NOVEL BIS M-BENZOTRIFLUORIDE COMPOUNDS

Abstract: Disclosed are bis-meta-benzotrifluoride compounds having the general formula where each A is independently selected from the group consisting of NO₂, NH₂, and NH₃⁺Z⁻, Z⁻ is an anion, and B is selected from the group consisting of O, CO, S, SO, and SO₂. The diamine compounds are useful as monomers in making polyimides, polyamide-imides, and polyamides.

Description: This invention relates to novel bis-m-benzotrifluoride compounds. In particular, it relates to bis-m-benzotrifluoride diamines, precursors for making the diamines, and to polymers made from the diamines. Polyimides are condensation polymers usually made by reacting a primary diamine with a dianhydride or tetracarboxylic acid. Aromatic polyimides, where both the diamine monomer and the dianhydride or tetracarboxylic acid monomer are aromatic, exhibit outstanding mechanical properties and excellent thermal and oxidative stability. They are widely used in place of metals and glass in high performance applications throughout the electrical, electronic, automotive, aerospace, and packaging industries. The properties of a particular polyimide depend, of course, on the particular diamines and dianhydrides or tetracarboxylic acids used in making it. Properties that are very useful in the electronics industry include a high solubility of the polyimide in organic solvents and a low dielectric constant. If the polyimide is to be used as a film, it is desirable that it be colorless and transparent so that the underlying substrate is visible and undistorted. The object of the invention is the provision of a new class of diamines, and precursors for making those diamines, which are very useful as monomers in making polyimides. The diamines of this invention contain two benzotrifluoride groups which give the resulting polyimides excellent electronic properties, particularly a high solubility in organic solvents and a low dielectric constant. Unlike other benzotrifluoride diamines known in the art, the benzotrifluoride diamines of this invention are meta -benzotrifluoride diamines which means that the substituents on the benzene ring are in the 1,3,5 positions. Because the substituents are meta, the resulting polyimides are much more stable than similar, but non-meta, benzotrifluoride diamines. The novel meta-benzotrifluoride compounds of this invention have the general formula where A is NO₂, NH₂, or NH₃⁺Z⁻, and B is O, CO, S, SO, or SO₂. The nitro compounds (where A is NO₂) are intermediate compounds used to make the diamine. When A is NH₃⁺Z⁻, an amine salt is formed where Z is an anion. Examples of suitable anions include chloride, bromide, fluoride, sulfate, and bisulfate. The chloride anion is preferred as compounds necessary to make the chloride salt are inexpensive and readily available. In the above formula, B is preferably O, CO, or SO₂ as those compounds are the most useful in making polyimides. The diamines of this invention can be prepared by a variety of methods, the appropriateness of a method depending upon the particular diamine that is being prepared. The ether (where B is O) can be prepared by heating 3,5-dinitrobenzotrifluoride in an organic solvent in the presence of water and about two equivalents (based on the product weight) of potassium or cesium fluoride which results in the dinitrodibenzotrifluoride ether: 1,1'-oxybis(3-nitro-5-trifluoromethyl) benzene In this reaction, it is preferable to use potassium fluoride as a catalyst and N,N-dimethylformamide (DMF) as a solvent and to heat at a temperature between about 120 and 160°C. The reaction also produces small amounts of higher ethers. The ether can also be prepared by heating a nitro benzotrifluoride compound having the formula where x is NO₂, Cl, F, or a mixture thereof, with potassium fluoride, cesium fluoride, or a mixture thereof, as described in co-pending European Patent Application EP90114684.5 filed of even date by Occidental Chemical Corporation, titled "Method of making 1-1'-Oxybis(3-nitro-5-trifluoromethyl) benzene''. The diamine can be prepared from the corresponding dinitro compound by heating in a reducing agent, such as 10 to 50% iron and 1 to 20% hydrochloric acid: 4,4'-oxybis(3-trifluoromethyl)-benzamine That reaction can be performed at a temperature of 0°C to room temperature; ammonium sulfide can also be used as a reducing agent. The presence of an acid in the reduction reaction results in the formation of an amide salt (i.e., A is NH₃⁺Z⁻). The amine salt can be easily converted to the amine by the addition of any base such as sodium hydroxide, triethyl amine, or pyrridine. The ketone diamine (where B is CO) can be prepared by reacting dibenzotrifluoride ketone with fuming nitric acid in the presence of fuming sulfuric acid to first produce the dinitro ketone: 3,3'-bistrifluoromethyl-5,5'-dinitro-benzophenone The reaction should be conducted at a temperature of less than 60°C to prevent the formation of undesirable products. The dinitro ketone can be reduced to the diamino ketone by the same reduction reaction described hereinabove. The sulfide compound (where B is S) can be prepared by reacting dinitrobenzotrifluoride with sodium sulfide or potassium sulfide to first produce the dinitro sulfide: 3,3'-thiobis(3-nitro-5-trifluoromethyl)-benzene That reaction can be conducted at about 150°C for about four hours and can be followed by gas chromatograph (GC). The yield from that reaction is about 10%. The dinitro sulfide can be reduced to the diamino sulfide by the reduction reaction hereinbefore described. The sulfoxide (where B is SO) can be made by oxidizing the diamino sulfide compound. This can be accomplished with an oxidizing agent such as hydrogen peroxide or, more preferably, metachloroperbenzoic acid, at a temperature of less than 0°C. The sulfone compound (where B is SO₂) can be prepared by reacting benzotrifluoride meta-chloride with sodium sulfide to prepare dibenzotrifluoride sulfide: This reaction is performed in an organic solvent such as NMP at a temperature of about 170°C. In the next step, the sulfide is oxidized to the sulfone using an oxidizing agent such as 30% hydrogen peroxide in acetic acid in a concentration of 30%: These first two steps are reactions known in the art, see Example 17 of U.S. Patent 3,538,166 and an article by J. R. Campbell and R. E. Hatton in J. Org. Chem. 26 , p. 2480 (1961). In the next step, the sulfone is nitrated using a mixture of at least two equivalents nitric acid (density = 1.5 g/cc or greater) and at least two equivalents sulfuric acid containing up to 65% SO₃ at a temperature of less than 80°C: 1,1'-sulfonyl bis(3-nitro-5-trifluoromethyl) benzene Finally, the dinitro compound is reduced to the amine compound by the hereinabove-described reduction reaction. A second way of making the sulfone is described in co-pending European Patent Application EP90114685.2 filed of even date by Occidental Chemical Corporation, titled "Method of making dinitro and diamino metabisbenzotrifluoride compounds". Briefly, dibenzotrifluoride sulfide is reacted with fuming nitric acid in the presence of fuming sulfuric acid at a temperature of 0 to 75°C: The diamines of this invention are useful in making polyimides, polyamide-imides, and polyamides. The polyimides can be prepared by well-known reactions of diamines with dianhydrides or tetracarboxylic acids, substituting the diamines of this invention for the diamines that would otherwise be used. While non-aromatic dianhydrides can be used, aromatic dianhydrides are preferred because the polyimides have better thermal properties. Examples of suitable dianhydrides include oxydiphthalic anhydride (ODPA), biphenyl dianhydride (BPDA), benzophenone tetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA), and "6-F" dianhydride (5,5'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene] bis-1,3-isobenzofurandione). Generally, the reaction of the diamine and the dianhydride or tetracarboxylic acid will proceed at room temperatures or under mild heat. Dianhydrides are preferred to tetracarboxylic acids as the reaction proceeds more easily. Polyimides can also be prepared from half esters of tetracarboxylic acids and from hydrolyzed nitriles, but the reactions are more difficult. Polyamideimides can be prepared by reacting the diamines with a trifunctional anhydride or carboxylic acid such as trimellitic anhydride or trimellitic acid. Polyamides can be prepared by reacting the diamine with a dicarboxylic acid or an acid halide, and polyurethanes can be prepared by reacting the diamines with diisocyanate. The following examples further illustrate this invention. EXAMPLE 1 Preparation of 1.1'-sulfonyl-bis(3-nitro-5-trifluoromethyl)benzene To a one liter flask was charged nitric acid (fuming, 50 ml.) and sulfuric acid (20% oleum, 130 ml.) and the flask was cooled to 0-5°C with an ice bath. 1,1'-Sulfonyl-bis(3-trifluoromethyl)benzene (23.5 g.) was added. The reaction mixture was heated to 65°C and after 3 hours GC analysis indicated complete consumption of the sulfone and appearance of 1-(3-nitro-5-trifluoromethylphenylsulfonyl)-3-trifluoromethylbenzene. Nitric acid (fuming, 75 ml.) and sulfuric acid (20% oleum, 195 ml.) were added and the reaction was heated for an additional 5 hours. The reaction mixture was purged with nitrogen until evolution of nitrogen oxides ceased. The reaction mixture was poured into 400 g. ice and the resulting solid collected. The solid was washed with cold water to give 26.8 g (91% yield) of the desired 1,1-sulfonyl-bis(3-nitro-5-trifluoromethyl)benzene. EXAMPLE 2 - Preparation of 1,1'-oxybis(3-nitro-5-trifluoromethyl) benzene To a 500 ml round bottom flask was charged 3,5-dinitrobenzotrifluoride (25.1 g.), potassium fluoride (21.2 g), water (2.4 ml.), and dimethylformamide (DMF, 125 ml.). The reaction was heated to 160°C for 24 hours. The reaction mixture was diluted with water (400 ml.) and extracted with ether (3x 150 ml.). The ether was dried with magnesium sulfate and cooled to 5°C and the resulting solid collected to give a total of 11.3 g (53.8% yield) of the desired 1,1-oxy-bis(3-nitro-5-trifluoromethyl)benzene. EXAMPLE 3 - Preparation of 4.4'-oxybis(3-trifluoromethyl)-benzamine hydrochloride To a flask containing about 0.88 g of the product of Example 2 was added 1.8 g iron powder and 10 ml of 50% ethanol. The mixture was heated to reflux and 1.5 ml of 50% ethanol and 0.1 ml concentrated HCl was added. The mixture was refluxed for 2 hours. The iron powder was filtered and washed with 95% ethanol. The ethanol was evaporated, water was added, and the product was extracted with ether. Hydrogen chloride was bubbled through the ether solution of the product and 0.38 g of 4,4'-oxybis(3-trifluoromethyl)-benzamine hydrochloride (43% yield) were collected. EXAMPLE 4 - Preparation of 1,1'-sulfonyl-bis (3-nitro-5-trifluoromethyl)benzene To a cooled (10°C) 250 ml. round bottom flask containing nitric acid (fuming, 50 ml.) and sulfuric acid (20% oleum, 90 ml.) was added 1,1'-thio-bis(3-trifluoromethyl)benzene (10 g). The reaction mixture was held at low temperature until sulfoxide formation was complete (circa 1.5 hrs) and then heated to 35°C. The reaction mixture was then heated slowly to 65°C. Analysis of the reaction mixture indicated a mixture of nitrated compounds had formed. The oxidation and nitration reactions were carried to completion by heating the reaction mixture to 85°C. The reaction mixture was then poured onto ice and the solid collected and washed with cold water to give 1,1'-sulfonyl-bis)3-nitro-5-trifluoromethyl)benzene as a white solid (7.16 g, 52% yield). EXAMPLE 5 - Preparation of 1,1'-sulfonyl-bis (3-nitro-5-trifluoromethy)benzene To a cooled (10°C) 250 ml. round bottom flask containing nitric acid (fuming, 50 ml.) and sulfuric acid (20% oleum, 90 ml.) was added 1,1'-sulfonyl-bis(3-trifluoromethyl)benzene (27.3 g). The reaction mixture was heated to 75°C and additional nitric acid (52 ml.) and sulfuric acid (130 ml.) were added. The reaction was heated for 7 hours at 75°C and additional nitric acid (3 ml.) and sulfuric acid (3 ml.) was then added. The reaction mixture was heated for an additional 2 hours. The reaction mixture was poured onto 600 g. ice and the collected solid was washed with cold water to give 1,1'-sulfonyl-bis(3-nitro-5-trifluoromethyl)benzene as a white solid (27.2 g, 79% yield). Additional 1,1'-sulfonyl-bis(3-nitro-5-trifluoromethyl)benzene could be obtained from an ether extraction of the filtrate (4.4 g, 92% total yield). EXAMPLE 6 - Preparation of 5,5'-bistrifluoromethy-3,3'-dinitro-benzophenone To a 250 ml. flask containing nitric acid (fuming 33.8 g.) and sulfuric acid (20% oleum, 83 ml.) was added first 3,3'-bistrifluoromethyl benzophenone (40.6 g.) followed by additional sulfuric acid (50 ml.). The temperature was maintained at less than 40°C by cooling with an ice water bath. The reaction mixture was heated at 40°C for approximately 3 hours. The reaction mixture was poured onto 300 g. ice and the precipitate was collected, washed with cold water, and dried to give 5,5'-bistrifluoromethyl-3,3'-dinitro benzophenone (51.4 g., 82% yield). EXAMPLE 7 - Preparation of 3,3'-thiobis(3-nitro-5-trifluoromethyl)benzene A 25 ml 2-necked flask was charged with 0.44 g Na₂S nonahydrate, and 2 ml NMP. The mixture was heated to 210°C to remove water and 0.99 g of meta-dinitrobenzotrifluoride was added. The yield of 3,3'-thiobis(3-nitro-5-trifluoromethyl)benzene was about 10%. EXAMPLE 8 - Preparation of 5,5'-bistrifluoromethyl-3, 3'-diaminobenzophenone, hydrochloride salt To a round bottom flask containing ethanol (80 ml.) and 5,5'-bistrifluoromethyl-3,3'-dinitro benzophenone (4.9 g.) at 50°C was added 10% palladium on carbon (0.05 g.) followed by hydrazine (3.0 ml.). The reaction temperature was raised to 70°C and the reaction stirred for 2 hours. The reaction mixture was filtered through filter aid, the ethanol removed under reduced pressure, and replaced with ethyl acetate (90 ml.). The ethyl acetate was washed with a saturated sodium chloride solution (10 ml.), followed by water (10 ml.) and saturated sodium chloride solution. The ethyl acetate was dried (sodium sulfate) and evaporated to give a residue (3.62 g.). The residue was dissolved in ether and the ether was washed with 10% aqueous HCl followed by a 5% aqueous bicarbonate solution. Hydrogen chloride gas was then bubbled through the ether solution to give 5,5'-bistrifluoromethyl-3,3'-diamino benzophenone, hydrochloride salt as a precipitate (2.1 g, 50% yield). EXAMPLE 9 - Preparation of 1,1'-oxybis(3-nitro-5-trifluoromethyl)benzene The following experiment was conducted to determine if the other leaving groups could be used in place of nitro for the preparation of 1,1-oxybis(3-nitro-5-trifluoromethyl)benzene. To a solution of 3-fluoro-5-nitrobenzotrifluoride, isolated by distillation from the mother liquor of Example 2, in DMF (5 ml.) was added potassium fluoride (0.7 g.). The suspension was heated to 150°C and 2 drops of water were added. The reaction progress was monitored by gas chromatography (GC). After 7 hours, GC analysis indicated a 0.17:1 mixture of 1,1-oxybis(3-nitro-5-trifluoromethyl)benzene to the starting fluoride had been obtained. This ratio increased to 2.1:1 after heating for 17.5 hours.

Claims: A meta-benzotrifluoride compound having the general formula where each A is independently selected from the group consisting of NO₂, NH₂, and NH₃⁺Z⁻, Z⁻ is an anion, and B is selected from the group consisting of O, CO, S, SO, and SO₂. A compound according to Claim 1 wherein A is NH₂. A compound according to Claim 1 or 2 wherein B is O. A compound according to Claim 1 or 2 wherein B is CO. A compound according to Claim 1 or 2 wherein B is SO₂. A polyimide comprising the reaction product of a compound according to Claim 2 with a tetrafunctional compound selected from the group consisting of dianhydrides, tetracarboxylic acids, and mixtures thereof. A polyimide according to Claim 6 where said tetrafunctional compound is oxydiphthalic anhydride. A polyimide according to Claim 6 where said tetrafunctional compound is biphenyl dianhydride. A polyimide according to Claim 6 where said tetrafunctional compound is benzophenone tetracarboxylic dianhydride. A polyimide according to Claim 6 where said tetrafunctional compound is pyromellitic dianhydride. A polyimide according to Claim 6 where said tetrafunctional compound is 6-F dianhydride. A polyamide-imide comprising the reaction product of trimellitic anhydride with a compound according to Claim 2. A polyamide comprising the reaction product of a dicarboxylic acid or a dicarboxylic acid halide with a compound according to Claim 2. A polyurethane comprising the reaction product of an isocyanate with a compound according to Claim 2. A meta-benzotrifluoride diamine having the general formula where B is selected from the group consisting of O, CO, and SO₂.

Inventors: LIN, HENRY C., STULTS, JEFFREY S.
Applicants: OCCIDENTAL CHEMICAL CORPORATION
Application year: 1990
Main classification: C07C205
IPC codes: C07C225, C07C205, C07C323, C07C317, C07C217