INDUSTRIAL A N D ENGINEERING CHEMISTRY
September, 1926
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Insecticides and Fungicides’ By E. C. Holton THCSHERWIN-WILLIAMS Co., CLEVELAND, OHIO
NSECT pests have harassed man in all ages. Whenever large areas come under intense cultivation, conditions become especially favorable for the development of insect life, food for the insects becomes plentiful, and natural enemies become scarce. Under these conditions’ it becomes necessary for man t o exercise great diligence and skill lest the insects deprive him of the fruits of his toil, even unto starvation. The use of many mineral, animal, and vegetable substances for the purpose of repelling or killing the insects infesting fields, orchards, and gardens dates back to very ancient times. The instructions given in gardeners’ handbooks in use two or three hundred years ago appear t o have been largely derived from. Pliny’s Satural History, written nearly two thousand years ago. Some of these instructions appear very foolish to us today, while others in a more or less modified form are still followed. Fumigation with smoke and vapors from burning asphalt, resins, and sulfur was practiced by the ancients. Anointments and dustings were made using ashes, sulfur, arsenic sulfide, and medicinal herbs. Similar practices are in vogue today.
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[I’liny,Book 17, Chapter 471
Ashes have the same virtues as salt only in a more modified degree, for which reason it is that fig trees are sprinkled with them, as also with rue, to keep away worms and t o prevent the roots from rotting.*** What is still more even, i t is recommended t o throw salt water on the roots of vines, if they are too full of humors; and if the fruit falls off t o sprinkle them with ashes and vinegar. or with sandarach (natural arsenic sulfide) if the grapes are rotting. [Pliny,Book 19, Chapter 581
Flies too infest well watered gardens and more particularly so if there happen to be any shrubs there; they may be gotten rid of, however, by burning galbanum. [I?liny, Book 23, Chapter 131
I would not recommend any one t o use the kernels of the wild astaphis (larkspur) as a purgative, as it is very doubtful whether they might not choke the patient, nor would I advise them t o be employed for the purpose of attenuating the phlegm as they are extremely irritating t o the throat. Beaten up, however, and applied topically they kill vermin in the head and other parts of the body, more particularly if they are used with sandarach (natural arsenic sulfide).
During the last hundred years nearly all of the readily obtainable inorganic chemical substances which are kn0R-n to be poisonous have been proposed or tried for insect control. A considerable number of natural organic substances have also been tried, but a relatively slight investigation has been made of the vast number of known synthetic organic compounds. It is only in the last fifty years, and more especially in the last twenty-five years, that the manufacture and use of insecticides in this country has assumed great commercial importance. Paris Green and London Purple
It may be said that the modern insecticide industry was started by a small beetle, whose habitat wae in the Rocky Mountains. This insect, quietly feeding in the hills, was agreeably surprised one day when it found potato plants growing in the gardens of the recently arrived settlers. These plants furnished a food agreeable and nourishing to this insect and it deserted its native hills and journeyed east 1
Received M a y 29, 1926.
in its quest for more potatoes. By 1839 it had nearly reached Omaha, and by 1874 it had spread out over the country eastward, even to the iltlantic Coast. Paris green came into use as a n insecticide for the control of this insect between 1860 and 1870, and by many farmers is still considered the most satisfactory insecticide for this purpose. Between 1870 and 1880 the canker worm was doing much damage in the apple orchards of the eastern states, and Paris green was used to combat this insect. I n spraying for the control of the canker worm it was found that the codlin moth also was held in check to a considerable extent. Spraying for the control of the codlin moth began to be carried on with success in many orchards, and besides Paris green other arsenicals were used. Hemingway’s London purple, which was introduced in 1878, became an active competitor of Paris green for use both on potatoes and trees. London purple was originally made as a by-product of the magenta industry, and its insecticidal properties were due to the calcium arsenite and calcium arsenate and other arsenites and arsenates present, Because its composition was rather variable in the early years of its production and the watersoluble arsenic a t times was considerable, i t was recommended that a n equal weight of lime should be used with it to prevent burning of the foliage. The same recommendation was made for Paris green, and whenever lime was used with these insecticides they gave satisfactory results except in a few sections where peculiar climatic conditions existed. It has been estimated that by 1896 the annual consumptions of Paris green had risen to 2000 tons in the United States and to 400 tons in Canada. For the year ending June 30, 1925, Department of Commerce report s h o w a production by nineteeh firms of 3,544,887 pounds, estimated to be about 70 per cent of the total production. Arsenate of Lead
I n the meantime a new pest was threatening great destruction and was creating a demand for a new use of a n old material. Acid arsenate of lead, first made by Scheele in 1775, was later studied by Klaproth and Chenevix and Thknard, and its composition was determined and methods for its production were established about 1801. A few years later Berzelius, hlitscherlich, and Graham studied the two arsenates of lead and established their composition and conditions for their production. However, it was not until about 1892-1893, when F. C. hloulton, chemist for the Massachusetts Gypsy X o t h Commission, prepared some arsenate of lead which was used in attempts to control the gypsy moth, that this insecticide came prominently before the public. Fortunately for the farmers and orchardists of this country, the U. S. Patent Office did not grant him the patent for which he applied and the manufacture of arsenate of lead was a n open industry. The Gypsy Moth Commission found this insecticide possessed good adherence, was practically harmless to the leaves, and quite fatal to the young larvae. The news of its success was rapidly spread. It was successfully used against the elm leaf beetle, the grape worm, and the codlin moth and other insects. It became a strong competitor of Paris green and in a short time had almost driven the latter out of the apple orchards.
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ciglitecn eorimns i n the Unit,t.d mere manufaotoring iL arid the coiiimcriial productioii ii t,liat,season was approximately 2500 tons, valued at more timi half a inillioii dollars. In addition to this, large quaniitics of horne-ruade material were used. Since the mininercial arsenate of lead a t that time averaged about 50 pcr cent water, t,lic production on a dry basis was about 2,500,000 pounds. In 1926 the Department of Commerce reported that nineteen companies or firms operat,ing twentythree plants reported for the year ending June 30, 1‘325, a produetion of 13,865,482 pounds of this insecticide. This RRS thought t,o be ahout 70 p’r cent of the total product.ion. 13~-l!iOi~~l!i(J8at, I tos
Calcium Arsenate
At about the time that the Gypsy Moth first attracted serious attention in Xassaehusetts, another foreign insect migrated to the United States. It is believed that the cotton boll weevil crossed the Rio Grande near Brownsville, Texas, almut 1892. Ry 1894 it had demonstrated its capacity for damage in a considerable portion of southern Texas. Year by year it has extended the area of infestation, until at last it, has praatically covered the cotton-growing distri Various inseeticides arid methods of control h suggested and tried, hut up to tlie present time the method whicli seeins to give the best success is dusting with calciuin arsenate. The dust has been applied by means of a hand gun carried and operated by the laborer, also hy a one-wheel, one-mule machine and by a two-wheel, two-mule macliine, and, finally, large areas have h e n dusted from airplanes. Alt,houglr arsenates of calcium have been known for a long time and to a limited extent have been used in insecticides for about fifty years, it is only in very recent years that extensive use has heen made of this economical insecticide. I n I919 five manufacturers reported a production of 1,191,868 pounds. I n 1921 seven reported 2,419,684 pounds. In 1923 nine reported 13,261,233 pounds and in 1925 nineteen reported 19,911,262 pounds.
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iny of the coni~n)x,iinilsof sulfur possess insecticidal pwIx:rtir:s. Carbon disulfide aird the soluble alkaline sulkearhoiiates and xautliatcs are used in this country to a lirnited extl?nt. Other Insecticides and Fungicides
flydrocyairic arid gas has come inbo quite exteiisive use as a ‘fumigant in grcenhousos and in citrus groves. A recent dcvclopmrnt is the commercial production of a powdered ralciuiii cyanide which may be used as an insectir:idal dust. This dust rapidly deeornposes in moist atniospliere liberating hydroryaniq acid gas. Para-dichlorobt?nnenefor the peacl~borcr, ethyl acetatecarhon tetrachloride mixture for insects in grain, airti carhon t.etracb1oride for the hookworm have recently come into use. Tuhacco, as a dust or in the form of concentrated extract or as nicotine salt, is still largely usnl. Compounds of mercury and zinc and fkwriiles axid silicofluorides of the alkalies and alkaline eart,hs find limited use as
Sulfur and Sulfur Compounds
Sulfur and the fumes of burning sulfur were used by orchardists in ancient times. Sulfur is repellent to many species of insects, but in the elemental form does not rank high as an insecticide. Sulfur in combination with alkalies and alkaline earths in t,he form of polysulfides bas been used successfully for many years in combating scale insects. Lime-sulfur solution, dry lime sulfur, barium tetrasulfide, and “soluble sulfur” arc being extensively used today, although a definite attempt is being made to discredit them in some quarters. Twenty-five years ago petrolaum emulsions enjoyed a good reputation, notwithstanding the fact that many trees were injured by their use. Gradually the use of lime sulfur in the liquid and dry forms iircreased until it generally became the standard insecticide for treating scale insects. Because these safe and very useful insecticides “appear to have failed to control under all conditions,” attempts are being made to stampede orchardists into abandoning t.heir use in favor of petroleum. It is believed that those orchardists who have sucreeded for years in keeping their trees free from scale by the use of these sulfur compounds will be slow to make a change. On the other hand, if there are those who have failed through peculiar climatic conditions or faulty application, or because of the development of peculiarly resistaiit strailis of scale, it would seem to he advisable for them to resort to a very careful use of petroleurn emulsions a t least for a few seasons. Lime sulfur is extensively used in sheep and catt.le dips to control the insect parasites on these animals.
known which specigc K’aproth’ fraction of uetroleum distillate is best adnwted for controlliiir a specific iisect in a specitic place. Commercial preparat.ions of arsenite of sodium in eombination wit.h soaps of resins, oils, and phenols, used in dipping oattle, have practically eliminated the great scourge of Texas fever by controlling the ticks which caused the fever. Various copper Compounds have been used as fungicides for about fifty years, but it is only within quite recent times that manufacturers have placed Bordeaux preparations on tlie market in noticeable quantities. Many of the larger users of this most important fungicide still prefer to prepare it in the field from blue vitriol, lime, and water. The use of formaldehyde in the treatment of seed has become commercially important. An insecticide greatly t.0 be desired is one that will prove as
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September, 1926
I-VDrSTRIAL A S D EXGIXEERISG CHEXIXTRY
harmless to the foliage as arsenate of lead and as deadly to the insect as Paris green and nicotine, as cheap as lime sulfur, and no more harmful to the soil than lime sulfur or nicotine. Doubtless there are many known synthetic organic conipounds which could be advantageously used as insecticides, but they have not yet been investigated for such use. Much
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is yet to be learned about petroleums and the products which it is possible to develop from petroleum. Many of the higher alcohols, ketones, aldehydes, and esters are insect repellents and insecticides. It may be possible to prepare synthetic compounds which will be much cheaper and yet stronger insecticides than nicotine. The field is wide and interesting.
The Development of the Aromatic Chemical Industry from 1876 to 1926’ By Martin Szamatolski GIVAUDAU-DELAWANNA, DELAWANNA, N. J.
HE year 1876 is one of the most important in the history of the aromatic chemical industry. At that time the manufacture of perfumes and similar materials was completely dominated by the use of natural products derived directly by nonchemical means such as extraction from flowers or animal products. Chemists u p to that time feared to tackle the complex problems involved in the analysis of perfume oils, etc., as the belief was prevalent that the delicate bodies constituting the odor of flowers would not survive the rough methods of chemistry and that even steam distillation would destroy them. We have to thank Tiemann and Wallach in Germany, and Tilden and Perkin in England, for the impulse which they gave this industry by their wonderful work. While Tiemann and Haarmann had found, in 1874, the connection between coniferin and T anillin and had succeeded in producing the latter, i t was only in 1876 that they discovered the relation between eugenol and vanillin, and on this base started the modern manufacture of vanillin and thus became the real fathers of the aromatic chemical industry. I n the same year Tiemann and Reimer discovered the synthesis of salicylic aldehyde from phenol and chloroform, which forms the raw material for the manufacture of cumarin, and allowed them to place the latter on the market in 1878. Great advance was also made in the manufacture of essential oils, Heinrich Haensel producing terpeneless oils for the first time in 1876. After the start had been made, new discoveries followed in rapid succession. I n 1877 Tiemann and Herzberg produced aubepine from p-oxybenzaldehyde, a by-product of the cumarin manufacture. I n 1878 Schimmel began the manufacture of heliotropine by the oxidation of piperinic acid, a process which prevailed until Eykmann, in 1890, discovered the relation between safrol and piperonal. It was also in 1878 that Tilden found the true nature of terpineol, which Schimmel placed on the market in 1890. The year 1888 brought the birthday of artificial musk, a discovery of Baur, while 1893 saw new worlds opened by Tiemann’s discovery of the constitution of irone, the synthesis of ionone and of similar violet products. Into the same period fall the isolation of geraniol from oil of citronella, linalool from oil of bois de rose, citral from oil of lemon grass, anethole from anise oil. A little later, the manufacture of cinnamic alcohol, menthol, santalol, borneol, citronellal, methylheptenon had its inception and the production of citronellol and cinnamic aldehyde (condensation of benzaldehyde and acetaldehyde) soon followed. On the other hand, careful analysis of natural products showed the presence of long- and well-known substances the perfume value of which had been overlooked. In this way * Received July 3, 1926.
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began the manufacture of benzyl acetate, methyl salicylate and benzyl alcohol. I n connection therewith the odor value of compounds was realized, which do not exist in natural products like amyl salicylate, beta-naphthol ether, phenyl acetaldehyde, bromostyrol, etc. I n the period 1900 to 1910 phenylethyl alcohol was discovered in rose oil, indole and scatol in jasmine, and methyl anthranilate in ylang-ylang oil, thus paving the way for their manufacture, while hioureu taught us the use of methylheptine carbonate and Coulin patented citronellal hydrate, the base of our lily of the valley perfumes. The years 1911 to 1926 brought us synthetic thymol, menthol, and cinnamic alcohol, as well as a number of products hitherto not fully appreciated, like phenylpropyl alcohol, the higher fatty alcohols and aldehydes, phenylpropyl aldehyde, (+naphthyl methyl ketone and, as crowning glory, the synthetic manufacture of real civet and musk by Ruzicka. Thus the half-century so auspiciously inaugurated by Tiemann’s classical discoveries is fittingly closed by the unraveling of a mystery which had baffled for decades the efforts of our greatest minds. While the synthetic aromatic industry made its marvelous strides, that of the natural materials advanced only moderately. A few new oils and raw materials made their appearance, distilling apparatus was greatly improved, the selection, crossing, and growing of odoriferous plants became the subject of scientific care and study, but on the whole the old methods, enfleuration and steam distillation, still prevailed and were only partly supplanted by the introduction of extraction with a volatile solvent. If we look over the achievements indicated above, we will readily see, that notwithstanding all our efforts, the surface of perfume chemistry has only been scratched. Hardly the main notes in the harmonies of floral odors are known and endless work may still be done, even on the most common materials. Even so, the values created by aromatic chemistry have been simply enormous. During a time when chemical industry doubled its output, that of the aromatic chemical factories quintupled. In the United States, notwithstanding that a real start was made only in 1913, a t this writing practically all the odoriferous materials consumed are produced a t home in a quality second to none and frequently by processes entirely original and superior to those employed abroad. Hand in hand with this development went a constan$ reduction in prices: vanillin fell from $1000 to $8 per pound, heliotropine from $400 to $3, cumarin from $50 to $3, terpineol from $11 to 50 cents-in short, thanks to chemistry, goods which once constituted a king’s ransom are now available and daily used by even the poorest among us.
