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According t o Schwalbe and Becker, another evi- of which i t is desired t o preserve, but t o impregnate dence for t h e colloidal nature of cellulose mucilage is such a product with a mucilage which has been sepai n its ready splitting of metal salts and adsorption of rately prepared, possibly using i t as a part of t h e size. t h e base. This is t o be expected from t h e more strongly SUMMARY negative residual valence of t h e hydrolyzed product. I n t h e foregoing t h e author has attempted t o deThe accumulation of residual valence over t h e surface velop t h e following propositions: of t h e molecule very largely favors t h e colloidal state ( I ) The first step in the decomposition of cellulose by its repulsion of its own particles carrying like forms a mucilaginous soluble dextrin which easily charges. Particles carrying opposite charges, like reduces Fehling’s solution. These dextrins, as soon metal ions, are readily adsorbed, and t h e rate of ad- as formed, are adsorbed b y pure cellulose, thus formsorption would increase with increased hydration and ing a reactive insoluble aggregate, called hydrocellulose. hydrolysis. A practical application of this is found ( 2 ) Mucilage differs from hydrocellulose in t h e in t h e partial conversion of t h e cloth of gas mantles larger per cent of soluble adsorbed dextrins present. into a hydrolyzed product before impregnation with (3) These adsorbed dextrins serve t o catalyze t h e metals, a treatment which, because of increased adsorp- hydrolysis of cellulose. tion, causes a better retention of metal. (4) Complete hydrolysis leaves only soluble dextrins. When a pulp is treated with alum, t h e liquid very ( 5 ) Mucilage, possibly through its colloidal nature, quickly becomes acid, b u t t h e acidity is very readily has a greater power of adsorbing water t h a n has pure washed out, leaving an alkaline pulp. This is due t o cellulose. a splitting of t h e salt and a n adsorption of t h e free (6) Cold water immersion causes a slow hydrolysis. base b y t h e fiber, leaving t h e free acid in the solution. H o t water hastens hydrolysis and weakens adsorption, The power of splitting salts and adsorbing their bases so t h a t mucilaginous products are destroyed as rapidly increases as t h e amount of mucilage in t h e pulp is as formed. increased, and this is further evidenced b y t h e in(7) With methyl red as an indicator, it is possible crease in t h e colloidal properties of the cellulose on t o detect t h e increase in t h e alkalinity of t h e hydrahydrolysis. tion of pulp. This theory would also explain why, when mor(8) Pulps with an original high copper number danting with t h e salt of a weak acid like an acetate, beat t o mucilage more easily t h a n those with a low the presence of some strong acid, like sulfuric, which copper number, owing t o the larger amount of catalyst aids the hydrolysis of t h e fibers, gives a better coloring. present. The adsorption of metal very markedly weakens (9) The copper number of bleached pulp can be the strength of the paper made from it, no doubt b y increased by a careful acid treatment prior t o beating. diverting some of t h e intermolecular affinities t o ( I O ) Cellulose mucilage will split a salt and adsorb t h e holding of the metal. By means of this loss of the metal ion more easily t h a n pure cellulose, owing t o strength, Schwalbe and Becker were able t o deter- t h e more colloidal state. mine t h a t papers impregnated with as little as 0 . 2 5 ( r I ) Moisture or acid treatment aids dyeing by per cent of magnesium chloride and hung in an forming mucilage. air which was partially saturated with moisture, were able t o split t h e salt and adsorb t h e metal, and t h a t THE PREPARATION AND TECHNICAL USES OF t h e amount of metal adsorbed depends on t h e amount FURFURAL’ of moisture present. The greatest effect was with a n By K. P. Monroe air which contained decidedly less moisture t h a n COLOR INVESTXGATXON LABORATORY, U. s. BUREAU OF CHEIISTRY, enough t o saturate it. The function of t h e air is, no WASHINGTON. D. C. doubt, t o aid hydrolysis of both salt and fiber. Although i t has long been known t h a t furfural (2-furThrough this theory of the easy hydrolysis of salt aldehyde) and fiber in moist air, one can explain the fact t h a t HC-CH loose piles of freshly colored, unwashed fibers take on (4JJ cI/ ( 3 )CHO a deeper color t h a n do fibers not so spread out. The (5) (2) loss of weight experienced in dyeing cotton goods may (1) be attributed t o the further fiber hydrolysis forming some soluble products. In steaming under pressure may be prepared by distillation of pentose or pentosan with basic dyes, we find not only t h e possible forma- containing substances2 with acid, and this has indeed tion of a dye-fixing hydrocellulose arising from t h e 1 Presented before the D y e Section at the 59th Meeting of the Amerihydrochloric acid of t h e dye, b u t also oxidation through can Chemical Society, St. Louis, Mo., April 14, 1920. Ann., 3 (1832), 141; Stenhouse, I b i d . , 35 (1840), 301; atmospheric oxygen in t h e steam, which would give P o m2eDobereiner, s , Ibid., 54 (1845), 52; v. Babo, I b i d . , 85 (1853), 100, Vdlckel, I b t d . , reactive oxycellulose. 85 (1853), 6 5 ; Schwanert. I b i d . , 116 (1860). 258; Stenhouse, I b i d . , 156 (1870), Although acid presence aids mucilage formation 199; Gudkow, 2. Chem., 1870, 360; Williams, Jahresb., 1874. 770; Heill, 10 (1877), 936, v. Meyer, I b i d . , 11 (1878), 1870; Hill, Am. Chem. J . , and dyeing, it must always be used with care, inasmuch Bev., 3 (1881), 36; Stone and Tollens, A n n , 249 (1888). 227; Gtmther, de Chalas excess causes loss of strength of t h e finished product. mot and Tollens, Ber., 25 (18921, 2569; Gross, Bevan and Smith, I b i d . , Looking a t t h e matter from a purely theoretic stand- 28 (1895). 1940; Tollens. Ann., 286 (1895), 301; Kruger and Tollens, 2. angew. Chem., 9 (1896), 44; Semmler, Ber., 89 (1906), 731; Brdmann and point, it would seem as if it would be much safer not Schafer, I b i d . , 43 (1910), 2401; Gildemeister and Hoffmam, “Die kterischen t o attempt acid treatment on t h e fiber, t h e strength Ole,” Leipzig, 1910, p. 44%
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column.' It is a somewhat anomalous fact in view been t h e basis for quantitative estimation of pentosans,' t h e published methods2 seem highly unsatisfactory on of t h e high boiling point of furfural (162") t h a t , by account of the low yields obtained, and on account of careful fractionation of t h e very dilute solution which t h e tedious processes involved in extraction of t h e constitutes the original distillate, nearly all the aldealdehyde from its dilute aqueous solution by immis- hyde is obtained in t h e first 100 cc. of distillate, boiling cible solvents.* The potential value of furfural in between 97.5" and 100". After fractionation, t h e chemical industry, which will be discussed later, led furfural phase (20 cc.) in t h e combined distillates was t o the present investigation of corncob pent0san4>~ separated from the supernatant saturated aqueous as a promising source and t o t h e following method, solution,2 which was returned t o the flask for rewhich yields as pure furaldehyde approximately 26 fractionation. The combined portions of t h e furfural per cent of t h e weight of t h e solids contained in corn- phase were then fractionated from a small distilling cob adhesive, and involves very simple and economical flask. After rejection of t h e first 2 or 3 cc. of distillate, operations for the production and subsequent separa- which contained water, t h e thermometer rose rapidly tion of t h e aldehyde from dilute aqueous solution: t o 161.5', and t h e remainder boiled between 161.5" . Five hundred grams of corncob adhesive, prepared and 162013which indicated a very satisfactory degree of purity. An average yield of 53 g. (or 26 per cent according t o the method of La Forge and and consisting of a concentrated aqueous suspension of the solid material contained in the adhesive) of of gums rich in pentosan, were thoroughly mixed in pure furaldehyde was so obtained. a 3-liter round bottom flask with a solution of sulfuric While furfural has hitherto chiefly been known as acid prepared by mixing 150 cc. of concentrated sul- a rare organic chemical, on account of difficulties of furic acid (sp. gr. 1.84) and 500 cc. of water. To preparation and the consequent high price, numbers prevent foaming during t h e subsequent heating opera- of uses are already known, and t h e future field for detion, a lump of paraffin was added and t h e liquid velopment seems very promising if i t becomes availheated t o boiling. Since preliminary experiments had able in quantity and a t less cost. An interesting indicated the desirability of removing furfural from portion of this field is t h e one concerning t h e dye int h e reaction mixture as rapidly as it is formed, a vig- dustry, since a t least two useful and promising direct orous current of steam was passed through t h e mix- dyes may be obtained by simple interaction of furalture; the rate of steaming and t h e flame under the dehyde with alkali sulfides and hydroxides.4~5~6 Hard flask were so adjusted t h a t the volume of liquid in the resins similar t o the well-known Bakelite and Condenflask remained approximately constant while the dis- site may be obtained b y the condensation of furfural tillate was collected a t the rate of 15 t o 20 cc. per 1 The ready separation of furfural from dilute aqueous solution by minute. After five 800-cc. portions of distillate had column distillation is mentioned in the European patents (Loc. cit.). This been obtained t h e operation was suspended. I n t h e method is not given in any of the hitherto published directions for laborapreparation although it has evidently been recognized t h a t simple meanwhile t h e portions of distillate were filtered t o tory distillation from aqueous or saturated salt solution concentrates the alderemove traces of paraffin and fractionally. distilled hyde in the first portions of distillate. O n the laboratory scale the effifrom a flask provided with an efficient fractionating ciency of a bare column in fractionation of relatively low boiling mixtures 1 Brown,
"Handbook
of Sugar Analysis,"
Wiley and Sons, 1912,
p. 372. 2 For example, the directions given in Beilstein, "Organische Chemie," 8, 3rd Ed., and by Emil Fischer, "Anleitung zur Darstellung organischer Praparate," Braunschweig, 1908. Bran is the source of pentosan; the yields reported are 3 and 2.5 per cent, respectively. 8 European patents have been issued on the technical preparation of furfural by treatment of cellulosic material with steam and acid a t temperatures below 150'. This process has been operated in France and Germany (Meunier, and Beckmann and Dehn, Loc. c z t . ) . The price quoted on French technical furfural is 20 francs per kilo, and two French firms have stated in private communications t o the author that furaldehyde is available in any quantity d&red. Fr. Patent 446,871, Dec. 17, 1912, process for simultaneous preparation of methylene and furfural from cellulosic material, issued t o V. Raisin: Swedish Patent 40,482, Dec. 16, 1913, process for production of furfural from cellulosic material, issued t o H. 0. V. Bergstrom: Fr. Patent 464,608, March 26, 1914, process for the separation and recovery of volatile acids, methylated products and furane derivatives from cellulosic material, issued to A. and E. Lederer; Fr.Patent 485,967, Feb. 26, 1918, improvements on the method of manufacturing pure furfural from cellulosic material, issued to E. Ricard. 4 Corncobs have long been known t o be rich in xylan, and consequently have been utilized for the preparation of xylose. Stone and Lotz, Am. Chem. J., 18 (1891), 348; Hudson and Harding, J. Am. Chem. Soc., 40 (1918), 1601; La Forge and Hudson, THIS JOURNAL, 10 (1918), 925; Monroe, J. A m . Chem. Soc., 4 1 (1919), 1002. 5 Another agricultural waste product which suggests itself as a promising source is cottonseed hulls, which are known t o be rich in xylan. Hudson and Harding, J. Am. Chem. Soc., 39 (1917), 1038. This method involves 6 LOG.cic.; L a Forge, U. S. Patent 1,285,247. the separation and partial hydrolysis of pentosans contained in the cobs by extraction with water at 150°. The aqueous solution of gums so obtained is theq evaporated to the desired concentration. 7 The author wishes t o express his gratitude to Dr. La Forge for kindly furnishing the corncob adhesive.
is known t o be low on account of the comparatively small heat loss to the surrounding air; this was partially compensated by substitution of an in-
verted Allihn condenser with bulbs loosely packed by broken glass. A rapid current of air was drawn through the jacket in a direction counter t o that of the stream of vapor. 2 The mutual solubility of water and furfural has been investigated by Rothmund, Z. physik. Chem., 26 (1898), 454. By interpolation of these data, the saturated aqueous phase a t room temperature (25') is seen to contain approximately 8 per cent furfural, while the saturated furfural phase contains approximately 5 per cent water. a Compare Schiff, Ann., 220 (1883). 103; Brlthl, Ibid., 285 (1886), 7. The freezing point of pure furfural is given by Walden, Z. p h r s i k . Chem , 78 (1910), 261, as -36.5'. 4 Austrian Patent 72,235, August 15, 1915, process for manufacture of a dyestuff from furfural, issued to A. and E Lederer. One dye obtained according t o the specifications of this patent by interaction of furfural and sodium sulfide is a direct dye, fast to wool and silk, and very readily gives shades ranging from light terra cotta t o deep seal-brown. The dye obtained by interaction of furfural with ammonium hydrosulfide is claimed by the produced patentees to be fast t o wool, silk, and cotton. 6 D. R. P. 264,915, March 15, 1913, process for the preparation of baths which dye animal and vegetable fabrics direct orange or reddsh brown, issued to A. and E. Lederer. These dyes are obtained by interaction of furfural and alkalies. Cotton absorbs the dye very slowllp; yeilow shades may be obtained by after-treatment in an acid bath. 6 Unfortunately the analog of malachite green w h w is obtained by condensation of furfural and dimethylaniline has little promise as a dye stuff, since i t is not fast t o light. Other interesting color bases have been prepared by condensation of furfural with aromatic amines: Stenhouse Ann., 156 (1870), 199; Schiff, "Ueber Farbstoffbasen aus Furfurol," I b i d . , 201 (1880),355; 289 (1887), 349; de Chalmot, I b i d . , 271 (1892), 11; Ehrhardt, Ber , 80 (1897). 2012; Rnovenagel, Ibid , 8 1 (1898). 2613; Zincke and MUhlhausen, I b i d . , 88 (1905), 3824; Dieckmann and Beck, I b i d . . 88 (1905), 4122; J. prakt. Chem., 121 72 (1905), 5 5 5 ; Carletti, Zentr , 11, 1906, 825, K6nig, J. prakt. Chem , [21 88 (1913), 193.
Feb., 1921
T E E J O U R N r l L O F I N D U S T R I A L Anl-D E N G I L V E E R I N G C H E M I S T R Y
with phenols.’ By interaction of furfural with aniline alone or with acetone in t h e presence of alkalies, soluble resins are obtained which may prove useful in t h e varnish industry.2 Furfural has also found use as a solvent and insecticide.
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have t o be obtained, ammonia is preferable. If ammonia is added t o formaldehyde or t o mixtures of phenol and formaldehyde, t h e ammonia disappears immediately and becomes hexamethylenetetramine:
FURTHER STUDIES ON PHENOLIC HEXAMETHYLENETETRAMINE COMPOUNDS3 By Mortimer Harvey and L. H. Baekeland LABORATORY OF T H S
DEPARTMENT OF CHEMICAL ENGINEERING,
COLUMBIA UNIVERSITY, NEWYORK,N. Y. Received May 12, 1920
The production of resins or resinoid substances of t h e Bakelite type4 by t h e interaction of phenols with compounds containing a n active methylene group has, of late, acquired considerable importance in t h e industry of coal-tar derivatives. The increasing number of applications of these products in t h e most diversified fields is stimulating research in many directions. T h a t this industry was born and developed in t h e United States, which to-day is still t h e leader in this branch of chemical industry, adds interest t o any subject of research which directly or indirectly may throw light on t h e unusually complicated chemistry of this subject. The theoretical interpretation of t h e different phases of t h e Bakelite reaction is not by any means an easy one, and considerable additional research work will be required before permitting ourselves t o do much beyond guessing at what really happens. I n t h e meantime, t h e careful study of t h e formation of intermediate products can render us considerable help in this subject. Among these intermediate products, t h e further advances are amorphous mixtures which are not amenable t o t h e usual methods of chemical purification or isolation. Therefore, it is more natural t o start first with t h e intermediates which are well-defined crystalline bodies of which t h e chemical composition can be determined b y wellestablished methods. The present research work was, therefore, confined t o some of t h e first phases of t h e reaction, and more particularly t o such bodies as are liable t o form when ammonia is used in t h e process, either as such or in t h e shape of hexamethylenet et r ami ne. I n the formation of these products of t h e Bakelite type t h e methylene-containing body may be commercial formaldehyde solution-known as formalin, formol, etc. This commercial product is practically a mixture of several bodies containing active methylene groups, as, for instance, methylal, formaldehyde, t h e polymers of formaldehyde, their hydrates, etc. The reaction is favored b y t h e addition of so-called condensing agents, or catalysts-whatever t h a t may mean. Acids, salts, and alkalies have been used for this purpose. I n some cases where particular effects 1 Beckmann and Dehn, Sitzb. A k a d . Wiss., Berlin, 1918, 1201; Chem. Abs.. 14 (1920). 642. 2 Meunier, “Application du Furfurol B Ia fabrication de resines B vernis,” Mat. grasses, 9 (1916), 4516. a Submitted by one of authors in partial fulfilment of the requirement for the degree of Doctor of Philosophy in the Faculty of Pure Science, Columbia University, New York, N. Y. 4 These substances are also known under other trade names, as for nstanse, Condens ite, Resinit, Sipilite, Redmanol, etc.
so t h a t all these reactions wherein formaldehyde and ammonia are used conjointly can be repeated by t h e direct use of hexamethylenetetramine. But in presence of phenol, t h e hexamethylenetetramine does n o t remain as such. I t combines with t h e phenol in t h e proportion of three molecules of phenol t o one molecule of hexamethylenetetramine and produces a welldefined crystalline product, hexamethylenetetramine triphenol, which has been described b y Moschatos and Tollens. I n 1909, Lebach2 pointed out t h a t whenever ammonia is used in t h e Bakelite reaction, hexamethylenetetramine triphenol is formed in t h e first stages of t h e process. Under t h e action of heat, this product undergoes a further decomposition and resinifies, emitting ammonia.3 Contrary t o t h e results of Moschatos and Tollens, who were unable t o prepare addition products of hexamethylenetetramine with any of t h e three cresals or with carvacrol or thymol, Baekeland had succeeded in his laboratory in preparing a corresponding crystalline cresol derivative, but inasmuch as this work had not been carried out with each one of t h e completely purified cresols and studied by itself, i t seemed desirable t h a t each one of t h e three homologs should be studied separately as t o its individual behavior. This research was also extended t o carvacrol and t h e results obtained thus far are set forth. Similar compounds obtained from other phenolic bodies are now under study. I n t h e meantime, the observations concerning the new cresol derivatives are submitted in t h e present paper. The reason of the non-success of Moschatos and Tollens in making t h e cresol derivatives of hexamethylenetetramine is, mainly, t h a t the isolation of these substances is incomparably more difficult t h a n in the case of phenol. The hexamethylenetetramine triphenol forms rapidly and visibly under almost all circumstances, and crystallizes very well from aqueous solutions or even from solutions when a considerable excess of one of t h e constituents is used. This is not t h e case with some of t h e cresol derivatives. Ann., 272 (1892), 271. Z. angew. Chem., 22 (1909), 1600; J . SOC.Chem. I n d . , 32 (1913), 559. 3 A resume of the literature on this subject is given by L. H. Baekeland, in “The Chemical Constitution of Resinous Phenolic Condensation Products,” THISJOURNAL, 6 (1913). 506. 1 2
