RA EKELA-VD 0.V C O S D E S S A T I O S PROD L-CTS.
545
stitute. H e boiled two molecules of formaldehyde in solution with two molecules of a phenol and one molecule of a n oxyacid (tartaric acid) and thus prepared a resinous mass which is purified by washing and can be melted like any ordinary resin and is soluble in alcohol as well as in watery solutions of NaOH. This substance, according to its method of preparation and the amount of free phenol i t contains, may be made to melt a t widely variable temperatures ranging from 50' C. to considerably above I O O O C . According to whether i t is prepared with pure white phenol or dark commercial cresol, i t will vary in hardness or color. I t is always more brittle than shellac and its appearance may vary from that of a colorless transparent vitreous mass to yellow-, brown or black. I t dissolves in alcohol in all proportions and gives a varnish which dries in about the same way as a n alcoholic solution of shellac, but the layer i t leaves after thorough evaporation is not so elastic nor flexible as that of shellac and is more brittle; this is probably the reason why i t does not sand-paper nor polish as well as shellac. Furthermore, this varnish has a decided tendency to oxidation. The alcoholic solution, which can be made colorless, assumes a darker color after a few days and may keep on darkening until i t finally becomes deep ruby. In the same way, objects varnished with this solution mill ultimately acquire a decidedly darker color which in time becomes a deep red mahogany stain. ON SOLUBLE, FUSIBLE, RESINOUS CONDENThis resin does not dissolve well in weak alkalies SATION PRODUCTS OF PHENOLS like shellac does, but i t is soluble in aqueous NaOH. AND FORMALDEHYDE.' The latter solution oxidizes rapidly in the air and By L H B A E K E L A S D . S c D. may acquire a vivid purplish red color. Carbonic ReceivedMay IS. 1909. gas and any acids reprecipitate the resin from this I n a former paper2 I have described the con- alkaline solution. ditions under which the condensation of phenols The varnish made with the resin obtained from and formaldehyde may produce infusible, insoluble, commercial impure phenol or cresol has a decided homogeneous bodies of great chemical inertness coal tar odor, which clings persistently to all obwhich can be used for many technical purposes. jects coated with it. I stated then and there t h a t , starting from the This resinous material is decidedly different in same raw materials, b u t operating under slightly chemical and physical properties from the product modified conditions, we may obtain, in other described by me as Solid A, or Initial Condensainstances, resinous substances which are soluble tion Product,l from which i t is easily distinguished and fusible and of very different chemical properties. by its great tendency to oxidation and its inAs far as I know, Blumer3 was the first one to ability of being transformed by simple heating publish an attempt to utilize this reaction com- under pressure into Bakelite C. At the time when mercially for the manufacture of a shellac sub- Blumer published his English patent, he seems to have given considerable importance to the chemical 1 Read before the New York Section, May 14, 1909. 2 ' The Synthesis, Constitution and Uses of Bakelite THIS r61e the oxyacid plays in this reaction. However,
location of milk-desiccating plants in such districts would do much not only to promote the interests of remote farming communities, but would largely increase the milk supply of the country. The question of time would be entirely eliminated and the distance from market would not be a factor except for a slight increase in freight rate. I t is well known t h a t the railroads make very close rates on long distance shipments of western products to eastern states and in fact the freight rates from Illinois and Iowa may be lower to Kew York than from some district in northern Vermont or northern New Tork. There is no reason therefore why New I'ork City should not draw its milk supply from the western states as i t now largely draws its supply of butter and eggs. I n fact most of the economic reasons for the reduction of milk to powder might be summed up in one phrase, a world market for milk. There is one reason, howeyer, which I wish to dwell upon that is rather sanitary than economic. Fresh milk is a substance upon which no pure food guaranty is possible. I t is drawn to-day and gone to-morrow. This renders adequate milk inspection practically impossible. n'ith milk supplied in the form of a permanent powder, i t is entirely possible to create a high standard of quality and purity because the stability of the product would permit of the enforcement of rigid regulations.
"
JOURYAL, 3
1, 149.
Louis Blumer, Eng P a t , June 5 , 1902, No 1'2,880.
1
L o c cal.
546
T H E J O U R N A L OF I N D U S T R I A L A N D E-VGINEERING C H E M I S T R Y .
later on, both Blumer and DeLaire' published processes where the same resin was obtained by the use of mineral acids as condensing agents. I n both methods as published, relatively large amounts of formaldehyde are used, namely about eqxal molecular proportions. Furthermore, the amount of acid condensing agent is relatively large and the latter has to be used in rather diluted form, otherwise the reaction becomes violent and irregular. On the other hand, in such diluted mixtures, the reaction begins by separating first a sticky mass containing a n excess of phenol while a considerable proportion of CH,O remains in the supernatant liquid. To Nathaniel Thurlow belongs the credit of having shown as far back as 1906 that such large amounts of formaldehyde are unnecessary and that they become harmful and produce insoluble bodies similar to the resinous mass described in 1891 by Kleeberg,, every time the reaction is conducted so that not too much formaldehyde escapes or remains uncombined. Thurlow used relatively small amounts of hydrochloric acid and kept the reaction under steady control by conducting it gradually and avoiding too violent self-heating during the first stages of the process. He thus succeeded in preparing more economically, a soluble fusible resin entirely similar to those described by Blumer and by DeLaire. DeLaire, in his French patent,3 mentions how this same resin can be obtained industrially by first making a n alkaline solution of a phenol-alcohol, and uses practically the same process as the one published many years ago by Lederer and by M a n a ~ s e ,which ~ consists in dissolving one mole. of a phenol in one mole. of NaOH, which gives a phenolate, then adding one mole. of CH,O and after the reaction is over introducing enough HC1 to liberate the phenol-alcohol. The latter, in presence of an excess of HC1 and more especially under the action of heat, gives resinous matters called saliretins known long On the other hand, I have shown that if a pure phenol-alcohol, for instance saligenin, be heated in sealed tubes a t 180' C., we do not obtain a DeLaire, Fr. Pat. 361,539. June 8 . 1905. Annalen. 165, 283 (1891). 3 DeLaire, French Pat. 361,539, June 8 , 1905. 4 Journal praklische Chemie [2]. S O , 224; Berichie, 1894,2409-2411; D. R. P . , Bayer. 85.588; U.S. P . . Manasse. 526.786, 1894. 6 Beilstein. "Organ Chemie." Vol. 2 , 1896, page 1109; R . Piria, A n n . C h m . , 48, 7 5 ; S6, 37; 81, 245; 96, 3 5 7 . Moitessier. Jahresbericht. 1886. page 676. K . Kraut, Ann. Chem.. 166, 123. Gerhardt, Ann. Chem. p h y s . [3], 7, page 215. F. Beilstein and F Seelheim, A n n . Chem., 117, page 83. 1
Aug., I909
fusible soluble resin as prepared by Blumer, DeLaire and Thurlow, but a saliretin product that is only partially soluble and is no longer iusible although it softens decidedly if heated; this substance is not my so-called Intermediate Condensation Product B, because i t cannot be transformed into Bakelite C by plain heating under pressure.' I shall mention now that I have succeeded in preparing this fusible, soluble resin by heating a phenol-alcohol in presence of a sufficient amount of phenol. For instance by heating in sealed tubes a t 180' C. for 8 hours, a mixture of 14 mole. of saligenin with at least one mole. of phenol, I obtained a resinous substance which can be melted to a transparent mass, soluble in alcohol in all proportions, soluble in NaOH, and which has all the characteristics of the fusible, soluble, resinous condensation products as described above. Whenever I used less phenol than the proportion I : 14 mole., I no longer obtained a fusible product, but a resinous mass which does not melt but only softens when heated; alcohol and acetone only swell it without dissolving it and its properties are entirely similar to the higher dehydrated saliretim2 On the other hand, if the amount of phenol be increased we obtain a much softer resinous mass, more fusible and better soluble. We also succeeded in preparing these same varieties by simply heating, in a sealed tube, mixtures of phenol with formaldehyde in presence of a few drops of hydrochloric acid, provided always the amount of phenol was present in sufficient excess over equimolecular proportions, this excess answering to a proportion of 15 mole. C,H,OH 14 mole. CH,O, or still better with somewhat of an excess of phenol. Instead of taking a n acid as a condensing agent, an acid salt will answer the purpose and even a n ammonium salt of the strong mineral acids can be used.' If, instead of heating in a sealed tube, the reaction is carried out in an open vessel or even with a return condenser which does not exclude the possibility that considerable amounts of CH,O may be entrained during the violence of the first stage of the reaction, this may result in a decided alteration of the composition of the mixture so
+
L. H. Baekeland, LOG.c i f . Dr. A. H. Gotthelf in repeating this experiment with another sample of saligenin, which was not so pure as mine, had to increase slightly the proportion of phenol before he succeeded in obtaining the fusible resin. His proportions were 13 mole. to 1 . 2
B A E K E L A N D 0-V COATDE,VSATION PRODLCTS.
'
that an excess of phenol may become predominant. Or again the reaction may not be carried far enough so that a large amount of formaldehyde remains uncombined as is the case when organic acids are used as condensing agents. This explains why under the conditions, soluble, fusible resins may be formed even when the original mixture was made tip with an apparent excess of formaldehyde ; this explains also why Blumer as well as DeLaire, even when mixing molecular proportions of formaldehyde and phenol, got as a final result a fusible and soluble product. It is self-evident that such methods of preparation involve a decided loss of formaldehyde. These losses are less liable to occur if the reaction be carried out in sealed tubes. On the other hand, i t is a noteworthy fact demonstrated by my prior work' that whenever basic condensation agents are used in small amounts, infusible, insoluble, products are obtained even if the phenol be used in decided excess and whether the reaction be carried out in closed or in open vessels. I n other words the formation of fusible, soluble resins or infusible, insoluble condensation products is not merely a matter of proportions as to the amount of phenol, but has more intricate chemical causes. I n either case, if an excess of phenol be used in the original mixture, i t will be found to exist as free phenol in the final product and can be eliminated as such in several ways. For instance the excess of phenol can be eliminated by blowing steam through the resin while i t is kept in molten condition or by heating the molten mass zn z~acuo until it has reached constant weight. I n some instances, I have thus kept this resin fused in vacuo for several days in succession a t 200' C. until all free phenol was eliminated. Although the hardness of the mass, a s well as its melting point, increased somewhat, i t did not change into the infusible, insoluble resin, The same thing happened if the resin obtained by heating together saligenin and phenol was heated in iiacuo. I n both instances a point was reached where no further elimination of phenol takes place. The remaining mass in both cases has the same composition. Purification by fractional precipitation of the alkaline solution by means of hydrochloric acid gave the same product. 1
Baekeland. L O L c i f
547
From the analytical composition of same we may assume an empirical formula, ClU4H9z01B, in which case the synthesis by means of oxybenzyl-alcohol and phenol could be expressed as follows: 14C,H,O,
+ CeHSOH
1jC,H,OH
+ 14CH,O = 13H,O + C,,,H,,O,,.
+
ISH20 C104H*201ej and the direct synthesis by means of phenol and formaldehyde as follows: The analytical results are condensed as follows:
-- ----
Found: Calculated Phenol CHfl. for C,OaHQnO,B C 78.16 78.04 77.95 H = 5.81 5.79 5.97 0 = 16.03 16.08 16.17
Saligenin phenol.
+
-
78.16 5.65 16.19
+
78.24 5.75 16.01
After fractional reprecipitation from N a O H solution.
-
78.24 5.75 16.01
78.65 5.49 15.86
An attempt was made to establish the molecular weight by the freezing point method. The substance was freed as completely as possible from phenol or other volatile impurities by heating in vacuo a t the temperature of boiling naphthalene. At first glacial acetic acid, then phenol were used as solvents with the following results. Solvent. (1) (2) (3) (4) (5) (6)
Acetic acid '( "
Concentration.
"
"
'/
"
1 gm. in 23 . 2 ', , I , '' 12.6 " I' (' 34.2 " ,< ,2
"
''
'' Phenol
'C
' I
"
"
13.3
,, " * 1 , 5
Molecular weight. 1142 1216 463 943 751 809
Result 3 may be unreliable for the reason t h a t in order to have complete solution, i t was necessary t o let the mixture stand over night thus giving the acetic acid. which may not be a n indifferent solvent, longer opportunity to react and disturb the results. I n the other determinations, solution was complete in a few hours. I n every case, however, some traces of transparent. insoluble matter could be seen suspended.
Admitting an empirical formula, C,,H,,O,, which would be one-quarter of the formula proposed above, we find that 3 is near its value 399, while 5 and 6 are near twice its value; I and z are nearly three times this value 1x97; and 4 is between twice and three times. I n order to simplify matters, I propose to call this substance Novolak. Salts.-An attempt was made to prepare some metallic salts of Novolak, by first bringing its alkaline solution as near as possible towards neutrality by careful addition of HCl, until the point was reached where permanent precipitation begins, then after filtering, adding solutions of Ca, Ba, Cu, Pb, etc. Potassiwn and Sodium Salts.-A solution of these can be made by dissolving the pulverized Novolak :n NaOH or KOH solution. Addition of acids
T H E JOUR-VAL OF IiVDUSTRIAL A S D ELVGISEERI-VG C H E J I I S T R Y .
48
reprecipitates the original resin. Even very weak acids, for instance CO,, will do this. Calcium Salt.-Prepared by the potassium salt with CaCl, solution. Analysis of two different samples gave 3.83 and 3.91 per cent. Ca. Dissolved in alcohol; after re-evaporation dried to constant weight contains 2.79 per cent. Ca. Fractional precipitation of potassium salt with CaC1, was tried. After drying to constant weight the first fraction gave 2.48 per cent. Ca and the second 3.j2 per cent. Ca. Comhustion gave. C = 72.70 H = 5.28 Ca = 3.53 0 = 18.49
Calculated for (C,,,H8801b)2Caa6H,0. C = 73.07 H = 5.60 Ca = 3.52 0 = 17 81
Barium Salt.----Prepared like calcium salt.
Xnaly-
sis gave: C = 67.36 H = 4.95 B a = 11.08 0 = 16.61
which agrees rather closely with results obtained for the calcium salt if allowance be made for the different atomic weights of Ba and Ca. Alcohol dissolves the greater part of this salt b u t seems to decompose i t and the soluble portion, after recovery, contains only 6.38 per cent. while a similar treatment with acetone gives a substance containing 3.04 per cent. It may be worth while noting that these amounts represent about onehalf and one-quarter of that of the salt washed with water. Lead SaZf.---Obtained by precipitation, contains 28.09 per cent. Pb. Copper Salt.-Contains 6.42 per cent. Cu. Aluminum Salt contains 2.87 per cent. Al. Alcohol almost completely decomposes this salt; the insoluble part on ignition carbonizes slightly b u t is practically entirely inorganic, while the soluble portion after evaporation and drying contains only 0.03 per cent. Al. Solubility of Novolak salts: The alkaline salts are soluble in water. The calcium, barium, lead, copper and aluminum salts are insoluble in water. The calcium and barium salts are almost completely soluble in alcohol; the aluminum salt is almost completely decomposed by alcohol; the lead salt is partially soluble in alcohol, but i t has not been determined whether it is decomposed by this treatment; the copper salt acts differently from the others in that the
Aug., 1909
particles swell and become translucent while dissolving partially. Acetone acts similarly to alcohol. All these solutions, on evaporation, leave a structureless varnish film that darkens rapidly by oxidation in the air. All these salts are insoluble in benzene, toluene, gasolene and chloroform. Acetyl Compoundr. -Novolak, when boiled with acetic anhydride, gives, after subsequent treatment with water, a white powder, insoluble in alcohol but soluble in acetone. Attempts to obtain i t in crystalline form were unsuccessful. Boiling with dilute alkali does not apparently affect it, b u t concentrated alkali decomposes it. In whatever way Novolak be prepared, its properties are very distinct from those of Rakelitel and it can not be transformed into the latter by simply heating. But I have found that by heating Novolak in sealed tubes a t 180'C. under pressure with a n excess of formaldehyde solution or any of the polymers of formaldehyde or other compounds which can generate formaldehyde, a n infusible, insoluble mass is obtained that does no longer soften under the action of heat, as is the case for saliretin products, but which has all the characteristics of Bakelite C. On the other hand, I have never succeeded in transforming Bakelite C into the soluble, fusible resins by heating i t with an excess of phenol.
coscLusIoss. ( I ) Formaldehyde heated with an excess of phenol and in presence of a n acid condensing agent gives fusible, soluble resins, which I call Novolak and which can not be transformed by simple heating in Bakelite. ( 2 ) Novolak is also obtained by heating, under pressure, mixtures of oxybenzyl alcohol and phenol in suitable proportions. ( 3 ) Novolak seems to be a definite chemical compound and not merely a mixture or a solid s o h tion. (4) Xovolak gives various salts, some of which are more or less soluble in alcohol or acetone and which on evaporation give amorphous transparent masses. ( j ) Novolak, heated in presence of a n excess of formaldehyde in sealed tubes, is transformed into Bakelite, b u t the latter does not change again to a fusible, soluble resin if heated with phenol. 1
Baekeland, LOC. czt.
T A I’LOR O S A C O S I T E . (6) The reason why Rlumer and DeLaire obtained fusible and soluble resins even when heating phenols with an excess of CH,O is very probably due to the fact that either some CH,O escaped during the reaction or remained uncombined, thus altering the proportion of reacting materials.
ACONITE. By
fRhKX
0 . TAYLOR
Received May 17, 1909
Despite the wonderful progress achieved in late years in the study of the toxic drugs and of their active constituents, we are yet forced to confess that our knowledge even of the most important of them is far from complete. Notable among these for several reasons is aconite. Known from time immemorial as a drug of exceeding potency, its use and more especially the administration of its various preparations have been attended with uncertainty and even danger because of lack of knowledge as to the quantity and character of active constituents present. To obviate this difficulty, numerous methods of assay have been proposed with varying results, but none of them are free from objectionable features. The quantitative valuation of aconite and its preparations has been attempted in two ways: I. Chemical assays, involving two general methods, zlu. : (a) Estimation of the aconit‘ine through determination of some derived product. ( b ) Direct estimation of aconitine as such. 11. Physiological assay by two methods: ( a ) Those based upon effects produced by administration to lower animals. ( h ) That known by the author’s name as the “Squibb Test” (see page j j 7 ) . As has been intimated above, there is no perfectly satisfactory method of valuing aconite preparations; and though, for the general pharmacist, chemical assays are to be preferred when available, yet I believe that in this instance the Squibb test is preferable to any of the chemical methods proposed, and in fact is the only one a t present which permits of a correct inference as to the therapeutic value of aconite preparations. These conclusions are based upon experience in the preparation of extracts and tinctures of aconite, the constant use of this test and a careful review and comparison of the various assays proposed.
519
There is presented herewith a brief resume of the literature on the subject and the results of comparative tests. Perhaps many readers will not agree with these conclusions, but i t is earnestly hoped that no one who is sincerely interested in this matter will be prevented from making an unbiased comparison through preferences which they may have for some special form of assay. I n reviewing the assay processes detailed criticism has in large measure been purposely avoided, except in case of one or two of the more recent articles, which have emphatically a t tempted to discredit the Squibb test. As these condemn this test by attempting to demonstrate the accuracy and reliability of chemical assay methods there given, I have criticized them somewhat more in. extenso in order to demonstrate the fallacy or weakness of the arguments advanced. Before discussing assay processes and the result of our comparison, i t would be advisable to review the statements made by various authorities as to the alkaloids of Aconitum napellus, because of the bearing this will have upon the reliability of the assays. As will be seen, there has been a great diversity of opinion, not only as to the number of such active principles normally present in the drug, but also regarding their identity and constitution, though by much laborious research the most important facts regarding aconite and aconite derivatives are now fairly well established. A l k a l o i d n l Constituents.- After the first isolation of an alkaloid from aconite by Geiger and Hesse in 1833, Groves in 1860 succeeded in obtaining a crystalline alkaloid; Wright in 1875 began his researches on the aconite alkaloids and later Gro\-es and also Jurgens added still more to the knowledge of the aconite alkaloids But the work of all these, while serving well its purpose, was nevertheless erroneous, chiefly because of impurities in the alkaloids examined. Practically all the authoritative work on this subject has been done since 1890, Dunstan and his coworkers contributing by far the most, with Freund and Beck, Ehrenberg and Purfurst, and H. Schulze as the other chief contributors. The number of alkaloids contained in the root has been variously stated by different investigators. Each of the earlier researches resulted in some difference in results and a new alkaloid would be recorded as occurring in aconite. Such confusion arose from the various names given to practically the same alkaloids, and the same name to different
