(C) Peter Meiers - http://www.fluoride-history.de
|Fluorocarbons - Charles Kettering, and "Dental Caries"|
Until they became famous for the "Freon" type refrigerants, the names of Charles Kettering and Thomas Midgley were widely known for their leaded gasoline battle. Tetraethyl lead was first prepared in Europe, in 1859, as a pure compound and during the slow development in European Universities there was no hint that once it would become very important commercially (Seyferth D.: "The rise and fall of tetraethyllead", Organometallics 22 (2003) 2346 and 5154).
"After leaded gasoline entered the market in 1923-24, a fatal refinery accident drew news media attention to the poisonous nature of the full strength additive and the potential public health risk from fuel containing the dilute additive. Public health scientists insisted that alternatives existed, but industry in general and GM in particular vehemently insisted that tetraethyl lead was the only additive that could be used ... When five men died in a New Jersey refinery in October, 1924, a storm of protest and scientific dispute surrounded General Motors, Standard Oil of New Jersey, and E. I. Du Pont de Nemours Corp., the three principal developers of leaded gasoline. G.M. and Standard together had formed the Ethyl Gasoline Corp., and Du Pont participated as one-third owner of G.M. and as the largest tetraethyl lead manufacturer ... " (http://www.runet.edu/~wkovarik/papers/kettering.html)
The same team that so successfully fought the leaded gasoline battle of the 1920´s, Charles Franklin Kettering, director of General Motors research, Thomas Midgley, his assistant, originator of the idea to use tetraethyl lead as an antiknocking agent, and their "toxicologist" Robert Kehoe, created another, not less important issue in the 1930´s: fluorocarbons used as refrigerants, propellants and fire extinguishers.
Again, Kettering presented the technical devices for the project, a refrigerator, a refrigerant dehumidifying apparatus, an (automatically controlled) air conditioner, an air conditioner for an automobile:
Charles F. KETTERING, assignor to Frigidaire Corporation, Dayton, Ohio: "Refrigerating apparatus", US Patent 1,886,339; filed Dec. 31, 1928; patented Nov. 1, 1932
Charles Frank KETTERING, assignor to Frigidaire Corporation, Dayton, Ohio: "Refrigerating apparatus", US Patent 1,955,192; filed Dec. 30, 1931; patented Apr. 17, 1934
Charles F. KETTERING, assignor to Frigidaire Corporation, Dayton, Ohio: "Refrigeration", US Patent 1,978,463; filed Jan. 28, 1933; patented Oct. 30, 1934
Charles F. KETTERING, assignor to General Motors Corporation, Dayton, Ohio: "Refrigerating apparatus", US Patent 2,093,968; filed Dec. 24, 1934; patented Sept. 21, 1937
Charles F. KETTERING, assignor, by mesne assignments, to General Motors Corporation: "Refrigerating apparatus", US Patent 2,130,092; filed Dec. 30, 1931, renewed April 28, 1937; patented Sept. 13, 1938
Charles F. KETTERING, assignor to General Motors Corporation, Dayton, Ohio: "Refrigerating apparatus", filed March 28, 1936; patented Sept. 13, 1938
Charles Franklin KETTERING, assignor to General Motors Corporation, Dayton, Ohio: "Refrigerating apparatus", US Patent 2,294,036; filed Dec. 29, 1938; patented Aug. 25, 1942
Interestingly, when Midgley developed the "Freon"-type fluorocarbons in 1930, related compounds had already been made elsewhere by a very similar procedure. The manufacture of "fluoroform" (trifluoromethane) was patented by the pharmaceutical company Valentiner and Schwarz, of Leipzig- Plagwitz, Germany, in 1899: German Patents DE 105,916 (filed Jan. 5, 1899), DE 106,513 (Feb. 26, 1899), and U.S. Patent 643,835 (filed May 4, 1899). The inventors reacted silver fluoride with iodoform in the presence of chloroform (i.e. by substitution of another halogen by fluoride derived from a heavy metal fluoride). Next came Methyl fluoride to be used as a "cold producer or refrigerating agent": Walter LACHMANN, of Hamburg, Germany: "Method of producing low temperatures by means of methyl-fluoride", British Patent GB 717; filed in the U.K. on Jan. 9, 1912; pat. Oct. 10, 1912.
In 1930, Thomas Midgley, in cooperation with Albert Leon Henne and Robert Reed McNary, developed the Freons, as a substitute for the toxic gaseous refrigerants (ammonia, butane, methyl chloride (or bromide), sulfur dioxide) in use at that time. "The pioneer work on organic fluorides of F. Swarts has been used as a basis for the manufacture of dichlorodifluoromethane." Even toxicity tests had been performed, probably to prevent any unwanted discussions: "Robert A. Kehoe made a preliminary investigation of the toxic properties of dichlorodifluoromethane from which it was evident that this compound was remarkably non-toxic" (Midgley & Henne: Ind. Eng. Chem. 22 (May 1930) 542)
Thomas MIDGLEY, Albert L. HENNE, Robert R. McNARY, assignors to Frigidaire Corporation: "Heat transfer", US Patent 1,833,847; filed Feb. 8, 1930; patented Nov. 24, 1931; also German Patents (DE) 623,322; filed Feb. 9, 1930, publ. Nov. 28, 1935; and 630,838; filed Feb. 9, 1930; publ. May 14,1936
Thomas MIDGLEY, Albert L. HENNE, Robert R. McNARY, assignors to Frigidaire Corporation, Dayton, Ohio: "Manufacture of aliphatic fluoro compounds", US Patent 1,930,129; filed April 5, 1930; patented Oct. 10, 1933; also German Patent (DE) 573,534 on the separation of certain aliphatic fluoro compounds; filed July 2, 1930; publ. March 16, 1933
Francis R. BICHOWSKY, assignor, by mesne assignments, to General Motors Corporation: "Self propelling fire extinguishing charge containing a double halogen hydrocarbon compound", US Patent 2,021,981; filed June 23, 1930; patented Nov. 26, 1935
Thomas MIDGLEY, assignor to Frigidaire Corporation, Dayton, Ohio: "Process of preventing fire by nontoxic substances", US Patent 1,926,395; filed July 31, 1930; patented Sept. 12, 1933
Thomas MIDGLEY, Albert L. HENNE, Robert R. McNARY, assignors to Frigidaire Corporation, Dayton, Ohio: "Process of preventing fire by nontoxic substances", US Patent 1,926,396; filed July 31, 1930; patented Sept. 12, 1933
I. G. Farbenindustrie Aktiengesellschaft of Frankfurt, Germany: "Manufacture of methane derivatives containing chlorine and fluorine", British Patent GB 370,356; priority Dec. 12, 1930 in Germany, filed in GB on Dec. 11, 1931; granted April 7, 1932
Albert L. HENNE, assignor, by mesne assignments, to General Motors Corporation: "Dehydration of antimony trifluoride and manufacture of fluorinated aliphatic compounds", US Patent 2,082,161; filed Jan. 30, 1931; renewed Oct. 16, 1935; patented June 1, 1937
Albert L. HENNE, assignor, by mesne assignments, to General Motors Corporation: "Fluorination of aliphatic compounds", US Patent 1,973,069; filed Jan. 30, 1931; patented Sept. 11, 1934 (silicon tetrafluoride + antimony chloride as catalysts for partial fluorination of carbon tetrachloride)
Albert L. HENNE, assignor by mesne assignments, to General Motors Corporation: "Fluoriation in the presence of chlorine as a catalyst", US Patent 1,990,692; filed Jan. 30, 1031; patented Feb. 12, 1935
Albert L. HENNE, assignor, by mesne assignments, to General Motors Corporation: "Manufacture of fluorated aliphatic compounds", US Patent 2,007,198; filed Jan. 30, 1931; patented July 9, 1935
Albert L. HENNE, assignor, by mesne assignments, to General Motors Corporation: "Method of manufacturing halo-fluoro hydrocarbons", US Patent 1,978,840; filed Jan. 30, 1931; renewed Sept. 9, 1933; patented Oct. 30, 1934
Thomas MIDGLEY, Albert L. HENNE, Robert Reed McNARY, assignors, by mesne assignments, to General Motors Corporation: "Manufacture of halo-fluoro derivative of aliphatic hydrocarbons", US Patent 2,007,208; filed Feb. 24, 1931; patented July 9, 1935
Thomas MIDGLEY, Albert L. HENNE, assignors to Frigidaire Corporation, Dayton, Ohio: "Preparation of aliphatic halo-fluoro compounds", US Patent 2,013,062; filed Feb. 26, 1931; patented Sept. 3, 1935
Thomas MIDGLEY, Albert L. HENNE, Robert R. McNARY, assignors, by mesne assignments, to General Motors Corporation: "Manufacture of Antimony trifluoride", US Patent 2,024,008; filed Feb. 26, 1931; patented Dec. 10, 1935
Albert L. HENNE, assignor, by mesne assignments, to General Motors Corporation: "Manufacture of pentavalent antimony compounds", US Patent 1,984,480; filed June 5, 1931; renewed Jan. 9, 1934; patented Dec. 18, 1934
Albert L. HENNE, assignor, by mesne assignments, to General Motors Corporation: "Fluoration of aliphatic halides", US Patent 2,013,050; filed June 26, 1931; renewed May 10, 1934; patented Sept. 3, 1935
Thomas MIDGLEY, Albert L. HENNE, Robert R. McNARY, assignors, by mesne assignments, to General Motors Corporation: "Heat transfer and refrigeration", US Patent 1,968,049; original application Feb. 8, 1930, divided and this application filed Nov. 19, 1931; patented July 31, 1934
Thomas MIDGLEY, assignor, by mesne assignments, to General Motors Corporation: "Process of testing for halogens", US Patent 1,990,706; filed Dec. 21,1931; patented Feb. 12, 1935
Werner URSUM: "Füllungen für Feuerlöscher", German Patent DE 587,932; filed July 1, 1931; pat. Nov. 10, 1933
In 1932, it was reported that dichlorodifluoromethane decomposes when passing through a flame (e.g. in an outbreak of fire in a kitchen whereby the refrigerant may be released from the refrigerator) and thereby delivers hydrogen fluoride and hydrogen chloride. Midgley and Henne (Ind. Eng. Chem. 24 (June 1932) 641) were quick to claim: "It is demonstrated that even under the worst possible circumstances life is not endangered." A footnote in their report (page 644) says: "Experiments conducted by R. A. Kehoe at Cincinnati demonstrate that hydrogen fluoride is not more toxic than hydrogen chloride and hence that these two may be considered together" (a claim contradictory to experiments performed earlier by other researchers).
Thomas MIDGLEY, Albert L. HENNE, Robert R. McNARY, assignors, by mesne assignments to General Motors Corporation, Dayton, Ohio: "Heat transfer and refrigeration", US Patent 1,968,050; original application filed Nov. 19, 1931; divided and this application filed April 30, 1934; patented July 31, 1934
Thomas MIDGLEY, Albert L. HENNE, Robert R. McNARY, assignors to General Motors Corporation, Dayton, Ohio: "Heat transfer and refrigeration", US Patent 2,104,882; original application Nov. 19, 1931; divided and this application filed May 1, 1934
HF Toxicity experiments in animals, carried out at the Kettering Laboratory in Cincinnati and reported in 1934 and 1935 by Willard Machle, Frederick Thamann, Karl Kitzmiller, Jacob Cholak, and Eugene W. Scott, were supported in part by Kinetic Chemicals Inc., a subsidiary of E. I. Du Pont de Nemours & Company, manufacturer of the Freons (J. Ind. Hyg. Toxicol. 16 (March 1934) 129; 17 (Sept. 1935) 223; 17 (Sept. 1935) 230).
Albert L. HENNE, assignor to General Motors: "Halide detector", US Patent 2,136,741; filed Feb. 9, 1935; patented Nov. 15, 1938
"Freon is used not only in household and larger mechanical refrigerating units in cold storage for perishable products but also in the air-conditioning field of buildings, mines, railroad passenger cars, etc. Approximately 1,700 tons of acid spar were used in the manufacture of the new refrigerants in the first ten months of 1935, since which time there has been a noteworthy increase. The Kinetic Chemicals Inc., a Du Pont subsidiary, Wilmington, Delaware, controls and manufactures the ´Freons´ and many of the refrigerator manufacturers are offering equipment containing these gases, particularly Freon." (Paul Hatmaker, Hubert W. Davis: "The fluorspar industry of the United States with special reference to the Illinois-Kentucky District", State Geological Survey, Bulletin No. 59, Urbana, Il., 1938, p.82).
Willard Machle of the Kettering Institute examined the "Normal urinary fluorine excretion and the problem of mottled enamel" (Dental Cosmos 78 (1936) 612).
Midgley was awarded the Perkin Medal of the Society of Chemical Industry on January 8, 1937, at a joint meeting of the American Section of the Society of Chemical Industry and the New York Section of the American Chemical Society at the Chemists´ Club, New York (Ind Eng. Chem. 29 (1937) 239). In his talk "From the Periodic Table to Production" (p. 241), Midgley remarked: "C. F. Kettering was a primary factor. Without his guiding genius, faith, patience, and financial support it is likely that neither Ethyl gasoline nor the Freon refrigerants would be in existence today."
Also in 1937 the idea of another public relations stroke originated in certain dental circles: dental researchers would be asked for a summary on their research efforts relative to the causes and control of dental caries; these summaries could be published in a monograph (J.W. Gies to R.W. Bunting, March 28, 1940; in the R. W. Bunting papers, Bentley Historical Library, University of Michigan). Charles F. Kettering became a counselor in an "Advisory Committee on Research in Dental Caries" of the American Dental Association.
Letters, i.e. requests for summaries, were sent to almost 200 dental researchers in 25 countries from the "Advisory Committee on Research in Dental Caries" of the American Dental Association´s Research Commission, detailing in the letter-head the participation of the famous Charles F. Kettering of General Motors.
Thomas MIDGLEY, Albert L. HENNE, assignors, by mesne assignments, to Kinetic Chemicals, Wilmington, Delaware: "Fluorination process", US Patent 2,192,143; filed May 7, 1938; patented Feb. 27, 1940
The compilation of the dental research summaries was published by the "Advisory Committe on Research in Dental Caries of the Research Commission of the American Dental Association" under the title of "Dental Caries".
Machle, Scott and Treon, of the Kettering Institute, published the "normal urinary fluorine excretion and the fluorine content of food and water" (Am. J. Hygiene 29 (1939) 139)
A review of "Dental Caries", which Russell W. Bunting called a "World Almanac of Dental Errors" (R.W. Bunting to J.W. Gies, June 22, 1940; in the R.W.Bunting papers, Bentley Historical Library, University of Michigan), stated: "A noteworthy departure from committees dealing with technical matters was the inclusion of Mr. C. F. Kettering, well known as an engineer and industrial manager. The inclusion of a layman of such ability brings a freshness of viewpoint from one well trained in scientific method and gifted with exceptional organizing ability" (J. Am. Dent. Assoc. 27 (Jan. 1940) 117).
Machle and E. E. Evans, of the Kettering Institute, examined the "Exposure to fluorine in industry" (J. Ind. Hyg. Toxicol. 22 (June 1940) 213)
After another set of letters was sent world-wide to dental researchers, the second edition of "Dental Caries" was published by the same Committe that compiled the 1939 version.
Lyle D. GOODHUE, William N. SULLIVAN, assignors to Claude A. Wickard, as Secretary of Agriculture of United States of America, and his successors in office: "Method of applying parasiticides", US Patent 2,321,023; filed July 29, 1941; patented June 8, 1943
Tests with hydrogen chloride published in 1942 led to the conclusion that "hydrogen chloride has nearly the same immediate toxic action as hydrogen fluoride, but produces less serious residual effects than this compound." The organs of animals "surviving exposure to hydrogen fluoride showed more frequent and more severe pathological changes than those of animals exposed to hydrogen chloride. The concentration level which appeared safe for long exposure was also much lower in the case of hydrogen fluoride" (J. Ind. Hyg. Toxicol. 24 (Oct. 1942) 222).
In the meantime, the aerosol propellants had also gained importance for military purposes:
Excerpt from Chapter 2, "Historical background", in Paul A. SANDERS, of E. I. Du Pont de Nemours & Company, "Principles of Aerosol Technology", Van Nostrand Reinhold Company, New York, etc., 1970:
"One of the most important developments in the aerosol field occurred during World War II. During an investigation to find a way of combating the insects which caused disease among overseas troops, Goodhue and Sullivan, of the Department of Agriculture, developed a portable aerosol dispenser which used "Freon" 12 fluorocarbon as the propellant ... From July 1942, when the requirement was 10,000 containers per day, until the end of the war, one company alone, Westinghouse Corporation, supplied over 30,000,000 aerosols to the Armed Forces. Other companies engaged in supplying aerosols for the military included Regal Chemical Company, Brooklyn, New York; Airsol Inc., Neodesha, Kansas; and Bridgeport Brass Company, Bridgeport, Connecticut. Immediately after the war, Westinghouse Corporation dropped out of the aerosol field, but the others continued to produce aerosol products."
Being active in fluoride research, the Kettering Institute was also approached by Mead Johnson and Company, manufacturer of "Pablum" infant food (J. Ind. Hyg. Toxicol. 24 (Sept. 1942) 199; 25 (March 1943) 112):
"Pablum, a popular infant food prepared from bone meal [*], formerly contained as much as 18 ppm. When this amount of fluoride was found to be excessive -it produced mottled teeth- manufacturers reduced the fluoride content of Pablum to between 1.33 and 2.12 ppm" (George Walbott, Albert L. Burgstahler, Lewis McKinney: "Fluoridation the great dilemma", Lawrence, Kansas, 1978, p. 39). Mead Johnson replaced the veal bone ash by tricalcium phosphate (George Waldbott: Am. J. Clin. Nutr. 13 (Dec. 1963) 393).
* Lambert D. JOHNSON, Nathan F. TRUE, Barry H. ENGEL, assignors to Mead Johnson and Company: "Food product and method", US Patent 1,990,329; filed May 8, 1933; patented Feb. 5, 1935
J. F. Treon, Instructor in toxicology, Kettering Laboratory of Applied Physiology, Cincinnati, Ohio, became one of the many people (besides Hodge, Voegtlin, Stokinger ...) to supervise research programs for the "Manhattan District" (the project for the construction of the first atomic bomb). In this project fluorocarbons played a major role as coolants and lubricants. "The toxicity of these substances was tested by an experimental program similar to that used by the Toxicology Division of the U. S. Public Health Laboratories." ... "These compounds were found to be moderately toxic to animals upon inhalation, but some of the intermediate products formed in the production of these compounds were found to be toxic to animals in concentrations varying from 70 - 500 parts per million parts of air. The animals exposed to toxic concentrations of these intermediate products of the fluorocarbons died apparently as a result of respiratory failure" (from: HREX Archives, "Manhattan District History, Book I - General, Volume 7 "Medical Program", printed Dec. 31, 1946; reproduced at the National Archives).
Meanwhile, Albert L. Henne was under contract for the National Defense Research Committee (from July 1, 1942 to June 30, 1943) to find new ways for the synthesis of fluorinated hydrocarbons. However, "the procedures proved insufficient and too lengthy, and were abandoned when it was realized that better results were claimed at Purdue (i.e. Purdue Research Foundation, -> McBee), and when direct fluorination was adopted for large scale production" (from: National Defense Research Committee of the Office of Scientific Research and Development, "Final Report on Fluorocarbons and Related Compounds", Report OSRD No. 1792, Sept. 10, 1943; "cleared" upon F.O.I.A. request on Sept. 18, 2001).
Harold Simmons Booth et al. describe the use of Freon 12 (dichlorodifluoromethane) for the manufacture of dry uranium tetrafluoride of high purity (J. am. chem. Soc. 68 (1946) 169). The publication of this paper "was delayed for war-time security reasons" as the editor notes in a footnote. Other methods for the preparation of this compound (which was essential for the Manhattan Project for the production of uranium hexafluoride) "yield products containing water and hydrogen fluoride from which it is difficult to separate uranium tetrafluoride without some decomposition." Freon 12 was found to react quantitatively with uranium trioxide to produce pure anhydrous uranium tetrafluoride at elevated temperatures.
A book by Kettering Lab scientist E. J. Largent, "Fluorosis. The health aspects of fluorine compounds", Ohio State University Press, 1961, was expressly designed, as indicated on its jacket, to "aid industry in law suits arising from fluoride damage."