Professor A. Schonberg and the History of Photochemistry in Egypt A. A. Nada Photochemistry Laboratory, National Research Centre. Cairo, Egypt C'rnrurirs n g o , thr Egypti,ms usrd the po\rdrrrd scrds ~ , i a plant ahirh grrw in rhc Yile dt Ita t u curt, wrt.~inskin diseoae, tLeukudermia). The rwwderrd seedsof Ammr m u i u j I. werr w t r n and the d ~ p i g n ~ r n ti~rear ~ ' d 01 the skin wrrt t hen r u l ~ u ~ et udsunlight.'l'hr .ire.is thus tredted rhwved hliiteriug tlJluwrd hy pigmenrarit,n. Then it gradually a-mned the ndor u t [he wrroundinc skin. Exvusure t u sunlicht was known to hr neceaaary. This was unt of the first cxunplrs of applicatiun of u h ~ ~ t u c h ~ m i sin t r ymedicine. In 194b I I , 21,Suntht~tuxil~ (I); a furocoumarin was isolated from the seeds of Ammi malus L. Upon irradiation of (I) in aqueous alcoholic solution, its dimer was detected on account of the spectroscopicchanges ( 3 ) , then was isolated when irradiation was carried out in dioxan (4). Later, much work was done in the field of photobinding of psoralens (a group of naturally occurring and chemically synthesized furocoumarins) to DNA (5).Psoralens are the key ingredients in the so-called PUVA therapy for psoriasis. They have been suggested for incorporation in anti-melanoma drugs (6).
In addition to the above example, there were many others showing the importance and place of the sun in Egyptian science and culture.
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Deutsche Arbeiter ~ a r t e i and ) condemned to exile in 1934, spent a few years in England, then decided to immigrate to Egypt. He was appointed professor of organic chemistry in the faculty of science of Cairo University. This signalled the start of research in the field of preparative photochemistry in Egypt. As a matter of fact, this field was then experiencing a revival following a dormant period after the studies of Ciamician at the beginning of the century. At that time, there was only one university in Egypt which was called Foad 1st University after King Foad. This university is now Cairo University in Giza, the Faculty of Science was a t Abassia (Fig. I), one of the old parts of Cairo where the affluent used to live in the thirties. The building of the faculty of science was an annex of Zaafran Palace, one of the former Kedewi Ismail Palaces. Some lecture theaters were built to make i t possible for such an annex to be used as a teaching institution. The shining sun of Egypt ( ~ 3 5 0 0hr per year) inspired Professor Schonberg to use sunlight for initiating organic reactions. His great interest in his work and the enthusiasm of young Egyptian graduates at that time led to the estahlisbment of an extensive research program in applied, pharmaceutical. and medicinal chemistrv. Members of this school t w k tI10ir placei in chemistry dcpsrt mvn~.;in Egyptiar univer>itie, (now thirteen umwriitiesl and in the Stltivnal IIcschool after the departure of Professor Schonherg in 1957.
Figure 1. Zaafaran Palace at Abassia-now
Ein Shams University.
During this period (1937-1957) an impressive number of puhlications in preparative organic photochemistry came out from Egypt. These were submitted either by Professor Schonberg and his students or by some of his Egyptian colleagues. Special attention was given to the chemistry of the medicinal herbs of the Islamic culture (7,8). Another subject of interest was organic sulfur compounds. One of the fundamental reactions discovered hv the group was the famous bouble bonds giving 1,cdioxene derivatives, e.g., the reaction of phenanthrene-quinone (11) with stilbene (111) in benzene solution under the influence of light to give 2,3-dihydro2,3-diphenyl phenanthro[9,10-b] [1,4] dioxin (IV).
Later, the stereochemistry of this reaction was investigated (10, 11). Thus, starting with either cis- or trans-stilhene, the corresponding cis and trans isomers of IV were obtained. Other Schonberg-discovered photodimerizations and rearrangements have been urobed bv modern mechanistic c h e k s t s . Schonberg's an2 his students' contributions have been the foundation of much of modern oraanic ~hotochemistry as shown by the number of citations'to him in any author-indexed current hook on organic photochemistry. The first edition of "Preparative Organische Photocbemie" ( I I ) , one of the first comprehensive books on photochemistry of organic molecules, was written in Cairo by Prof. Schonherg with the assistance of Prof. Ahmed Mustafa. It was published in 1958. The second edition was written in English and appeared in 1968 (12). Two years ago, on the occasion of the 85th birthday of Prof. Schonherg, he travelled from Berlin (where he is living now) to Bonn. In a celebration at the Egyptian Embassy in Bonn Volume 60 Number 6 June 1983
451
Figure 2. Schdnberg receiving medal from the Egyptian government in appreciation of his contribution t o t h e development of scientific research in Egypt.
he was awarded a decoration (Order of the Republic, 2nd class) from the Emtian eovernment in aonreciation of his valuable .., . .. w n t r i h u t i m 10 t h c d w e l ~ p n i r n uf t Aenritic reieruch in K K ~ I I !Fir. 21. . A r t i c I t i a h u u t 5chi;nhrre have a r ) r ~ w r r dinsucciali/~d journals both in Germany and & ~ g y p113). i As a continuation of the Schonberg period, Egyptian scientists carried on research in photochemistry using mainly solar irradiation. The on-going interest in this field was summarized in reviews by Mustafa (14,151. Some Egyptian scientists have had thechance to carry on advanced research work in photochemistry in laboratories where modern instrumentation is available (16). Photochemistry was one of the fields recommended in 1976 by the Egyptian Academy of Science as a potential j o i n t research project with advanced as well as in research centers. New laboratories, well equipped for this field, have been established in the last few years. However, it is only natural for the Egyptian to be interested in making use of the sun's energy and to think of its radiation as one of the greatest powers on earth because this belief originated thousands of years ago with the great Akhenaten (Fig. 3). Literature Cited (1) Sehbnberg,A.,hndSma.A.,Nafure,161.481 (1948). I21 Sch6nbeir,A.,andSina,A.,J.Amer Chem Soc.,72,4326 (1950),
452
Journal o f Chemical Education
Figure 3. TuYankhamun'sthrone which was t h e sun (Aten). Goddess of Tell ElAmma, sending its vital rays tothe king and queen on the backrest. The previous n a m e of the king "Tut'mkhaten" is s t a t e d in the inner pan.
,.",",. ( 6 ) Adamson, Cancer Tmotmeni Reports, 60,217 (1976). (7) El-Bitar, Ibn, '~MafradstEl Adwia: Vol. I, p. 4. (8) El-Antski, Dawond,"TazakaretOliEl-Albab: 3rd ed., Yoi. I, p. 32 (1925). (9) Schbnberg,A., andMustafa.A..Noturr, 153,195 (1944). (10) Pfundt, G., and Fsrid, S., Tetrahedron, 22,2237 (1966). I l l ) Saltiel. J. in '"Survey of Progress i~ Chemistry,* A. F. Scott, (Editor),AcrdemicPress, New Ymk, 1964, Vol. 2.0. 279. (12) Schunbeig, A , "Pre~amti;e Orgsnische Photuchemie: Spiinger~veilag,1958. (18) Sch6nbeg.A.. "Preparative Organic Photochemilry: in cooperation with Schenck, G. O., and Neumuller,0. A., Springer-Vdag 1968. (14) sidky, M . , E ~ J.I c h e m . , 2 0 , 5 , 4 2 ~ 2 5(19mi. (15) Mustafa, A.;'Dirnerization in Sunlight." Chem. Re", 61.1-22 (1952). (16) Mustafa, A.. Adoance. Pholorhem., 2,63 (1964). (17) EILSayed. E. H., MA., Dept Chem.University California, Los Angeles. CA:Farid, S., Eagtman Kodak Co., Research Laboratories, Rochester (U.S.A).
