Henri Moissan : Winner of the Nobel Prize for Chemistry 1906 (A. TRESSAUD, Volume 45, Issue 41 , Pages 6792-6796, Sep 2006, Angewandte Chemie International Edition)

Article : Le Fluor, MOISSAN Henri, LA NATURE , 701, 6 novembre 1886, pp 363-366

Book : Le fluor et ses composés par Henri MOISSAN. Edité par G. Steinheil, Paris, 1900.

Thesis Henri MOISSAN 1880

The search for the missing halogen through the XIX^th century : from A-M. Ampère and H. Davy to E. Frémy. In 1809, when the discovery of sodium and potassium by English chemist Humphrey Davy (1778-1829) was announced in France, André-Marie Ampère (1775-1836) grasped the idea that chlorine and fluorine were both chemical elements but did not publish his hypotheses. He was astonished by the analogies between muriatic acid (chlorhydric acid) and fluoric acid (fluorhydric acid) and concluded that an element first called oxy-fluoric and then fluorine (in French) must exist, once he had understood that fluorhydric acid did not contain any oxygen. Among the letters that he exchanged with Davy during the war raging between their two nations, he even suggested on 1st November 1810 the possibility of isolating the element fluorine through the electrolysis of anhydrous fluorhydric acid [1]. "We remains to be discovered is whether the electricity will not decompose the hydrofluoric acid into its liquid form, when we have removed the water to the greatest extent, by bringing the hydrogen to one side and the oxy-fluoric to the other.’ In his reply in February 1811, Davy does not concede that a single body be present as Ampère asserts, but rather, considers that this body also contains oxygen. At that time, Davy could not state categorically that fluorine was an element: “In the views that I have ventured to develop, neither oxygen, chlorine or fluorine are asserted to be elements”. However, Ampère allowed Davy, now convinced that the French scientist’s views were correct after three years of corresponding with him, to reap the glory of announcing in 1813 that a new element had been discovered [2]. An autobiographical note by Ampère, in which he refers to himself in the third person, does however establish the anteriority of his own discovery, which is also fully recognised by Davy, "During the period I was engaged in these investigations, I received two letters from M. Ampère of Paris, containing many ingenious and original arguments in favour of the analogy between the muriatic and fluoric compounds. M. Ampère communicated his views to me in the most liberal manner; they were formed in consequence of my ideas on chlorine and supported by reasonings drawn from the experiments of MM Gav-Lussac and Thénard” .

The isolation of this new element continued to occupy many researchers for most of the nineteenth century. A first step was the preparation of pure water-free hydrofluoric acid by L.J. Thénard (1777-1857) and L. J. Gay-Lussac (1778-1850). Their product fumed strongly in air, rapidly dissolved glass and caused extraordinary burns if it entered into contact with the skin -a phenomenon the authors described in great detail. Later on, J. J. Berzelius (1779-1848) characterised ammonium fluoride. Other researchers paid a high price to the even more toxic effects of this element, without for so much succeeding in isolating the element: G. and T. Knox were severely intoxicated and the Belgium chemist P. Louyet lost his life. Meanwhile, J. C. Marignac (1817-1894) described in minute detail around 1860, the preparation and crystal morphology of a good number of anhydrous or hydrated fluorosalts, such as fluorotitanates or fluorozirconates, and most of his accurate conclusions are still valid today [3]. Many new inorganic fluorides were also characterised by scientists such as H. Sainte-Claire Deville (1818-1881) or E. Frémy (1814-1894). Nevertheless it seemed almost impossible to synthesise fluorine, despite numerous attempts carried out during the latter part of the century.

An important step was made by Frémy, Moissan’s first mentor, when he succeeded in preparing pure, anhydrous HF and also KHF₂, so-called Frémy’s salt, expressed “KFl.HFl” using the notations of that time [4]. Frémy had come very close to finding the solution by electrolysing anhydrous HF, molten calcium fluoride or potassium fluoride, but he seemed not to have had the idea of replacing these compounds by KHF₂, perhaps because of the high melting point of the compound, T_F = 293°C, which would have led to insurmountable technical difficulties.

Finally, on june 1886, the French chemist Henri Moissan (1852-1907), a former student of Fremy, succeeded in isolating fluorine gas One year before he had shown that solutions of potassium fluoride in hydrogen fluoride remained liquid and conducted electrolytically at low temperatures. The decisive idea of Moissan was to use a conducing solution of potassium acid fluoride, KHF₂ (in anhydrous HF) as the electrolyte.During the electrolysis process, fluoride ions were oxidised at the anode where F2 gas was produced.

A few months before this discovery, on April 1886, two 23-years old scientists, Paul Héroult (1863-1914) in France and Charles Martin Hall (1863-1914) in the USA simultaneously (and independently) succeeded in obtaining large amounts of pure aluminium by electrolysing alumina at 960°C in molten cryolite, a sodium fluoro-aluminate: Na₃AlF₆. This invention is now known worldwide as the Hall-Héroult process and is still used today to produce more than 30 millions tons every year.

[1] "Correspondance du Grand Ampère”, with the correspondence between the two scientists from 1810 to 1825, Gauthiers-Villars, Paris, 1936. "Reste à savoir si l’électricité ne décomposerait pas l’acide hydro-fluorique sous sa forme liquide, lorsqu’on en aurait écarté l’eau le plus possible, en portant l’hydrogène d’un côté et l’oxy-fluorique de l’autre. "

[2] Davy H., Philos. Trans. Royal Soc. London, 1812,102, 352; ibid. 1813, 103, 263; ibid. 1814,104, 62.

[3] J.-C. Galissard de Marignac, "Œuvres Complètes", Tomes 1 & 2 (1840-1887), Société de Physique de Genève, Masson, Paris, 1890; A. De Cian, J. Fisher, Acta Cryst., 1967, 22, 338 ; J. Fisher , G. Keib, R. Weiss, ibid. 1967, 22, 340 ; W. Massa, Z. Anorg. Allgem. Chem., 1977, 436, 29.

[4] Frémy E., “Recherches sur les fluorures" Ann. Chim. Phys., 1856, 47, 5-50.

[5] J. R. Partington, General and Inorganic Chemistry, MacMillan, London (1947)

Alain TRESSAUD, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB-CNRS), Université Bordeaux1, 87 Avenue Dr. A. Schweitzer, 33608 Pessac Cedex, France E-mail : This email address is being protected from spambots. You need JavaScript enabled to view it.

The isolation of fluorine and scientific achievements of Henri Moissan Henri Moissan (1852-1907) was the first French chemist to be awarded the Nobel Prize, which he received in 1906 (Fig. 1). At the award ceremony, the President of the Royal Swedish Academy, Professor P. Klason, described the two essential aspects of this great scientist’s work in the following terms, saying the prize had been attributed to him, "for having isolated and investigated the chemical element fluorine and for having introduced the electric furnace into the service of science - exploits whereby he has opened up new fields for scientific research and industrial activity".[1] Indeed, twenty years prior to this in 1886, Henri Moissan isolated fluorine during an experiment which has now become history and also paved the way for high temperature synthesis.

— The early years Henri Moissan was born in Paris in 1852, but spent much of his teenage years and his early professional life in Meaux where he was an apprentice clockmaker. In 1870, war against Prussia obliged his family to return to Paris and he joined the army for a year before enrolling at the Ecole Supérieure de Pharmacie de Paris. Henri Moissan was divided for many years between his two loves, pharmacy and experimental chemistry and enrolled first in 1872 at the Ecole de Chimie expérimentale, headed by Edmond Frémy at the Muséum, before joining P.P. Dehérain’s research laboratory, also at the Muséum, where he carried out research into vegetable physiology, the absorption of oxygen and the emission of carbon dioxide in plants kept in obscurity. In 1879, he became a senior chemist. His research of this period into the chemistry of pyrophoric iron and metal oxides of the iron family can be found in the doctoral degree he obtained in 1880. Simultaneously with this, he climbed the hierarchical ladder at the Ecole Supérieure de Pharmacie de Paris. In 1880 he was appointed Maître de Conférences and Chef de Travaux Pratiques before becoming Professeur Agrégé in 1882 with a thesis entitled ’Série du cyanogène ’ (The cyanogen series). [2,3]

It was only in 1884 that Henri Moissan began to concentrate solely on isolating fluorine, a halogen discovered in the early years of the nineteenth century thanks to the work of A.M. Ampère in France and H. Davy in England. Yet the gas had never been isolated because of its violent reactivity.

— 1886 : A great year for fluorine Several generations of chemists had tried in vain to isolate fluorine, notably by electrolysing phosphorus and arsenic fluorides, but H. Moissan was determined to find a way. His genius laid in his idea of turning the bath into a conductor by adding a molten fluoride potassium salt, KHF2. Indeed pure hydrogen fluoride, HF, could not suffice as its capacity as an electric conductor was too weak. Henri Moissan devised a platinum electrolyser and lowered the reaction temperature of the electrolytic solution of HF + KHF₂ to limit corrosion. The platinum electrolyser was U-shaped and was stopped with fluorine stoppers, CaF₂ (Fig.1). The cathode and the anode were made of irridated platinum to provide better resistance to the fluorine. The traces of hydrogen fluoride were condensed at the end of the apparatus in a low temperature trap and also by sodium fluoride. On 28^th June 1886, a gaseous product was identified at the anode of the electrolyser - the fluorine (F2) had been successfully isolated, thus resolving one of the most difficult challenges in the realm of inorganic chemistry (Fig.2). [4] The gas obtained, yellow-green in colour, was highly toxic and proved to be a powerful oxidising agent, causing organic material to burst into flame on entering into contact with it and combining directly, and often violently, with almost all other elements. [5-7]

— Henri Moissan, the great scientist Several months after having isolated fluorine, Moissan was appointed Professor of Toxicology at the École supérieure de pharmacie. Although this discipline was not his speciality, he taught toxicology for 13 years until he was appointed Professor of Inorganic Chemistry at the École de pharmacie in 1899. During this period, he drew up a highly detailed list of rules to be respected for drafting expert reports in, for instance, the study of epidemics. He also carried out studies into hygiene in the professional environment, the analysis of air in factories, urban sanitation, diet and food etc. His rethinking of the teaching of toxicology was rewarded with a seat on the prestigious Académie de médecine in 1888. Yet Moissan’s work as Professor of toxicology did not stifle his passion for inorganic chemistry and his research in this field quickly brought him to the forefront of chemistry in France along with wide international acclaim. In 1891 he was appointed to the Académie des Sciences and in July 1900, he became Professor of inorganic chemistry at the Faculté des sciences, Université de Paris. Up until 1890, his research was devoted entirely to fluorine and the properties of its derivatives, in partnership with his students: P. Lebeau, M. Meslans, C. Poulenc, [8-10] or eminent colleagues such as H. Becquerel or M. Berthelot. Moissan was a first-class teacher and he published a multitude of books dealing with the main aspects of the inorganic chemistry of his period. [11]

In the latter part of his career, Henri Moissan had great success in the field of inorganic syntheses. He obtained a pure state of boron together with a good number of borides. From 1890 on, he worked on an even more challenging task than that of isolating fluorine - that of artificially creating diamonds.[13] In order to achieve the extremely high temperatures required to transform carbon into diamond, he designed an electric furnace based on the principle of an electric arc between two blocks of limestone (Fig. 3). He described this furnace in a work dating from 1892, and explains how the furnace allowed temperatures between 3000 - 3500°C to be reached, quite exceptional for the period. He carried out the following experiment: a compound of iron and sugar carbon was heated to a temperature of 3 000 °C and then the carbon crucible was immersed into cold water. High pressure was thus created inside the solid. In the residues, Moissan found microscopic crystals of different types of diamond, even if only a few milligrams. Even if in this field, Moissan was never able to totally fulfil his dream and his research was contested by H. Le Chatelier and C. Parsons, his ideas were nonetheless visionary and paved the way for high pressure experiments that led to the industrial synthesis of an artificial diamond by General Electric fifty years later. Today the world production of synthetic diamonds is estimated at around 450-500 million carats.

This technological breakthrough allowed Henri Moissan to turn a near page in the history of chemistry, that of high temperatures. The list of his discoveries is impressively long:
  crystallisation of a large number of oxides that were reputed infusible,
  obtaining refractory metals by reducing their oxides in the presence of carbon,
  discovering a large number of metallic carbides such as calcium carbide which then made way for the discovery of acetylene, but also new borides, nitrides and silicides,
  method for preparing calcium in a pure state by reducing calcium iodide with excess sodium, developing metallic hydrates, etc. We may also conclude that, along with R. Collongues, Henri Moissan is the forebear of high temperature chemistry.[12]

The Nobel Prize for Chemistry crowned the career of this great scientist, but Moissan also received an impressive number of other titles and distinctions, among which entry into the scientific academies of France and countries abroad, honorary doctorates, and other prestigious distinctions (Fig. 4). Nor did Moissan’s work mean that he neglected the other sides of intellectual life. Although he cared little for music and the theatre, he showed great admiration for the work of Jean-Baptiste Corot, and had several magnificent canvasses by the painter that he would sit and contemplate to rest his mind. He was also a passionate collector of works by contemporary artists and antique engravings. He also had a very fine collection of autographs relating to the French Revolution. [14]

Moissan died at the age of 54 on 20th February 1907 from acute appendicitis, just two months after having been awarded his Nobel Prize. Fluorine and its highly toxic gaseous compounds, together with the carbon monoxide that was emitted from his electric furnace had doubtless weakened his health and may well have been responsible for his low resistance to the infection.

— Our inheritance from Henri Moissan

Today, in these early years of the twenty-first century, Henri Moissan is still considered to be a precursor in most of the fields into which he carried out his research and a long list of new technological methods and scientific discoveries of the utmost importance are the direct result of his innovative work. In 1986 the International Henri Moissan Prize was created for stimulating research in the field of fluorine chemistry. [15]

The electric furnace paved the way for breakthroughs in the fields of electrometallurgy, in aluminothermics and the acetylene and calcium cyanamide industries. The production of crystalline oxides, the industrial production of ceramics and refractory techniques also owe a great deal to his innovative work. The importance of carbides, as Henri Moissan foresaw, is illustrated by the important role played by composites in a wide range of strategic fields. [16]

Toady, fluorine is still synthesised electrochemically using the principle Henri Moissan elaborated.[17, 18] One of the main uses of this process today is the transformation of uranium tetrafluoride into hexafluoride and this is an essential stage in the production of nuclear energy.[19] There are over 600,000 compounds which contain at least one atom of fluorine and the chemistry of fluorine and fluorine-based products has allowed huge breakthroughs to be made in a wide variety of fields - organic chemistry,[20] materials,[21] polymers,[22] drugs and medical applications.[23] Among the great discoveries that have rhythmed the twentieth century we can note :
  the use of organic and/or inorganic fluorine in a number of energy conversion processes: Li- ion batteries, fuel cells and nuclear energy ,[19, 24]
  fluoride polymers like Teflon®, which resist corrosion so remarkably and are used in packaging highly reactive products, ’non-stick’ kitchen utensils, materials for cardio-vascular implants, membranes for fuel cells,[22]
  the strategic role played by fluorine and fluoride gases in micro-electronics within the production chain of silicon components, means that all impurities can be eliminated from the surface of a semi-conductor thus allowing our computers to function efficiently,
  the use of fluoro-surfactants to protect fabrics, carpets, leather and in fire-proofing,
  the surface coating of materials to make them graffiti-proof, UV absorbent or protecting our cultural heritage by injecting fluoride polymers into lithic objects and coating metallic structures: for example, coating the metallic framework of the Louvre Pyramid or the metallic parts supporting the structure of the Grande Arche at La Défense in Paris.
  numerous therapeutic properties are known to characterise many fluoride molecules and are found in: cancer repressant drugs, anti-inflammatories, antibiotics, neuroleptics or antihypertensive drugs, and there are possibilities for using perfluorocarbons in vitreoretinal surgery and as substitutes for blood in emergency transfusions.[23]

The element F is of great value nowadays for medical imaging to detect the early presence of tumours and for diagnosing some diseases of the brain like Alzheimer’s using ¹⁸F positron emission tomography or ¹⁹F nuclear magnetic resonance and there are a whole host of molecules containing one or several atoms of fluorine which constitute efficient herbicides, fungicides or insecticides.

It is clear that some drawbacks caused to our environment by fluorinated products should not be underestimated,[25] but this constitutes a great challenge for the groups dealing with fluorine and fluoride products, in order to find solutions to overcome these problems, such as supervising the use of fluoride molecules in agrochemicals, as a definitive substitute for chlorofluorocarbons (CFCs) which are partly to blame for destroying the ozone layer, the defluoridation of drinking water in many areas of the world where there is a risk of people contracting fluorosis etc....[26] Although the isolation of fluorine by Henri Moissan is now a hundred years old, the fabulous destiny of this element seems only to be in its early years today, as the breakthroughs and new vistas brought by it to so many fields of science are brimming with potential.[27]

— References and notes [1] “Nobel Lectures, Chemistry 1901-1921”, Elsevier Publishing Company, Amsterdam, 1966

[2] C. Viel, J. Flahaut, "Vie et œuvre de H. Moissan", J. Fluorine Chem. 1986, 33, 27-44, lecture given during the International Symposium on the Centenary of the Discovery of Fluorine, Paris, 1986.

[3] C. Viel," Aspects historiques de l’isolement du fluor. Travaux d’Henri Moissan et de ses collaborateurs directs jusqu’au début du XXe siècle" in the special issue of "Actualité Chimique" commemorating the 1906 centenary, Société Française de Chimie, 2006.

[4] H. Moissan, "Sur la décomposition de l’acide fluorhydrique par un courant électrique", C. R. Acad. Sci., séance du 28 juin 1886, 1886, 102, 1543-1544 ; ibidem, 1886, 103, 202-205 ; ibidem 1886, 103, 256-258.

[5] E. Banks, “Isolation of fluorine by Moissan: setting the scene”, J. Fluorine Chem. 1986, 33, 3-26 and R. E. Banks, (Ed.), “Fluorine Chemistry at the Millennium: Fascinated by Fluorine”, (partly in 100th Volume, J. Fluorine Chem., 1999), Elsevier Science & Technology, 2000.

[6] H. Moissan: "Das Fluor und seine Verbindungen", transl. by Dr. Theodor Zettel, German Edition, Verlag von M. Krayn, Berlin 1900.

[7] P. Lebeau, "Notice sur la vie et les travaux d’Henri Moissan", Bull. Soc. Chim. France, 1908, [4], 3-4, ; the same text appeared in "Hommage à Henri Moissan", Chimie et Industrie, Paris, 1932.

[8] Among the numerous publications of H. Moissan on fluorine and fluoride compounds, we can quote : "Recherches sur l’isolement du fluor", Annales Chim. Phys. 1887, 6ème série, t. XII, 472 ; " Nouvelles recherches sur le fluor", Annales Chim. Phys. 1891, 6ème série, t. XXIV, 224 ; "Fluorure double de chrome et potassium", Annales Chim. Phys. 1894, 7ème série, t. II, 66 ; "Le bifluorure de platine anhydre", C. R. Acad. Sci. 1889, 109, 807.

[9] C. Poulenc, "Contribution à l’étude des fluorures anhydres et cristallisés", Annales Chim. Phys. 1894, 7^ème série, t. II, 5.

[10] H. Becquerel et H. Moissan. "Etude de la fluorine de Quincié", C. R. Acad. Sci. 1890, 111, 669-672.

[11] H. Moissan, "Le Fluor et ses Composés", G. Steinhel Ed., Paris, 1900 ; Le four électrique, G. Steinhel Ed., Paris, 1897 ; Traité de Chimie Minérale, Masson Ed., Paris, 1904-1906.

[12] R. Collongues, F. Galtier, "Henri Moissan, chimiste expérimentateur", Pour la Science, 1996, 230, 46-52.

[13] O. Krätz, “The rocky road to literary fame: Marcel Proust and the diamond synthesis of Professor Moissan”, Angew. Chem. Int. Ed. 2001, 40, 4604-4610.

[14] At the auction of his collection of autographs at Drouot on 14th October 1921, more than 6000 items and manuscripts were sold off.

[15] Following the International Symposium commemorating in 1986 the isolation of fluorine, the International Moissan prize was established by co-chairmen, P. Hagenmuller and P. Plurien, for recognizing achievements in the various fields of fluorine chemistry. Besides this international prize, Moissan grants are regularly proposed to students by the Fluorine Division of the American Chemical Society.

[16] W. Krenkel, R. Naslain, H. Schneider, “High Temperature Ceramic Matrix Composites”, Wiley, 2001.

[17] M. Jaccaud, F. Nicolas, Techniques de l’Ingénieur, 1990, J6020-J1453.

[18] D. Pletcher, “Industrial Electrochemistry”, Chapman and Hall, London, 1982 (Chap. 5).

[19] H. Groult, F. Lantelme, C. Belhomme, B. Morel, F. Nicolas, J.P. Caire, "Synthèse électrochimique du fluor de 1886 à 2006 : le fluor, élément clef pour l’énergie nucléaire", in the special issue of "Actualité Chimique", Société Française de Chimie, 2006.

[20] K. Uneyama, “Organofluorine Chemistry”, Blackwell Publ., 2006; R. Chambers, "Fluorine in Organic Chemistry", Blackwell Publ., 2004; J. A. Gladysz, D. P. Curran, and Istvan T. Horvath (Eds), "Handbook of Fluorous Chemistry", Wiley, 2004; P. Kirsch, "Modern Organofluorine Chemistry - Synthesis & Applications", Wiley-VCH 2004; R.E. Banks, B.E. Smart, J.C. Tatlow, "Organofluorine Chemistry: Principles & Commercial Applications", Kluwer Academic / Plenum Publishers 1994 ; G. A. Olah, G.K.S. Prakash, R. D. Chambers, "Synthetic Fluorine Chemistry", John Wiley & Sons Inc. 1992.

[21] T. Nakajima, B. Zemva, A. Tressaud, (Eds), “Advanced Inorganic Fluorides : Synthesis, Characterization and Applications”, Elsevier, 2000 ; N. Watanabe, T. Nakajima, H. Touhara, “Graphite fluorides”, Elsevier, 1988; P. Hagenmuller (Ed,), “Inorganic solid fluorides : chemistry and physics”, Academic Press, 1985.

[22] B. Ameduri, B. Boutevin, “Well-Architectured Fluoropolymers”, Elsevier, 2004

[23] J.P. Bégué et D. Bonnet-Delpon, "Chimie bioorganique et médicinale du fluor", EDP-Sciences, 2005; I. Ojima, J.R. McCarthy, J.T. Welch, “Biomedical Frontiers in Fluorine Chemistry”, American Chemical Society, 1996; J. T. Welch, S. Eswarakrishnan "Fluorine in Bioorganic Chemistry”, John Wiley & Sons Inc., 1991.

[24] T. Nakajima, H. Groult (Eds), “Fluorinated materials for energy storage”, Elsevier, 2005.

[25] L. H. Weinstein, A. Davison, "Fluorides in the Environment: effect on plants and animals”, CABI Publishing, Cambridge, Mass., 2004.

[26] A. Tressaud (Ed.), volumes dedicated to “Fluorine and the environment” in the book series “Advances in Fluorine Science”, Elsevier, 2006.

[27] Among the celebrations that took place in 2006 for the centenary of Henri Moissan’s Nobel prize, we can quote: Session at 18th International Symposium on Fluorine Chemistry in Bremen (July 30, 2006); special issues of “Actualité Chimique”, SFC, and J. Fluorine Chem; International Colloquium at Maison de la Chimie, Paris (Nov. 10, 2006).

[28] Alain TRESSAUD, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB-CNRS), Université Bordeaux1, 87 Avenue Dr. A. Schweitzer, 33608 Pessac Cedex, France e-mail : This email address is being protected from spambots. You need JavaScript enabled to view it.

Fig.1 Henri Moissan’s Nobel Diploma and the electrolytic cell for producing fluorine (courtesy Moissan Museum, Faculté de Pharmacie, Université Paris5 - René Descartes ; photograph by A. Tressaud)

Fig.2 Henri Moissan’s very first Note on the isolation of fluorine. C.R. Acad. Sc., June 28, 1886, t. CII, pp. 1543-1544.

Fig.3 Henri Moissan and his electric furnace at Faculté des Sciences, Université de Paris.