contemporary history series
edited by
LEONARDFINE Columbia Univesity
New Yo*, NY 10027
ERIC S. PROSKAUER
DOT (Dichlorodiphenyltrichloroethane) A Chemist's Tale Harold B. ~riedman' By their very nature, wars are accompanied by destruction and devastation. Yet, occasionally, benefits result according to the axiom, "Necessity is the mother of invention." For example, synthetic detergents were first developed i n German chemical laboratories after World War I a s advantageous replacements for soaps in the face of extreme shortages of edible animal fats. World War I1 led to the invention and accelerated development of diverse products and technologies, from radar and the computer to synthetic rubber and penicillins. The Wartime Need for a Pesticide World War I1 also led to the use of DDT (dichlorodiphenyltrichloroethane) a s a n insecticide, when one was needed by our own troops in the South Pacific. DDT bad already saved hundreds of thousands of lives in Italy by arresting and preventing the spread of typhus among war refugees in the winter of 1944. The population of Naples was sprayed en masse, thus preventing lice infestations, which almost certainly would have caused a typhus epidemic. A similar epidemic was stopped during the American occupation of Japan in late 1945. Although DDT fell from grace due to its toxicity, it remains one of the most effective and economical of all insecticides. Half a century ago, it ranked with penicillin as one of the great wonder drugs of modern chemistry. Whether it was wise to abandon DDT is still debatable. Certainly, no similar product was then available. Pyrethrum, made from the flowers of Chrysanthemum (Pyrethrum) cinerariaefolium had long been used in insecticide
'As told to Dr. Harold B. Friedman, Vice President (retired),Zep Manufacturing Company, 1310 Seaboard Industrial Blvd., N.W., P.O. Box 2015, Atlanta, Georgia 30301, (404)352-1680.
Editor's Note (LWF) Doing good science is a highly personal activity. Unfortunately, those who are good at it are often too busy doing it to be interviewed. Gften they do not recognize the need to share their experiences with students. Indeed, most students are familiar with the names of precious few scientists whose work is widely recognized, cited, and recited. It is in the very nature of science and its methods that good work soon becomes part of the mainstream of ideas. Althouah the work itself mav become known to more Deope me mov'b~alchem~sts oftenq~o~eo by fewer peope. Jnu tnc crcat ve ano nnovatlve ndtv aJa 1s f nally emoalmeo between the endpapers of our textbooks. This problem is compounded forthose chemists who enjoy their success in industry. There it is often necessary to be secretive to protect propietary information. The patent literature can hardly be
362
Journal of Chemical Education
preparations. In 1924 Staudinger and Ruzicka isolated two highly insecticidal components from the natural product. Both were shown to be cyclopropane derivatives related to sterculic acid. However. supplies of pvrethrum were drasticallv curtailed beca'useAlayo heloed to build the American chcmical industrv into ocrhaps our nationH most successful industrial beichmaik. At age 83 (Fig. 11, he was still the consummate chemist, industrialist, and entrepreneur. Frank Mayo passed away on October 13, 1989. T h e t h r e e companies t h a t h e founded-the Mayo Chemical Company, the Farm and Industrial Chemical Comoanv. . ". and Mavo Chemical of Tenn e s s e e r e m a i n as testaments to his long career in industrial chemistrv. His contribution to the chemistrv . and manufacture O ~ D D deserves T special recognition. Frank Mayo, the Chemical Manufacturer Mayo's hterest in DDT
I n 1944 Frank Mavo became interested in DDT. The Atlanta chemist and chemical manufacturer was seeking additional products of commercial value. For some years his fledgling company had been manufacturing chlorine-based bleaching. compounds (Fig. - 2) and other products for the textile industry. Before this time DDT had received some use as a n insect killer, but unfortunately it was only available to the military whose production of itiaas on a relatively small scale. Certainly much less was being manufactured than could meet civilian demand. Furthermore, the very existence of DDT was still a military secret. (Long before its famous acronym was used, DDT was assigned the military code name G-4, as one compound in a series. The other compounds were fungicidal agents.) The US. Armv Quartermaster Corns had limited auantities, which w&e Lsed primarily to treat the canva; and leather .. eoods used bv our trooos in the South Pacific thea t r r ofopemtions. Withunt DD'C, the insccrs ate just about eventhjne that was made of l'nbric or lerrther. The domrstic i&ectsywith which we are more familiar, are mild compared to the voracious species found in the jungles of Southeast Asia and the Philippines. Mayo's Search for the Formula Begins
As luck would have it, Mayo happened upon a n unclassified article published in The Atlanta Journal about this
,1
Figure 2. The Farm and Industrial Chemical Company label for their sodum hypochlorite product. circa 1944. Volume 69 Number 5 May 1992
363
obscure compound and its valuable and exceptional abilities as an insecticide. However. the article did not eive the formula for DDT or the full name of the compounld. It revealed only very little information that could be useful in tracking down the formula-that DDT had been synthesized by Othmer Zeidler as part of his doctoral thesis, which was awarded in 1874 from a German university. However. that oroved to be a sufficient starting for - point . this d e t e k i n e i and intrepid chemist. Mayo was aware that, in the latter half of the 19th century, i t was customary for German doctoral students to publish their dissertations within six months of their a a d ;ation, which usually occurred in May or June. comequently, Mayo knew that he could expect to see these published reports in the renowned Berichte der Deutschen Chemischen Gesellschaft (Reports of the German Chemical Society) as early as October of the same year. So Mayo set off for Georgia Tech where he had been a student years earlier. However, their volumes of Berichte commenced with the year 1910. The library at nearby Emory University held volumes beginning with 1915. Not much help! A Daughter's Help
"It seemed like the end of the road." Mavo recalled. However, he recognized the possibility that t h i treasured 1874 or 1875 volume m i ~ h be t available a t the librarv of the much older university of Georgia, which was 75 miles awav in Athens. As luck would have it. one of Mavo's four danihters, Bebe (class of 19481, w a s a n undergraduate student there. Frank phoned Bebe and asked her to check the chemistry literature for him. Well. the precious issue ofBerichte was and wasn't available. kthoLgh the University owned a copy, i t was stored in one of many boxes in the library attic. It had been relegated there along with many other unbound issues that were not considered to be of general interest to regular library users. Only after much persuasion and many long delavs was Mavo's young daughter able to convince a librarian to allow a fr&hman student-and one who was not studying chemistiy or German-to go up and look through the boxes of dust~journalswrittenTn a-language that she could not read. Frank had told his daughter to look for a paper by Othmer Zeidler bv examining the title page of each month's issue for 1874:~he was tobegin withthe month of October, which was probably the earliest month in which the thesis could have been published. "Believe it or not," says Mayo, "there it was, in the October issue." His dutiful daughter copied i t word-for-word in the unfamiliar German, and then immediately called her father. As Mayo told the story, he raced over to Athens in his old ialopvon a rainv Fridavaftemoon. En mute, he had to stop ionijtwim!) torepair flats on the wom-outwartime tire8. H e arrived, alas, too l a t e for visiting hours a t his daughterb dormitory. In those days, the r d e s of a ladies' dormitory were very strict, forbidding even a doting father from see& his own daughter. Nevertheless, being the ingenious and enterprising fellow he was, Mayo drove up and parked under Bebe's dormitory window and honked his horn. (The horn still worked!) Out came the precious envelope, dropped by his young accomplice into his waiting hands. According to Frank, it sailed gently to the ground, I opened it in front of the headlights and read what she had copied. It was in German, hut I could read it. I saw 'dichlorodiphenyltrichloroethane'. That was it! That was DDT. I knew at that moment that I held in mv hands somethine priceless, romethmg as wonderful and as miracle-hkras pen)cillin itrdf. Thr government was umng i t but there was not n
-
364
Journal of Chemical Education
pound nvailablr for clvilian use. A billion dollar market was waltinz fur somebody. I might as well tv to get a share. I had visions ofrugarplums, ynchri i n the Caribbeort. Kobudy to put
it on the market but me. The Search for the Ingredients
As Frank Mayo drove back to Atlanta late that night, his mind went into action. Zeidler's article had recounted the author's method of preparing DDT. Even more important than this, i t divulged the chemical names of the two principal ingredients, monochlorobenzene and chloral, which were to react in the presence of concentrated sulfuric acid. Frank had the acid-that was no problem. But gettimg the other two starting materials-in sufficient auantities. not to mentlon d u n n ~ w s n l m c w o u l dbe as much trouble as gcttlng hold of Zrldler's anlcle in thp first place. Fortunately, he had a liter bottle of monochlorobe&ene in his small stockroom. But where could he get - holdofthe chloral he needed to test his new "recipe'? Chloral hydrate (trichloroacetaldehyde monohydrate) was actually better known then than i t is today. It was the active ingredient in the old "Mickey Finn" knockout drops, which were chloral mixed with water. Would the pharmaceutical preparation suffice? Where could he get it? In desperation he woke up his friendly neighborhood druggist in the middle of the night and posed the question. He was grumpily informed that a doctor's prescription was required for the chloral. The druggist also admonished him, "No damned doctor is going to give you a prescription for as much as a pound of the stuff." The ordinary dose was then measured in minims. which was a customam and very small pharmaceutical dosage unit. (There are approximately 16 minims in a milliliter.) Reluctantly, but excitedly, Mayo told the druggist about DDT and about how close he was to being able to make it now that he had the correct information. "If you can do that," said his friend, "I'll go down and open up the drug store and give you a pound of the choral hydrate, but" he added, "I want a gallon of that DDT solution!" The Successful Trial Run
Frank got the chloral and went home and weighed out the chemicals in a fruit jar packed in ice. He stirred the mixture well with a wooden kitchen spoon. In about twenty minutes, the top of the liquid was covered with floating white lumps. I felt as thrilled as Zeidler must have felt 70 vears earlier. synthesmng thr* new urmpaund for the very first t l m o only he waq wholly unnu,are of an)' posslble use for ~t Or perhdps ar Keats' sonnet has it,
Stout Cortez when with eagle eyes, He stared at the Pacific and all his men, Look'd at each other with a wild surmise, Silent, upon a peak in Darien. Frank continued, I strained the lumps out using my wife's buttermilk strainer. I carefully dried the powder and smelled it; it didn't smell like anything familiar. It was something new.
Then he slept. In the morning he made up a 5%solution of the new material using mineral spirits as the solvent. Then he sprayed the area in his basement where the laundry was done. It had previously been heavily infested with fleas from his dogs. An hour later, be and his wife went back down into the basement. Not a flea -ium~ed . on mv wife's ankles. I oulled down mv
sock$. Nothing happened-no flmsfThr flies, formerly plenuful, were dead. Cockruarher.were lying on their hneks W I Ih feet in the air ns if waving gnndhyr to mr I was n hnppy man.
Mavo's Plant and His Process
Frank built a plant to manufacture DDT. He built it almost single-handedly using materials that most chemists would now consider scrap and junk. He had to scrounge for his ~arts-not for lack of money, hut for lack of equipment thai could he purchased without a wartime Such priorities were granted only to those who were manufacturing directly on behalf of the war effort. Mayo was eventually able to salvage several used 55gallon steel drums. He welded them together vertically, one on top of another, until he had several tanks that were each h e drums high. The only corrosive ingredient would be the sulfuric acid. Since he was usma a 985 acid, he knew the drums would be safe as long as water was avoided. In place of a stirrer, he simply bubbled air through the mixture using an old air compressor attached to a garden hose that was immersed to the bottom of the tank. Asteel wire basket was also immersed to the bottom of the tank, and it was slowly pulled up aRer all the DDT had precipitated from the mixture. Then the DDT was spread out on concrete slabs and allowed to air-dry From this Mayo made a 5% solution in deodorized kerosene. He filled his product into pint, quart, and gallon bottles. Even the bottle-filling machine was homemade.
The whole array was not much to look at-but it worked. The plant operated day and night ceaselessly, ultimately producing hundreds of thousands of pounds of powdered DDT and DDT solution. This product was shipped all over the world with little, if any, competition at the time. As conditions permitted, Frank acquired better equipment, piece by piece, until he had a more respectable looking plant-but the new plant wasn't any more efficient. He enlarged the plant several times to increase its capacity. His methods were somewhat bizarre, and more than a little ingenious. The demand Mayo received for DDT persisted for a while even after the war ended. Eventually, those who had made the wartime product in one form or another converted their more efficient plants for civilian production. Naturally, the price plummeted and the demand dropped. Frank returned to manufacturing his earlier products: chlorine bleach and disinfectants. In these two items alone, his company played a significant role in the war effort, and it continues to this day making large quantities of chlorine-eontaining compounds. At one time, Mayo also built and operated a large plant for the manufacture of hydrated and anhydrous sodium metasilicate of the highest purity.
Volume 69 Number 5 May 1992
365
