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Aug. 22, 1950 J. H. SIMONs 2,519,983 ELECTROCHEMICAL PROCESS OF MAKING FLUORINE-CONTAINING CARBON-COMPOUNDS Filed Nov. 29, 1948 Aaaaf cozierzser Mésozzye77 soain? (7%aracaravoas, ef.) v%2/22 Avaazrae 23, 32 canaerzser /zctor 47?r 26-29/37 Mérvive ar 22seous meet sales arvava?s Ayaayer rariae Zawa air eferry a2^6Aarza7 a.4/ A %2 - Zia Z Ya?ade 3/. 27-M -472c/zózsas Ce// -Zawaayaaye777%rae so/2//a/7 conv2z/7/47 M N arzmie starfiry compound 67as 72eer //aviaowfief proa/cts for Zzzerzzor 344,42.277zaz75 Patented Aug. 22, 1950 2519,983 - UNITED STATES PATENT OFFICE 2,519,983 ELECTROCEMICAL PROCESS OF MAKNG FJOR NE-CONTAINING CARBON COM POUNDS Joseph H. Simons, State College, Pa., assignor to Minnesota Mining & Manufacturing Company, St. Paul, Minn, a corporation of Delaware Application November 29, 1948, Serial No. 62,496 20 Claims, (C. 204-62) This application is a continuation-in-part of ditives to permit of electrolyzing liquid hydrogen my copending application Ser. No. 677,407 (filled fluoride solutions thereof admixed with rela June 17, 1946), since abandoned. The latter was tively insoluble organic starting compounds, such filed as a continuation-in-part of the following as alkanes, which do not provide adequate con prior applications which thereafter were aban ductivity. Pure anhydrous liquid hydrogen fluo doned in its favor: Ser. Nos. 384,729 (filed March ride, per se, is non-conductive. The electrolyte 22, 1941), 569,265 (filed December 21, 1944), and is free from water in more than a small pro 626,434 (filed November 2, 1945). portion but need not be anhydrous in a strict This invention relates to my discovery of a Sense. basically new process of making fluorocarbons O Excellent results can be obtained with simple and other fluorine-containing carbon compounds. single compartment electrolytic cell arrange The process is simple in operation, does not in ments. No diaphragm is needed between elec volve the use or formation of free fluorine at any trodes. Fluorination can be completed in one stage, and has great versatility in enabling the step to directly obtain fully fluorinated product direct production of many types of product com 15 compounds which are relatively insoluble and pounds using organic starting compounds which either evolve with the cell gases or settle to the are readily available and relatively inexpensive. bottom of the cell from which they can be It is an electrochemical process and its utility drained, depending upon their boiling points. has been demonstrated by extensive pilot plant The process is suitable for continuous as well as operations employing a 2000-ampere cell, as well batch operation. The cell can be operated at as by many laboratory experiments. atmospheric pressure. The cell and the cathodes This process was publicly disclosed in the oral can be made of iron or steel, and the anodes of presentation on September 15, 1948, at the Port nickel, and such cells have been satisfactorily land, Oregon, session of the 114th meeting of the operated at 5 to 8 volts, D.C., in producing a wide American Chemical Society, of five papers aur variety of product compounds. thored by me and my assistants. Abstracts of The reaction mechanism is not fully under these papers had been previously published in stood but the electrolyzing process apparently the advance 'Abstracts of Papers' volume issued transforms the organic starting compounds at or by the society (pp. 42-0 to 45-0). News items adjacent to the anode and may be regarded as an relating thereto and briefly describing the process 30 anodic process. Hydrogen is evolved at the cath have been published in the society's magazine ode, being derived from the hydrogen fluoride; Chemical and Engineering News, vol. 26, p. 2428 and will also evolve in the cell by derivation from (Aug. 16, 1948) and pp. 2878-9 (Sept. 27, 1948). other hydrogen-containing compounds which These papers were subsequently published in the may be present. Fluorine is not evolved, and the Journal of the Electrochemical Society, vol. 95, 35 reaction mechanism does not involve the forma No. 2, pp. 47-67 (Feb. 1949). tion of molecular (free elemental) fluorine as an Briefly stated, this new and useful electro intermediate agent. chemical process involves electrolyzing a liquid Product compounds are obtainable (both cyclic hydrogen fluoride (HF) Solution containing a and non-cyclic) which have the same number of fluorinatable organic starting compound, at an 40 carbon atoms and same carbon skeletal structure electrolyzing potential which is insufficient to as do the starting compounds, but with partial generate free fluorine under the existing condi or total fluorine atom replacement of hydrogen tions, but which is sufficient to cause the pro atoms and other atoms and radicals bonded to duction of fluorine-containing carbon compound the carbon skeleton of the molecule. Fluorine products at a useful rate. A wide variety of 45 addition occurs in the case of unsaturated and organic compounds are soluble in anhydrous aromatic types of starting compounds to produce liquid hydrogen fluoride and provide adequate fully saturated product compounds. Non-cyclic electrolytic conductivity. Use can also be made compounds (in addition to cyclic compounds) of soluble organic and inorganic conductivity ad having the same number of carbon atoms are ob a,b10,088 3 tainable from cyclic starting compounds as the fewer or more carbon atoms than the paren result of bond cleavage and fluorine addition. hydrocarbon groups can also be obtained from Also, the use of polycarbon cyclic and non-cyclic such compounds. A feature of the present proc starting compounds generally results in appre ess is that it provides a simple and economical cable yields of product compounds having fewer procedure for making normally liquid fluorocar carbon atoms in the molecule, due to fragmenta ition of the carbon skeleton and fluorine addition. bons, having five or more carbon atoms in the Compounds having a greater number of carbon molecule. atoms than the starting compounds are obtain The formation of fluorocarbons is accompanied able as the result of coupling of carbon radicals bypartially the formation fluorinated of hydrocarbons, fluorocarbon duehydrides to income and formed in the solution. The kinds and relative plete hydrogen replacement in the case of one proportions of product compounds obtainable in molecules. The proportions depend upon the any given case will depend upon the starting conditions. The fluorocarbon monohydrides and compound and the operating conditions. By ... dihydrides are of particular value because they proper selection it is possible to obtain excellent 15 have a high degree of thermal stability and yields of desired products, which can be readily chemical inertness and are non-combustible, and separated by fractional distillation from each yet the hydrogen atoms offer points of attack for other and from low-yield by-product compounds. the synthesis of fluorocarbon derivatives. Thus In commercial operations, use can be made of the these fluorocarbon hydrides can be thermally production of multiple products in building up chlorinated and brominated to yield the corre stocks of many useful compounds from a much. sponding fluorocarbon chlorides and bromides, as more limited number of starting compounds. disclosed in a paper published in the Journal of In some cases resinous material is formed in the American Chemical Society, vol. 88, pp. 968 the cell but is generally soluble in the electrolyte 989 (June 1946) of which I was a co-author. olution and does not interfere with the opera Saturated fluorocarbons and fluorocarbon de ton. Resinous products containing combined rivatives are obtainable in good yields ranging fluorine in proportions up to 60% have been ob from the simplest compound, CP, which is a low ... tained. In many cases no solid residual mate ... boiling gas, up to high-boiling compounds hav rials are found even after extended use of the ring eight or more carbon atoms in the molecule cell. In general, there is little or no corrosion of and having boiling points above 100 C. the electrodes. The fluorocarbon and related compounds ob To briefly indicate at this point the versatility tainable by this process have utility for many of the process in enabling the production of purposes. The saturated fluorocarbons, fluoro fluorocarbon derivatives, mention is made (for carbon hydrides, fluorocarbon ethers, and tri illustration and not limitation) of the following fluorocarbon amines, for example, have a high types designated by generic formulae wherein R degree of thermal stability and chemical inert represents saturated fluorocarbon radicals (cycle ness, they do not burn, and they have uniquely or non-cyclic) consisting solely of carbon and low refractive indices and dielectric constants fluorine atoms: R'OR' (obtainable from ethers), as compared with ordinary organic compounds. R'R'R''N (obtainable from tertiary amines), 40 The liquid compounds (containing five or more R'R''N (obtainable from secondary annes), carbon atoms) have exceptionally low surface RN (obtainable from primary amines), RCO tensions and viscosities, coupled with high densi (obtainable from monocarboxylic acids), ties. These and other compounds can be used for such purposes (depending upon boiling RicooR' points) as refrigerants, fire extinguishers, inert solvents and diluents, heat exchange fluids, tur (obtainable from esters), RCN (obtainable from bine impellents, dielectrics, hydraulic mechanism nitriles) and RSF (obtainable from mercaptains). fluids, and lubricants. The products of this proc Fluorocarbon compounds which contain con ess can also be used as intermediates in the syn bined chlorine can be obtained from chlorine thesis of other chemical compounds. In particu containing starting compounds (e. g., chloroe lar, the fluorocarbon acid fluorides (RCOF) pro acetic acid). Heterocyclic compounds contain vide the reactive starting compounds for making ing one or more oxygen or nitrogen atoms in the a vast number of derivative compounds contain ring can be obtained by replacement of the ing a fluorocarbon radical and having unique hydrogen atoms by fluorine atons in starting SS properties on that account.