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Патент USA US3082256

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United States Patent 0
3,082,246
Patented Mar. 19, 1963
2
1
effectively suppresses the undesirable polymerization of
3,082,246
the ole?n, does not favor the formation of secondary
and primary esters and can be readily separated from the
Inc, New York, N.Y., a corporation of Delaware
ester product without decomposition of said product.
In a typical operation of my novel process the tertiary
PREPARATION OF TERTIARY ESTERS
_ Harry Chafetz, Poughkeepsie, N.Y., assignor to Texaco
No Drawing. Filed Feb. 17, 1960, Scr. No. 9,162
7 Claims. (Cl. 260-—497)
ole?n is contacted with a carboxylic acid in a mol ratio
of between about 1:10 and 10:1, preferably between
about 1:4 and 4:1, at a temperature between about 135
and 350° 'F., preferably between about 150 and 225 ° F.
the preparation of carboxylic acid esters of tertiary alco
hol and, more particularly, to such a process where a 10 and under a pressure between about 50 and 2000 p.s.i.g.,
preferably between about 100 and 300 p.s.i.g. in the pres
“tertiary base” or, more simply, a “tertiary ole?nic com
ence of between about 0.5 and 20 mol percent sulfur
pound” is reacted in an esteri?cation Zone with a car
The instant invention relates to a catalytic process for
‘dioxide, preferably between about 1 and 10 mol percent,
boxylic acid employing sulfur dioxide as the catalyst.
Using, for example, acetic acid and the hydrocarbon
isobutylene, the reaction can be represented as follows:
15
011300013 + 04113 2* CHgCOOCrHg
Acetic
acid
Isa‘
butylene
be thoroughly mixed prior to or during the reaction period
in order to insure high yields of ester product.
Tertiary-bury]
acetate
Such ester is useful as a paint solvent and as a grease
component.
20
In addition, it is a valuable additive for
improving the octane rating of high quality leaded gaso
line.
based on the total mols of said ole?n and acid.
The novel process is operative whether the reactants
and catalyst be in the liquid phase or in a liquid-vapor
phase equilibrium. In any case, it is desirable that they
As a group these esters are solvents for many
The process can be either continuous or batch.
If a
continous operation is employed, it is desirable to admix
the reactants and catalysts with one another prior to their
exposure to the reaction zone. In such a system the ad
mixture can be fed into the reaction zone at temperatures
organic materials and, therefore, are useful as vehicles
25 less than are found in the’major portion of said zone and
‘therefor.
The condensing of a tertiary ole?nic compound with a
then allowed to reach the reaction temperature autog
enously by exothermic heat of reaction. Alternatively,
carb-oxylic acid is usually done in the presence of a cata
lyst. Some of the catalysts employed in the past were sul
indirect reactor cooling or heating can be used. In a con
tinuous process the reaction mixture is continuously with
furic acid, complexes of boron trifluoride, orthophos
phoric acid suitably supported on an inert support such as
drawn from the'reaction zone. The components compris
kieselguhr, benzenesulfonic acid, alkyl sulfates, or other
ing the Withdrawn stream can be separated from one an
other by any standard means such as fractionation. For
mally present as a distinct liquid phase in the esteri?ca
economc purposes it is desirable to recycle the sulfur
dioxide and 'unreacted reactants to the reaction zone.
tion reaction mixture, or are homogeneous therewith,
My novel process may also be a batch or a combination
or are sorbed on a solid porous carrier such as silica, 35
of a batch or continuous process. In the latter, the re
charcoal or alumina.
strong mineral or organic acids. Such catalysts are nor
In the condensation of a tertiary ole?n compound with
a carboxylic acid to ‘form a tertiary ester there is a serious
competing reaction, namely, that of polymer formation
from the tertiary ole?nic material.v The esteri?cation re-~ 40
action involving tertiary ole?ns is far more sensitive to'
polymer competition than is the corresponding reaction
actants, catalyst and formed products are passed through
the reaction zone and continuously recycled therethrough
with batch ‘or incremental withdrawal of the reaction mix
ture‘ for the separation ‘of the ester product therefrom
and the subsequent return of the catalyst and unreacted
reactants to the circulating reaction system.
involving a secondary ole?n or a primary ole?n. Actu
ally, when secondary ole?ns such as butene-2 are con
Corrosion resistant reaction vessels are in order, e.g.
ones of austenitic stainless steel, high chrome stainless
densed with carboxylic acids, it is conventional to rid 45 steel and the like because of the possible corrosive tend
the hydrocarbon feed of “tertiary ole?ns” by causing them
encies of the carboxylic acid reaction in the process.
to polymerize, then to operate with the remaining sec
By the ‘term “tertiary ole?nic hydrocarbon,” I intend
a hydrocarbon'containing at least one tertiary ole?nic
ondary ole?n containing feed. By means of our process
hydrocarbon streams can be freed of tertiary ole?ns with
carbon. The useful ole?nic starting materials for my
out signi?cant polymerization to make a valuable ester 50 process have at least ‘one side chain branching from an
product e?iciently and the so-treated unreacted- hydrocar-q ole?nic carbon ‘atom (including anlole?nic carbon atom
bons separated from the ester for other use.
in a cyclic structure). Speci?c examples of suitable ole
An advantage of our process over conventional proc
?nic hydrocarbons for use in my process include isobutyl
essing of tertiary ole?nic compounds for the tertiary ester,
ene, 2-methyl-l-butene, 2-methyl-2~butene, 3-ethyl-3lhep
formation is the effect of suppressing the polymerization 55 tene, 2,3-dimethyl-3-decene and l-rnethyl-l-cyclohexene.
of these ole?ns while esterifying at temperatures up to
about 350° F. A further advantage of our process over‘
ability the aliphatic C4_12 tertiary monoole?nic hydrocar
conventional treatment is it permits the separation of the
ester product from the reaction mixture by heat treatment
bons are the most desirable for my process.
The ole?ns can be pure, mixed with each other or mixed
As a practical limitation because of the cost and avail
methods such as distillation without undesirable decom 60 with unreactive or substantially less reactive materials.
position of the ester product. Distillation or other heat
Thus, ‘for example, we can use pure isobutylene made by
treatments of the crude ester product in the presence of
crackingan isobutylene dimer. On the other hand, we
strong acids such as sulfuric acid, phosphoric acid, sul
can use a C, and/or a C5 cut ‘from a catalytic or a thermal
fonic acid, hydrochloric acid and the like even in the
cracking operation, which would ordinarily contain some
presence of an extremely small amount of said acids 65 what less than 20% of the tertiary ole?n and the balance
usually results in the rapid breakdown of the ester. > of other diluent hydrocarbons. A typical so-cal-led
“B-B” stream from catalytic cracking can contain 10'—25
In accordance with the foregoing, I have discovered
mol
percent isobuty-lene, 50 mol percent para?‘ins and
that sulfur dioxide is extremely effective in catalyzing the
reaction between a tertiary ole?nic compound and a car 70 the balance preponderantly butene-l, and cis- and trans
butene-Z. A suitable stream for making tertiary-butyl
boxylic acid to form the corresponding tertiary ester. In
carboxylic acid esters is a stream containing about 25
addition, I have discovered that the sulfur dioxide catalyst
product.
3,082,246
4.
3
In runs Nos.‘ 550 and ‘562 found in Table B the tertiary
butyl acetate was recovered from the withdrawn reaction
mol percent butylenes and the balance predominantly
‘
normal butane.
Other ole?ns which ‘may be employed in my process
are the polyole?ns such ‘as 2,4-dimethyl-2,4-hexadiene and
Also suitable are oxygenated aliphatic hydro
isoprene.
carbon compounds of tertiary base ole?nic carbon con
?guration, e.g., alkyl vinyl ethers such as ethyl or methyl
vinyl ether. Conceivably, the tertiary base ole?n com
mixture utilizing the following procedures:
Atiary phosphate‘or phosphate radical or an aromatic such
tiary butyl acetate.
Run No. 550.—One=part of the liquid reaction mixture
removed from the batch reactor was mixed with 2.5
parts of water and 2.1 parts of ether. The resulting or
ganic layer was separated ‘from the aqueous layer and
washed with 2 parts of 10% aqueous sodium hydroxide,
dried over anhydrous potassium carbonate and distilled.
pound can be onewherein oneor more hydrogen atoms
are substituted with an inert substituent such as halogen 10 The ‘fraction recovered at a distillation temperature of
between 201 and 207° 'F. at 1 atm. was identi?ed as ter
(e.g. chlorine), an alkoxy radical, 'a nitro group, a ter
Run N0. 562.-0ne part of the ?nal reaction mixture
was removed ‘from the batch reactor and mixed with 2.1
parts of triisobutylene, 1 part of crushed ice and 1.8 parts
as a phenyl group.
The particular carboxylic acid used is dictated by the
particular product‘ desired. Because the presence of water
in the esteri?c‘ation‘reactor induces a competing reaction,
'of’potassiurn carbonate. The resultant mixture foamed
‘ and after the foaming had ceased the organic layer was
namely, one wherein tertiary valcohols are made, the re
actions should be virtually anhydrous for best results to
make the ester exclusive. Thus, for example, when ace
separated from the aqueous layer, washed with 1 part
pure) should be used.
tertiary butyl acetate.
of water, dried over anhydrous calcium sulfate and dis
tates are made exclusively, glacial’acetic acid (99.5% 20 tilled. The ‘fraction recovered at a distillation tempera
ture between 201 and 207° F. at 1 atm. was identi?ed as
The car-boxylic acid reactants can be fatty acids suit
ably in the range from formic to stearic acids and advan
In Table A below are found the reaction data for the
tageously C1~C8 faty acids. Alternatively, they can be
conversion of isobutylene in admixture with one or more
acids such as malonic, oxalic and so on suitably up to
Table A
polybasic, e.g. saturated aliphatic hydrocarbon dibasic 25 C; hydrocarbons.
sebacic or even higher. They can have inert nuclear
substituents for hydrogen atoms (such as keto, nitro,
Run No.
halogen, alkoxy tertiary phosphate, etc.). They can have
572
an aromatic nucleus such as benzoic, phthalic, toluic or 30
the like.
Reaction Ingredients:
Typical of the carboxylic acids which can be employed
in the condensation with ole?ns contemplated herein in
573
Hydrocarbon Reactant, Mol—
Isobutylene-..
,clude the following: acetic, malonic, propionic, butyric,
isobutyric, valeric, isovaleric, acetone dicarboxylic, 2 35
ethyl hexanoic, benzoic, caproic, octanoic, ‘formic, oxalic,
monochloroacetic and cyclohexane carboxylic.
H
585
enacts»
Sulfur dioxide, M01
M01 percent of SO, based on total acid and
The reaction can be conducted in the presence of an
hydrocarbon reactant ....................... -_
inert’ vehicle, e.g. ether, benzene, toluene or the like. 40
Such a technique can be useful ‘for dissolving one or both
reactants.
'
Wt. percent of SO, based on total acid and hy
drocarbon reactant ......................... _
Reaction Conditions:
Temp., "F .................................... -_
Time, Hrs ...... __
Pressure, p.s.i.g ............................... -.
The subsequent example shows ways 'in' which my in
Products, mol percent yield 1:
vention has been practiced but should not be construed
t-butyl acetate .... ._
see-butyl acetate
as limiting the invention.
45
diisobutylene 2.
5
‘Ea
a
o0c1»;m
_ Products, wt. percenfyicld
EXAMPLE I
t-butyl acetate
sec-butyl acetate
In all runs reported in subsequent Tables A and B the
dilsobutylene ................................. ..
following procedure was employed:
The isobutylene or C4 fraction containing isobutylene, 50
acetic acid and sulfur dioxide were introduced into a one
gallon enclosed stainless steel batch reactor ?tted with
an agitator, thermometer, pressure gauge, heat exchange
coils, and valved entrances and exits.‘ The mixture was
stirred from 1/2 to 4 hours‘and at the close of that period,
the reaction mass was cooled to room temperature.
1 Based on isobutylene charge.
2 Mols diisobutylene formed/Mols isobutylene charged.
As can be seen from the above, little or no polymeriza
tion takes place With sulfur dioxide as the catalyst. In
addition, there is shown that S02 selectively forms terti
ary-butyl esters to the substantial exclusion of secondary
butyl esters.
In Table B below, are found data concerning the con
version of isobutylene to tertiary-butyl acetate, the iso~
The pressure in the batch reactor was reacted to atmos
pheric and the liquid remaining therein was withdrawn.
The withdrawn liquid was analyzed by mass spectrometry.
butylene being the only hydrocarbon present.
Table B
Yield
Run
No.
Mol Ratio,
GRID/acetic
acld
571 ____ ._
1/2
567B_.--
1/2
583 ____ -_
582 ____ ._
550 ____ __
562 ____ ..
111. 07
1/3. 44
4/1
4/1
80:, M01
S02. Wt.
Percent of
Total Reactants
Percent of
Total Reactants
Temp.,
‘’ F.
Pres.
p.s.l.g.
React.
Time,
hrs.
t-butyl
acetate.
t~butyl Dilsobu
aoetute. tylcne, wt
mol per-
wt. pcr-
cent 1
cent 1
percentI
5
5. 4
175
115
4
31
64
0. 3
5
5. 4
200
140
3
47
97
O. 8
3. 9
5.6
10
10
4. 3
6.1
11.3
11.3
250
200
250
300
300
155
360
500
2. 5
4
4
4
29
54
41
31
60
111
79
60
1.2
0.9
0. 4
1. 0
1 Based on isobutylene reactant.
3,082,246
5
6
The data in above Table B shows the effectiveness of
Products, mol percent yield 1
my method in converting isobutylene into tertiary butyl
acetate while at the same time desirably producing only
a minimum amount of polymerization product.
t-Butyl acetate ________________________ __
1.5
Diisobutylene
0
________________________ __
Products, wt. percent yield 1
EXAMPLE III
The procedure of this example is comparable to the
procedure of Example I with the exception that sulfuric
acid was substituted for the sulfur dioxide catalyst. The
t-Butyl acetate _______________________ __
Diisobutylene ________________________ __
3.1
0
1 Based on isobutylene reactant.
As can be seen by comparing the yield of the above
liquid product was analyzed by mass spectrometry. The 10 run No. 588 with those of Tables A and B, the presence
reaction data and results are reported below in Table C.
Table C
Reactants and catalysts, mol:
Isobutylene
of sulfur dioxide in applicant’s process is necessary to
produce a tertiary ester in signi?cant quantities.
All percentages, parts and ratios herebefore and here
Run No. 600
__
1
Acetic acid ___________________________ __
Sulfuric acid _________________________ __
2
0.9
after recited are based on weight unless otherwise stated.
15
departing from the spirit and scope thereof and therefore
only such limitations should be imposed as are indicated
M01 percent of H2804 based on total mols of
acetic acid and isobutylene ___________ __
3
in the appended claims.
Wt. percent of H2804 based on total weight of
acetic acid and isobutylene ___________ __
I claim:
1. In a process for the condensation of an aliphatic
5
Reaction conditions:
tertiary monoole?nic hydrocarbon of 4 to 12 carbon
Temp., ° F. __________________________ ___ 130
Pressure, p.s.i.g _______________________ __
1
28
13
Products, wt. percent yield 1
t-Butyl acetate ________________________ .._.
58
Diisobutylene
26
________________________ __
atoms with a carboxylic acid selected from the group con
60
Time, hrs.
Products, mol percent yields 1
t-Butyl acetate ________________________ __
Diisobutylene 2 _______________________ __
Obviously, many modi?cations and variations of the
invention as hereinbefore set forth may be made without
1 Based on isobutylene reactant.
9 Mols diisobutylene formed/mols isobutylene charged.
25
sisting of a monobasic fatty acid, saturated aliphatic hydro
carbon dibasic acid, aryl monocarboxylic acid and alkaryl
monocarboxylic acid to form the corresponding tertiary
ester in the reaction zone, the improvement which com
prises: contacting said monoole?nic hydrocarbon with
said acid at an elevated temperature and pressure in the
30 presence of sulfur dioxide.
2. A method in accordance with claim 1 wherein said
pressure is between about 50 and 2000 p.s.i.g, said tem
perature is between about 135 and 350° F., said hydro
As can be seen by comparing the yields of diisobutylene
carbon and said acid are in a mol ratio between about 1:10
of Table C with those of Tables A and B, the replace 35 and 10:1 and said sulfur dioxide is present in a mol
ment of sulfur dioxide with a sulfuric acid catalyst results
percent between 0.5 and 20 based on the total mols of
reactants.
in the undesirable production of substantially larger quan
tities of polymerized product even at a reduced tempera
3. A method in accordance with claim 1 wherein said
ture.
pressure is between about 100 and 300 p.s.i.g, said tem
EXAMPLE III
40 perature is between about 150 and 225° F., said hydro
carbon and said acid are in a mol ratio between about 1:4
The procedure of this example is the same as the
and 4:1 and said sulfur dioxide is present in a mol percent
procedure of Example I with the exception that catalyst
was not employed and the reactor was pressured with
between 1 and 10 based on the total mols of reactants.
4. A method in accordance with claim 1 wherein said
nitrogen to the indicated pressure. The liquid product '
was analyzed by mass spectrometry. The reaction data 45 hydrocarbon is isobutylene.
5. A method in accordance with claim 1 wherein said
hydrocarbon is in admixture with at least one other hydro
carbon having 4 carbon atoms.
6. A method in accordance with claim 1 wherein said
Reactants and catalysts, mol:
Run No. 588
50 acid is a monobasic fatty acid having from 1 to 8 carbon
Isobutylene __________________________ __
3
atoms.
Acetic acid
6
7. A method in accordance with claim 6 wherein said
Reaction conditions:
’
acid is acetic acid.
Temp., ° F.
___
200
and results are found below in Table D.
Table D
‘Pressure, p.s.i.g _______________________ __ 600
Time, hrs.
6
No references cited.
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