edited by JOHN H. WOTlZ Southern Illinois University
Carbondale, Illinois 62901
Mendeleev's Other Prediction Harold Goldwhite California State University Los Angeles, California 90032 Mmt book? conrerned with the history of chemistry, and even many general chemistry texthooks, discuss the brilliant series of predictions oi new elements and their properties made hy Mendeleev in I871 after he had introduced his version' of the I'erindic Law of the Elements in 1869. Mendeleev's eka-aluminum was discovered by Lrroq de Boiehaudran in 1875, and named gallium. Similarly scandium, discovex-d in 1879 hy Lars Fredrick Nilson had the properties of .Mendeleev's eka-borcm, and germanium, discovered in lab6 hy Clemens Winkler, corresponded m Mendeleev's eka-silicon." In 1889 Mendeleev was invited to rive the Faradny 1.ecture of the Chemical Society of ~ o n d o n m dalmost , as-an afterthought, he included in his discussion of the periodic law a predktion of the existence and properties of ).it another new elemrnt.3 "I [Mendeleev] forsee some more new elements, t ~ u t not with the same certitudeas before. I shall eive one examole. and yet I do not see it quite distinctly. 1 n i h e series wiich contains Hg = 204, P h = 206, and Bi = 208, we can guess the existence of an element analogous to tellurium, which we can describe as dvi-tellurium. Dt. havine an atomic weizht of 212 anrl the property of forminK'theoxide DtO,. If this element really exists, it ourht in the free state to t)r an easily fusihlt:, crysAline, non-voiatile metal of a grey color, havinga density of ahout 9.3, capable of giving a dioxide DtOa, equally endowed with feeble acid and basic properties. This dioxide must give on active oxidation an unstable higher oxide, DtOs, which should resemble in its orooerties PbOl and BiqO.. Dvi-tellurium hydride, if it he f k n d to exist, wh be a l&itable comoound than even HoTe. The com~oundsof dvi-tellurium will be easily reduced, i d it willformcharacteristic definite alloys with other metals." Menddeev made this prediction before radiuactivity was discovered. His dvi-tellurium u,as to he found in I898 as the iirst of the neu, radioactive elrments, p ~ l o n i u m named ,~ by i t s discoverer, Marie Curie, for her native land. Polonium is undoubtedly the predicted congener of tc4urium; it is a Main-group 6 element, and a variety of isotopic speries have been ohser\.ed, covering the mass range 198 11, 218, and all radioactive. (The most stahle isotope is 'WPo, with a 103 year half-life,. Hecause of the intense radioactivir\, of oolonium its r of conventional chemistry is hard to study. ~ o w e k e many
Mendeleev's predictions have been confirmed. Polonium is a metallic conductor, and is easily fusible (m.p. 254-C) and not very volatile (h.p. 962°C). The unstable higher oxide, PoOa, is not known, but the dioxide, Poop, is apparentiy amphoteric, giving a hydroxide P o ( O H ) ~and Po(1V) halides. There is marginal evidence for the existence of a very unstahle hydride, H2Po.5 Thus the example of polonium, no less than those of the better known eallium. eermanium. and scandium. illustrates the power of thk ~eriohycLaw, in the hands of its &discoverer, in ~ r e d i c t i n ethe existence and o r o ~ e r t i e sof unknown ele-
The Discovery of lproniazid and Its Role in Antidepressant Therapy George R. Kauffman ('ulifornia Start- lJnroersi/y, Fresno Fresno. C'nlifornra 92740 T h e discovery of iproniazid or 1-isonicotinyl2-isopropyl hydrazine (trade name, Marsalid) constitutes a notable case of serendipity of great importance in the chemotherapy of mental illness. In 1951 the late Dr. Herbert Hyman Fox of the Hoffmann-La Roche Laboratories, Nutley, N.J., and Dr. Harrv L. Yale of the Sauihh Institute for Medical Research independently discovered the antituberculous drug isoniazid or isonicotinyl hydrazine, which has been credited with reducing the incidence of tuherculosis in the United States from 188 deaths annually per 100,000 population in 1904 (the leading cause of death) t o 4 per 100,000 (1 ). In 1953 Dr. Fox and John T. Gihas continued their search for synthetic tuherculostats with the preparation of alkyl, cycloalkyl, and arylalkyl derivatives of isoniazid, which they prepared by the catalytic reduction of the corresponding alkylidene or arylalkylidene compounds with a platinum catalyst (2). None of these derivatives were found to be more active than isoniazid CONHNH, but the isopropyi derivative (~proniarid)
$QNHN=CHCH(CH,h
vONHNHCHFH(CH,),
Iproniazid
'Lothar Meyer was a simultaneous codiscoverer of the Periodic Law. 2Weeks,M. E., and Leicester, H. M., "Discovery of the Elements," 7th Ed., Journal of Chemical Education, Easton, 1968, Chapter 15. 3MendelCeff,D. I., J. Chem. Soe., 634 (1889). 'Reference (2),Chapter 19. SCotton,F. A., and Wilkinson, G., "Advanced Inorganic Chemistry," 3rd Ed., Interscience, New York, 1972, Chapter 15.
which has a tuherculostatic activity of the same order as isoniazid in animals (3).was found to be more active in humans (4,5). Its use, however, was accompanied by a higher incidence of toxic side reactions (6). In 1952 Drs. Selikoff, Robitzek, and Ornstein, in clinical tests of iproniazid and isoniazid against tuberculosis a t Sea View Hospital a t Staten Island, noted that "central nervous stimulation is apparently also to he listed among the side effects [of iproniazid]" (7). Inasmuch as this undesirable side Volume 56, Number 1, January 1979 1 35
