Mar. 15,1925 Physical and Chemical Properties of Xanthophyll 
579 
Table II .—Solubility of xanthophyll in 
absolute ethyl alcohol at 25° C. 
Experi¬ 
ment 
No. 
Dilution 
Time in 
water 
bath 
Trans- 
mit- 
tancy 
Xantho¬ 
phyll per 
liter 
1 
Times 
100 
Hours 
16 
0.0696 
Mgm. 
276 
100 
47 
. 0742 
271 
100 
64 
.0822 
258 
2 
100 
22 
.0846 
256 
100 
46 
.0952 
243 
100 
94 
.1020 
237 
3 
50 
42 
.0192 
206 
50 
56 
.0214 
199.5 
4 
50 
60 
.0215 
199 
Table III .—Solubility of xanthophyll 
in methyl alcohol at 25° C. 
Experi¬ 
ment 
No. 
Dilution 
Time in 
water 
bath 
Trans- 
mit- 
tancy 
Xantho¬ 
phyll per 
liter 
Times 
Hours 
Mgm. 
1 
200 
22 
0.4420 
166 
100 
70 
.2620 
138 
2 
50 
42 
.0754 
134 
50 
56 
.0740 
135 
3 
50 
60 
.0816 
129 
4 
50 
60 
.0649 
141.5 
Willstatter and Mieg (11) state that 
the; oxidation product of xanthophyll 
is very easily soluble in methyl alcohol. 
Tests made during the course of this 
investigation confirm this statement. 
They further state that the addition of 
ether to a solution of oxidized xantho¬ 
phyll in methyl alcohol will cause the 
oxidized xanthophyll to separate as a 
white powder. These statements as¬ 
sist materially in understanding the 
solubility of xanthophyll in the four 
solvents used as shown in the tables. 
The tables show that the alcohols would 
tend to exhibit too great a solubility 
when impure xanthophyll is used if 
the impurity is oxidized xanthophyll; 
and, on the other hand, the solubility 
in ether .would not be greatly affected, 
for oxidized xanthophyll is very diffi¬ 
cultly soluble in ether. Petroleum 
ether apparently behaves as does ether, 
for Table I does not show any great 
difference in solubility in the sample 
used in experiment 1 and experiment 2. 
The average of the determinations 
(Table IV) shows the solubility of xan¬ 
thophyll in ether to be 952 mgm. per 
liter. 
In Table V the solubility of xantho¬ 
phyll and carotin in these solvents is 
compared. 
Willstatter and Stoll (12) state 
that 1 gm. of xanthophyll dissolves in 
700 c. c. of boiling, or in 5 liters of cold, 
Table IV. — Solubility of xanthophyll 
in ether at 25° C. 
Experi¬ 
ment 
No. 
Dilution 
Time in 
water 
bath 
Trans- 
mit- 
tancy 
Xantho¬ 
phyll per 
liter 
1 
Times 
500 
Hours 
22 
0.151 
Mgm. 
975 
500 
46 
.161 
945 
500 
94 
.155 
965 
2 
500 
42 
.174 
910 
500 
56 
.156 
965 
Table V .—Solubility of xanthophyll 
and carotin 
i 
Solvent 
i Milligrams per 
i liter 
1 
Xantho¬ 
phyll 
Carotin 
Petroleum ether °_ 
9.5 
626.0 
Absolute alcohol (ethyl)_ 
201.5 
15.5 
Absolute alcohol (methyl) _ 
134.9 
( b ) 
1,005.0 
Pure ether (anhydrous).. 
952.0 
° The boiling point of the petroleum ether used 
was 50 to 55° C. for xanthophyll and 35 to 50° for 
carotin. 
b Nearly insoluble. 
methyl alcohol; in ethyl alcohol it 
dissolves more easily; 1 gm. dissolves 
in 300 c. c. of boiling ether and it is 
so insoluble in petroleum ether that 
the solvent is not even colored. 
From Table V it is seen that carotin 
and xanthophyll have nearly the same 
solubility in pure ether. At 25° C. 
xanthophyll is 13 times as soluble as 
carotin in absolute ethyl alcohol. 
The greatest difference in solubility 
of the pigments in the same solvent is 
observed in petroleum ether, which 
dissolves 60.5 times as much carotin 
as it does xanthophyll. 
STABILITY 
Four solvents were chosen in which 
to test the keeping qualities of xantho¬ 
phyll. All of these are or may be used 
in the isolation of the pigment from 
plant materials. The solvents used 
were: Absolute ethyl alcohol, pure 
ether, U. S. P. ether as it comes in the 
container, and redistilled petroleum 
ether (B. P. 50° to 55° C.). 
A solution of xanthophyll (0.210 
gm. per liter) was made in freshly dis¬ 
tilled anhydrous ether, and of this 
10 c. c. portions (2.1 mgm.) were 
carefully evaporated to dryness in 
vacuum at room temperature, the 
solvents were added immediately and 
