Patented Mar. 7, 1944
2,343,644
UNITED: STATES ‘PATENT OFFICE ,
12,343,044‘
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rnocnno'nn son ‘THE ‘nonunion or
SUBSTANCES CONTAINING comuos'mn
DOUBLE nouns
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john D. Cawlewltocheoter, N. Y.,' assignor to Dis
tillation Products, Inc., Rochester, N. 1., a cor
poration of Delaware
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No Drawing. Applicntlon vJuly 30,1941,
Serial No. 40;,658
,
'9 Claims. (01. zoo-405.6)
and disethylene "glycol monoethyl ether are al
This application relates to an improved method
for preparing substances containing conjugated
double bonds and in particular to the preparation
of fatty acid compounds containing coniugated
double bonds.
,
’
ready available commercially and are quite satis
factory solvents.‘ Glycol monomethyl ether gives
a higher conversion in a shorter time than any
solvent of this ‘group, and is much superior to any
'
solvent which‘ has heretofore been utilized in this
It has heretofore been known to convert un
conjugated polyene substances into conjugated
reaction.
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A convenient method of determining the de
polyene substances by heating vveith an excess
of s. basic substance in the presence of‘ various
gree of conjugation, and which may be used to
test the course of the reaction, is to treat the me
See Burr Patent 2,242,230, May 20, 10 ‘ terial
to be tested with a chloroform or similar
. 1941. In a. publication by this author (see J. A.
solvent
solution of a chloride‘ of a polyvalent
C. A. 61 (1939) page 3292) it was shown that
metal, as antimony trichloride. This‘msterial
ethylene glycol was the most satisfactory solvent
gives a reaction product with conjugated fatty '‘
for this process, giving a completed conversion in‘
acids having a blue or purple color. This enables
from one-half to two hours as compared to six
a colorometric method of analysis of considerable
to twenty-four hours for butanol.
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solvents.
accuracy. The reaction product is observed in an
This invention has for its object to provide an
improved method for carrying out the foregoing
Evelyn photoelectric colorimeter with 520 mu
?lten The‘ preparation showing the highest ex
‘ procedure. Another object is to provide a. method
whereby the time required for the conversion of 20 tinction co-ef?cient can be assumed to contain
1000 “units of conjugation" per gram and the
unconjugated substances into a conjugated sys
subsequent test material can be‘ referred to this
tem is materially reduced. A further object is to
as a standard. I The following units of conjuga
provide procedure whereby the conversion into a
tion per gram were found upon heating uncon
conjugated system is substantially more com
plete than has been heretofore possible with 25 jugated acids with'alkali and the following sol- .
vents, ‘all other variables being held constant:
known conversion methods. A still further ob
Ject is to provide improved solvents for carrying
out the conjugation conversion;
will appear hereinafter.
Other objects 7
-
8mm '
Units P8’ mm
These and other objects are accomplished in 5"
"
accordance with my invention which includes
'I1;§'(1)‘;§g°e----
treating the substance which is $0 be converted
into s. conjugated system and which contains two
Butyleth-er:
§g§§rh°11ne<
or more uneonjugsted double» bonds .(i. e., e; poly-
None_'_:.___
------ --
2g
.
64 soaps lhs'cluble, polymerization
10g , during the reaction
‘
III: on. 100
'
"
ens substence)
with an excess
of an alkaline sub- 35 glycol
mmmethyl
“um-11°00
.
.
iethylene
glycol ________
._
515
stnnce while in the presence of a solvent comprisDiethylene glycol mono~
ing an ether or" s polyhydric alcohol which con-
EtG?EiQn‘ZtQg-CB-lZIIZI
‘{gg
tcins s free hydroxyl group.
‘in the following description I have given sev-
Dietbylene glycol mono“meme” ------------ "
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34“
ersl of the preferred embodiments of my inven- to
The extinction coe?cient iii-ultra’ violet light"
tion. ‘However, these are set forth for the pur
is also a satisfactory method i’ordete'rmlnin‘g the
pose of illustration and not in limitation thereof.
degree of conjugation produced; The conjugated
Examples of improved solvents are alkoxy, aryl
products have a higher extinction coe?cient then ,
or arelirony-ethenois such as glycol monomethyl
ether, glycol ‘monobenzyi ether, and glycol mono
ethyl ether; (2~(alhoxy-' aralkoxy-ethoxy) eth
(iii the . unconjugated’ materielsb '1 The following
' values-obtained from the literature, can be’u'sed '
cnols) such as diethylene glycol monoethyl ether, -
as a basis of comparison and as an indication of
diethylene glycol monobutyl ether, and diethyl—
ene glycol monobenzyl ether; similar derivatives
the. degree ‘of conjugation: 2 conjugated double,’ ‘
of other glycols, such as propylene glycol mono 50
methyl ether, polyethylene glycols, such as di=
,
E
propylene glycol ethyl ether; glycerylmonoalkyl
or cry] or aralkyl ethers or glyceryl a, gamma, di
(2so-msi.)=1200
i ‘ V
3 conjugated double buds E <27o>='200o;_ 4; con-‘5 L
sikyl or aryl or aralkyl ethers. Glycol monometh
yl ether, glycol monobutyl ether, dbethylene glycol
bonds;
v
iugated double bonds E (302) _-_'2000 and 5 double
2
2,343,644
bonds E (328)=1700. The following table illus
trates the extinction coemcient
all conditions being the same, other
the
amount of solvent, it will be found that lessening
the
action.
amount
However,
of solvent
this brings
cannotabout
be carried
a quicker
too
E 17
1 gm.
5 because there is danger of the reaction proceed»
at the wave lengths indicated of the conjugated
ing with polymerization or other destructions.
reaction products produced by treatment with
If the amount of alkali is increased, the amount
alkali in the presence of various solvents:
Solvent
E (230)
E (270)
E (302)
E (328)
481
438
400
443
E (348)
10 1 volume of polyene ‘substance will be. found to
be satisfactory. However, larger or smaller pro
G l y c 01 m o n 0
methyl ether.__..
of solvent should be increased for best results.
For most purposes 1/2 to 10 volumes of solvent to
400
Ethylene gl col--__ ....... _.
3%
215
134
99
Propylene ycol...
386
25
172
151
portions can be used and are to be understood as
being within the scope of my invention.
The treatment is continued until the required
15 degree of conjugation has been obtained. The
From the foregoing it is seen that the new sol
degree of conjugation will increase with time and
vents described herein result in a very complete
491
temperature. Heating at re?ux temperature for
and rapid conversion into conjugated systems
a period of two hours results in substantially
compared with solvents heretofore known and
complete
conjugation when methyl cellosolve is
used for this purpose. In each of the foregoing 20
used. The reflux temperature will of course vary
determinations the unsaturated material treated
with each solvent. As a general rule tempera~
was the highly unsaturated acids of. Sardine oil.
tures of 60° to 200° are to be preferred, while
temperatures of about 20° to 300° C. can be used.
After the reaction has proceeded to the desired
or alcoholates thereof; also the alkali should be 25 stage
the conjugated product is recovered. Con
used in excess, i. e., in excess of the stoichio
ventional
methods of recovery can be used; for
metric amount, such as that required to neu
instance, when fatty acid derivatives are treated
tralize the free fatty acids or to saponify the free
the addition of mineral acid is all that is neces
fatty acid derivatives such as esters thereof
when esters or the like are treated. I prefer to 30 sary. The soaps may, of course, be recovered as
such and utilized where soaps containing con
use amounts of alkaline substance greatly in
jugated double bonds are needed.
excess, such as amounts of alkali equalling one
The conjugated products are useful for making
half or the same as the weight of the fatty acids.
resins, drying oils, inks and the like. Free fatty
When the amount of alkali is used which is one
half the weight of the fatty acids, it means that 35 acids are useful for converting into resins, drying
oils or the like, or they may he esterified with
approximately three and one-half times the
glycerine, etc., and used to form high quality
amount of alkali necessary to neutralize the free
paints or varnishes.
fatty acids (if they are the substance treated) is
The following illustrates the effect of propor~
being used. However, it is to be understood that
tions
of alkali and solvent:
40
It is preferable to use a strong alkali such as
sodium, potassium, cesium, or lithium hydroxide
this constitutes my preferred proportions of alkali
and that amounts greatly in excess or greatly
less than those specifically mentioned can be uti
lized with satisfactory results.
.The invention is preferably applied to free fatty
Example
Three 5-gram portions of highly unsaturated
sardine oil fatty acids were heated at re?u tem~
perature, one sample containing an equal weight
acids or their esters and preferably to free fatty 45 of potassium hydroxide and four volumes of
acids which have been purified so that substan~
glycol monomethyl ether, the second one-half
tially all contain at least two double bonds. How
the weight of alkali and two volumes of glycol
ever, the invention is applicable to the treatment
monomethyl ether and the third one half the
of mixed or impure unconjugated polyene sub 50 weight of alkali and four volumes of glycol mono
stances. For instance, the invention can be used
methyl ether. The heating was continued for
to convert mixed fatty acids such as are obtained
by saponiiication of an oil such as a fish oil (sar
dine, manhaden, cod liver, etc.) or a vegetable
oil such as linseed or cottonseed oil. In such a
55
case fatty acids containing two~ or more double
bonds are converted into conjugated systems
while saturated acids or those‘ containing only
two hours. The following extinction coeilicients
were obtained:
I
‘13g? Ease) some new) seas) Ems)
5
481
438
400
440
400
2.5
635
612
336
185
198
one double bond are largely unaffected. It will
2.5
600
74.2
305 ................ __
be realized that this procedure with mixed acids
is more expensive because the acids must be neu 60
To obtain a commercial rate of conversion it
tralized with alkali even though they are un
is essential that the reaction mixture be‘ sub
affected by the reaction. Vegetable or animal
oils or waxes maybe directly treated. Methyl
esters of polyene fatty acids, others, fatty acid
halides, nitriies, amides, alcohols and soaps may
be similarly treated.
stantially anhydrous. Of course, water may be
formed during the reaction so that the reaction
mixture is not completely anhydrous. However.
accumulation of water should preferably be
avoided by conducting the reaction at a. tempera~
The amount of solvent can vary to a consider
mm at which water is distilled off and prevented
able degree. My experiments indicate that for
from returning to the reaction mixture.
optimum results four volumes of solvent to one 70
No special precautions need be taken to avoid
of polvene substance should be used when the
oxidation during the reaction. As ordinarily
weights of polyene substance and alkali are equal
carried out in a still little or no contact with
and that two volumes of solvent to one of polyene
air takes place. If desired the treatment can
substance should be used when the weight of
alkali is half that of the polyene substance. With’
be carried out in the presence of an inert gas.
condition of the polyhydi'ic alcohol~ether
3
‘ assaeu
solvent in the reaction mixture is not known.
It is possible that reaction products between the
alkali and the solvent such as alcoholates are
formed, and I include such products within the
meaning of the term “ether of a polyhydric al
which contains a free hydroxyl group,_in the
presence of an excess of strong‘ alkali under sub
stantially anhydrous conditions and continuing
the heating until conjugation of double bonds in
the polyene substance takes place.
5. The process of claim a in which the sol
vent'used is equal to two to fourtirnes the vol
ume of the fatty acid.
6. The process of causing conjugation of the
sentially of the unsaturated C20 and C22 acids 10 double bonds in a fatty acid compound which
contains at least two unconjugated double bonds,
contained therein.
cohol."
.
The highly unsaturated sardine oil fatty acids
mentioned herein were obtained by fractionat
ing the fatty acids of sardine oil and consist es
double bonds in a fatty polyene substance con
which process comprises heating the fatty acid
compound in the- presence of a member of the
group consisting of glycol monomethyl ether.
which contains a free hydroxyl group, under sub
monobenzyl ether, in the presence of an excess
double bonds in a fatty polyene substance con
7. The process of claim 6 in which about two
What I claim is: -
l. The process of causing conjugation of the
taining unconjugated double bonds, which proc 15 glycol monoethyl ether, glycol monobenzyl
ether, glycol monobutyl ether, diethylene. glycol,
ess comprises treating the polyene substance
diethylene glycol monoethyl ether, diethylene
with an excess of a basic substance while in the
glycol monobutyl ether, and diethylene glycol
presence of an ether of a polyhydric alcohol
stantially anhydrous conditions and continuing 20 of strong alkali under substantially anhydrous
conditons and continuing the heating until con
the treatment until conjugation of double- bonds
iugation of double bonds in the polyene sub
in the polyene substance takes place.
stance takes place.
2. The process of causing conjugation of the
taining unconjugated double bonds, which proc 25 to four volumes of' solvent to one of fatty acid
compound and about 1/2 to one weight or alkali
ess comprises heating the polyene substance in
for each weight of fatty acid compound is used. ‘
the presence of an ether of a polyhydric alcohol
which contains a free hydroxyl group, in the
presence of an excess of strong alkali under sub
stantivally anhydrous conditions and continuing
the heating‘ until conjugation of double bonds
in the polyene substance takes place.
3. The process of causing conjugation of the
8. The process of causing conjugation of the
double bonds in a fatty acid compound which
contains at least two unconjugated double bonds,
which comprises heating the fatty acid com
poundinthc presence 01'- glycol monomethyl ether,
in the presence of a substantial excess of strong
alkali under substantially anhydrous-conditions
contains at least two unconjugated double bonds, 35 and continuing the heating until conjugation of
double‘ bonds in the polyene substance takes
which process comprises heating the fatty acid
double bonds in a fatty acid compound which
compound in the presence of an ether of a poly
hydric alcohoL-which contains a free hydroxyl
group, in the presence of an excess of astrong
place.
place.
which contains a free hydroxyl group, in the
presence of strong‘ alkali under substantially an
hydrous conditlons and continuing the heating.
.
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9. The process of causing‘ conjugation of the
double bonds in a soap 0! a fatty acid which con
‘alkali under substantially anhydrous conditions 40 tains at least’ two unconJugated double bonds
which comprises heating the fatty acid soap in
and continuing the heating until conjugation of
the presence of an ether of a‘polyhydric alcohol
double bonds in the polyene substance takes
4. The process of causing conjugation of the
double bonds in a fatty acid which contains "at
least two unconjugated double bonds, which
process comprises heating the fatty acid in the
presence of an ether of a polyhydric alcohol‘
untilconiugation of double bonds in the polyene
substance takes place.
JOHN D. CAWLEY.