Feb., 1 9 1 4
THE J O C R S A L b F I S D C S T R I A L A N D ENGINEERING CHEMISTRY
THE ANALYTICAL CONSTANTS OF HYDROGENATED
OILS By CARLETON ELLIS
Received January 5 . 1913
The hydrogenation of oils has t o such a n extent changed certain of t h e consLants b y which oils a n d fats are a t least in p a r t identified, namely, t h e iodine n u m ber a n d t h e specific gravity, t h a t t h e identification of a fat or f a t t y mixtures, often heretofore a troublesome m a t t e r a t best, now promises t o become even more difficult.
t
T h e reduction of t h e iodine number through t h e introduction of hydrogen into t h e oil, in a sense is arbit r a r y ; there is no difficulty in reducing t h e iodine n u m ber almost t o zero through t h e hydrogenation process, or a t a n y moment t o interrupt t h e operation a n d from one and t h e same initial material t o produce products having t h e most varied iodine numbers. The specific gravity a n d melting point advance h a n d in h a n d as saturation progresses, t h e specific gravity approaching t h a t of tristearine, while t h e resultant melting point in considerable measure depends upon t h e molecular weight a n d t h e hydroxyl content of t h e f a t t y acid components of t h e oil. T h e specific gravity of a hardened cottonseed oil whose iodine number had been reduced t o zero was found b y Normann a n d Hugel' t o be 0.9999 at 1 5 C., ~ while t h e y note t h a t tristearine has n specific gravity of 1.0101a t t h e same temperature.? T h e index of refraction also is strongly modified. j 6 O C., according t o Normann a n d Hugel, showed a figure of j3.8; while after hardening t o an iodine number of 2 2 . 5 t h e index was 36' C. a t t h e same temperature. (Scale of t h e Zeiss b u t t e r refractometer.) ,
4 sample of fish oil a t
Observations made in t h e writer's laboratory on t h e index of refraction of a n u m b e r of hydrogenated oils gave t h e results noted below: INDEX OF REFRACTION AT 5 5 ' C .
(Abbe Refractometer)3 Original Oil Corn., . . . . . . . . . . . . . . . . . . . . . . . . 1.4615 Whale (No. 1 ) . . . . . . . . . . . . . . . . . . . 1.4603 Soya b e a n . . . 1.4617 Cocoanut oil ( ) . . . . . . . . . . . . 1.4429 1.4730 1.4523 1.4523 Peanut (edible). . . . . . . . . . . . . . . . . . 1.4567
Melting point
1.4514 ( M . P. 55.7'C.) 1.4550 (M. P . 41.5OC.) 1.4538 ( M . P . 50.3' C . ) 1.4425 (M. P . 24.7O C . ) 1.4610 ( M . P . 42.3O C.) 1.4517 (M. P . 3 8 . 7 O C . ) 1.4494 ( M . P. 44.8O C . ) 1.4547 (M. P . 34.7" C . )
Cottonseed oil was hydrogenated for a period of t e n hours a n d samples were drawn at one hour intervals. Chem. Ztg.. 1913, 815. The specific gravity of tristearine is given by the "Chemiker Kalender"
a5 1.0101 at 1 5 ' C.,while Lewkowitsch reports the specific gravity of a specimen of not quite pure stearine in the melted state as 0.9235 at 65.5' C. 3 Refraction values are given in terms of true refractive index and also according to the arbitrary scale of the butyro-refractometer, in order to follow the data available, as rendered.
Index of refraction
Original Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 h o u r . ,. . . . . . . . . . . . . . . . . . . . . . . . . . . 2 8 . 2 ' C. 2 hours, . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 I . 3 .................... 34.3 .................... 37.9 5 " .......................... 40.8 ............................ 43.8 6 ............................ 45.6 8 " ............................ 47.3 10 " ............................ 55.9
-
I'
,I
550
c.
1 ,4588
1,4577 1.4568 1,4557 1 ,4549 1 ,4540 1.4527 1.4518 1.4510 1 ,4496
T h e saponification number practically does not change. T h e content of free f a t t y acids changes b u t little. A sample of cottonseed oil containing 1.8 per cent f a t t y acid was found, after hardening t o various degrees. t o have a f a t t y acid content ranging from 1.3per cent t o 1.9 per cent. K i t h sesame oil containing 2.44 per cent f a t t y acid t h e resulting hardened oil contained 2 . j j per cent of acid. T h e content of unsaponifiable bodies does not essentially change. Cottonseed oil having 0 . j j per cent unsaponifiable m a t t e r , after hardening, showed a content of unsaponifiable bodies ranging from 0 . 4 j per cent t o 0.55 per c e n t ; sesame oil with a n unsaponifiablecontentof o.7opercent, after hardening contained 0.8 j per cent unsaponifiable. Cholesterol a n d phytosterol, according t o Bomer, are not changed by treating oils with hydrogen, although this is somewhat contrary t o t h e statement of Windaus,' according t o whom cholesterol may be easily reduced b y t h e catalytic process. Willstatter and ZIIayer2 hydrogenated cholesterol in ether solution with a platinum catalyzer. I n t h e case of t h e acetyl number more noticeable changes t a k e place according t o Normann a n d Hugel. When hardening castor oil, for example, t h e hydroxyl number in one sample dropped from 156 t o 1 0 2 ; in another sample t h e number fell t o 131. The hydroxyl group is t h u s more or less broken down by t h e hydrogenation process, a t least under some conditions of treatment. .............................. r..............................
Hydrogenated Oil
T h e gradual reduction of t h e index of refraction b y progressive hydrogenation is shown in t h e following table compiled from determinations made i n t h e writer's laboratory.
1
It is of interest t o note t h a t while t h e addition of h y d r o g e n t o f a t t y oils reduces t h e index of refraction, t h e addition of o x y g e n increases t h e index as is shown in t h e case of blown or ozonized oils.
Iodine number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acetyl number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
......... Melting point of the f a t , . . ,
3.5 183.5 4.8 153.5 143.1
...............
Meiting point of the acetylated acids.
.................
47" C .
T h e properties of hardened castor oil have been noted b y Garth,3 whose observations differ somewhat from those of Normann an,d Hugel. As is generally known, castor oil differs materially from m a n y other common oils in such respects as its high viscosity, solubility in alcohol a n d difficulty of salting o u t its soaps by electrolytes. Hardened castor oil dissolves in alcohol only b y heating a n d separates on cooling, but is soluble a t ordinary temperature in chloroform. T h e constants of one sample of hardened castor oil examined b y G a r t h are given in the above table. 1
2
*
Ber. d . chem. Ges., 1912, 3051. [ b i d . , 1908, 41, 2199. Seifen Z l g . , 1912, 1309.
T H E J O U R i V A L OF I N D U S T R I A L AA'D E N G I N E E R I N G C H E M I S T R Y
28
shows t h e location of cracks which h a d started near t h e rivet holes, largely on t h e inner side of t h e plate.
Vol. 6 , No.
I
a t t h e left end are pointed, while t h e single one, a t a distance of 17 inches from t h e first two, is slightly rounded. The pointed legs are forced into t h e cover plate near its outer edge, by light blows when t h e instrument is first in place, so t h a t in subsequent readings i t is necessary only t o set t h e pointed legs back into
r / r3
The general nature a n d location of these cracks pointed strongly t o a failure by repeated bending of t h e cover plate under stress. While measurements on t h e inside of a similar digcstcr showed a slight flattening of t h e curve near t h e seam, due probably t o difliculty*in t h e bending rolls, this peculiarity wotild prove rather a benefit t h a n a n injury, since t h e tendency of t h e cover plate is t o t a k e this formation under stress. T h e line of resistance in cylindrical shells under internal pressure tends t o conform t o t h e circle and since t h e single outside cover plate construction throws this line of resistance outside of t h e true circle, t h e tendency under stress is t o restore i t by bending t h e cover plate inward, a s illustrated in Fig. 4.
these little depressions t o insure a n exact reproduction of t h e original setting. T h e cover plate is polished where t h e single rounded screw-leg rests, a s are also t h e spots m-here t h e micrometer measurements are made. Fig. 9 indicates the method of application of t h e FlG.4. instrument f o r measurements of deflections a t t h e T o exhibit this action mare clearly, a one-fourth center of t h e 17-inch span. T h e micrometer is firmly size rubber model of n section of this seam was made, fixed in t h e center of t h e instrument frame f o r this a s scen in Fig. 5. Fig. 6 shows a profile of t h e model setting, a n d in making observations, t h e micrometer before tension was applied, and Pig. 7 indicates clearly screw is advanced until t h e sense of touch lightly indicates t h a t its point rests upon t h e polished plate. 1
h
.9 .
--
CPPLll^i,oY
L)CILCCI,QN nj"*E
ClG
F I G S 5 ,6
nnb7
I
t h e effect of tension (in t h e seam. Particular attention is invited t o t h e concentration of bending between t h e inner rows of rivets, corresponding in t h e full size seam t o z span of about 3 inches. This evidence naturally led t o a desire t o determine, if possible, t h c nature a n d extcnt of t h e inward deflection of t h e vertical cover plate iindcr working conditions, a n d for this purpose a deflection gauge was devised, as shown in Fig. 8. Thc irame of t h e instrument was made from a piece of 4-inch steel channel bar. The set screws constituting t h e legs are of hardened tool steel. The two
9.
I n exploring t h e curve formed by t h e deflections i n t h e cover plate t h e micrometer was relocated a t a point 4 inches off-center, a s shown in Pig. IO. Measurements were taken a t intervals ranging from thirty minutes t o a n hour, starting before the steam was turned on and continuing for a t least half an hour after t h e digester was blown. The diagram, Fig. I T , which is typical, presents a graphical record, on a time base. of t h e deflections observed a t t h e center of t h e rj-inch span, while t h a t of Fig. T Z is for a point 4 inches off-center. T h e maximum deflections obtained in t h e tests represented by Figs. 1 1 and I Z are replotted on t h e diagram i n Fig. 1 3 , on a base line represcnting t h e 17-inch span. The ordinates a t t h e center a n d a t points 4 inches off-ccnter are plotted t o a magnified scale a n d t h e smooth curve drawn through these points
Fell., 1914
T H E JOCR-TAL OF I S D 1 7 S T R 1 4 L A S D E S G I S E E R I S G C H E M I S T R Y
unsaturated acids as clupanodonic (in v h a l e oils). ,5nyone r h o has seen a malodorous oil converted into a bland odorless talloIy realizes t h e commercial possibilities of t h e process. . h d \?-hen it is remembered t h a t t h e process can be stopped m h e n , t h e iodine value reaches a desired number! t h e possibility becomes e r i dent of t h e preparation of a f a t with a n y required analytical figiires.!' I n support of t h e foregoing, K n a p p furnishes t h e following d a t a : Original Hardened oils I oil Clear Solid particles S o f t greasy Brittle liquid floating in oil solid solid I
Appearance. . . . . . . . . . . . . . .
Butyro-refractometer (corrected t o 40° C.) . , . , 57.7 ,. F a t t y acids Iodine v a l u e . . . . . . . . . . . 110 94 . . . . . . . . . . 3 4 . 7 ' C. 3;.Oo C . Titer.. ... Seutralization value (mg. K O I I ) . . . . . . . . . . . . . 197 196
.. 55 4 2 . 5 O C.
196
47.7 72 52.2OC.
192
T h e analyst is chiefly interested in t h e question of how these fats are t o be detected. It is doubtful if their most characteristic feature, t h e relati\-ely high percentage of stearic glycerides which t h e y contain, will be of much service. K n a p p states t h a t until t h e manufacturer accomplishes t h e difficult step of completely removing t h e nickel, t h e detection of traces of this metal will be t h e simplest a n d most reliable test for hardened oils.' Although t h e catalyst is very finely divided, t h e manufacturer can obtain a perfectly clear f a t b y careful filtration, a n d hence i t is t h e nickel contained i n t h e nickel soaps formed b y t h e free f a t t y acids present t h a t one has t o detect. T h e following method is suggested: 5 0 grams of t h e fat are heated in a flask n-ith 2 0 cc. hydrochloric acid, with continued vigorous shaking. T h e mixture is allowed t o separate while h o t , a n d p a r t of t h e acid solution is evaporated t o dryness, dissolved in a drop of water, a n d placed on a white tile. One drop of ammonium sulfide is added t o this a n d also t o a drop of water for comparison. K n a p p however, tried. this test only on a few hardened oils, a n d in some cases with negatire results. Dimethyl,glyosime is a much more delicate test, b u t unfortunately Prall has found? t h a t certain pure untreated oils give a red coloration. Hence further investigation is needed. One of the most characteristic tests for fish oils-the bromide estimation-is q u a n t i t a t i r e l y useless for these oils after hardening, as t h e percentage of ether-insoluble brominated glycerides is greatly reduced thereby. S o t only are t h e analytical figures for t h e oils altered by this absorption of hydrogen, b u t also t h e traces of substances which often serve as a useful test for t h e particular oil in which t h e y occur-e. g., Halphen's reaction. K n a p p believes Bomer's observation t h a t phytosterol a n d cholesterol are not changed in this process is of great analytical value. Three fats obtained b y K n a p p from a clear cottonseed oil, hardened b y hydrogen with t h e help of different catalysts, gave t h e following figures: 1 Too much reliance should n o t be placed on t h e nickel test as evidencing t h e presence or absence of hydrogenated oils. It is known t o t h e writer t h a t hardened oils Tvhich are free from nickel are on t h e market, these in some cases presumably having been prepared with t h e aid of palladium as a catall-zer. 1 Bomer, Zeilsch. r n l r v s t c c h . S a h r . Genussm., 1912, 24, 104; and A n a l y s t , 1912, 3 7 , 452.
Percentage of catalyst in oil
Catalyst
S i c k e l . ,. . . . . . . . . . . 1.00 Platinum.. . . . . . . . . . 1 , l O Palladium. . . . . . . . . . 0 . 0 6
Character of product
119
Butyro-refrachleltini: tion (Corpoint rected t o 40' C . ) OC.
45.7 47.8 45.5
Hard Hard Brittle
49 46 52
T h e keeping properties of these hardened oils were found t o be remarkably good. Although prepared nearly a year a n d a half previously a n d having often been exposed t o d a m p air, yet t h e y showed n o signs of rancidity. T h e free acidity ( 0 . 7 0 per cent as oleic acid) did not appreciably change during t h e period of observation. Bomerl is in substantial agreement with t h e foregoing, for he states t h a t ( I ) t h e hardened oils, as a result of t h e more or less complete trhnsformation of unsaturated f a t t y acids (oleic, linoleic, linolenic) into stearic acid, shorn a n increase in t h e melting a n d soliciifying points as well as a lowering of the refractometer number a n d iodine number while t h e saponification number is b u t little altered. ( 2 ) Judging b y t h e iodine numbers of t h e liquid f a t t y acids, these acids appear t o he not uniformly transformed into stearic acid, b u t t h e transformation of oleic acid appears t o progress more slowly t h a n t h e less saturated linoleic a n d linolenic acids, etc. (3) -Among t h e hardened oils, t h e soft a n d medium hard products, in color, consistency a n d in p a r t also in odor a n d taste, show a greater or less similarity t o beef or m u t t o n tallow, so t h a t b y external appearance one cannot distinguish these hardened oils from such animal f a t s ; for example medium hard peanut oil is so completely like neutral lard, a n d hardened whale oil is so like m u t t o n tallow, t h a t one is n o t able t o distinguish between these fats b y appearance. consistency, odor nor taste. (4) K o t only in their outward properties are these hardened oils like hog fat a n d m u t t o n tallow, but also t h e usual analytical constants are so similar t h a t one cannot distinguish some samples of hardened peanut oils a n d hardened sesame oil from hog f a t , nor whale oil, in some cases, from m u t t o n or beef tallow. I n t h e latter case even t h e Polenske numbers agree while in t h e case of sesame oil t h e y are somewhat lower t h a n hog f a t .
P e a n u t oil untreated P e a n u t oil hardened
i
56.8
1.1
1
30.1
1.0
188.7
47.4
3 8 . 4 ( b ) 4.7
188.9
25.4
Yellox liquid.. . . . . . . . . . . . ( X'hite talloivp . . . . . . . . 51.2 3 6 . 5
( n'hite tallowy . . . . . . . 6 2 . 1 4 5 . 3 Cottonseed Yellowish oil hardened lard l i k e . . . . . . . 3 8 . 5 2 5 . 4 Cocoanut oil untreated . . . . . . . . . 25.6 2 0 . 4 Cocoanut oil White lardlike . . . . . . . 44.5 2 i . i hardened IVhale oil Yellowish hardened tallowy . . . . . . . . 4 5 . 4 3 3 . 7 ( a ) 3Iilligrams potassium hydroxide for 1 ( b ) Determined a t 50' C.
Sesame oil hardened
1
-i 1 { {
191.1
84.4
53.8
0.6
195.;
69.7
37.4
0.3
255.6
11.8
35.9
0.4
254.1
1.0
49.1 1.1 gram fat.
193.0
46.8
Bomer examined a number of hydrogenated oils a n d tabulated t h e results of his investigations a n d from these t h e above condensed table has been compiled 1
Chem.YRe.i. u . d Fell u n d Hauz.Ind..
1912, 220.
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 N G I N E E R I N G C H E M I S T R Y
I20
The solid a n d liquid f a t t y acids separated from t h e hydrogenated fat b y t h e method of Farnsteiner showed t h e following properties: Liquid fatty acids Solid fatty acids __h-
M . P.
Oil Peanut oil untreated.. . . Peanut oil hardened, . . . Sesame oil hardened.. . Cottonseed oil hardened.. Whale oil hardened.. .
. .. . ..
.. .. 56.4 45.0
..
Acid No.
.. 199.7 199.5 206.8 199.5
Refraction at 4 O o C . 47.6 42.9 44.7 48.3 44.4
Iodine No. 91.8 82.9 88.9 115.6 96.0
Samples of these hardened oils were examined for cholesterol a n d phytosterol. Hardened peanut oil was found t o contain 0.4 per cent, sesame oil 1.9 per cent, cottonseed oil 1.6 per cent, a n d whale oil 0.2 per cent of sterol, of which t h e three first hardened products mentioned exhibited t h e typical crystalline form of phytosterol. T h e melting point of these sterols ranged from 1 3 2 t o 139' C.,yielding acetates melting between about 126 a n d 129' C. T h e hardened whale oil gave a sterol melting a t 149.7' C. Bomer made a series of fractional crystallizations of hardened oil a n d from a sample of hydrogenated peanut oil obtained tristearine (amount ng t o a b o u t 2-3 per cent). Bomer has called attention t o t h e rather striking behavior of cocoanut oil. He calculated from t h e iodine number t h a t t h e natural oil contained 13 per cent of oleic acid a n d after hydrogenation approximately about I per cent of this acid wa's present. As a result of t h e transformation of 1 2 per cent of oleic acid into stearic acid, t h e melting point increased from 2j.6' C. t o 44.5' C., or t h u s 18.9' C., while t h e sojidifying point advanced from 20.4' C. t o ~ 7 . C., 7 ~ or only 7.3' C. A species of hardened fish or whale oil known as "Talgit" has been examined b y Muller,1 who found t h e product t o have a n acid value of 12.8,a n iodine number of 49 a n d a titer ( f a t t y acids) of 39.4' C. T h e f a t was saponified a n d pressed t o obtain stearic acid. It was found t h a t t h e operation of pressing could be carried out effectively t o yield a product technically free from liquid f a t t y acids: 3 j per cent of solid f a t t y acid having a titer of 48.7' C. was t h u s obtained. Muller states t h a t since mixtures of stearic a n d palmitic acids possess a solidifying point above j3.j o C. t h e low titer of t h e solid acids of Talgit points t o t h e presence of solid acids other t h a n stearic a n d palmitic. Dubovitz2 thinks t h e low melting point t o be due t o t h e presence in t h e original fish or whale oil of hypogaeic a n d physetoleic acid or similar acids with possibly unsaturated f a t t y acids of a still lower number of carbon atoms. Leimdorfer3 regards t h e stearine produced by t h e hydrogenation of some oils t o be perhaps a n allotropic form of natural stearine. An a t t e m p t is made by Grimme4 t o identify fish oils a f t e r they have been hardened. As stated, t h e ordin a r y constants give no clue t o t h e original source of a hardened oil a n d hence Grimme resorts t o color rei
2 3
'
Seifen Z t g . , 1913, 1376 I b i d . , 1914, 1445. I b i d . , 1913, 1317. Chem. Rev. u. d. Fell und H a m I n d . , 1913, 129:and:ljj.
1'01. 6, No.
2
actions. A list of tests is given for each of t h e four classes of fish oils: ( I ) Seal oils; (2) Whale oils; (3) Liver oils; (4)Fish oils; a n d also characteristic tests for individual oils. These tests were also applied t o t w o hardened oils of unknown origin a n d Grimme believes from his results t h a t t h e color reactions are characteristic enough t o establish t h e presence of fish oils. Nickel was found in t h e samples, Fortini's test (as detailed below) giving t h e strongest coloration. Color reactions were applied t o six authentic whale oils from t w o different sources, a n d hardened t o different degrees. These tests were carried o u t by dissolving 5 parts of t h e sample in 9j p a r t s of benzine-xylene (I:I) a n d agitating j cc. of t h e solution with t h e reagent; after j minutes a n d 60 minutes t h e color was noted. Grimme finds t h e iodine-sulfuric acid reaction ( I cc. concentrated sulfuric acid a n d I drop tincture of iodine) t o give a characteristic violet-red color for whale oil though t h e intensity of coloration decreases with increasing hardness. T h e constants of t h e six samples of hydrogenated fish a n d whale oils employed a n d t h e coloration produced b y different reagents are tabulated b y Grimme. A draft of t h e Codex alimentarius Austriacus, which has been prepared b y a board of prominent chemists a n d officials including Hefter, Wolfbauer, Fischer, Hart1 a n d Pellischek,' embraces t h e subject of hydrogenated oils a n d i t is s t a t e d t h a t considered a s a food product these oils will require further careful investigation before i t is determined with certainty just what r a n k t h e y will t a k e as edible products. It is noted t h a t the fats now offered for edible purposes are white t o yellowish in color, almost odorless a n d tasteless. Usually t h e consistency lies between t h a t of ordinary b u t t e r a n d hard tallow. A'ow a n d t h e n samples are found which melt a t about 60' C. a n d are as brittle a s carnauba wax. These hard products, of course, are not intended by themselves t o be used for edible purposes, b u t are employed t o raise t h e melting point of soft fats. Samples of hardened peanut a n d sesame oil with iodine numbers reduced t o jo or lower, sometimes down t o 20, have been examined. Cocoanut oil with a n iodine number of 2 or even lower has been met with. T h e cholesterol of animal fats a n d t h e phytosterol of vegetable oils is not altered by the hydrogenation process. The hardened fats, i t is stated, scarcely ever appear on t h e market in their t r u e light b u t usually are p u t o u t under some trade name such as " Peanut-oleo," " Sesame-oleo," '' Peanut-margarine," " Sesame-margarine," Crisco," a n d t h e like. Hardened oils examined by Aufrecht2 in outward appearances resembled palm kernel oil. T h e y were very hard a n d of granular fracture, were either pure white or yellowish in color. A distinct odor was perceptible on melting or heating. T h e t a s t e recalled t h a t of tallowy fats. T h e products were readily soluble in t h e usual f a t solvent mediums, b u t t h e solubility in methyl a n d ethyl alcohol was very slight. T h e f a t s were easily saponifiable. T h e content of free f a t t y acid fluctuated between 0.j1-0.83per cent. T h e ash ('
1 2
Scifcn Z t g , 1913, 1087. Pharm. Z t g . . 1912, 876.
Feb., I 1 4 ’
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 N G I N E E R I N G C H E M I S T R Y
reacted alkaline a n d consisted of alkali carbonate a n d t r a e s of iron oxide, b u t n o nickel or o t h e r constituent could be detected. T h e following analytical results are given: 1. Durotol (yellow) Color., . . . . . . . . . . . . . . . . . . . . . . . . . . yellowish 0.9252 Specific gravity at 1 5 O C . , , . , . , , , . Melting point 46.5 43.5 Solidification p Viscosity at 50’ C . . . . . . . . . . . . . . . . . 5.4 Acid No. (calculated as oleic acid). .. 0 . 51 162.2 Saponification No 1.92 Unsaponifiable matter per cent). . . . Acetyl N o . , ...................... 1.2
.
............... Ash. .............................
95.8
0.037
2. Durotol (white) white 0.9257 46. 43.5 5.4 0.57 161. 2.1 1.2 4.2 95.8 0.36 0. 0.03
3. Hydrogenated Tram white 0.9268 48. 45.5 5.6 0.83 173.5 2.4 0.95 7.8 96.4 0.52 0. 0.05
T h e detection of traces of nickel b y t h e usual analytical methods is often difficult. Dimethylglyoxime, proposed b y Tchugaeff, is a reagent of great sensitiveness. I t s application has been investigated b y a number of chemists, a n d among these Bianchi a n d DiNola’ report t h a t t h e presence of copper a n d iron interferes with t h e test. T h e y worked with a n acid reagent a n d used t h e following procedure: T o t h e substance supposed t o contain nickel one or t w o drops of concentrated hydrochloric or nitric acid are added a n d t h e acid solution so obtained is placed i n a porcelain dish, or preferably on a strip of filter paper. A few drops of ammonia are added, or in case the strip of filter paper is used, ,this m a y simply be exposed t o t h e vapors of ammonia. T h e liquid is acidified with acetic acid a n d a drop of concentrated alcoholic solution of dimethylglyoxime is added. T h e presence of nickel is shown b y a red coloration which grows more pronounced in t h e course of time. This reaction is a very simple one a n d does n o t require a n y particular technical knowledge for carrying out. Fortin? has simplified this reaction a n d uses a n alkaline instead of a n acid reagent which apparently gives more satisfactory results t h a n t h e above procedure. Fortini mixes one-half g r a m of dimethylglyoxime, 5 cc. 98 per cent alcohol, a n d j cc. concentrated ammonium hydroxide in t h e order as given, yielding a clear, faintly yellowish liquid which in glass-stoppered bottles m a y be kept for a long t i m e unchanged. T h e test is carried o u t as follows : T h e sample t o be examined is freed from f a t by extraction with ether a n d t o t h e residue a dro? of t h e reagent is added. When nickel is present there will appear in a few seconds a rose colored flock caused b y reaction with t h e nickel oxide present on t h e surface of t h e metallic nickel. Of course, if nickel is present i n t h e form of a soap, t h e f a t should be extracted with, for example, aqueous hydrochloric acid i n t h e manner prescribed b y K n a p p i n t h e foregoing. I n order t o make t h e reaction even more sensitive, t h e residue m a y be heated f o r a f e w moments in a n oxidizing flame t o produce nickel oxide. T h e detection a n d determination of small quantities
I21
of nickel b y a-benzildioxime is described b y Atack’ as follows : An alcoholic solution of a-benzildioxime gives with nickel compounds a bulky red precipitate which is insoluble in water, alcohol, acetone, I O per cent acetic acid, a n d ammonia; t h e precipitate becomes reddish yellow on boiling. T h e reagent is much more sensitive t h a n dimethylglyoxime, showing I p a r t of nickel in 5 million of water, a n d t h e precipitate is readily filtered.2 Small quantities of nickel are determined as follows: I jo cc. of a h o t saturated alcoholic solution of t h e oxime are added for every 0.01 g r a m of nickel, t h e mixture is heated for a few minutes on t h e water-bath, filtered, t h e precipitate washed with h o t alcohol, a n d dried at I I O ~ - I I ZC ~ . ; i t has t h e formula C28H22N404Ni a n d contains 10.93 per cent Ni. Nickel m a y be separated from cobalt in ammoniacal solution. a-Benzildioxime is prepared b y boiling I O grams of benzil, dissolved in jo cc. of methyl alcohol, with + concentrated aqueous solution of 8 grams of hydroxylamine hydrochloride, for 6 hours, washing t h e precipitate with hot water a n d t h e n with a small q u a n t i t y of ethyl alcohol, i n which i t is only slightly soluble. It m a y be crystallized from acetone. T h e hydrogen value is proposed b y Fokin3 as a means of determining unsaturated organic compounds in a manner similar t o t h e iodine values of Hub1 a n d Wijs. T h e “hydrogen value” of a n organic compound is defined as t h e number of cubic centimeters of hydrogen ( a t o o a n d 760 m m . ) , which are absorbed b y I gram of t h e compound. For t h e test, a n a p p a r a t u s is devised consisting of a distillation flask (50-150 cc.) having a small beaker fused inside on t h e bottom, a n d connected b y means of t h e side-tube t o a gas burette a n d a gasometer containing hydrogen. I n t h e small beaker are placed a b o u t 0.1gram of catalytic platinum, moistened with ‘ / 2 cc. of water, a n d in t h e flask t h e substance t o be examined a n d 2 0 - 3 0 cc. of alcohol free from dissolved oxygen. Hydrogen is admitted a n d the flask is shaken b y a shaking machine until absorption is complete. T h e following hydrogen values were obtained b y Fokin, t h e figures in parentheses being either t h e hydrogen values corresponding with Wijs’ iodine value, or! where indicated, t h e theoretical hydrogen values. Elaidic acid, 78.6-81.4 (78.8);oleic acid, 86.2-87.2 (86.2);f a t t y acids from sunflower oil, 119.6-120.8(122.9); f a t t y acids from linseed oil, 164.9-166.3 (166.0); castor oil, 7.3.; (7 j.j); Croton oil, 260.9 (theoretical. 2 j8.4); undecoic acid, 11j.6 (114.1); erucic acid, 39.4 (6j.6). Colophony does not absorb hydrogen under t h e conditions of t h e test. T h e “hydrogen value” of course is not a determination as yet of use in t h e identification of hardened oils, b u t is noted here because of its incidental interest. T h e foregoing embraces most of t h e information available from published sources on t h e analytical side of hydrogenated or hardened oils a n d i t is hoped t h a t t h e very meagreness of t h e d a t a m a y serve as a stimclus ’Chem. Z f g . , 1913, 37, 7 7 3 . Compare Ibbotson; J . S. C. I.,1911, 1317. 3 J . R u s s . P h y s . Chem. S O L . ,40 (1908). 7 0 0 ; J . Chem. SOL. Abslr (19081, 11. 637. 2
1
Boll. C h i m . Farm., 1910, 5 1 7 . 1912, 1461.
* Chcm. 21g..
94
I22
T H E J O G R S A L O F I S D l - S T R I A L ALtTD E S G I S E E R I S G C H E M I S T R Y
for a b u n d a n t investigations tending t o clarify t h e subject a n d enabling fairly definite procedures t o be adopted for t h e qualitative a n d quantitative examination of these products. 92 GREENWOOD AVE.
T‘ol. 6 , A-0,
2
ro.cH P H 2 O H \CH,OH
0.CH,.CHOH.CH,OH OP-0.CHz. / CHOH.CHzOH
MONTCLAIR, N J.
:
\OH
/CHzoH
OP-0.
CH
I
\cH,o H L-OH 4. p diglycerophosphoric acid
THE CHEMISTRY AND PROPERTIES OF GLYCEROPHOSPVATES (GLYCERINOPHOSPHATES) B y GASTONDEBOIS
~
3.
CY
diglycerophosphoric acid
Received October 16, 1913
In a n article on “ Calcium Glycerophosphate,” which appeared in t w o numbers of t h e Joi4rqial d e Pharmacie et d e Chimie of M a y I a n d 16, 1913, t h e authors, E. FranGois a n d E. Boismenu, s t a r t their critical review of t h e literature on glycerophosphates b y pointing t o t h e great n u m b e r of publications on t h e subject. T h e y believe t h a t in spite of t h e comparatix-ely voluminous literature few of those interested i n this subject can draw exact conclusions from those publications as t o t h e n a t u r e or composition of synthetic glycerophosphates a n d of t h e products found on t h e market. I n t h e literature including t h e leading authoritative publications on organic chemistry we find such contradictory s t a t e m e n t s as t o make i t impossible for a n y one unfamiliar with t h e subject t o recognize which a r e correct. T h e writer having h a d some experience i n t h e m a n u facture of glycerophosphates, a n d having, therefore, s p e n t some time studying t h e chemistry of these products, deemed i t advisable t o collect t h e most imp o r t a n t known facts on t h e subject a n d t o endeavor t o d r a w conclusions b y adding his experience t o t h a t gathered from t h e research work of others, a n d also t o point o u t a few of t h e erroneous s t a t e m e n t s a n d inconsistencies found i n some publications. Before going into t h e details of t h e chemistry a n d properties of glycerophosphates, a n d t h e findings of t h e various chemists mho have developed this field, let us briefly examine w h a t compounds are theoretically possible as a result of t h e action of phosphoric acid o r i t s salts, on glycerine. B y t h e interaction of I molecule phosphoric acid with one molecule glycerine, t w o isomeric monoglycerophosphoric acids are possible.
Some authors claim diglycerophosphoric acids t o h a v e t h e following constitution:’ CH,OH
I
,O- CH,
/‘
OP--OH
0 ‘ 5.
CY
,0-CH
‘
/
CHOH
-H Z!( diglycerophosphoric acid
I
O p t - 0 -CH, \ ‘OH 6. p diglycerophosphoric acid
T h e diglycerophosphoric acids, whatever their constitution m a y be, can form only monobasic salts. T h e salts of these acids are readily partly saponified b y t h e action of alkali hydroxides yielding mainly monoglycerophosphates. Diglycerophosphoric acids are formed when phosphoric acid is mixed with glycerine, preferably a n excess of t h e latter, a n d t h e mixture heated t o above 1 1 0 ’ under reduced or atmospheric pressure. T h e formation of diglycerides a t temperatures above I 10’ was demons t r a t e d very conclusively b y Adrian a n d Trillat,2 b y Power a n d T ~ t i na,n~d also b y Car1-6.~ T h e question, which are t h e correct formulas for the a and diglycerophosphoric acids, formulas 3 a n d 4 or j a n d 6 is not settled yet. Adrian a n d Trillat analyzed diglycerophosphoric acid a n d obtained figures for C a n d H corresponding a b o u t with t h e a m o u n t contained in formulas 3 a n d 4. It is possible t h a t both are correct as i t is reasonable t o expect t h a t monoglycerophosphoric acid when heated could, by t h e elimination of m-ater. form diglycerophosphoric acid:
/OH PHZoH OP$OH ,O.C H /
/ O . C Hz CHO H . C HzO H OPLOH \OH I. CY monoglycerophosphoric acid
P monoglycerophosphoric acid
.
2.
These acids can form mono- a n d dibasic salts. T h e dibasic calcium salts of above acids are t h e main components of calcium glycerophosphate of t h e market. If one molecule phosphoric acid interacts with two molecules glycerine, again two isomeric diglycerophosphoric acids are possible :
/
/OH
OP’-O.CH.CH,OH
‘ \o.I
CH,
+ H,O or
/
/O-CH2 CHOH
OP/--OH
\
\O-(!H,
We now come t o t h e last class of esters formed 1
2 3 4
Card, C . r. de l ’ d c a d . d e s Sciences, 137, 1070-73, also 138, 47-49 J . Phar. el Ch., [ 6 ] 7, 226-30. Power and r u t i n , J. Chem. SOL.,87, 240-57. Card, C. Y. de 1’Acad. d e s Sciences. 137, 1070-73.
