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Патент USA US2411536

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" Patented Nov. 26,
- 2,4115%
‘UNITED STATES PATENT orrics
METHOD FOR PRODUCING ALKYL ESTER
or means FATTY ACIDS
, y '
Frederick H. Gayer and Charles E. Fawkes, Chi
cage, lll., assignors to Continental Research
Corporation, Chicago Heights, Ill., a corpora- v
tion of Illinois
No Drawing. Application January 21, 1942, x
Serial No. 427,536
14 Claims. (01. zed-97.5)
1 ,
tion could be'eifected without the use of a'icata
This invention relates to an improved method .
for producing alkyl esters of higher fatty acids,
and particularly to the esteri?cation'of fatty
acids tin, mixtures thereof with resin acids, and
lyst, would be of great practical value. The pres
ent application discloses such a process.
.
is a continuation-impart of our copending- v‘ap
~
plication Serial No. 284,915, filed, July 17, 1939.
Our improved method is especially useful as a
preliminary step in processes for the separation " ,
of the constituents of organic mixtures contain‘
ing both fatty and resin acids,'as for example 10
'
'
' Brie?y our process comprises subjecting a"mix
ture of tall oil and a monohydrlc aliphaticvalco
hol, in the absence of a catalyst, to treatment
under pressure by heating to a suitable tempera
ture and discontinuing such treatment at a point
where the fatty acids are completely esteri?ed and ,
at. which point esteri?cation of the resin acids
has not yet begun. The important'elements en
tering into our process are: The kind of alcohol
applications? Serial Nos: 284,917, new Patent No Y used, the quantity of alcohofused, the time re»
quired for the treatment and the'temperature at
2,288,946, and‘ 284,918, new Patent No. 2,288,947,
‘
'
both filed July 1'7, 1939. These processes com 15 which the treatment is e?ected.
The alcohols we use in our process are mem
prise esteriflcation of the fatty acids, transform
tall oil.
Such processes are set forth in our Pat-v . ._
ent No. 2,166,812 and. in the following copending
"ing ‘the resin acids into resinates,‘ and separating
' bers of the monohydric aliphatic~ alcohol series
and include methyl, ethyl, propyl, butyl, and
the esters from-the resinates. The ‘present ap
plication discloses a method whereby the fatty
amyl alcohols and the isomers of the last three . ‘
acids can be‘ quantitatively esteri?ed in such av 20
.way' that the esteri?cation reaction is sharply
restricted'to the fatty acids and does not atlall '
extend to the resin acids.
Esteri?cation ofithe'fatty acids is usually ac-‘
complished by reacting the mixture with an ex
cess of an alcohol irrthe presence of a catalyst.
Due to the greater reactivity of thelfatty acids
esteri?cation is restricted to the fatty acids if the
catalyst concentration 2.is kept within certain
limits. This forms the basis for present methods
for the quantitative determination of‘ fatty and
resin acids. The esteri?cation reaction, however,
alcohols and which are hereinafter, and partic
ularly in the claims termed, ‘fl'ow molecular”
weight monohydric aliphatic alcohols. The choice
of the alcohol depends on the ,type of fatty acid
ester desired as one of the end products. If our
object is only the separation vof the fatty and
resin ‘acid’ portion of tall oil regardless of the
type of esters obtained, we prefer, for simple rea
sons, the use of methyl alcohol.
'
'
The quantity of alcohol we use is always in
30 excess of the calculated quantity required for the
esterification of the fatty acids. In calculating
the theoretically required quantity of alcohol, we
ceases to be selective towardv the fatty acids and ’_ assume the ?gure of 282 for the average molec
will be extended to the resin- acids if the catalyst : ular weight of the fatty acids contained in tall
concentration is materially increased (Patent No. 85 oil. " For example, 100 parts by weight of a tall
oil containing 52% fatty acids will require 5.9
1,829,481).
parts of methyl alcohol for the esteri?cation of
Numerous catalysts for the esteri?cation re
the fatty acids. In practice'we may use from
action have been described in the literature and
slightly more than thecalculated quantity up to
in patents. By far the most active catalysts are
4 or more times that quantity‘ of alcohol. The
40
strong acids such as hydrochloric or sulfuric.
They have the disadvantage that their action on
' excess used depends on the particular nature or
source of the tall oil treatedfidifferent oils re
the equipment is rather destructive and that they
quiring different proportions of excess-alcohol for
cause discoloration of the reaction" product.
esteri?cation in the same period of time. With
Sulfonic acids have a milder action on the equip
ment but also cause discoloration. Anhydrous 45 the same tall oil, the time needed for esteri?ca
metallic chlorides and sulfates, metallic soaps ' tion of its fatty acids is shorter when the‘ pro
portionof excess alcohol present is higher. For
and finely divided metals also have been recom
example, in the above tall 011 the fatty acids were
mended as catalysts. They are much less active
esterified in 8 hours when using 3.2 times the
catalysts than mineral acids. All catalysts have
. the added disadvantage in common that they 50 calculated quantity of methyl alcohol, whereas
at the same temperature, 22 hours were required
, must be removed after the reaction has pro
when only 1.35 times the calculated quantity of
ceeded to the desired point, which means an ad
Y‘ alcohol was used. After esteri?cation of the
ditional operation.
'
'
Considering the disadvantages connected with . fatty acids is complete, the excess of alcohol is
the use of catalysts, a process whereby esteriilcad 55 removed by distillation. Together with the al
at
acids duringwhich period the acid number stays
cohol we also distill off the water formed in the
esteriflcation reaction.
The alcohols are preferably used in a'rather
constant. This inhibition period may be of a du
ration from about one-half hour to several hours.
concentrated form but our process does not re—
Its existence enables us to-stop the reaction sharp
quire the use of anhydrous alcohols. We have
1y at a point at which the fatty acids are com
successfully used, for example. methyl alcohol of
pletely esterifled and before commencement of
80% strength by volume, or the constant boiling
esteri?cation of the resin acids. This is an im
mixture of isopropyl alcohol with water which
portant requirement of the usefulness of our proc
contains only 91% by volume of anhydrous iso
ess since our ultimate purpose is to enable a sharp
10 separation of the fatty acid component of tall oil
propyl alcohol.
‘
‘
The temperature for esterificatlon, according to
from the resin acids to be made by methods such
our process, ranges between the following limits.
as those set forth in our aforesaid patent and
copending applications.
The lower limit is the temperature at which the
mixture of tall oil and alcohol would boil at at=
According to our process, the esterification is
mospherlc pressure. This corresponds closely to 15 e?ected in a pressure vessel which may be con
the boiling point of the alcohol used which is 66°
structed of any metal reasonably corrosion-proof
C‘. for methyl alcohol and 140° C. for n-amyl alco»
hol. The upper limit of temperature is approxi
mately 200° C. The corresponding pressures range
against tall ' oil, such as stainless steels, Monel
metal, aluminum, etc. We charge the tall oil to
gether with an excess of the alcohol into the pres
_ from atmospheric to approximately 500 pounds per 20 sure vessel and raise the temperature to the de
square inch. Esteri?cation is extremely slow on
re?uxing a mixture of tall oil and an alcohol in
the absence of a catalyst at atmospheric pressure.
If, however, the mixture is heated in a closed sys
sired level. The progress of the esteriflcation can
be easily followed by withdrawing samples from
time to time and, after evaporating the excess al~
cohol and the water formed during the reaction
tem to a temperature above its boiling point at
determining the acid number of the oil. At the
atmospheric pressure, the reaction Velocity in
point where the fatty acids will be completely es»
creases as the temperature is raiscdj We have
teri?ed, the acid number will be entirely due to
found that the effect of the temperature on the
the resin acids. The acid number expressing the
velocity of the esteri?cation reaction conforms to
quantity of resin acids present varies with differ
the general rule according to which a rise of 10° 30 ent oils depending on their resin acid content and
C. approximately doubles the rate of reaction. In
has to be determined previously by analytical lab
the following Table I the velocity of the reaction
oratory methods. When the acid number indi
is expressed as the time required to reduce the
cates complete esteri?cation of the fatty acids,
initial acid number of 173 of a refined tall oil to
the heating is discontinued and the excess alcohol
the same extent on heating it with four times the 35 and the water formed in the reaction are removed
theoretical quantity oi’ methyl alcohol in experi
by distillation, at first at atmospheric pressure
ments made at different temperatures. With this
and then finished in vacuo. We obtain an esteri»
particular oil, a decrease of 106 points in acid
?cation mixture of good color, unharmed by side
number corresponds to a complete esterification of
reactions which are liable to occur in processes in
the fatty acids.
so which‘ catalysts are used. The use of pressure
'
Table i
a
Egg: Pressure, Decrease
tum
0G '
72
l
lbs/1n.B
Ga.
Atm.
of acid
‘ 0.
.
Time
recgilred,
rs.
9
6
9
0.5
Decrease
of acid
No.
Time
re mood,
re.
Decrease
of acid
No.
Time
relglired,
rt.
...................................... __
100
50
22
108
180
120
__________________ __
89
3
10d
8
146
iso
_________________ ..
s9
89
1
106
3.5
The foregoing table clearly shows the time ele
ment involved, and indicates that with four times
the theoretical quantity of methyl alcohol a tem
perature of approximately 130440" C. insures a
sumciently high reaction velocity for commercial
operation. With. lower ratios of excess alcohol the
temperature must be correspondingly raised if es
terirlcation is to be effected in the same time, and
86
equipment at first appears to be a complication as
compared to processes using catalysts at atmos~
pheric pressure. Actually, however, it is a great
simpli?cation, since materials can be used for the
construction of the pressure equipment which
under the influence of active catalysts would dis
integrate in a short time. Whatever corrosion ac
tion free fatty and resin acids have at higher tem
we may use temperatures up to approximately 60 peratures on most metals is greatly reduced due
to the presence of the alcohol. Instead of using a
200° C. Thus within the limits of.our invention
pressure vessel and working by the batch method.
we can control the time factor by either the tem
perature or the excess of alcohol used or by both.
our process may also be carried out in a con
While the esteri?cation of resin acids becomes
tinuous manner by supplying a mixture of tall oil
of an important magnitude only at temperatures
above 200° C. (Patent No. 1,924,934) we have
found that the resin acids may undergo a slow
esteri?cation even between the temperature limits
kept at a suitable temperature and continuously
discharging the reacted mixture at the other end
of our process. So slow are the resin acids to re
act, however, that the beginning of their reaction
is always preceded by the complete esteri?cation
of the fatty acids. We have actually found an in
and alcohol into one end of a reaction chamber
of said reaction chamber.
'
The following Table II shows the change of
the acid number with time for two different tall
oils reacted with methyl alcohol.
Oil No. 1 was
a crude tall oilcf acid number 166, containing
hibition period between the point of the comple
55 per cent fatty acids and 38 per cent resin acids.
Oil No. 2 was a tall oil re?ned according to our
tion of the esterification of the fatty acids and
the beginning of the esteri?cation of the resin 75 Patent No, 2,223,850, of acid number 173, con
ounces
S
Example s
taining 57 per cent fatty acids and 37 per cent
resin acids. The table clearly indicates the 111-‘
300 grams of a crude tall oil song 42%
hibition periods of approximately’ 1 hour and
1% hour respectively after which a further slow
resin acids were reacted with 65 cc. normaly amyl
. alcohol at a temperature 0! 167-167’ (3., thepres
sure rising up to about 2'1 pounds. Esterification
of the fatty acids was complete in 23 hours.
decrease of the' acid ‘number indicates a slow
esteri?cation of the resin acids.
'
We claim as our invention:
Table II
a
1. The process of esterifying the fatty. acids
contained in a tall oil mixture of fatty acids and
on No. 1, reacted at 145° 0.
10 resin acidawhich comprises treating a mixture
a on No. 2, reacted M103“ 0.
consisting of said tall oil and an excess of a low
Time,
hours
t
Acid ‘ Inhibition
number
period
'
Hour:
»1
104
2
7c
molecular .weight monohydric aliphatic alcohol.
Time,
Acid Inhibition
hours‘ number
period
__
1
.......... ..
~
1%
l - in the absence of a catalyst, at a superatmos
pheric pressure and ‘a temperature of from about
the boiling point or the mixture to approximate
.
'n
iy 200° C. and discontinuing the reaction as soon
71
" as the fatty acids are completely esteri?ed and ;
5:2
as
.......... _.
s5 "s1.
- before esterification of the resin acids begins.
'3"
The
s tall asoil we
..........
use can
-- be
3t either,
1 [somice or Ire
2. The‘ process of esterii'ying fatty acids con
"so
v - tained in tall ‘oil, which comprises heating a mix
_ . ture consisting of at all oil and a low molecular
weight monohydric aliphatic alcohol. in the ab
‘?ned.
. z
}
: ., sence of a catalyst, at a superatmospheric pres
Example 1 '
sure and a temperature or from above that at
which the mixture boils at atmospheric pressure
‘ number
Five hundred
173, containing
grams of fatty
a'reiined
acidstall
57 oil‘
percent,
of acid . _‘ " and below approximately 200° C. for a period sum
> ' cient to effect esteriiicaticn of only the fattycacids
resin acids 3''! per cent and 160 cc. of methyl val_
cohol are" charged into a steel'pressure bomb " and discontinuing the reaction before esteri?co
t_ion of the resin acids occurs.
'
‘ lined with aluminum and. equipped ‘with a 30
3. The process of esterifying fatty acids con- '
sampling valve. The bomb is heatedin an oily
tained in tall 011, whichcomprises heating a mix
bath which is kept at a_ constant temperature of
ture. consisting of a tall oil and a low‘ molecular
180° C. After 6 hours'heating, the acid'num
ber of the oil as determined von samples with
drawn, decreases to 68,. which ?gure‘gdoes not
change on further heating for one-half hour.
weight monohydric aliphatic alcohol, in the ab
- ‘sence of a catalyst, at a superatrnospheric pres
sure and a temperature?of from above that at
which the mixture boils at atmospheric pressure
Heating is stopped, the‘ ‘excess methyl alcohol ‘ ' and below approximately 200° C. for a "period
and the-‘water. formed distilled off. We obtain
flve‘hundred and fifteen grams esteriiled mixture .
oi’ good color. . ‘
'
Example 2
200 pounds of a crude tall oil containing 35%
resin acids and 50 pounds methyl alcohol were
heated in a steel pressure tank under a pressure
of 170 pounds. After 13 hours, the acidnum
her was 63 and remained constant for the next
4 hours. The heating was, now stopped and the
excess alcohol and the water distilled off.
Example 3
250 grams .of a crude tall oil containing 42%
resin acids and 40 cc. of 80% methyl alcohol by
'volume were charged into a pressure vessel and
heated 23 hours at a temperature of l'70-5° C.
when the acid number became constant at '78.
Example 4
su?lcient to effect. esteri?cation. of only the fatty
acids, the said alcohol being in molal excess of
the fatty acid content of the tall 011 and before
esteri?cation or the resin acids begins.
4. vThe process of esterifying fatty acids_,con-_
tained in tall oil, which comprises heating a
.
ture consisting of a tall oil and a low molecular "
weight monohydric aliphatic alcohol, in the sb~
sence of a catalyst, at a superatmospheric pres
sure and a temperature of from ‘about the boil
ing point of they mixture at atmospheric pressure
to apprately 200° C. and discontinuing the
reaction as soon as the fatty acids are completely
esterified and before esterincation of the resin
acids begins.
v
v
I
‘
‘ 5. The process of esterifying fatty acidscon»
tained in tall 011, which comprises heating a mix-‘
‘ ture consisting of a tall oil and an excess of a low
molecular weight monohydric aliphatic alcohol,
in the absence of a catalyst, at a superatmos
pheric pressure of from about atmospheric to
300 grams of ‘a crude tall 011 containing 42%
about 500 pounds per square inch, and at a tem
resin acids were treated with 30 cc. methyl alco 80 perature of from about the boiling point of the
hol (corresponding to an excess of approximately ,
mixture at atmospheric pressure to approximate
1y 200° C. and discontinuing the reaction as soon
50%) at a. temperature of 166-170° C., the pres
sure rising to about 210 pounds. The acid num- ‘ as the fatty acids are completely esteri?ed and
before esterification of the resin acids begins.
ber became, constant at '78 after 20 hours heat
6. The process of esterii'ying fatty acids con
ing when the excess methyl alcohol and the
tained in tall oil, which comprises heating a mix
water were distilled off.
ture consisting of a tall oil and a. low molecular
Example 5.
weight monohydric aliphatic alcohol, in the ab»
sence of a catalyst, at‘a superatmospheric pres
300 grams of, a crude tall oil containing 42%
sure and a temperature of from above the boiling
resin acids were reacted with 60 cc. isopropylal
point of the mixture at atmospheric pressure to
cohol containing 9% water at a temperature of
approximately 200° C. and discontinuing the raw
165-170” C. the pressure rising to about 85
action as soon as the fatty acids are ccmpletel
pounds. The esteri?cation of the fatty acids was
esteri?ed and before the esteri?cation of the to!
completed in 23 hours when the acid number be
oil resin acid content begins.
came constant for one hour at 78.
2,411,586
8
7. The process of esterifying fatty acids con—
tained in tall oil, which comprises reacting a mix
ture consisting of tall oil and an excess of a low
molecular weight monohydric aliphatic alcohol,
in the absence of a catalyst, at a superatmos
pheric pressure and a temperature of from above.
' an iso-propyi alcohol, in the absence of a catalyst,
at a superatmospheric pressure and a tempera
ture of from above the boiling point of the mix
ture at atmospheric pressure to not in excess of
approximately 200° C. and discontinuing the re
action as soon as the fatty acids are esteri?ed
and, before esteri?cation of the resin acids begins.
12. In a process for separating the fatty acid
and resin acid constituents of tall oil, the step
ing the reaction as soon as the acid number of
the tall oil becomes constant and before esteri? 10 of esterifying the fatty acids, which consists in
the boiling point of the mixture at atmospheric
pressure to approximately 200° C. and discontinu
_ cation of the resin acids begins.
reacting a mixture of a tall oil with a monohydric
aliphatic alcohol, in the absence of a catalyst,
8. The process of esterifying fatty acids con
tained in tall oil, which comprises reacting a mix
at a superatmospheric pressure and a tempera
ture consisting of a tall oil and an excess of a low
ture of from above the boiling point of the mix
molecular weight monohydric aliphatic alcohol, 16 ture at atmospheric pressure torapproximately
in the absence of a cataylst, at a superatmos
pheric pressure and a, temperature of from above
the boiling point of the mixture at atmospheric
200° C. and discontinuing the reaction after'the
fatty acids are completely esteri?ed and before
esteri?cation of the resin acids begins.
13. In a process for producing fatty acid esters
pressure to approximately 200° C. and discontin
uing the reaction as soon as the acid number of 20 from fatty acids contained in a tall 011 in admix
ture with resin acids, the step which consists in
the tall oil becomes constant for at least one hour
reacting said. mixture with a low molecular weight
and before esteri?cation of the resin acids begins.
monohydric aliphatic alcohol, in the absence of
9. The process of esterifying fatty acids con
a catalyst, at a superatmospheric pressure and a
tained in‘tall oil, which comprises reacting a
mixture consisting of a tall 011 and an excess of 25 temperature of from above the boiling point of
the mixture at atmospheric pressure to approxi
a methyl alcohol, in the absence of a catalyst, at
mately 200° C. and discontinuing the reaction
a superatmospheric pressure and a temperature
after the fatty acids are completely esterified and
of from above the boiling point of the mixture at
before esteri?cation of the resin acids begins.
atmospheric pressure to not in excess of ap
14. The process of producing a mixture of fatty
proximately 200° C. and discontinuing the reac 30
acid esters and resin acids, which comprises
tion as soon as the fatty acids are esteri?ed
' treating a mixture consisting of a. tall 011 and a
and before esteriflcation of the resin acids begins.
low molecular weight monohydric aliphatic al
10. The process of esterifying fatty. acids con
001101, in the absence of a catalyst, at a superst
tained in tall oil, which comprises reacting a
mixture consisting of a tall oil and an excess of 85 mospheric pressure and at a temperature of from
above the boiling point of the mixture at atmos
an ethyl alcohol, in the absence of a catalyst, at
pheric pressure not in excess of approximately
a superatmospheric pressure and a temperature
200? 0., discontinuing the reaction as soon as the
of from above the boiling point of the mixture at
fatty acids are completely esteri?ed and before
atmospheric pressure to not in excess of approx
imately 200° C. and discontinuing the reaction as 40 esteri?cation of the resin acids begins, and re
moving the excess oi‘ alcohol and water formed
soon as the fatty acids are esteri?ed and before
duringthe reaction.
esteri?cation of the resin acids begins.
11. The process of esterifying fatty acids con
tained in tall oil, which comprises‘ reacting a
‘
,
FREDERICK H. GAYER. ,
’CHAS. E. FAWIGL’S.
mixture consisting of a tall oil and an excess of
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