Jan.,
1920
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 EE R I N G C H E M I S TR Y
.........
0.8997 Specific gravity (15' C . ) . . . . . . . . . . . . . . . . . . . 91.3 Acid value.. ..................... Saponification value. . . . . . . . . . . . . . . . . . . . . . 107.0 177.6 Iodine value (Wijs). 1.4769 Refractive index (20' C . ) . . . . . . . . . . . . . . . . . . . 33.00 per cent Unsaponifiable matter.
OCCURRENCE OF SQUALENE IN THE EGG OIL FROM SHARK By Mitsumaru Tsujimoto IMPERIAL INDUSTRIAL LABORATORY, YETCHIU-SHIMA, TOKYO, JAPAN Received May 14, 1919
A female specimen of t h e shark named Kinbei-zam6, Lepidorhinus k i n b e i (Tanaka), which was used for t h e examination of liver oil, contained twelve eggs. The eggs were soft and had a light orange-yellow color. They were of large ellipsoidal forms, with longer diameters of about 7 cm., and weighed on an average of 140 g. Nine eggs which had a total weight of 1 2 6 0 g. were crushed t o a paste and heated with an excess of alcoholic potash, then t h e soap decomposed with hydrochloric acid and the f a t t y matter taken u p with ether. On evaporating off t h e ether from t h e extract, 218 g., 17.3 per cent of t h e f a t t y matter, were obtained. It was a light brown-colored substance and mainly solidified at the ordinary temperatures. The numerical properties of t h e substance were as follows :
73
.............. ......... ........... .........
On passing dry HC1 into t h e well-cooled ethereal solution of this substance, about 2 0 per cent of a white crystalline precipitate was obtained. On recrystallizing i t from acetone it sintered a t about 110' C. and melted t o a clear liquid a t 123'-124O C. 0.2470 substance gave 0.3374 AgCl (Carius method) C1 = 33.77 per cent CsoHso.6HCl requires 33.82 per cent C1
The substance has therefore been confirmed t o be squalene hexahydrochloride. As t h e eggs were separated very carefully from t h e body of t h e shark, there is no doubt as t o t h e absence of t h e liver oil in t h e egg oil. Subsequently squalene has been directly extracted from t h e dried eggs with et%er. The egg oil from frill-shark, Chlamydoselachus anguineus (Garman), has also been found t o contain squalene.
LABORATORY AND PLANT CONSTANT TEMPERATURE STILL HEAD FOR LIGHT OIL FRACTIONATION1 By Frederick M. Washburn BUREAUOF STANDARDS, WASHINGTON, D. e. Received May 22, 1919 GENERAL CONSIDERATIONS
Because of t h e greatly increased production of cokeoven light oil, a n d t h e growing importance of the benzol industry, i t was felt t h a t a more accurate method of analysis for light oils was needed, as there is frequently a great discrepancy between t h e results of analysis of t h e same light oil, using different methods, and between t h e results obtained by different analysts, using t h e same method. This paper represents t h e results of a brief search for an improved method for t h e determination of benzene, toluene, and solvent naphtha in coke-oven or coal-tar light oil. After the light oil has been passed through t h e usual treatment for t h e determination of t h e percentage of wash oil present and t h e determination of t h e percentage of loss on washing with concentrated sulfuric acid, i t is practically a mixture of benzene, toluene, t h e three isomeric xylenes, and higher aromatic hydrocarbons, together with t h e small amounts of paraffins usually present. The xylenes and t h e higher hydrocarbons boiling between 1 3 5 O and 160' C. are classed as solvent naphtha, so t h a t t h e problem resolves itself into a separation of a mixture of benzene, toluene, and solvent naphtha. Fractional distillation furnishes t h e easiest means of accomplishing this. There are three main types of methods generally in use for t h e fractional distillation of light oil. ' I n t h e first of these, t h e light oil is distilled through a fractionating column and separated into two fractions, one a mixture of benzene and toluene, and t h e other 1
Published by permission of the Director of the Bureau of Standards.
a mixture of toluene and xylene. A portion of each of t h e two fractions obtained is subjected t o distillation in a side-neck flask, and t h e percentages of benzene and toluene and of toluene and xylene are read off from t h e curves or tables giving t h e relation between t h e composition of t h e fraction distilled and t h e temperature of distillation. The method of Hugh W. James* is an example of this type. This method is open t o objection on account of t h e serious errors introduced b y t h e estimation of t h e percentage composition from t h e boiling-point curves or tables, since small amounts of impurities materially influence t h e boiling points of t h e fractions. I n t h e second type of method, distillation is made through an efficient fractionating column, a n d t h e receiver is changed at 9 5 O C. and at 1 2 5 ' C. The fraction under 95' C. is considered as benzene, t h e fraction 95 O t o I 25 ' C. as toluene, and t h e residue as solvent naphtha. The methpd of Gustav Egloff2 is a n example of this type. This method is more logical t h a n t h e first, since it aims a t a more complete separation of t h e mixture, but i t gives fractions which are not pure. The first fraction consists of a mixture of benzene and toluene; t h e second of benzene, toluene, and xylene; and t h e residue of toluene and xylene. The results obtained depend upon t h e assumption t h a t there is t h e same amount of toluene in t h e benzene fraction as there is benzene in t h e toluene fraction, and, similarly, as much xylene in t h e toluene fraction as there is toluene in t h e residue, in which case t h e errors introduced b y assuming t h e fractions t o be pure would neutralize each other. The objection t o this method is t h a t this relation does not usually exist, since t h e amount of toluene distilling below 95' C., t h e amount of benzene 1 2
J . Soc. Chem. I n d , 35 (1916), 236. Met. & Chem. Eng., 16 (1917), 259.
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
74
distilling above 95' C., and t h e amount of xylene distilling below 1 2 5 ' C. vary with t h e rate of distillation, efficiency of t h e column, composition of the oil, etc. I n t h e third t y p e of method, t h e light oil is separated into t h e largest possible fractions which distill respectively below 81.0' C. (for benzene), and from 109.0" t o 111.5' C. (for toluene). The intermediate fractions (81.0' t o 10g.o" C. and 111.5'to 137.0' C.) are then subjected t o distillation in a side-neck flask. The percentage composition of t h e intermediates is then read off from previously constructed curves, similar t o those in Figs. 3 and 4. The amounts of benzene, toluene, and xylene obtained from these intermediates are added t o t h e benzene, toluene, and solvent naphtha fractions, respectively, t o give t h e total percentages. The method of Dyke Wilson and I v a n Roberts' is an example of this type. This method is t h e most logical of t h e three, since t h e percentage composition of t h e intermediates is actually determined, giving less probability of error t h a n if t h e percentages were taken as some arbitrary amount. Furthermore, t h e error introduced by estimating the percentage composition by boiling point curves is comparatively small since it is applied t o small volumes.
AGITATOR
-T RECEIVER I
t
a
BURNER) FIG. 1-CONSTANTTEMPERATURE STILL HEAD
The fractionating apparatus used b y Wilson and Roberts consists of a 40 in. Hempel column, filled for 36 in. of its length with glass beads; above this is a vertical reflux condenser, the purpose of which is t o condense out t h e higher boiling constituents, and allow only t h e lower boiling constituents t o pass. The objection t o this form 0-f apparatus lies in t h e difficulty of control of t h e temperature of t h e reflux condenser, or dephlegmator. This temperature is regulated by t h e flow of liquid through t h e jacket of t h e condenser. Near t h e end of a fraction t h e variation of 0.2' C. in t h e temperature will mean t h e difference between completely condensing t h e 'vapors and allowing t h e 1
Gas Recovd. March 1916, p. 210.
Vol.
12,
No.
I
lower boiling constituent t o pass. For this reason it is practically impossible t o use the dephlegmator efficiently, as t h e temperature is extremely difficult t o control with any degree of accuracy. CONSTANT TEMPERATURE
STILL
HEAD APPARATUS
DESCRIPTION-The constant temperature still head is merely an improvement on t h e dephlegmator used in t h e Wilson a n d Roberts still. With its use i t is possible t o control absolutely the vapor temperature, thus making it possible t o condense out practically t h e last traces of constituents having a higher boiling point t h a n t h e fraction desired. I t is not a new idea, b u t was first worked out b y Frederick A. Brown.' The fractionating apparatus used in the experiments described in this paper, consisted of two parts, a Hempel column and t h e constant temperature still head. This latter consisted of a spiral of iron pipe immersed in a bath of oil. The temperature of t h e oil bath was controlled b y means of a thermostat, t h e bath being heated electrically, and stirred by a motor-driven agitator. The pipe spiral was made from a 1 2 ft. length of 3 / 8 in. wrought iron pipe bent cold around a mandrel of 5 in. diameter, giving a coil of about 6 in. diameter and 3 / 4 in. between t h e turns. A piece of copper t u b ing in. inside diameter) was soldered t o t h e coil as shown, t o act as the outlet t o t h e condenser. The Hempel column was made of glass, ~ l / g in. inside diameter, and so formed t h a t a thermometer could be inserted in t h e top. A metal column would be better, because there is danger from fire in case of breakage of t h e glass column. A 1500 cc. pyrex glass flask was used, b u t here again metal would be more suitable, for t h e same reason. The flask was heated by means of a Rose burner with a hemispherical top covered with an asbestos covered gauze. Three high precision thermometers (70" t o 200' C.) were used, one at t h e top of t h e Hempel column, one a t t h e top of t h e spiral, a n d one immersed in t h e oil b a t h (this last not shown in t h e figure). O P E R A T I N G DIRECTIONS-The bath was brought U p t o t h e required temperature b y means of a coil of resistance wire immersed in t h e bath, and was maintained a t t h a t temperature b y means of four 50-watt tubular carbon lamps. A mercury thermoregulator of t h e usual type, used with a relay, controlled t h e temperature of t h e bath t o 0.2' C. A 1000 cc. sample, measured a t 15.5' C., was used. The temperature of t h e b a t h was brought rapidly up t o 7 5 ' C. b y means of t h e heating coil, and then slowly up t o t h e temperature necessary t o allow t h e vapors t o pass through t h e coil when t h e liquid in t h e flask was boiling briskly. The temperature of t h e oil b a t h was then controlled b y regulation of t h e thermostat so t h a t 3 t o 4 drops per sec. fell from t h e end of t h e condenser. This temperature was about 0.1' C. below t h e vapor temperature a t t h e top of t h e still head, as may be seen from t h e curve given in Fig. 2. Toward t h e end of t h e benzene fraction it was necessary t o raise t h e temperature of t h e bath t o allow t h e vapors 1
Trans. Chem. Soc., 37 (ISSO), 49.
Jan., 1920
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
D%S
135 130 125
{KEY
F
TEMPERATURE AT TOP OF STILLHEAD ------ TEMPERATURE AT T O P OF HEMF'EL COLUMN
previously constructed curves (Figs. 3 and 4). T h e amounts of benzene and toluene obtained from t h e intermediate fractions were added t o t h e amounts obtained in t h e benzene and toluene fractions t o give the percentage of benzene and toluene, and the amount of xylene obtained from t h e toluene-xylene intermediate fraction added t o t h e residue t o give t h e percentage of solvent naphtha. The distillation loss was determined b y subtracting t h e total amount of distillate plus the residue from t h e volume taken for distillation. All volume measurements were made a t a temperature of I j . 5 O C. R E S U L T S OBTAIsED-Table 1 gives t h e results Of fractionating mixtures made up of known amounts of pure benzene, toluene, and xylene, and shows the high degree of accuracy obtainable. It also Shows t h a t t h e apparatus works equally well with varied percentages of benzene, toluene, and xylene, even though one of t h e components may be present in a comparatively small amount. 'N OF MIXTURES OF KNOU TABLE I--RESULTSOF DISTILLATIOH POSITION
Benz ene Present Found Per Per cent cent 80.00 80.05 70.00 70.12 67.50 67.52 57.50 57.59 55.00 55.07 40.18 40.00 30.00 29.92 20.21 20.00 10.00 10.47
Distillation NO.
I
I1 I11 IV
V VI VI1
VI11 IX
FIG. 2-TYPICAL DISTILLATION CURVES
t o pass through. This was done gradually, keeping t h e vapor temperature a t t h e top of t h e still head under 81 ' C. The rate of distillation gradually slowed down t o about I drop per IO sec., when t h e temperature of 81' C. was reached. The receiver was then changed and t h e temperature of t h e b a t h gradually raised, keeping t h e rate of distillation under I drop per sec. until a temperature of 110.0' C. was reached. The receiver was then changed, and t h e temperature of the oil b a t h was held by t h e thermoregulator t o such a temperature t h a t t h e rate of distillation was about z drops per sec., and the vapor temperature was under 111.5' C. Near t h e end of the toluene fraction it was necessary t o raise t h e temperature of t h e bath, as was done in the benzene fraction, until t h e temperature of 1 I I . j ' C. was reached. The receiver was then changed and t h e temperature of t h e oil bath gradually raised, keeping a rate of distillation of under I drop per sec., until t h e temperature of 137.0 C. was reached. The distillation was then stopped and t h e residue allowed t o cool. Then t h e residue was drained carefully into a graduate and measured. The intermediate fractions were distilled in a standard boiling-point apparatus,* except t h a t a '50 cc. pyrex flask was used in place of t h e larger flask, and t h e rate of distillation kept at I drop per sec. A 60' t o 140' C. thermometer, graduated in o.z', was used. The temperature a t which exactly one-half of t h e liquid passed over was noted, and t h e percentage of benzene and toluene, and of toluene and xylene read off from THISJOURNAL, 10 (1918), 1006.
Xylene Toluene Present Found Present Found Per Per Per Per cent cent cent cent 10.00 9.93 10.00 9.99 10.00 9.84 20.00 19.81 15.00 14.80 17.50 17.22 12.50 12.47 30.00 29.87 20.00 19.85 25.00 24.72 15.00 14.69 45.00 45.02 15.00 14.40 55.00 55.66 12.50 12.04 67.50 67.65 15.00 14.09 75.00 75.16
COX-
Distillation
Loss
Per cent 0.03 0.23 0.46 0.05 0.36 0.11 0.02 0.10 0.28
OBTAINED WITH THE CONSTANT
1 1 0
TEMPERATURE STILLHEAD
1
75
108
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mz
IO6
k& 0
Ir,
104
IY - IO2
Qk
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