US 3535387 A
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United States Patent U.S. Cl. 260-612 6 Claims ABSTRACT OF THE DISCLOSURE Non-spreading lubricants and fluids which are oxidatively stable as low and high temperatures and comprising a mono or di-sec-butyl-biphenyl or terphenyl or mono or di-sec-butyl-methoxybiphenyl or methoxyterphenyl.
The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to us of any royalties thereon.
This invention is a continuation-in-part of our copending patent application, Ser. No. 568,680, filed July 28, 1966, assigned to the same assignee hereof, now U.S. Pat. No. 3,426,076, and relates to fluids and lubricants and more particularly concerns new and improved nonspreading fluids which are stable to oxidation.
Many nonspreading fluids are useful as lubricants in applications such as watch mechanisms, clocks and fuzes where a continual supply of lubricating substance cannot readily be provided and where the lubricant film is placed between components having low relative speeds such that the resistance of the lubricant to spreading governs the accuracy of the mechanisms. Since the non-spreading component of such nonspreading lubricant is an important factor contributing to the performance of the lubricant, control of the nonspreading ingredient will usually lead to control of the compounded lubricant. Prior art researchers have compounded lubricants from blends containing a nonspreading ingredient comprising a diester made from an aromatic alcohol and a dibasic acid, having the general formula:
where X and R are aliphatic (straight or branch chain) groups: X having up to 4 carbon atoms, R having up to 5 carbon atoms, and M is 5 through 7. The lubricant would normally contain a suitable oxidative inhibitor, among other possible additives. Since addition of oxidation inhibitors to fluids can change the physical properties thereof e.g., freezing point, and since aromatic compounds do not respond well to antioxidants, it would be advantageous if a nonspreading fluid which is also stable to oxidation could be provided.
It is therefore an object of this invention to provide improved non-spreading lubricants.
Another object of the invention is to provide improved nonspreading lubricants which are stable to oxidation up to at least 100 C.
Other objects and features of the invention will become apparent as the invention is more fully hereinafter disclosed.
In accordance with these objects it has been discovered ice that a mono or di-sec-butyl-biphenyl or terphenyl or mono or di-sec-butyl-methoxybiphenyl or methoxyterphenyl will provide a nonspreading oxidatively stable fluid. The alkyl group or groups are attached to the ring through a tertiary carbon atom. Examples of structures of this type are as follows:
BIPHENYL RI! RI! 0-TERPHENYL m--TERPHENYL R=sec-butyl R=sec-butyl, hydrogen, or methoxy R"=sec-butyl or hydrogen Since the higher the symmetry of a substituted biphenyl or terphenyl the higher the melting point, it is important that the compounds be as unsymmetrical as possible in order to obtain liquids. For example, 4,4-di-secbutyl-biphenyl is a liquid yet 4,4-dibutylbiphenyl (M.P. 585 C.) and 4,4'-di-tert-butylbiphenyl (M.P. 128.5 C.) are solids. Therefore, substituted and unsubstituted biphenyls and terphenyls were reacted with sec-butyl chloride to form liquid sec-butyl derivatives which were unsymmetrical compounds.
In Table I below, spreading data are presented for our nonspreading oxidatively stable fluids, the data being obtained at room temperature under anhydrous conditions.
1 Evaporated, 2 Compound 1s a known spreading fluid and is presented for comparison purposes.
Despite the high boiling point of 4-sec-butylbiphenyl (107 C. at 0.7 mm.), it completely evaporated within about 4 days leaving no residue on the disk on which it was being tested. This compound would be useful therefore in closed systems. While a drop of 4-S of 4-sec-butyl- 4'-methoxybiphenyl only spread 0.9% after 30 days, its volume had noticeably decreased indicating that this compound (B.P. 146 C. at 0.7 mm.) was also evaporating but at a much slower rate.
Spreading of an oil was determined in the following manner: One inch diameter disks of Wd 52-100 steel, hardened to Rockwell C-62, were polished successively with 0, 2/0, 3/0, and 4/0 every paper, washed under warm tap water while being scrubbed with cotton gauze, then washed with distilled water followed by redistilled methanol. The disks were then dried by clean dry air. To determine cleanliness, a drop of redistilled methanol was placed on the surface of each disk. Complete and uniform evaporation indicated surfaces acceptable for these tests. A drop of the oil to be tested, 1 to 2 mm. in diameter, was placed on each disk by means of platinum wire. The degree of spreading was obtained by measuring the change in diameter after 7 and 30 days, respectively, using a traveling microscope.
Our nonspreading fluids may be prepared as follows:
4-sec-butyl-4'-methoxybiphenyl and 3,4-di-sec-butyl-4'- methoxybiphenyl.p-Phenylsanisole (0.25 mole, 46 gms.) was dissolved in 700 ml. of hot heptane contained in a 1000 cc. four-necked flask, fitted with a stirrer, reflux condenser, thermometer and dropping funnel. Fourteen grams of anhydrous aluminum chloride was then added. The solution was heated, and while maintaining a temperature at 75-85 C., 0.27 mole (25 gms.) 2-chlorobutane was added dropwise over a period of 2.5 hours. After addition was complete, stirring was continued for an additional 5.5 hours, the temperature being maintained at 75 -85 C. The reaction mixture was poured over an equal volume of cracked ice and stirred vigorously to decompose the aluminum chloride complexes. The organic layer was washed free of acid with distilled water. The unreacted p-phenylanisole was removed by distillation using a steam condenser. The remaining mixture was distilled in a molecular pot still to separate the product from solids and tarry products. The liquid was then fractionated using a vigreux column to yield both 4-sec-butyl-4'-methoxybiphenyl (B.P. 137 C. at 0.65 mm.) and 3,4 di-sec-butyl-4-rnethoxybiphenyl (B.P. 162 at 0.75 mm.). Both compounds were then fractionated for further purification using a vigreux column until the distillation range was less then 2 C.
4-sec-butyl-m-terphenyl and 4,4" di-sec-butyl-m-terphenyl.--m-Terphenyl [0.43 mole (100 grams)] was dissolved in 100 ml. of warm carbon disulfide contained in a 500 ml. four-necked flask, fitted with a stirrer, reflux condenser, thermometer, and dropping funnel. The solution was cooled to C. and 7 grams (0.05 mole) of anhydrous aluminum chloride were then added. Maintaining the temperature at 0 C., 40 grams (0.43 mole) of 2- chlorobutane was added dropwise over a period of 1.5 hours. After addition was complete, stirring was continued for an additional 4.5 hours, the temperature being maintained at 0 C. The reaction mixture was poured over an equal volume of cracked ice and stirred vigorously to decompose the aluminum chloride complexes. The organic layer was washed free from acid with 10% potassium carbonate, washed with distilled water until neutral to pH paper, dried over anhydrous sodium sulfate, and filtered. Carbon disulfide was removed under reduced pressure. Unreacted m-terphenyl was removed using a steam condenser. The products were separated by fractionation in vacuo using a vigreux column to yield two liquid products. The lower boiling fraction was identified as 4-secbutyl-m-terphenyl, B.P. 182 C. (0.3 mm.), 11.2% yield (13.7 grams). Calculated for 0 1-1 C, 92.26; H, 7.74; M.W., 286. Found: C, 92.30; H, 8.03; M.W., 289. The high boiling fraction was identified as 4,4"-di-sec-butyl-mterphenyl, B.P. 213 C. (0.4 mm.), 11.4% yield (16.7 grams). Calculated for C H C, 91.17; H, 8.83; M.W., 342. Found: C, 91.11; H, 8.99; M.W., 335.
4-sec-butyl-o-terphenyl and 4,4" di sec butyl-o-terphenyl.The reaction was performed in the same manner and at the same temperature as for the preparation of the above two compounds, employing 100 grams (0.43 mole) of o-terphenyl, 40 grams (0.43 mole) of 2-chlorobutane, 7 grams (0.05 mole) of anhydrous aluminum chloride, and 100 ml. of carbon disulfide. Addition of 2-chlorobutane was done over a 1.5 hour period, and the total reaction time was 7 hours. Sec-butyl-o-terphenyl [B.P. 183-85 C. (0.3 mm.)] was obtained in 20.9% yield (27 grams). Calculated for C H C, 92.26; H, 7.74; M.W. 286. Found: C, 92.22; H, 7.85; M.W., 295. 4,4"-di-sec-butyl-o-terphenyl was obtained in 7.0% yield (10 grams). Calculated for C H C, 91.17; H, 8.83; M.W., 342. Found: C, 91.53; H, 8.81; M.W., 340.
4-sec-butyl 2" methoxy-p-terphenyl.2-methoxy-pterphenyl [0.092 mole (24 grams)] was dissolved in 500 ml. of hot heptane contained in a 1000 ml. four-necked flask, fitted with a stirrer, reflux condenser, thermometer and dropping funnel. Five grams of anhydrous aluminum chloride were then added. The solution was heated, and while maintaining a temperature at -85 C., 0.094 mole (8.7 grams) chlorobutane was added dropwise over a 1 hour period. After addition was complete, stirring was continued for an additional two days. Completion of the reaction was indicated by the fact that hydrogen chloride stopped evolving rapidly, and, upon cooling to room temperature, unreacted Z-methoxy-p-terphenyl no longer crystallized out of solution. Fractionation of the reaction mixture yielded three products, one of which was the 4-secbutyl-2"-methoxy-p-terphenyl [B.P. 181 C. (0.16 mm.)] was obtained in 23.9% yield (7 grams). Calculated for C H O; C, 87.30; H, 7.64; O, 5.05; M.W., 316. Found: C, 86.99; 0, 5.09; M.W., 306. The other two products obtained were a solid isomer and di-sec-butyl-2-methoxy-pterphenyl.
The reactant 2-methoxy-p-terphenyl (M.P. 223 C.) was prepared by a diazo reaction similar to that described for 2-methoxy-4'-bromobiphenyl (Adams, R.; Bachman, W. E.; Fieser, L. F.; Johnson, J. R.; Snyder, H. R., Organic Reactions, R. Adams ed., vol. II, p. 246, Wiley, New York, 1944) employing 1.25 moles (211 grams) of 4- aminobiphenyl and 4.6 moles (497 grams) of anisole.
In the table below, some oxidation rates of our inventive nonspreading compound are represented. As can be readily observed from the table, there is very little oxygen uptake even after hours.
TABLE II.OXIDATION RATES AT 100 C.
(Moles oxygengmole compound/hr. X10
Initial rate Final rate (during (durin Compound 535 hrs.) 65-100 hrs.
4-sec-buty1biphenyl 0. 03 0. 03 4,4-di-sec-butylbiphenyl 0. 13 0. 17 4-sec-butyl-4-methoxybiphenyl 0. 00 0. 00 3,4-disec-butyl-4-methoxybiphen 0. 12 0. 20 4-sec-butyl m-terphenyl 0. 00 0. 00 4,4-di-sec-butyl-m-terphenyl. 0. 32 0. 21 4-sec-butyl-o-terphenyl 0. 00 0. 00 4,4"-di-sec-butyl-o-terphenyl 0. 30 0. 23 4-sec-butyl-2-methoxy-p-terphenyl 0. O0 0. 00
5 off so that 0.1 to 0.5 cm. of pressure remained. Oxygen consumption was calculated as moles or oxygen per mole of compound.
1. A nonspreading fluid oXidatively stable at elevated temperatures for extended periods, said fluid being selected from the group consisting of 4-sec-butyl-m-terphenyl, 4,4"-di-sec-butyl-m-terphenyl,
4 sec-butyl-o-terphenyl, 4,4 di-sec-butyl-o-terphenyl, and 4-sec-butyl-2"-methoxy-p-terphenyl.
2. A nonspreading fluid as described in claim 1, said fluid being 4-sec-buty1-m-ter-phenyl.
3. A nonspreading fluid as described in claim 1, said fluid being 4,4"-di-sec-butyl-m-terphenyl.
4. A nonspreading fluid as described in claim 1, said fluid being 4-sec-buty1-o-terphenyl.
5. A nonspreading fluid as described in claim 1, said fluid being 4,4"-di-sec-butyl-o-terphenyl.
6. A nonspreading fluid as described in claim 1, said 5 fluid being 4-sec-butyl-Z"-rnethoxy-p-terphenyl.
References Cited Mahoney et 211.: W.A.D.C. Technical Report, 59-173 BERNARD HELFIN, Primary Examiner U.S. Cl. X.R. 260-668