US3423469A

US3423469A - Polyphenyl ether compositions

Info

Publication number: US3423469A
Application number: US191337A
Authority: US
Inventors: Roger E Hatton; Louis R Stark
Original assignee: Monsanto Co
Current assignee: Monsanto Co
Priority date: 1962-04-30
Filing date: 1962-04-30
Publication date: 1969-01-21
Anticipated expiration: 1986-01-21
Also published as: GB1024920A; NL292095A; DE1235938B; FR1356569A; NL6616920A

Description

United States Patent 3,423,469 POLYPHENYL ETHER COMPOSITIONS Roger E. Hatton, Kirkwood, Mo., and Louis R. Stark,

East St. Louis, lll., assignors to Monsanto Company,

a corporation of Delaware No Drawing. Filed Apr. 30, 1962, Ser. No. 191,337 US. Cl. 260-6115 13 Claims Int. Cl. C07c 41/12, 43/22 This invention relates to polyphenyl ether compositions having improved oxidative stability. More particularly, this invention relates to polyphenyl ethers stabilized against oxidative degradation by the incorporation therein of certain organolead compounds.

The polyphenyl ethers are compounds known to the art. It has been proposed to use the polyphenyl ethers as gas turbine (jet) engine lubricants, as hydraulic fluids, as electronic equipment coolants, as atomic reactor coolants, as diffusion pump fluids, etc., since they possess many desirable properties such as high and low temperature stability, foam resistance and good storage stability, even where the temperatures encountered range up to 700 F. and higher. Because of their good balance of properties, the polyphenyl ethers have recently been receiving increasing consideration as lubricants for jet engines. However, as the speed and altitude of operation of jet engine-containing vehicles increases, lubrication problems also increase because of increased operating temperatures and higher bearing pressures resulting from the increased thrust needed to obtain higher speeds and altitudes. As the service conditions encountered become increasingly severe, the useful life of the polyphenyl ethers is shortened, primarily due to their deficiency in oxidative stability above 500 F.

The useful life of a lubricant can be adjudged on the basis of many criteria, such as the extent of viscosity increase, the extent of corrosion to metal surfaces in contact with the lubricant, and the extent of deposit formation. Those skilled in the art have found many ways to improve lubricants and to thereby retard or prevent the effects which shorten their useful lives. Thus, it is a general practice to add small amounts of other materials, or additives, to lubricants in order to affect their properties. It is difificult, however, especially as operating temperatures are increased, to find additives which will perform the function for which they are added and yet not interject other problems, such as increasing corrosion and engine deposits.

It has now been found that the oxidative stability, and thus the useful life of the polyphenyl ethers, can be greatly extended, even under the severe conditions encountered in jet engines and other devices operating at temperatures of the order of 600 F. and higher, by the addition to polyphenyl ethers of an organolead compound.

It is therefore an object of this invention to provide polyphenyl ether compositions having increased resistance to oxidation. A further object is to improve the viscosity stability of polyphenyl ether compositions. A still further object is to provide polyphenyl ether compositions having increased color stability.

The objects mentioned above and others, which will hereinafter be apparent, are accomplished by adding to the polyphenyl ethers an organolead compound selected from (a) phenyl lead compounds represented by the structural formula, (Ph) -Pb-(X) where Ph is phenyl, X is halogen, and m is a whole number from 1 to 4, and (b) lead acid derivatives represented by the structural formula,

Pb O( iR 3,423,469 Patented Jan. 21, 1969 where R is an alkyl or a phenyl, and y is selected from 2 and 4.

Examples of compounds falling within the definition above are, in (a) tetraphenyllead, triphenyllead chloride, triphenyllead fluoride, diphenyllead dichloride, diphenyllead diiodide, phenyllead trichloride, and diphenyllead dibromide; and, in (b) lead benzoate, lead vanillate, lead tetraacetate, lead acetate, lead ethylcaproate, lead ethylhexoate, lead 2-ethylhexanoate, lead naphthenate, lead octoate, lead oleate, lead oxalate, lead palmitate, lead tungstate, lead vanadate, lead salicylate, lead stearate, lead subacetate, and lead tallate.

Generally, the phenyllead compounds of this invention can be prepared by the action of a Grignard reagent on lead chloride, and lead acid derivatives can be prepared by salt exchange, neutralization, etc., as from salts of sodium benzoate or acetate and lead chloride.

The polyphenyl ethers to which this invention pertains can be represented by the structure,

F A l UL L in where n is a Whole number from 2 to 5. The preferred polyphenyl ethers are those having all of their ether linkages in the meta position, since the all-meta-linked ethers are the best suited for many applications because of their wide liquid range and high degree of thermal stability. However, mixtures of polyphenyl ethers (i.e., either isomeric mixtures or mixtures of homologous ethers) can also be used to obtain certain properties; e.g., lower solidification points. Examples of the polyphenyl ethers contemplated are the bis(phenoxyphenyl)ethers, e.g. bis(mphenoxyphenyl)ether; the bis( phenoxyphenoxy)benzenes, e.g., m-bis(m-phenoxyphenoxy)benzene, m -bis(p-phenoxyhenoxy)benzene, o bis(o-phenoxyphenoxy)benzene; the bis(phenoxyphenoxyphenyl)ethers, e.g., bis[m- (mphenoxyphenoxy)phenyl]ether, bis[p (p henoxyphenoxy) phenyl] ether, m- (m-phenoxyphenoxy) (o-phenoxyphenoxyphenoxy)phenyHether, bis[p (p phenoxyphenbenzenes, e.g., m bis [m (m-phenoxyphenoxy)phenoxy] benzene, p-bis [p- (rn-phenoxyphenoxy phenoxy] benzene, m-bis[m-p-phenoxyphenoxy)phenoxyjbenzene. It is also contemplated that mixtures of the polyphenyl ethers can be used. For example, mixtures of polyphenyl ethers in which the non-terminal phenylene rings (i.e., those rings enclosed in the brackets in the above structural representations of the polyphenyl ethers contemplated) are linked through oxygen atoms in the metaand para-positions, have been found to be particularly suitable as lubricants because such mixtures possess lower solidification points and thus provided compositions having wider liquid ranges. Of the mixtures having only metaand paralinkages, a preferred polyphenyl ether mixture of this invention is the mixture of five-ring polyphenyl ethers where the non-terminal phenylene rings are linked through oxygen atoms in the metaand para-positions and composed, by weight, of 65% m-bis(m-phenoxyphenoxy) benzene, 30% m [(m phenoxyphenoxy)(p phenoxyphenoxy) jbenzene, and 5% m bis(p phenoxyphenoxy) benzene. Such a mixture solidifies at about lO F., whereas the three components solidify individually at temperatures above normal room temperatures.

The aforesaid polyphenyl ethers can be obtained by the Ullmann ether synthesis which broadly relates to ether-forming reactions of, for example, alkali metal phenoxides such as sodium and potassium phenoxides with aromatic halides such as bromobenzene in the presence of a copper catalyst such as metallic copper, copper hydroxides, or copper salts.

The major bench scale method used for evaluating the oxidative stability of a lubricant is the Procedure given in Federal Specification 791, Method 5308.4, according to which the lubricant to be tested is heated at a specified temperature in the presence of certain metals and oxygen, and the viscosity increase of the lubricant is determined. Additionally, information as to the corrosivity of a lubricant to metals can be obtained.

Various polyphenyl ether compositions were tested according to the procedure of Federal Specification 791, Method 5308.4, except that the temperature was held at 600 F. instead of 250 F. as specified in that procedure, and the metal specimens used were steel, copper, silver, titanium, magnesium alloy, and aluminum alloy. The compositions tested had essentially no elfect on steel, titanium and aluminum alloy, and generally showed a slight increase in copper corrosion. In some tests, no metal specimens were included and only the viscosity increase was measured. The results observed using the above-described procedure are recorded in the table below. Viscosity measurements were made according to ASTM Method D-445-5 3T using a Cannon-Fenske modified Ostwald viscosimeter. The percentage of viscosity increase was determined by taking the difference in viscosity of a composition before and after it was heated, dividing that difierence by the original viscosity, and multiplying the quotient by 100. The corrosivity to metals was determined by weighing the metal specimens before and after the test. The base stock used was composed, by Weight, of about 65% m-bis(m-phenoxyphenoxy)benzene, about 30% m-[(m-phenoxyphenoxy) (p-phenoxyphenoxyfl benzene, and about 5% m-bis(p-phenoxyphenoxy)benzene.

organolead compound as described above. Since the amount of organolead compound added above the minimum amount mentioned has little or no effect on the degree of stabilization obtained, considerations other than stabilization have to be taken into account in selecting the quantity of organoleadcompound to be added to a particular polyphenyl ether. As a practical matter, about 5% by weight of an organolead compound is the maxi-mum amount to be used, although it is preferred to use from about 0.05% to about \1% by Weight, since, within that range of concentrations, the amount of additive used is low enough so that solubility considerations are not limit ing, yet there is no significant difference in the degree of stabilization obtained. Because of the various considerations which go into the choice of the amount of organolead compound used and also because of the slight differences existing between various polyphenyl ethers and mixtures thereof, the amount of organolead compounds can be expressed as a stabilizing amount; i.e., an amount which is effective to provide an increase in the oxidative stability of the polyphenyl ether compositions contemplated.

It is also contemplated that other additives, such as pour point depressants, crystallization. suppressants, viscosity index improvers, dyes, rust inhibitors and materials to improve extreme pressure properties, can be added to the compositions of this invention.

Other modes of applying the principles of this invention will be apparent to those skilled in the art. Accordingly, while this invention has been described with reference to various specific examples and embodiments, it is understood that the invention is not limited to such examples Organolead compound Viscosity Inc.,

Weight change,

Composi- Percent mg. per sq. cm. tion No.

Description Percent 100 F. 210 F. Mg. Ag.

by Wt.

1 38 1 38 1 41 2 414 No metals .0 18 0.14 0. 34 0 17 0. 47 0. 39 1.0 11 1. 6 0.02 0. 5 12 No metals 7. 0.2 16 0.10 0.16 8. 0.5 12 No metals 9. 0.5 16 .12 10 0.2 11 No metals 0. 5 63 23 -0. 78 0. 12 do..." 0.5 16 No metals Diphenyllead Diehloride.. 0.5 17 -2. 02 0.34 14 do 0.5 47 12 No metals 1 Average of 16 separate tests representing 3 lots of base fluid. 2 Average of 7 separate tests representing 3 lots of base fluid.

From the above, it is clearly evident that the addition of an organolead compound to the polyphenyl ethers provides polyphenyl ether compositions having a greatly in- 5 creased oxidative stability and, therefore, a greatly extended useful life. In regard to the extension of useful life, it has been found that the test procedure described above correlates quite well with the results obtained under full-scale aircraft gas turbine-bearing tests and under conditions of actual use. It has been found that the magnitude of change in the viscosity at 100 F., as measured by the test procedure, is representative of the extent of increased service life obtainable under actual conditions.

It is also evident from the data presented above that the addition of an organolead compound to the polyphenyl ether provides polyphenyl ether compositions having significantly reduced rates of corrosion to certain metals and reduced varnishing. It was also noted, by visual inspection, that the organolead stabilized polyphenyl ethers had significantly less sludge than did the unstabilized polyphenyl ethers.

The improved polyphenyl ether compositions of this invention can be obtained by the addition to the polyphenyl ethers of at least about 0.01% by weight of an and that it may be variously practiced Within the scope of the following claims.

What is claimed is:

1. A composition comprising (a) a polyphenyl ether represented by the structural wherein n is a whole number from 2 to 5, and (b) a stabilizing amount of an organolead compound selected from the group consisting of (l) phenyllead compounds represented by the structural formula, (Ph) Pb-(X) where Ph is phenyl, X is halogen, and m is a whole number from 1 to 4, and

(2) lead acid derivatives represented by the structural formula,

i Pb0 -R where R is alkyl or phenyl, and y is selected from 2 and 4. 2. A composition comprising (a) a polyphenyl ether represented by the structural formula,

OLQ OL L 1 where n is a whole number from 2 to 5, and

(b) a stabilizing amount of a phenyllead compound represented by the structural formula,

where P11 is phenyl, and m is a whole number from 1 to 4.

3. A composition comprising (a) a polyphenyl ether represented by the structural formula,

(Lg OL J11 where n is a whole number from 2 to 5, and (b) a stabilizing amount of tetraphenyllead. 4. A composition comprising (a) a polyphenyl ether represented by the structural formula,

6 where R is alkyl or phenyl, and y is selected from 2 and 4.

6. A composition comprising (a) a mixture of fixe-ring polyphenyl ethers wherein the non-terminal phenylene radicals are linked through oxygen in the meta-and para-positions, and

(b) a stabilizing amount of tetraphenyllead.

7. A composition comprising (a) a mixture of five-ring polyphenyl ethers wherein the non-terminal phenylene radicals are linked through oxygen in the metaand para-positions, and

(b) a stabilizing amount of lead benzoate.

8. A composition comprising (a) a mixture of five-ring polyphenyl ethers having, by

weight, about m-bis (m-phenoxyphenoxy)benzene, 30% m [(m phenoxyphenoxy) (p phenoxyphenoxy)]benzene, and 5% m-bis(p-phenoxyphenoxy)benzene, and

(b) a stabilizing amount of tetraphenyllead.

9. A composition comprising (a) a mixture of four-ring polyphenyl ethers, and

'(b) a stabilizing amount of tetraphenyllead.

10. A composition comprising (a) a mixture of four-ring polyphenyl ethers, and

(b) a stabilizing amount of lead benzoate.

11. A composition comprising 21) bis [m-(m-phenoxyphenoxy) phenyl ether, and

(b) a stabilizing amount of tetraphenyllead.

12. A composition comprising (a) a seven-ring polyphenyl ether, and

('b) a stabilizing amount of tetraphenyllead.

13. A composition comprising (a) a four-ring polyphenyl ether, and

(b) a stabilizing amount of tetraphenyllead.

References Cited UNITED STATES PATENTS 2,307,090 1/1943 Yngue 260-4575 2,679,459 5/1954 Rosenwald 260611.5 XR 2,711,401 6/1955 Lally 26045.75 2,720,544 10/1955 Mallinckrodt et a1. 260-611.5 2,720,546 10/1955 Mallinckrodt et al. 260611.5 2,181,914 12/1939 Rosen 252-464 2,940,929 6/1960 Diamond 260613 XR 2,354,218 7/1944 Murray 252-377 XR 2,681,891 6/1954 Bas et a1 25232.7 XR 2,813,076 11/1957 Edelmar et a1 252 XR 3,244,627 4/ 1966 Smith 252-611.5 XR

BERNARD HELFIN, Primary Examiner.

U.S. Cl. X.R.

Claims

1. A COMPOSTION COMPRISING (A) A POLYPHENYL ETHER REPRESENTED BY THE STRUCTURAL FORMULA,