Complete Recovery of Vitamin A from MolecularDistillation Residue of Whale-liver Oil

BYYOSHIMORI 0MOTE

When the whale-liver oil is treated with molecular distillation,
more than 100% of vitamin A (to be abbreviated A hereafter) can berecovered in a distilled concentrate, as the thermal decomposition ofkitol produces A during distillation. ·The residual oil has an absorption
maximum at 290 mµ and gives a bluish violet color with antimony
tricholride. The absorption maximum which is identical with that ofkitol indicates the presence of kitol, while the color reaction is considered due to the blue color by A and red by kitol. Now it· is probablethat the thoroughgoing molecular distillation can recover not only theremaining A in the residue, but also the newly produced A from kitol.
The presumption is discussed with several fundamental experiments
and the pratical thoroughgoing distillation, with the result of which
this paper is· concerned.

Analysis of Absorption Spectrum of Residue Oil.-Table I shows anexample of absorption spectrum of molecular distillation residue ofwhale-liver oil. For the sake ofTable I. Absorption Spectrumconvenience, Oser's correction i>of the Residue Oil
was directly applied to Table I,
wave length,
Absorption coefficient,though the method strictly must
E (1%, lcm.)(mµ)
be used upon the unsaponifiable
280
49.65
fraction. The corrected coefficient,
290
52.05
310
48.1
E (1 %, 1 cm, 325 mµ) was much
325
37.75
lower than that of the original.
328
35.1
The authors' so-called AK method,
330
33.55
334
29.95
which is grounded on the assumpTable II. Comparison of Corrections about the Absorption
Spectrum of Residue
MethodNon-correctedOser'sAKE (1%, lcm)
E (325) 37. 75
E (328) 35.1
E (325) 6.8
E (328) 22.5

tion that the absorption spectrum of sample is mainly due to A andkitol, was also applied (see Table II). Both corrected values showed

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YOSHIMORI 0MOTE

a considerable difference, the true A value probably being between
them, and their mean value of ea. 15 for E (328 mµ) was taken as thatof A. Kitol content was calculated with AK method to be nearly fivetimes as much weight as A.

Distillation Time and Recovery of A.-The residual oil was distilled
in a semi-micro molecular pot still at a constant temperature of 200°,
the relation between distillation temperature and A recovery being
studied (Table III). As Table III shows that one hour heating wasable to distil A, but not enough to decompose kitol, heating time wasextended (Table IV).
Table III. Distillation Time and Recovery of A
(in case of short time)
Time (min.)
0-2
2-5
5-10
10-15
15-20
20-25
25-55

A Unit*
17.9
17.9
11.2
8.97
3.58
3.58
7.16

Time, total (min.)
251015202555* Cod Liver Oil Unit, cf. Experiment 2.

Unit, total
17.9
35.8
47.0
56.0
59.6
63.2
70.4

Table IV. Distillation Time and Recovery of A(in case of long time)
Time (hr.)
0.0-0.5
0.5-1.0
1.0-1.5
1.5-2.0

A Unit
71.7
8.96
7.17
2.39

Time, total (hr.)
0.5
1.0
1.5
2.0

A Unit, total
71.7
80.7
87.9
90.3

By making distillation curves based on data from Table III and IV
one can recognize the discontinuous point near 10 minutes' heating,where A is almost recovered and kitol begins to decompose to form
new A. The recovery of A, however, was about 100% after 30 mins.,
and 130% after 2 hrs., so the decomposition rate of kitol seemed verysmall at a· temperature 200°..

Distillation Temperature and Recovery of A. - Using the same apparatus as above the recovery of A at discontinuously elevated temperature was measured (Table V).
As shown in Table V, the recovery of A was about 60 units at200°, about 220 units at 270°, so the difference of 160 units may beconsidered to represent newly produced A from kitol pyrolysis. ThisComplete Recovery of Vitamin A from Molecular Distillation Residue

189

Table V. Relation between Distillation Temperature
and Recovery of A
Temperatureoc*
200220250270Time (min.)
30304040* Cf. experiment 4

Recovered A
Time, total
Recovered(hrs.)
total
A**
0.5
57.8
57.8
133.9
76.1
1.0
205.5
71.6
1.67
216.3
2.33
10.8
** Cod Liver Oil Unit for the source oil.

corresponds to about 2. 7 times as much as first contained A. If it isassumed that kitol content in the sample was about five times as muchas A and one mole of kitol can produce two moles of N>, five times
as much A as first A must be newly obtained theoretically. On theother hand, 2.5 times of A must be produced under the assumption ofone mole A being obtainable from one mole kitol 3). Considering thedestructions of A during distillation the result of above experiments
seems accorded with theoretical value of 5 times, nevertheless it isclose to 2.5 times in case of neglecting the destruction of A.
Thoroughgoing Molecular Distillation in Falling-film Still.-Being
clarified fundamental conditions about the complete distillation in amolecular pot still, two hundred grams of the sample was distilled ina falling-film still. The' sample was somewhat different from thatused by the foregoing fundamental experiments, so that assays wereconducted again in detail. The result of the distillation was that about
two times as much as original A was obtained (Table VI).
Table VI. Recovery of A from Residual Oil with Complete
Molecular Distillation in Falling-film Still

Original
Fr. 1
Fr. 2
Residual

Temperature, Weight,Vitamin A Unit (U.S.P.)*
ocAKgOshima's
Oser'sWhole-oil
26,00015,800(200)
30,40031,200121,800
93,700185,000
190-20590
124,000
49,20041,20046,80050,000205-215
40
5,500
133
8,500
70
Recovery of Vitamin A
Whole-oilOser's
(100)
(100)
268
180
52
32.0
0.3
9.5

AKOshima's
(100)
(100)
Original
211
266
Fr. 1
37.8
30.8
Fr. 2
7.4
Residual* Conversion factor, Oshima's Cod Liver Oil Unit was multiplied by
380, others by 1900.

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YOSHIMORI 0MOTE

Further discussions may be described below. Contents of A andkitol in the original residue was calculated with AK method, A being
ea. 0.76% from (328 mµ)=l3.7, kitol ea. 1.5% from K (290 mµ)=l0.6.
Assuming that kitol changes into A completely, and one mole kitol
forms two moles A, the content of A must be about three times asmuch as that of original A, the result of the experiment corresponding
with the calculation. Furthermore, the calculation on this experiment
led to the conclusion that one mole kitol produced 1.69 moles A considering the distillate only, and 1.53 moles A considering both the distillate
and residue.
Experimental Part

1. Analysis of Absorption Spectrum Curve.-Oser's correction1) was
made through the following revised equation, employing data from
Table I.
f=7-2.625E (310/325)-4.375E (334/325)
Also AK method was adopted as stated in the previous paper, 2)A(328) =22.5 and K(290)=43.4 being obtained.
Distillation Time and Recovery of A (Short Time).-The semimicro molecular still was of great value,in which 279 mg. of the sample
was taken. The distillation was effected under the vacuum of 10- 3 to10- 4 mm. arid a constant oil bath temperature of 200°. As the distillate
was cooled, little or no A was destroyed. At first, after two minutes'
heating, the distillation was stopped and the condenser was taken out
to be washed in an aliquot of benzene, which, after suitable dilution
with chloroform was treated with Oshima's colorimetry to determine
the blue value. Cod liver oil unit was tentatively calculated using
279 mg as the weight of oil. Similarly the process was carried on as
follows (see Table II). Cod liver oil unit of the original sample wasfound to range 80 to 90, though the violet color prevented exact
colorimetry.
2.

3. Distillation Time and Recovery of A (Long Time).-The same
conditions as Experiment 2 · were adopted except for the range ofheating time extended (Table III). The final residual of this experiment gave a reddish color with antimony trichloride, while the originalresidual oil showed bluish violet.
4. Distillation Temperature and Recovery of A. - Also the same
apparatus was appreciated, but the temperature was raised step byComplete Recovery of Vitamin A from Molecular Distillation Residue

191

step (cf. Table V). In spite of its strong fluorescence, the yellow distillate at 270° had a low potency of A. And the gray black final
residue gave a reddish brown color with antimony trichloride.

5. Complete Distillation with Falling-film Still.-The sample was
the residual oil obtained from· the Antarctic whale-liver oil, distilled in
the molecular still to concentrate A in a distillate, about 30% of thetotal oil being distilled (The sample used in Experiment 1 to 4 wasabout the same as this). The still was falling-film cyclic type, thetemperature was of falling liquid (Table VI). The process of distillation was not so smooth because of occasional sudden bubbling on thedistilling surface.
6. Calculation of A Formation Ratio from Kitol.-Moie of A
formed from one mole of kitol is expressed as follows :2)
A mole--:-[ A(328 mµ) increased/K (290 mµ) decreased] x O. 786.
A (328) and K (290) were calculated by AK from the absorption spectrum
data of each fraction, the result of which already appeared in thepreceding explanation.
Grateful acknowledgment is expressed to Dr. S. Ishikawa for his
advice and encouragement during the course of this research.
Summary

Molecular distillation residue of whale-liver oil, containing vitamin
A and kitol of about 1% and 5% respectively, was distilled in a semimicro molecular pot still. At a constant temperature of 200°, about
100% of A was recovered through thirty minutes' heating, yet only
130% of A by two hours' heating; while, by raising the temperature
up to 270°, approximately 400% of A could be recovered.
Fqrthermore, the practical thoroughgoing distillation showed that
kitol in the residue was completely converted into A, the absorption
curve analysis proving that one mole kitol produced two moles A.
References
1) B.L. Oser, Anal. Chem., 21, 529 (1949).
2) S. Ishikawa, Y. Omote, M. Kijima, H. Okuda, Sci. Rep. Whale Res. Inst., Vol. 5,53 (1951).
3) F.B. Clough, H.M. Kascher, C.D. Robeson, J. G. Baxter, Science, 105, 436 (1947);
N.D. Ernbree, E-M· Shantz, J. Am.. Chem. Soc., 65, 910 (1943).