October, 1927
I,VDUSTRIAL A N D ENGINEERING CHEMISTRY
When sand filters were being used the average drop in alkalinity between the station and the laboratory was about 10 p. p. m.,8 indicating that the long storage is much more effective than sand filtration in preventing after-precipitation. Effect of Sand Filtration on Stored Water
As there is a slight after-precipitation in the mains, even with the stored water, i t was thought advisable to test also t h e effect of sand filtration. To this end a miniature filter was constructed, consisting of a 2-inch (5-cm.) glass tube containing a layer of fine, well-washed sand 30 inches (76 cm.) deep. A constant-level device was arranged, so that the water stood 2 inches (5 cm.) above the sand. Filtration proceeded a t the rate of 30 cc. per minute. The effect of this filter was tried first on the water a t the 8
Gerrish, 09. c i t . , p. 436.
1187
laboratory and then on water a t the pumping station, and with the results as shown in Table 11. Table 11-Effect of S a n d Filtration on Stored Water (Figures in p. p. m. total alkalinity) WATER AT LABORATORY WATERA T PUMPING STATION Tap Filtered Tap Filtered 39 38 44 42 40 38 44 42 39 39 42 41 39 38 43 41 39 39 42 41 40 39 43 41 Av. 39f 38 43 41 f
+
These tests indicate that sand filtration would not materially reduce the hardness of the stored water. Its only beneficial effect would be t o make the water possibly a ,little clearer, provided it were not already clear-as, for example, when the alum treatment is not working a t its highest efficiency.
Isolation of the Natural Oxidation Inhibitors of Crude Hevea Rubber'pz By H. A. Bruson, L. B. Sebrell, and W. W. Vogt GOODYEAR TIREA N D RUBBERCo., AKRON, OHIO
T HAS been generally rec-
Two natural oxidation inhibitors of crude Hevea It seemed, therefore, that rubber have been isolated from the unsaponifiable mato g n i z e d t h a t crude the acetone extract of crude ter of the acetone extract. They appear to be liquid Hevea rubber, as it comes Hevea rubber might contain sterols having the composition C2?Ha203 and C V H ~ ~ O , a naturally occurring antioxifrom the plantation in the and occur in pale crepe to the extent of about 0.08 and form of pale crepe or smoked dant because if the concen0.16 per cent, respectively. A third antioxidant possesss h e e t s , i s m o r e resistant trated extract is returned to ing powerful reducing action occurs in the aqueous toward atmospheric oxidation the rubber from which it has extract from the acetone-soluble material and consists than the same rubber when b e e n r e m o v e d the aging of phenolic and ketonic bodies. The stability of crude purified by extraction with qualities of that rubber are rubber in air is dependent upon the presence in the acetone. greatly improved and become rubber of these natural antioxidants which, when Peachy,3 Stevens,4 Beadle practically equal to those of removed by acetone extraction, leave the rubber in a and Stevens,5 and Peachy and the original unextracted rubstate that is readily susceptible to autoxidation and to Leona observed that acetoneber. On the other hand, the formation of taclly products. e x t r a c t e d rubber oxidized s a m e e x t r a c t e d rubber to Three inert constituents have also been isolated from faster than non-extracted rubw h i c h t h e acetone-soluble the unsaponifiable matter-namely, (a) n-octadecyl ber. Furthermore, it is comalcohol, ( b ) a highly fragrant liquid ketone, C15H~0, resin is not returned ages mon experience that highly very poorly both in the unand ( c ) a CI5H24hydrocarbon. purified rubber w h i c h h a s cured and cured state. been freed f r o m p r o t e i n That an appreciable amount of a natural antioxidant may material is extremely autoxidizable. Unless kept in the dark in a dry, inert atmosphere, there is rapid deterioration with be lost during ordinary coagulation of latex" was shown by formation of sticky substances. Levulinic aldehyde has the fact that the latex serum from the coagulation by either been definitely found among the products of oxidation of acetic acid or alcohol possessed powerful antioxidant action tacky rubber by Whitby.7 The importance of the natural when concentrated to a sirup and milled into extracted rubber. resins in the vulcanization and aging of raw rubber has been (Table I) With the object, therefore, of determining the identity known for some time.8-1e of the natural substances present in crude Hevea rubber which 1 Presented before the Division of Rubber Chemistry at the 73rd Meetare vital to the stability of that rubber, particularly in retardi n g of the American Chemical Society, Richmond, Va., April 11 t o 16, 1927. 2 For a preliminary report of this work see Dinsmore, THISJOURNAL, ing oxidation, a study was made of the antioxidant activity of 18, 1140 (1926). each individual constituent of the acetone extract of Hevea 8 J . SOC.Chem. Ind., 31, 1103; C. A . , 7, 905 (1913). pale crepe. 4 J . SOG.Chem. Ind., 35, 874 (1916); C . A , , 11, 107 (1917). Whitby, Dolid, and Yorston's had made a thorough study 6 G u m m i - Z l g . , a'/, 1907; C. A , , 7, 4085 (1913). 6 I n d i a Rubber J . , 54, 850; C. A , , 12, 439 (1918). of the components of Hevea rubber resin and had reported 7 India Rubber J . , 63, 742 (1922). the presence of quebrachitol, &valine, a phytosterol, phytos8 Seidl, Gummi-Zlg., 25, 710, 748 (1911). terol glucoside, a sterol ester, together with oleic, linoleic, 9 Beadle and Stevens, Bthlntern. Cong. A p p l . Chem., 1912, pp. 25 and 581. and stearic acids. Kone of these substances, however, either 1 0 Weber, Ibid., 1912, pp. 9 and 95. alone or in combination with the others show any appreciable 11 Kratz and Flower, THIS JOURNAL, 12, 971 (1920). 19 Maximoff, Rubber A g e , 10, 53 (1921). antioxidant power. This suggested that there might be 18 Martin and Davy, J . SOG.Chem. I n d . , 41, 3261' (1922). present in the acetone extract a very minute amount of 1 4 Bedford and Winkelman, THISJOURNAL, 16,32 (1924).
I
1'
Sebrell and Vogt, Ibid., 16, 792 (1924). Whitby and Greenberg, Ibid., 18, 1168 (1926).
1'
'8
British Patent 260,001 (1926). J . Chem. SOL. ( L o n d o n ) , 1926. 1448.
.
INDUSTRIAL A X D ENGINEERIXG CHEMISTRY
1188
VOl. 19, No. 10
hitherto unisolated constituent in t'he non-crystalline liquid The work of Whitby, Dolid, and Yorston18 was repeated fractions which were previously not investigated. to obtain samples of the known constituents for testing purThe unsaponifiable portion of the acetone extract was there- poses. The results agree well with those given by these fore carefully separated and from it were obtained two com- investigators and are included in this paper as a matter of pounds having pronounced antioxidant properties. These record. The separate crude fractions of the acetone extract, compounds are high-boiling viscous oils and appear to be such a? crystalline material, fatty acids, aqueous extract, sterols. They have the formulas CnH4203 and C~OHSOO,and unsaponifiable material, as well as the individual comrespectively, but their exact constitution is not yet known, pounds present in these fractions were each tested for antias they do not agree in chemical properties with any known oxidant power in the following formula: pale crepe (acetonecompounds. Three other compounds which are without extracted) 100, zinc oxide 5, sulfur 3, hexamethylenetetramine protective action against the oxidation of rubber were also 0.9 parts. This formula was also used as a control stock, being isolated-+-octadecyl alcohol, a ketone (CljH,,O), and a itself devoid of any antioxidant action and readily indicating the presence of small amounts of any antioxidant that might hydrocarbon having the formula CI5H24. be added. A convenient quantity of this control stock (usuExperimental Method ally 500 grams) was compounded with an amount of the The rubber used in this research was from a specially se- resin constituents equivalent to the percentage of the latter lected lot of good grade Hevea pale crepe. Altogether, about in the original crude rubber. 225 kg. of rubber were extracted and the extract was worked Cures were made for 30, 50, and 70 minutes a t 2.8 kg. per up as described below. The acetone extract from a batch sq. cm. (40 lbs. per sq. in.) steam pressure (141.5' C.). The of 98 kg. of rubber was worked up at once and the data in samples of the cured stock were tested in the Bierer-Davis this paper are on this lot of extract. oxygen bomb, the test sheets being variously aged for 16 hours at 60' C. and 21 kg. oxygen pressure per square centiT a b l e I-Oxygen Absorption D a t a meter, and if they survived this treatment similar samples (Percentage increase in weight after aging 50-minute cure test strips containing representative fractions of acetone extracta) were aged for 6 days and upward a t 50" C. and 10.5 kg. oxyTIMEIN BOMB gen pressure per square centimeter. The increase in weight 16 hours, 60" C. a t 144 hours, 50' C. at 21 kg./sq. cm. 0 2 10.5 kg./sq. cm. 0% due to oxidation and the general physical appearance, as well Control (extracted pressure pressure rubber) > 12%-totally melted > lO%-totally melted as the decrease in tensile, served as criteria for determining (A) Crystalline first the antioxidant power of the compounds in question. separation > 12%-totall~y melted (B) Second fraction
(C) (D)
(E)
(F)
(G)
Stearic acid Phytosterol Liquid fraction Aqueous extract of (E)
4 . 2 %-resinous 12~o-totally melted 1070-totally melted 3 . 3Yo-fair condition 0.5%-excellent condition
Liquid fraction af- 0.45%--excellent ter Hz0 extraccondition tion Unsaponifiable 0.2-0.5% (0.5% matter after 48 hours) Regenerated liquid acids 2.6870 Crude oil from (H) 0 . 3 % after 48 hours
Top layer from (J) Bottom layer from
(J)
n-Octadecyl alcohol Ketone mixture Ketone mixture Fract. of (K), b. p. 230-270° C. Fract. of (K),'b. p. 276-276' C. Fract. of (K), b. p. 277-285' C. Fract. of ( K ) , b. P. 285-320" C. Still residue
Separation of Acetone Extract into Fractions
> l05&-totally
melted 5% (fair shape after 48 hours)
0 . 747,-good after 72 hours 12.787, - a f t e r 3 2 hours, melted 0.4%-good after 72 hours
0,47* after 48 hours 0 . 3 % after 48 hours
> 12%-totally melted > 1 2 ~ l c - t o t a l l ymelted > 1270-totally melted
0.3%-excellent condition 0.2%-excellent condition 0.18%-excellent condition 0 . 15%O-excellent condition 0 . 27q-excellent condition 0.270-excellent condition
CzlHa203 (analytical sample) Fraction of (K'), b. p. 100-150° C.:>l2%-melted Fraction of (K') b. p. 150-225O'C. > l2%-melted 1 . 1%-medium proFraction of (IC'), tection b. p. 225-240' C. 0 . 8 7 % Fraction of (K') 0 67c-good b. p. 240-255O'C. Fraction of (K'), 0 7%-gOOd b. p. 255-265' C. Fraction of (K'), 0 47,-goOd b. p. 266-290" C. 0 . 4 % 0.87,b-good Still residue CzoHsoO, b. p. 2500 6%-good 2520 c. CmHm0, b. p. 2450 4%-goOd 250' C. CmHmO, b. p. 2550 77c-gOOd 260' C. Concentrated serum from 4 liters latex (ammonia 0,8470 preserved) a For the sake of brevity, the tensiles and the behavior of the 30- and 70-minute cures are omitted. In general, the higher cures showed higher oxygen absorption, due probably t o destruction of the antioxidant.
The acetone extraction was carried out in a large tin-lined Soxhlet extractor capable of holding 25 kg. of rubber. The rubber was sheeted out to 3 mm. thickness, rolled up in Holland cloth, and extracted for 4 to 5 days wit,h acetone.
It was shown by Carson,'9 in a series of preliminary experiments, that the unsaponifiable fraction of the acetone extract was the most potent in preventing the oxidation of the rubber. I n order to obtain this fraction reasonably free from inert resin constituents, the method employed by Whitby and his co-workers for separation of these materials was used. I n addition, the extract was given a thorough water extraction before the final saponification. CRYSTALLINE FIRSTSEPARATION-The acetone extract from 98 kg. of Hevea pale crepe was concentrated to 8 liters and allowed to stand for several days at room temperature; 130 grams of a grayish crystalline mixture separated out. This mixture showed no protective action (A) .20 Water extraction of this crystalline material yielded 12 grams of quebrachitol, m. p. 188" C., after recrystallization from dilute alcohol. Some crystalline nitrogeneous material was also present which Whitby and collaborators have identified as d-valine, but which, since it showed no protective action, the present writers did not further investigate. The crystalline residue after water extraction was then extracted with ether. Upon standing, the ethereal extract deposited a crystalline powder which, after washing with acetone, was recrystallized twice from ethyl acetate, using Norit as a decolorizing agent. This powder had a melting point of 88" C. (uncorrected). It was doubtless the sterol ester isolated previously by Whitby. (Whitby recorded a melting point of 83" C.) On saponification with alcoholic potassium hydroxide it gave phytosterol, m. p. 133" C., together with a solid acid to which the formula C17H34O2has been assigned by the earlier investigators. The remainder of the ether extract contained a mixture of fatty acids and a small amount of free phytosterol. The residue after ether extraction was a grayish, very difficultly soluble powder, which dissolved in boiling butyl alcohol and upon cooling separated in the form of a gel. I t was thus twice "recrystallized," washed with ether, and dried in high uucuo at 100" C. It formed a white powder, m. P. 288" 18
20
Unpubliqhed mork of Goodyear Research Laboratorxes. The letters ( A ) , ( R ) , etc refer t o Table I.
October, 1927
INDUSTRIAL A S D EAVGINEERI-VGCHEMISTRY
to 290" C., with decomposition. The acetate, prepared by boiling with ten times its weight of acetic anhydride and crystallizing from alcohol, melted a t 164" C. From these considerations, and also from the fact that the original compound gave glucose and phytosterol when hydrolyzed by boiling with strong hydrochloric acid in amyl alcohol solution, it is concluded that the compound was phytosterolin,21 previously isolated by Whitby. Kone of the preceding compounds showed antioxidant power. SECOXD S E P A R A T I O N - Aremoval ~ ~ ~ ~ of the first separation the extract was concentrated to 4 liters and allowed to stand 2 m e k s in a refrigerator at 5" C. The solid mixture which separated showed slight protective action due to the mechanical inclusion of an oily constituent (B). Neither the stearic acid (C) nor the free phytosterol (D) isolated from this fraction by saponification showed protective action. THIRDSEPARATION : LIQUIDFRACTIOX--After removal of the second fraction and further concentration to 3 liters, there remained a brown, semi-liquid mixture of oleic and linoleic acids, together with sterols, stearic acid, and other materials. This mixture, when compounded in the test stock, showed protective action against oxidation (E). AQUEOCSEXTRACT O F LIQUID FRACTIoF--This mixture of liquid acids (E) was evaporated on the steam bath until the odor of acetone no longer persisted. It was then extracted with hot water (emulsions) in small quantities a t a time until the filtered aqueous extract was no longer yellow. The concentrated extract was a red liquid possessing an agreeab!e cinnamon-like odor and reacted acid toward litmus. I t readily reduced ammoniacal silver nitrate solution, previously made alkaline with potassium hydroxide in the cold. With ferric chloride it gave a blue-black coloration. With bromine water it gave a precipitate which sintered a t 100110" C. It did not give an aldehyde reaction with Schiff's fuchsin reagent, but did give a precipitate in sodium acetate solution with phenylhydrazine hydrochloride. Furthermore, it gave a copious precipitate with basic lead acetate and with phosphotungstic acid solutions. The concentrated extract showed strong protective action (F). D e k k e P has pointed out that the aqueous extract of the acetone-soluble constituents of Hevea rubber contains formic and higher aliphatic acids. The aqueous extract was neutralized with sodium carbonate, filtered from a small amount of tarry matter, and then extracted with ether. About 0.05 gram of a sterol melting a t 137" C. separated out from the ether in the form of tiny needles which in form and melting point differed from the ordinary phytosterol of m. p. 133" C., found in the other fractions. No especial attention was paid to these various modifications of phytosterol, which, as Whitby pointed out, differ somewhat in specific rotation and melting point. Anderson23 has shown that ordinary phytosterols consist of a mixture of crystalline sterols which possess different melting points and can be separated from each other only with extreme difficulty. I n addition, about 0.5 gram of a n oil having the cinnamonlike odor was removed by the ether. The sodium carbonate solution was then acidified with hydrochloric acid and again extracted with ether. A brown oil showing some protective action was obtained on evaporation of the ether. Its lead salt was prepared and decomposed with hydrogen sulfide, whereupon the oil was recovered. It still showed the characteristic reducing action and could not be distilled without resinification. Apparently. it consisted of a mixture of phenols and keto acids. The small quantity precluded further investigation. Phenols common in vegetable materials, such as phloroglucinol, gallic acid, etc., which show reactions 2' 2%
23
Power a n d Salway, J . Chem Soc ( L o n d o n ) , 103, 399T,1022 (1913) I n d z a Rzrbber J . , 70, 815 (1925). J A m Chem Soc , 46, 1450 (1924)
1189
similar to those mentioned, gave only slight protective action. Levulinic acid and aldehyde showed no protective action. U~YSAPOKIFIABLE MAmER-The liquid mixture remaining after the water extraction still showed powerful protective action (G). Steam distillation removed traces of mesityl oxide, as observed by Whitby. Tests showed mesityl oxide to be inactive as an antioxidant. After steam distillation the mixture was saponified by boiling under reflux for 15 hours with excess alcoholic potassium hydroxide, and the mixture of soaps thus obtained thoroughly extracted with ether. The acids were then regenerated from the soaps by treatment with hydrochloric acid and extraction with ether. Tests a t this point indicated that all the remaining natural antioxidant was in the unsaponifiable matter (H) and none in the regenerated fatty acids (I). The ether solution of the unsaponifiable matter was thoroughly washed with water to remove tracei of soaps, and the ether was distilled off. The weight of unsaponifiable matter thus obtained was 602 grams equivalent to 0.6 per cent of the weight of the rubber used. The unsaponifiable material contained about 60 per cent of phytosterol, m. p. 133-134" C., which is itself inactive as an antioxidant. The remainder consisted of a thick, reddish, pleasant-smelling oil showing very powerful antioxidant activity (J). SEPARATIOK O F UNSAP~KIFIABLE MATTER-The mixture of phytosterol and oily matter was boiled with 500 cc. of 95 per cent alcohol until all had gone into solution. It was then set aside for 24 hours and the crude phytosterol, which crystallized out, filtered off and washed with absolute alcohol cooled to 0" C. This removed the greater portion of the oil; the last traces were removed by stirring the crude phytosterol with a mixture of 500 cc. alcohol and 200 cc. acetone a t 0" C., whereby the oil went into solution, leaving most of the phytosterol in the form of nearly colorless crystals that were filtered off. The combined washings and the original filtrate containing practically all the oil and considerable phytosterol were united and evaporated on the steam bath until all the acetone was remored. The alcoholic solution of the oil which thus remained was allowed to stand a t 0" C. for 24 hours and any phytosterol which separated out was filtered off. Upon standing the filtrate gradually separated into two well-defined layers. the lower one being a reddish, heavy oil. The two layers were separated, and each was repeatedly frozen and concentrated until phytosterol no longer separated out. Each layer was finally dissolved in hot alcohol and allowed to stand 3 weeks a t 0" C. to remove the last traces of phytosterol. At this point there would usually be a separation from each layer of a yellowish waxy solid, which was later found to be impure octadecyl alcohol. Tests made with digitonin showed rfo more phytosterol to be present. The characteristic blue color shown by common sterols in the Liebermann-Burchard reactions,*4 as well as in the more sensitive Whitby sterol reaction^,^^ could not be detected. Instead, deep brown or red colors were formed which, even at high dilution, were so pronounced that the presence of sterols of a different type is concluded. These will be described later. Both the top and bottom layers showed powerful protectii e action (K) (K'). Each layer was separately worked up :I' described below. TOP LAYER:SEPARATION O F TL-OCTADECYL ALCOHOL-Upon concentrating the alcoholic solution after phytosterol was completely removed, there separated, a t 0" C., 13.2 grams of a yellowirh solid, melting crude a t about 42" C. It waq recrystallized from dilute alcohol several times. The melting point rose to 55' C. Further crystallization, followed b) 24
2:
B e y , 18, 1804, Chem Zentr , 60(I),25 (1890). Biochenr. J., 17, 5 (1923).
INDUSTRIAL A N D ENGINEERING CHEMISTRY
1190
preparation of its acetate, m. p. 29' C. and saponification of the acetate, yielded a substance melting constant a t 57-58' C. A sample mixed with n-octadecyl.alcoho1 gave a slight depression, as did the mixed melting point of the acetates. Analysis: Calcd. for C1nHas0: C 79.91, H 14.16 per cent Found: C 79.32,II 14.17 per cent
This, together with the analysis, which is too low in carbon, indicated the presence of an impurity. A sample was vacuumdistilled, b. p. 193-200'C. a t 3 mm., andgave values which were too high-81.00 per cent C and 14.50 per cent H-indicating hydrocarbon formation through slight decomposition. The compound was therefore oxidized by boiling 3 hours with excess chromic-sulfuric acid mixture. It was then diluted with water, neutralized with potassium hydroxide, and extracted with ether. This removed a small amount of a white crystalline compound, m. p. 61" C., which was found to be the contaminating agent. Regeneration of the free acid from the soap by means of hydrochloric acid and extraction with ether gave a white crystalline solid that melted a t 68-69" C. after one recrystallization from alcohol, and proved to be stearic acid. Analysis: 0.0756 gram substance: 0.0869 gram Hz0 and 0.2103 gram COz Calcd. for C~sHsaOz: C 75.95, H 12.79 per cent Found: C 75.87, H 12.73 per cent
The octadecyl alcohol showed no protoctive action (L). SEPARATION OF ANTIOXIDANT C27H4203-After removal of the n-octadecyl alcohol by freezing, the ethyl alcohol was evaporated off and the brown oily residue distilled in vacuo with a current of dry nitrogen passing through the capillary. Attempts to separate the oil into alcohol and hydrocarbon fractions by converting it into alkali-soluble acid phthalic ester derivatives proved unsuccessful.2e The following fractions were collected: BOILING
FRACTION POINT
PRE55URE
APPEARANCE
WEIGHT O c. Mm. Grams I 90-130 Yellowish oil 10 3 Yellow solid 15 166-230 I1 3 Yellow oil 20 solid 230-270 I11 1.9 275-276 Very viscous reddish oil 5 1.9 IV Very viscous reddish oil 105 277-285 1.9 V 285-320 1.9 VI Verv viscous brown oil 205 VII still residue vitieous resin 15 Evidence of decomposition.
DESIGNATION
+
~
Fractions I and I1 did not protect; I11 to VI1 protected strongly. Fraction I was refractionated three times in vacuo, the first and last portions of the distillate being rejected. The fraction boiling a t 105-107' C. at 3 mm. was collected and analyzed: Analysis: 0.1184 gram substance: 0.1135 gram HzO and 0.3382 gram Cot. 0.0974 gram substance: 0.0954 gram HzO and 0.2903 gram COz Calcd. for C1aHz40: C 81.74, H 10.99 per cent, Found: C 81.33, H 11.20, 81.38; 10.97 per cent
This substance was a light yellow oil having an intense, fragrant, eedar-like odor. It gave ketone reactions with phenylhydrazine acetate, but no crystalline semicarbazone could be isolated that might serve for identification. Such substances occur in various essential oils and have not been identified. It can be steam-distilled. Fraction I1 consisted of octadecyl alcohol together with small amounts of the ketone in fraction I. Fraction 111 contained octadecyl alcohol together with an oil from which no sharp fraction could be distilled. Fraction IV was refractionated. It boiled a t 258-260" C . at 1.9 mm. after elimination of the first and last runnings. This oil went through six fractionations. When compounded in the control stock to the extent of even 0.1 per cent it gave practically complete protection against oxidation (T). It Fargher and Higginbotham, J . Textile Insl., 16, 4261' (1924).
Vol. 19, No. 10
was an odorless, transparent, reddish, viscous oil, which solidified a t low temperatures to a glassy, non-crystalline mass. It was optically inactive (1 gram in 100 cc. chloroform); n2i = 1.5395. It contained no nitrogen and rapidly turned dark when exposed to the air; was insoluble in water or alkalies, but readily soluble in organic solvents. Analysis: 0.1128 gram substance: 0.1034 gram Hz0 and 0.3246 gram C 0 2 Mol. wt., cryoscopic in benzene (K = 50): 0.0415 gram substance in 16.56 grams benzene, dT = 0.030°, M 417.6 0.1850 gram substance in 16.56 grams benzene, dT = 0.134', M = 416.9 0.2774 gram substance in 16.56 grams benzene, dT = 0.203', M = 412.6 Calcd. for CzrH4zOa: C 78.26, H 10.14 per cent; mol. wt. 414 Found: C 78.48, H 10.27 per cent; av. mol. wt. 415 ( M = molecular weight; d T = depression in freezing point)
-
The analysis indicates that this natural antioxidant is probably a derivative of phytosterol. It gave the Salkowskiz7 and Tshugajeff 28 color reactions for sterols very distinctly. I n the Whitby125as well as the Liebermann-Burchard124reactions for sterols it gave an intense red or reddish brown color, instead of the characteristic blue. When heated with acetic anhydride a t 100' C. for 2 hours, the compound took up nearly the theoretical amount equivalent to one hydroxy group, and thereby lost its antioxidant power. The acetate thus obtained was a light red oil which solidified to a crys' C. When hydrogenated in ether solution talline mass a t 0 with platinum black as a catalyst, a t ordinary pressure, the antioxidant took up almost two moles of hydrogen and formed a crystalline compound which no longer acted as an antioxidant. Fractions V and VI showed evidence of decomposition during the distillation. Upon refractionating fraction V at 3 mm. it yielded, in addition to the CnH4203 compound, a small quantity of a light yellow oil possessing an orange-like odor and having the formula CI~H,. It boiled a t 240-245" C. a t atmospheric pressure; specific gravity at 25' C. 0.8924. Analysis: 0.1087 gram substance: 0.1124 gram Hz0 and 0.3499 gram COz. Mol. wt., cryoscopic in benzene: 0.1708 gram substance in 15.95 grams benzol, dT = 0.286' Calcd. for C I S H S ~C : 88.15, H 11.85 per cent, mol. wt. 204 Found: C 87.80, H 11.59; mol. wt. 190
LOWERLAYERFRACTIONATION: SEPARATION OF ANTIC20H300-The lower layer was distilled in vacuo under the same conditions as the top layer. OXIDANT
BOILING FRACTION POINT
c. I I1 I11 IV V VI VI1
100-150 150-225 225-240 240-255 255-265 265-290 Still residue
PRES5URE APPEARANCE WEIGHT Mm. Grams 7 Yellow oil 9 7 Yellow solid 16 5 Red oil 20 5 Red oil 24 3 Red oil 32 3 Red oil 20 Black tar 35
DESIGNATION
(U) (VI (W) (XI (Y) (2; (A )
Fractions I and I1 did not protect; I11 gave medium, and I V to VI1 very powerful protection. Fractions I, 11,and 111 agreed substantially with those obtained from the upper layer. Fraction IV was refractionated thrice, eliminating the first and last portions of the distillate each time. The fraction boiling at 280-252' at 3 mm. was collected (B'). Analysis: 0.1402 gram substance: 0.1336 gram Hz0 and 0.4302 gram COa Calcd. for CmHsaO: C 83.85. H 10.55 per cent Found: C 83.68, H 10.68 per cent
Fraction V was fractionated similarly. It gave the CuH24 hydrocarbon previously mentioned and a fraction boiling at 245-250' a t 2 mm. (c'). Analysis: 0.0860 gram substance: 0.0838 gram Hz0 and 0.2641 gram COS Calcd. for CzoHsoO: C 83.85, H 10.55 per cent Found: C 83.75, H 10.92 per cent 2' 28
Arch. ges. Physiol. (Pfliiger's), 6 , 207 (1872). Chem.-Zlg., 24, 542 (1900).
October, 1927
INDUSTRIAL A S D EXGINEERISG CHEJfISTRY
Fraction VI gave, after two refractionations, a distillate boiling a t 255-260’ a t 2 mm. (D’). Analysis: 0.1017 gram substance: 0.1004 gram Hz0 and 0.3134 gram COz Calcd. for CzoH300: C 83.85, H 10.55 per cent Found. C 84.04, H 11.06 per cent
All of these analytical samples were tested and each one was found to protect. Acetylation destroyed their antioxidant power. They are all probably the same substance, and form a clear, reddish oil which is, however, not so viscous as the C2,H420acompound isolated from the upper layer fractionation. The wide range of boiling points is no doubt due to overheating the thermometer during the distillation which was conducted over a Wood’s metal bath heated a t 350400° C. They show the same sterol reactions given by the C 2 ~ H 4 2compound. 0S Since it was possible that these substances might be a constant-boiling mixture of alcohols or of alcohols and hydrocarbons, the probability of oleic and linoleic alcohols being present seemed reasonable in view of the presence of octadecyl alcohol.*g These alcohols were therefore prepared and tested, but they showed no antioxidant power; in fact the linoleic alcohol accelerated the oxidation. Such alcohols are therefore very likely not present. No mention of linoleic alcohol in the literature could be found but by employing the Bouveault and Blanc30 method of preparing alcohols from their esters by means of sodium no especial difficulty was encountered in preparing linoleic alcohol from pure linoleic ethyl ester, which was in turn prepared from pure tetrabromolinoleic acid by the method of Rollet.31 The linoleic alcohol thus obtained in 40 per cent yield was a colorless, mobile liquid, b. p. 203’ C. at 7 mm., ny = 1.4615; specific gravity 0.8586 a t 20” C. It readily oxidizes in the air, takes up practically the theoretical amount of bromine to form a crystalline and a liquid bromide, and does not solidify a t 0’ C. 29 Attempts t o separate hydrocarbons from unsaponifiable matter by the usual methods (Lewkowitsch, “Oils, Fats, and Waxes,” 5th ed., p. 601) were unsuccessful. 8 0 Compt. rend., 136,1676; 137, 60 (1903). 8 1 Z.physiol. Chem., 62, 411 (1909).
1191
Other Substances Tried
Inasmuch as Whitby had found evidence of magnesium compounds in the liquid f a t t y acid fraction of the resin, the presence of chlorophyll was suspected. When compounded, however, chlorophyll failed to show protective action. Other compounds tried were sitostene, the hydrocarbon derivative of phytosterol, the crude distillation products of rubber, and the crude unsaponifiable material from cottonseed oil, arachic oil, and balata resin, none of which protected. Since radiation of phytosterol and cholesterol with ultraviolet light forms waxy compounds which are so-called “antiisolated ricketic” vitamins, and since the vitamin A, CnH4402 from the high-boiling liquids of the unsaponifiable material of cod-liver oil by Takahashi and his ~ o - w o r k e r sbore ~ ~ some resemblance to our compound, the products of ultra-violet radiation of cholesterol and phytosterol, as well as the ozonides of these sterols and their decomposition products with water, were tested for antioxidant action, but without success. The compound C27H4203 from diacetylpentane, described by Kipping and Perki11,~3was also prepared, but it did not protect. Conclusion
Very little is known about the liquid constituents present in small quantities in the unsaponifiable matter of various plant products. The recent isolation of vitamin E from the unsaponifiable matter of wheat oil by vacuum distillationa4 and the biological significance of these complex substances, which are probably in the nature of enzymes, will no doubt be a stimulating influence in working out better methods for their isolation and may pave the way for their identification.
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Acknowledgment
The authors wish to express their appreciation to C. M. Carson for valuable preliminary work, and to W. C. Calvert for the preparation of octadecyl and linoleic alcohols. 82 Sci. Papers Inst. Phys. Chem. Research ( T o k 3 o ) ,3, 38 (1925); J . Chem. SOC.( L o n d o n ) , 1926, 3658. Ibid., 67, 26 (1890). Evans and Burr, Proc. Xatl. A c a d . Sci., 11, 334 (1925).
Measurement of the Adhesive Strength of Glue’ By C. E. Lanyon MANNING ABRASIVE COMPANY, TROY,N. Y.
M
ANY methods have been proposed for measuring the adhesive strength of glueJ2 but the results have in general been far from satisfactory. Other investigat o r ~ have ~ , ~ measured the tensile strength of glue. It has often been suggested that the tensile strength of glue is the property upon which the adhesive qualities depend. While for joints of the mechanical type, as in the wood-working industries, this may be true, in the abrasive industry, where we are interested in measuring specific adhesion-i. e., the bond between an abrasive particle and glue-this does not necessarily follow. As a measure of the strength of this bond the breaking strength of briquets made from abrasive and glue solution suggests itself, Received June 13, 1927. For a summary of these methods, see Bogue, “The Chemistry and Technology of Gelatin and Glue,” p. 527. 8 Hopp. THISJOURNAL, 12, 356 (1920). McBain and Hopkins. Second Report of Adhesives Research Committee (British), 1926. 1
Gill6 made briquets of various materials using glue as a binder. He experienced difficulty in drying them and in obtaining consistent results. However, with care in manufacture and by drying in air under natural conditions, this method is capable of giving very satisfactory results. Preliminary Work
A series of tests showed that with 40-mesh sand to obtain even wetting of the grain without having excess glue solution present, about 50 or 60 grams of solution should be added to 400 grams of sand. These quantities will just fill a 3-gang mold. Enough material for each set of three briquets was made up separately and used as quickly as possible in order to keep the mixture fluid and facilitate filling the molds. Force-drying these briquets a t 54’ C. in 20 per cent humidity for 5 days, then seasoning in ordinary air for 2 weeks, gave low and inconsistent results. Examination of the fractured 6
THIS JOURNAL, 7, 102 (1915).
