt of resorcinol or an aminophenol with a bromoaniline in an amine solvent with a copper 35 catalyst. Aminophenols or resorcinol is converted to their potassium salt before reaction with the

bromoaniline generally by reation with a basic potassium compound in the reaction medium. The copper catalyst is a copper (I) salt such as cuprous chloride.

DETAILED DESCRIPTION OF THE INVENTION The process of the present invention forms diamines of the formula

where n is 0 or 1 and -Ar- is or by reacting a bromoaniline with a potassium salt of aminophenol or a dihydroxyaromatic compound. The aminophenol or dihydroxyaromatic compound is converted to an alkali metal salt such as lithium, sodium, potassium or cesium salt, which can be done in the reaction medium or the alkali metal salt can be charged to the reactor directly. Potassium and sodium salts are preferred with potassium salts being especially preferred. The reaction proceeds

2H ₂ N ι--f : KO-Ar-OK ....

or

The preferred bromoaniline is 3-bromoaniline. The preferred dihydroxyaromatic compound is resorcinol. The preferred aminophenol is 3-aminophenol.

The reaction is carried out in solution in an amine solvent. The amine solvent may be aromatic

amine such as pyridine, 4-picoline, 3-picoline, 2-picoline, quinoline, 2,6-lutidine, 3,4-lutidine, 3,5-lutidine, 2,4,6-collidine, 2-ethylpyridine, 3-ethyl pyridine, 4-methylmorpholine, N-methylpyr- rolidinone, N,N-dimethylacetamide and mixtures thereof. Pyridine and picoline are the preferred amine solvents with picoline being especially preferred.

Generally, from 0.02 to 0.15 mol catalyst is present per mol bromoaniline in the reaction medium. Copper (I) chloride is the preferred catalyst.

Generally, the reaction is carried out at 80" to 180 ^β C, with 120° to 160"C being the preferred range. Above 160 ^β C and especially above 180°C degradation of the organic materials begins to occur while below 120*C and especially below 80"C the reaction time becomes undesirably long.

The pressure is not critical and nominal atmospheric pressure is normally used. Of course, in order to use the higher temperatures possible, some pressure must be employed to maintain the reactants in the liquid phase. Normally the reaction is carried out at the atmospheric reflux temperature of the reactants. If a aminophenol or dihydroxyaromatic compound rather than their potassium or sodium salts are used as starting material, a basic potassium or sodium compound is added to the reaction to form the corresponding potassium or sodium salt. The potassium salts are preferred. Suitable potassium compounds include K 0, KOH and potassium salts which do not leave a residue deleterious to the reaction or materials used. Potassium carbonate is the preferred potassium compound. The potassium is resupplied to the reaction medium after _^ the compound KO-Ar' where -Ar' is-[[ J

bromoaniline so that the potassium compound can be present in the reaction medium in an amount less than a molar equivalent to the number of aromatic OH groups present. The catalysts are Ullmann ether synthesis catalysts, i.e., a metal salt such as a copper salt and in the presence of a suitable solvent for the reaction such as pyridine. Preferred are the copper salts such as cuprous chloride (Cu Cl ) or cupric chloride (CuCl ) albeit other soluble copper salts can be used.

The reactants preferably are present in the reactor in about the molar amounts necessary to form the desired product. Thus, from 0.8 to 1.2 mols of bromoaniline is preferably persent per mol of aminophenol (or its potassium salt) or 1.6 to 2.2 mols of bromoaniline per mol of resorcinol (or its potassium salt) present.

The preferred products are 1,3-bis(3-amino- phenoxy)benzene and 3-(3-aminophenoxy)aniline which are useful in forming polyamides and polyimides by reaction with aromatic diacids or diacid chlorides or aromatic dianhydrides such as terephthalic acid, terephthalolyl chloride, pyromellitic dianhydride or benzophenonetetracarboxylic dianhydride. The product aromatic polyamides and aromatic polyimides are useful as structural resins, high temperature coatings and in forming gas separation membranes.

EXAMPLE 1

To a 1000 ml four-necked flask equipped with a mechanical stirrer, thermometer with a Thermowatch, a Dean-Stack trap with a condenser, a nitrogen supply and a heating mantle were added 3-aminophenol (140.0 g, 1.28 mols), potassium carbonate (120 g, 0.86 mol), copper (I) chloride

(8.0 g, 0.08 mol) and 600 ml pyridine. The mixture was heated to reflux. After two hours 150 ml of distillate was removed and 3-bromoaniline (200.0 g, 1.16 mols) was added. Molecular sieves (4A) were added to the trap after 13 hours to absorb the bulk of the water in the pyridine being distilled. The reaction mixture was cooled to 80*C and mixed with 600 ml of toluene. The mixture, at 85*C, was filtered through a bed of Celite** filter aid in a sintered glass funnel. The toluene was extracted once with 200 ml of 10% aqueous sodium hydroxide and twice with 200 ml of water. The toluene was heated to 100 ^β C and treated with 15 g of decolorizing carbon. At 85*C the mixture was filtered to remove the carbon. The solution was concentrated by distilling off about 200 ml toluene and cooled in an ice bath. The product was isolated by filtering and washed with 40 ml of toluene. After air and vacuum oven drying 135.7 g of nearly white crystals were obtained which had: mp 84.5 ^β -85.2*C; no observable impurities by gas chromatographs; NMR (DMS0-D6) 6.95 (m, 2H) , 6.28 (m, 2H) , 6.13 (m, 4H) , 5.15 (5, 4H) ; UV (CH3CN) 292 (2.02); ir (KBr) 1150, 1180, 1485, 1570, 1600, 1620,

3200-3600. On concentration of the mother liquor, a further 11.3 g of product was obtained.

EXAMPLE 2 To a four-necked round bottom flask equipped with a mechanical stirrer, thermometer with a Thermowatch, Dean-Stack trap with condenser, heating mantle and a nitrogen supply was added resorcinol (15.8 g, 0.144 mol), potassium carbonate (30 g, 0.215 mol), copper (I) chloride (2.5 g, 0.025 mol) and 200 ml of pyridine. The mixture was heated to reflux and 50 ml of distillate removed. 3-Bromoaniline (50.0 g, 0.291 mol) was added all at once. The mixture was

held at reflux and the course of the reaction followed by gas chromatography. After 26 hours most of the pyridine was removed by distillation under reduced pressure. The residue was treated with 300 ml of toluene and 3.5 g of decolorizing carbon. The resulting mixture was heated to 75 ^β C and filtered through a pad of Celite* filter aid. While still warm, the toluene solution was extracted with 100 ml of 10% sodium hydroxide twice and three times with 200 ml of water. By distillation 200 ml of toluene was removed and the remaining solution cooled first in water and then ice. The resulting crystalline product was collected on a filter and washed with 40 ml of toluene. After drying in a vacuum, over 28.9 g (58.8% yield) of off-white crystals were obtained which found by gas chromatography to be

1,3-bis(3-aminophenoxy)benzene with a purity of 99.4%: mp 103*-108'C.

EXAMPLE 3

To a 1000 ml four-necked flask equipped with a mechanical stirrer, a thermometer with a Thermowatch, a Dean-Stark trap, a nitrogen supply and a heating mantle were added resorcinol (23.7 g, 0.215 mol), potassium carbonate (45.0 g, 0.326 mol), copper (I) chloride (5.0 g, 0.050 mol) and 275 ml of 3-picoline. The mixture was heated to reflux, held at 150 ^Q C for 60 minutes and 50 ml of distillate removed. To the flask was then added 3-bromoaniline (75.0 g, 1.68 mols). The mixture was held at reflux and the course of the reaction was followed by gas chromatography. After 9 hours the reaction was judged complete and the bulk of the solvent removed by vacuum distillation. Toluene (300 ml) and decolorizing carbon (4 g) were added to the residue and the mixture heated to 100 ^β C and held for 30 minutes. The mixture

was cooled to 80"C and filtered through a pad of Celite* filtering aid and the cake washed with 30 ml of toluene. The warm filtrate was washed with 200 ml of 10% sodium hydroxide and with 200 ml of water twice. The toluene layer was concentrated by the evaporation of 160 ml of toluene and cooled to 0 ^β c to cause crystallization of the product. The product was collected by filtering and dried in a vacuum oven at 90"C and 125 mm giving 39.2 g (62%) of product which was >99% pure by gas chromatography.