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melting point of this substance (64” C.) casts a doubt on its ability to remove water from the liquid reaction phase. Further in the first four experiments recorded, where time and water are varied (water was in these four case5 1.6 M), the yield is practically constant over a range of time from 10 minutes to 3 hours. This leads me to believe that the entire reaction was complete in less than 10 minutes and the 54 to 55 per cent yield shows that the first methyl group reacted completely and the second methyl group to the extent of, say, 10 per cent. If it were assured that all sodium methyl sulfate had reacted-and it is quite possible that considerable proportion remains unreacted-to form sodium sulfate and anisoie or methanol after 10 minutes-and this should not be difficult t o determine by titrating excess sodium hydroxide with the proper indicator-it might be concluded that the reaction forming anisole is but one-tenth as fast as the hydrolysis reaction velocity. This conclusion, however, is not warranted in view of present insufficient experimental data. There are other interesting relations between various magnitudes of yield, the discussion of which could become very extended. It is sufficient t o say that all these depend on competing reaction velocities, the investigation of which would be pertinent. Even the order of the methylation reaction, whether mono-, di-, or tri-molecular, is unknown. In 1924 I had occasion to prepare anisole in commercial quantities by a method which, in view of its strict analogy t o Cade’s work, I had not heretofore considered to be of sufficient novelty t o warrant publication. The equipment was a clean, dry, steam-jacketed Duriron kettle provided with a condenser and reflux condenser, interchangeable a t will by a three-way cock at the base of the reflux, a solids charging port, a deep liquids charging line, an anchor type stirrer (30 r. p. m.), and deep and shallow thermometer wells. Through the solids port two molecular parts plus 2 per cent of molten phenol and two molecular parts plus 5 per cent of flake caustic soda were introduced. As soon as the charging port was closed, the careful introduction of one molecular part of dimethyl sulfate was begun a t a rate to keep the temperature of the reaction mass above 45“ C. Cooling water was applied to the jacket t o keep the temperature below 60’ C. as indicated by the thermometer in the deep well, while the dimethyl sulfate was introduced as rapidly as consistent with this limitation. The introduction of dimethyl sulfate generally required about half an hour. Steam was then applied t o the jacket quickly raising the temperature of the reaction mass to 100-105” C., whereupon some refluxing Of water with a little anisole occurred. Gentle refluxing was maintained for a half-hour to an hour, depending on the magnitude of the reaction mass. Then, stopping the refluxing momentarily, the vapor was diverted to a condenser by the three-way cock and live steam was blown into the reaction mass through the liquids charging line. The anisole was rapidly steamdistilled out of the kettle, The aqueous layer of the distillate was separated and, while the anisole might be further purified by distillation, the steam-distilled material when properly dried was of satisfactory quality for use as a raw material for further reactions. The excess of phenol, if of sufficient quantity, could be recovered by acidifying the reaction residue with sulfuric acid and steam-distilling. The chemical efficiency of the reaction calculated on both methyl groups of dimethyl sulfate was always better than 90 per cent, generally 95 per cent, and occasionally as high as 97 per cent, I believe that, with stirring and minimization of water content of the reaction mass, similar high yields result when dimethyl sulfate is replaced by sodium methyl sulfate. The publication of Professor Lewis’s studies on methylation of phenol with sodium methyl sulfate is anticipated with interest. INDUSTRIAL R E S E A R C H E. YEAKLEWOLFORD AND
ENGINEERING COMPANY
PITTSBURGH,
PA.
February 13, 1930
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Editor of Industrial and Engineering Chemistry: I quite agree with Mr. Wolford in his implication that the data necessary for an improved technic in the use of dimethyl sulfate as a methylating agent are to be found by analogy in the paper of Cade, as referred to above. In spite of this, the use of dimethyl sulfate as a methylating agent, as outlined even in the recent literature, is following the older procedures of Dumas and Peligot (Centralblatt, 1835, 279) and Ullmann and Wenner ZBer., 33, 2476 (1900)j. For this reason the data presented in our paper call attention to the relative influence of varying amounts of sodium hydroxide, sodium phenolate, dimethyl sulfate, and water on the course of the reaction and on the yield of anisol. I n the latest volume of “Organic Syntheses” [Vol. IX, p. 12 (1929) J there is outlined a preparation of anisole in which the relatively large quantities of water present cut down the yield of anisole to the extent of 15 per cent. This in itself justifies the presentation of our data. The method for making anisole outlined by hlr. Wolford is a valuable addition to the literature of the subject and should be used in place of the above method as given in “Organic Syntheses.” The questions raised by Mr. Wolford in regard to the relative reactions of hydrolysis and methylation, the influence of stirring by convection, etc., are debatable. On the basis of past experience [Lewis, Mason, and Morgan, IND.ENG.CHEM.,16, 811 (1924)], it appears that reactions or hydrolysis are favored by relatively smaller concentrations of water, rather than the opposite. HARRY F. LEWIS OHIO WESLEYAN UNIVERSITY DELAWARE, OHIO
March 4, 193C
Mothproofing Editor uj Industria2 and Engineering Chemistry: I n the recent article under this title by Minaeff and Wright, IND.ENG.CHEM., 21, 1187 (1929), statements are made regarding the application of cinchona alkaloids for mothproofing that are at variance with observations made by the writer and ENG.CHEM.,19, 1175 (1927). Helen E. Wassell, IND. From the inception of the work that led t o the publication of our original paper on the application of the cinchona alkaloids in mothproofing textile products, our constant aim has been t o obtain dependable and confirmable results. Methods for testing the mothproofing properties of substances had to be devised. Then, too, the development of suitable criteria for judging the relative mothproofing values of various materials required considerable time. The final result of this study was that, instead of depending upon one single method, six different procedures were evolved by us in reaching our definite conclusions. In brief, these methods are as follows: (1) Exposure of treated pieces of wool in a cupboard containing wool materials infested with moths. (2) Exposure of treated and untreated pieces in Petri dishes to twenty-five full-grown larvae. (3) Exposure of treated pieces in Petri dishes, with no other choice of food, t o twenty-five full-grown larvae. (4) Observation of moth-infested pieces of wool clothing that have been treated and hung in closed cupboards, with and without reinfesting the garments with m x e clothes moths. ( 5 ) Exposure of treated pieces of wool in Petri dishes to six to twelve moth flies, followed by incubation. (6) Treatment of moth-infested furniture, rugs, and clothing in homes under actual conditions as they occur in everyday life. When treated pieces of wool withstood the attack of moths in the preliminary test (l), then similarly treated pieces were tested by as many of the other methods as the progressive results of the observations indicated t o be desirable. When continued test
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observations showed a n insufficient protection for a specific treatment, another series of tests with increased quantities of the prospective mothproofing agent was started and carried on until the quantity used reached an unreasonable amount or proved satisfactory. Minaeff and Xl'right chose to mention in their article only the preliminary test described in our paper. They ignored the other methods of testing described fully by us. Rather than to attempt to explain the variance of the Minaeff and Wright conclusions from our own by a difference in testing methods, it is the opinion of the writer that there are two other reasons. One is that, when the petroleum naphtha solutions of the cinchona alkaloid oleates were prepared by Minaeff and Wright, the strengths of the solutions were the minima described in the Jackson and Wassell patent (V. S. 1,615,843). The minima mentioned in the patent specification are purposely low, in order to provide adequately broad patent protection. Although the minimum concentrations of the alkaloid oleates referred to do offer protection to wool against moth attack under many natural conditions, they are not sufficient to withstand the particular test which apparently was chosen by hlinaeff and Wright because of certain definite characteristics of their mothproofing material. Furthermore, these concentrations are lower than those used in commercial practice. The test in which Minaeff and Wright dissolved 1 gram of quinidine per se in 100 cc. of acetone is not conclusive, because acetone solutions do not readily penetrate wool fibers. This fact is shown by the observation that wool fibers are only superficially colored by solutions of dyes in acetone. On the other hand, solutions of dyes in petroleum naphtha give good penetration of the fibers. In our experimental work it was learned that the cinchona alkaloids per se, alone or in mixture, do not equal certain of their salts in mothproofing power. The fatty acid salts were found to be outstanding in mothproofing effectiveness. It is doubtful, in the writer's opinion, whether the reaction between quinidine and oleic acid was really complete under the conditions of the hlinaeff and Wright experiment. I n preparing naphtha solutions of cinchona alkaloid oleate for commercial use, the reaction is carried out slowly with heating. Even granting that the reaction was complete in the experiment described by Minaeff and Wright, the concentration of the quinidine oleate was the minimum claimed i n our patent and lower than that used in actual practice. Minaeff and XVright allude t o the mothproofing quality of oleic acid and imply wrongly that they told the writer of this characteristic for the first time. Although this property of oleic acid was discussed with Minaeff and Wright prior t o the application for the patent embracing the use of fatty acids for mothproofing, this discussion did not antedate the basic experimental work on the subject as conducted by the writer and Miss Wassell. Fatty acids, including, of course, oleic acid, have mothproofing qualities when used in relatively high concentrations; but the concentrations required are much greater than those for the cinchona alkaloid oleates. hlinaeff and Wright have evidently been unsuccessful in confirming our findings respecting the effectiveness of cinchona alkaloids as mothproofing agents, but our results have been substantiated in full by no less than five other investigators. Two of the other researchers are chemists and three of them are entomologists. The chemists are Glen S. Hiers, Industrial Fellow of Mellon Institute of Industrial Research, and A. H. Ryan, of the Hoover Company, Chicago, Ill. The entomologists are E. A. Back and R. T. Cotton, of the Bureau of Entomology, Vnited States Department of Agriculture, and William Moore, of the American Cyanamid Sales Company, New York, N. Y . The findings of Hiers and Ryan have been given to the writer in personal communications. The results of Back [Furniture Warehouseman, 8, No. 10, 800 (1927); Furniture Mfr., 95, No. 4, 35
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(1928)), and Moore (Nutl. Cleaner Dyer, 20, N o . 5, 77 (1929)l have been published. The cinchona alkaloid oleates have had a successful history as mothproofing agents over a period of four years. They were first introduced in the dry-cleaning industry in 1926, when they were made the basis of a mothproofing service that is guaranteed to be effective. The demand has grown rapidly since then. The product now being marketed is being used widely and successfully in the dry-cleaning, furniture, warehouse, and textile products industries, and recently has been made available in convenient packages for household use. A product with such a successful commercial history cannot be based upon a substance that accelerates clothes-moth attack, as is incorrectly and unjustly asserted by Minaeff and Wright. The evaluation of any substance for mothproofing quality is always more or less arbitrary. The procedure is not by any means comparable in exactness with a chemical analysis. It has been demonstrated by Moore (private communication) that the llinaeff and Wright method of testing a small area of treated cloth, without including any untreated material, is far more favorable to a fluoride- or silicofluoride-treated sample than any of the other tests used by Moore, who employed the same tests that were followed by Jackson and Wassell. The explanation of this fact is that the fluorides are stomach poisons, so that where the moth larvae are confined to the poisoned food, without any opportunity to eat unpoisoned food, they consume enough t o kill them rather quickly. But where there is a choice of poisoned and unpoisoned food, which is generally the case under natural conditions, larvae live much longer and do more damage to both samples of material, because the worm feeds indiscriminately from both. In other words, a sample cloth treated with fluoride or silicofluoride exposed to larvae in a dish also containing an untreated sample of cloth is damaged more severely than a similarly treated piece of cloth exposed to larvae without any choice of food. It should be borne in mind that the cinchona alkaloid oleates are true moth repellents and protect treated materials even in the presence of a choice of moth food. When two pieces of cloth, one treated with a silicofluoride and the other with a chinchona alkaloid oleate, are placed in a Petri dish with moth larvae, without other choice of food, the silicofluoridetreated samples will be eaten while the cinchona alkaloid oleate treated sample will not be attacked. I n view of the facts presented and especially in view of the successful industrial use of cinchona alkaloid mothproofing products, the conclusions of Minaeff and Wright are regarded as unfair and unsound. After all, the proof of the value of any industrial research is brought out clearly in its commercial application.
LLOYDE. JACKSON ?"IELLON INSTITUTE OF INDCSTRIAL RESEARCH
PITTSBURGH, PA.
January 20, 1930
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Editor of Industrial and Engineering Chemistry: Our experiments with alkaloids were not confined to solutions prepared only with acetone as a solvent. Several other solvents were used, including petroleum distillates, as stated in our article. I n fact, the petroleum solution investigated by us and referred to in our article was one supplied to us by Doctor Jackson. At the time of the issuance of Jackson and Wassell's first patent, the Larvex Corporation conducted a rather careful investigation, being interested in the patent to the extent of possibly negotiating for the commercial rights, in order to provide a mothproofing agent soluble in petroleum distillates, which could be utilized by the dry-cleaning trade. The particular solution in question was furnished by Doctor Jackson as an example of the product which had been found efficient and practical for commercial purposes. We assumed that it was pre-
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pared in accordance with the patent specifications, and that it represented the most desirable product for commercial use. Another experiment, not previously reported by us, is of decided interest in this connection: Cloth was treated in the same manner as described in our article, with a solution consisting of 2 per cent quinidine and 4 per cent oleic acid in a petroleum distillate (Varnolene, manufactured by the Standard Oil Company of New York). The treated fabric was air-dried overnight and when exposed to moth larvae (as usual, in Petri dishes) there was not the slightest indication of damage; in fact, when tested immediately after application, we considered the treated material as entirely moth-resistant. Another portion of the same treated fabric was aired on a line in the laboratory for about one month and then exposed to larvae attack in the same way. I n this case the larvae actually placed in the dish would not eat the fabric, but spun cocoons and started transformation into the pupae. After the usual length of time, the pupae hatched, a number of flying moths appeared, and in a few weeks young larvae were observed. The young larvae had no food but the treated fabric: several of the larvae of this second generation continued to grow during a period of several months, and the fabric gradually became more and more damaged Now it is quite badly damaged and some larvae are still alive. We believe there is no question but that the treatment of woolen fabric as described by Jackson and Tassel1 does provide a certain degree of resistance to moth damage. However, in our experience this resistance is not permanent, and disappears after treated material has been exposed to the air for a period of months. The question as to who was the first to note the mothproofing quality of oleic acid is of no practical importance, fatty acids in general being of such a nature as to render them entirely impractical as mothproofing agents. However, it is apparent t h a t Doctor Jackson’s recollection of this situation is not entirely correct. During the conference in New York (held on September 28, 1927) referred to by Doctor Jackson, he was quite surprised a t our suggestion that perhaps oleic acid was a more important mothproofing agent in his compound than the alkaloid itself, and expressed considerable skepticism as to the possibility of oleic or any other fatty acid imparting any mothproofing qualities whatsoever. During this conference we showed Doctor Jackson the actual dishes containing samples of cloth experimentally treated with alkaloids and oleic acid, these being the actual dishes which were later reported in our article which AND ENGINEERING CHEMISTRY. appeared in INDUSTRIAL Doctor Jackson’s comments upon the method of testing the resistance of treated fibers to the action of moth larvae are interesting, but in our opinion do not give a true understanding of the situation. To a certain extent Doctor Jackson is undoubtedly correct. We believe that there is no question that wool fiber treated with cinchona alkaloids may show more resistance t o damage by moth larvae than will fiber that has not had a n efficient treatment with silicofluorides, provided an ample supply of untreated wool is immediately available. I n other words, cinchona alkaloids in petroleum distillates are objectionable as food t o moth larvae. If there is a choice, the moth larvae will undoubtedly eat untreated fibers in preference to those containing the above substances. On the other hand, silicofluoride is not repellent; it is effective only as it is taken into the digestive tract of the larvae. It is quite obvious that when two food supplies are available side by side, neither of which is repellent, the larvae may (provided that one material is somewhat undertreated) maintain a degree of normal health by eating the untreated fiber and a t the same time do considerable damage t o the poorly treated. On the other hand, it is probably quite true that fibers treated with alkaloids, oleic acid, and petroleum distillates would show less resistance t o moth larvae when tested in the absence of other food than when an unlimited
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supply of more suitable food were available. However, one could hardly expect a treated garment to be intentionally hung beside an untreated one in order that the moth larvae might always have a choice of material on which to feed.
M. G . MINAEFR J. H. WRIGHT THELARVEXCORPORATION 250 PARK AVE. NEW YORK, N. Y. February 20, 1930
Drying of Exterior Paints under Various Weather Conditions and over Different Woods Editor of Industrial and Engineering Chemistry: The article under this title by Schmutz and Palmer, IND. ENG. CHEM.,22, 84 (1930), should not go unchallenged, because the authors pass adverse judgment upon two woods widely and properly used for such purposes as exterior construction on houses. Their experimental data are susceptible of very different interpretation, more in line with common experience with paint on these woods. The authors report observations of the time required for a single coat of paint t o dry when applied to glass or t o wood under certain weather conditions produced artificially in the laboratory, some of which are considered adverse. Four different paints, described only as A, B, D, and E, were used in the experiments on wood. Five species of wood were used and named. The following observations are recorded:
(1) All four paints dried promptly on all woods under good drying conditions. (2) All paints were retarded by low temperature (32’ F.) both on glass and on wood, “but the average time differences were not so great (on wood) as on glass.” (3) Paints B and E in the presence of high humidity, either a t 100’ or a t 32” F., dried very much more slowly on cypress than on other woods or on glass. (4) Paint B in the presence of high humidity dried much more slowly a t 100” F. on redwood than on other woods (except cypress) or on glass, but at 32” F. this paint dried about as rapidly on redwood as it did on the other woods and more rapidly than on glass. On the basis of these findings the authors conclude that “excessive moisture and low temperature, particularly the latter, contribute to poor painting conditions, and this retarding effect can readily be intensified by poor lumber.” Although not expressly so stated, the reader is evidently expected to understand that cypress and redwood are “poor lumber,” a n inference that is totally unjustified. It would be far more logical t o conclude that paints B and E are poor paints, because they are not so well adapted as paints A and D to some of the extreme conditions that might conceivably be encountered in practice. However, it would be just as unfair to pass judgment upon the paints on the basis of the evidence presented as it is to condemn the woods, for it is not yet clear that the findings reported are of practical significance and the paints, if their composition were revealed, doubtless possess substantial merit. The following quotation from page 80 of my “Fourth Progress Report for the Study of the Painting Characteristics of Wood,” a copy of which was sent t o the Research Laboratory of the New Jersey Zinc Company on April 10, 1929, contributes additional experimental evidence and offers suggestions that should not be overlooked: Paint applied to dry redwood hardens as rapidly as it does on other woods, but if the redwood is wet, with a moisture content of 30 per cent or more, the paint remains tacky for many days pro-
