US2680770A - Fluorinated biphenyl derivatives - Google Patents

Description

Patented June 8, 1954 STATES PATENT OFFICE g Moushy Markarian, North Adams, Mass, assignor to Sprague Electric Company, North Mass, a corporation of Massachusetts Adams,

- 1 J No Drawing. Application November 28, 1951, Serial No. 258,757

invention relates to new fluorinated biphenyl derivatives and more particularly refers to biphenyls having substituted thereon at least oneft rifluo'romethyl group. The present applicationis a continuation-in-part of my copending U. S. patent application Serial No. 785,533, filed ,Nfiyinber 12; 1947, now abandoned.

It, is an object of this invention to produce chemically stable biphenyl derivatives which have subst'itfi't'edthereonfluorine atoms. In a more restricted sense, the invention is concerned with trifluoromethyl substituted bipheny'ls possessing unusual chemical and electrical stability.

These objects .are attained in accordance with the present invention which is directed to biphenyl derivatives having at least one triflurcmethyl group substituted on at least one phenyl nucleus. In one of its limited embodiments the invention is concerned with biphenyl derivatives having a trifiuoromethyl group substituted oneach' of the phenyl nuclei. In one of its preferred embodiments the invention is concerned with a biphenyl derivative having a trifiuoromethyl group substituted on one phenyl nucleus and'an alkyl group substituted on the other phenyl nucleus.

The compounds of my invention conform to the following general formula:

R whereinR represents a substituent selected from the group consisting of alkyl groups and fluorinated derivatives thereof.

Among the compounds which conform to the first general formula are the following:

Compound R n R n biphenyl and isomers 02H; 1 OH; 1 3,3-bis-trifluoromethyl-4,4-diethyl OF 2 C H 1 biphenyl and isomers 01H; 2,4,6-trichloro-3-trifluoromethyl biphenyl and isomers Cl 3 0 a-trifluoromethyl biphenyl 0 0 3 Claims. (c1. 260 649) Among the preferred compounds of the inven tion, conforming to the second general formula dielectric materials, as lubricating materials, as

heat transfer materials, etc. While the boiling points of some of these compounds are not especially high, all of them are stable and possess desirable viscosity characteristics. Because of the structure of these polar molecules, it is feasible to employ them as intermediates in the syn? thesis of fine chemicals, pharmaceuticals, dyestuffs and the like. In such applicationsato-ms other than carbon, hydrogen and halogens can be incorporated in the molecule. For certain applications, the presence of a nitro group is beneficial. For example, 3-trifluoromethyl-2-nitro biphenyl and 3-trifluoromethyl-4'-nitro biphenyl are desirable dielectric additives and, further more, are readily prepared.

The following examples will serve to illustrate how the herein described compounds may be. prepared. V

To cc. of dry ether in a 2 liter 3 necked flask set up for a Grignard reaction were added. 24.5v gms. of magnesium turnings and gms. of anhydrous cupric chloride. Agitation was started, and 10 cc. of m-bromo benzotrifluoride were run in. When the reaction started, the rest (225 gms. total) was run in at such a rate that reflux continued. The mixture was then refluxed for 2 hours, cooled, poured on ice, and treated with excess I-ICl to redissolve cupric chloride. The ether extracts were shaken with water, dried and filtered, and the ether distilled off. The residue was distilled at reduced pressure through a- Wid- 3 mer column. There was obtained approximately 65 gms. of liquid boiling at 30-35 C. at 2 mm. (the m-bromo compound) and '75 gms. of the desired product boiling at 8085 C. at 2 mm. The low boiling material was refractionated to yield 44 gms. of m-bromobenzotrifiuoride. The biphenyl derivative was redistilled at 1 mm, and 62 gins. were collected at 78-81" C. to give a yield of 53% based on unrecovered meta-bromo compound. Fractionated at 1 mm., B. P. 78.5-79.5 C. Refractive Index 20 C.=1.4899. Density 20/4=l.3675

EXAMPLE 11 Preparation of 3 trifluoromethyl :1." methyl biphenyl 200 gms. of m-aminobenzotrifiuoride (prepared as described in J. A. C. S. 68 (1946), p. 1603) were dissolved in 300 cc. of concentrated hydrochloric acid to which were added 200 cc. of water. The suspension of amine hydrochloride was cooled to -5 C. and diazotized by adding a solution of 94 gms. of sodium nitrite in 186 cc. of Water. 760 cc. of toluene were then added to the clear diazo solution. With vigorous agitation 500%. of 5 N sodium hydroxide solution were added, the mixture being held at 0-5 C. Agitation was continued for 2 hours at 0-5 C. and for about 16 hours at room temperature. The aqueous layer was removed, and the residue steam distilled. The toluene was removed by distillation at atmospheric pressure and the residue distilled at reduced pressure to give a broad fraction boiling between 71 C. and 80 C. at a pressure of about 0.3 mm. This broad fraction was shaken with concentrated sulfuric acid, washed with caustic and with water, dried and redistilled to give 26 gms. of a colorless liquid boilin between 65 and 68 C. at 0.25-0.13 mm. The product thus obtained had a refractive index at 20 C. of 1.5226 and a density of 1.192.

EXAMPLE III Preparation of 4,4 bis (trifluoromethyl) biphenyl 2,2'-diamino 4,4 bis (trifluoromethyl) -biphenyl (5 g.) was dissolved in 50% hypophosphorous acid (123,6 g.; 0.94 mole). Water (50 cc.) was added, and the solution was cooled to 5. A solution of 97% sodium nitrite (2.3 g.) in water cc.) was added, with stirring, over fifteen minutes while the temperature of the reaction mixture was maintained at 0-5. Durin the addition of the nitrite solution a tan-colored solid deposited. After addition of the nitrite solution, the reaction slurry was stirred at 0 for one hour, allowed to come to room temperature and finally permitted to stand four hours. The crude product was filtered and steam distilled to yield 1.25 g. (27.6%) of 4,4'-bis (trifiuoromethyl) -biphenyl; colorless crystals; M. P. B2-87. Crystallization from methanol-water gave colorless plates; M. P. 93-94.5.

4 EXAMPLE 1v Preparation of 4,4 bis-trifluoromethyZ-biphenyl 6.2 g. of parabromo benzotrifluoride, .67 g. of magnesium turnings and 50 cc. of dry ether were employed in the usual manner to make a Gri nard complex to which was added 6.2 g. of anhydrous silver bromide. The mixture was stirred over night and filtered. The filtrate was washed with dilute hydrochloric acid, then with water, then with dilute sodium hydroxide and finally with water. The organic layer was separated and the ether evaporated therefrom. The residue was 3 g. of crude product with the melting point '75- 85 C. Recrystallization was accomplished from water and methanol to give a final pure product melting at 91-92 C. A mixed melting point with this compound and the one produced by Example III gave no melting point depression.

While the examples given above illustrate methods for preparation of the compounds of the invention, other procedures may be employed. For example, it is contemplated that compounds possessin a trifluoromethyl group on each of the phenyl nuclei may be produced by reacting diazotized 3-amino benzotrifluoride with benzotrifluoride, instead of with toluene as in Example II, or by the Ullman synthesis with halogen substituted benzotrifiuoride.

As mentioned heretofore, the compounds disclosed herein are useful in a number of fields where great stability to chemical and electrical action is desired. They are especially useful as dielectric materials, for which purpose they must be stable in the electrical field, as well as to oxidation, hydrolysis and the like. For example, the 3,3'-bis-trifluoromethyl biphenyl has a dielectric constant at 1000 cycles and at 28 C. of 8.1 and a power factor under these conditions of 0.06%. Thus the high dielectric constant obtained with such a polar molecule does not sufier from a coincident high loss factor, such as is found with many of the random chlorinated aryl compounds.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope hereof, it is to be understood that the invention is not limited to the specific embodiments hereof except as defined in the appendedclaims.

What I claini is:

1. A symmetrical bis-trifiuoromethyl biphenyl.

2. 3,3'-bis-trifluoromethyl biphenyl.

3. 4,4J-bis-trifiuoromethyl biphenyl.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,836,180 McCullough et al. Dec. 15, 1931 2,414,330 Reno-11 Jan. 14, 194'? OTHER REFERENCES Henne et al., Jour. Am. Chem. Soc., vol. 60, pages 864-5 (1938).

Claims (1)

1. A SYMMETRICAL BIS-TRIFLUOROMETHYL BIPHENYL.