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Патент USA US2408941

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Patented Oct. 8, 1946
John E. Mahan, Bartlesville, Okla, assignor to
Phillips Petroleum Company, a corporation of
No Drawing. Application June 24, 1944,
Serial No. 542,011
6 Claims. (01. 260—486)
This invention relates to the production of
esters of carboxylic acids by the novel interaction
of olefinic hydrocarbons with nitriles (cyanides)
in the presence of an inorganic acid. In one of its
more speci?c aspects, this invention relates to the
production of such esters by a single-stage oper
ation involving the interaction of a mono-ole?n
with a saturated or unsaturated nitrile (alkyl or
alkenyl cyanides) in the presence of an inorganic
Numerous methods for the preparation of esters
are known. According to one method, carboxylic
acids are reacted with ole?ns in the presence of
catalysts such as salts of mercury, copper and
The value of nitriles as intermediates for the
production of a wide variety of chemical prod
ucts, such as acids, aldehydes, ketones, amines
and the like, has long been recognized. However,
it has not been known that nitriles and ole?ns
undergo interaction in the presence of aqueous
solutions of inorganic acids with the resultant
formation of esters.
It is an object of the present invention to pro
vide a process for the production of esters at low
Another object of the present invention is to
provide a process whereby esters of carboxylic
acids may be produced by the interaction of ni
other heavy metals, relatively non-volatile in 15 triles with ole?nic hydrocarbons.
A further object of the invention is the provi
organic acids such as phosphoric acid and sulfuric
sion of a single-stage process for the production
acid and their salts, and other similar materials.
of esters by the interaction of nitriles of either
In recent years the use of ole?ns as a source of
saturated or unsaturated carboxylic acids with
esters has attracted considerable industrial atten
tion largely because of the increasing demand for 20 mono-ole?ns in the presence of a solution of sul
furic or other inorganic acid.
esters for use as lacquer solvents, emulsifying and
Further objects and advantages of the inven
wetting agents, detergents, plasticizers and the
tion, some of which are referred to speci?cally
like. Recommended ole?ns for the production of
hereinafter, will be obvious to those skilled in the
such esters have ranged from ethylene to octenes
and higher homologs. The manufacture of gaso 25 art to which the invention pertains.
I have found that nitriles and ole?ns interact
line by cracking processes has furnished a ready
in the presence of an inorganic acid such as sul
source of butenes and lower ole?ns at a relatively
furic acid under reaction conditions speci?ed here
low cost. In addition, substantially mono-ole?nic
hydrocarbons of relatively high molecular weights
are obtained from polymerization processes in
which butenes, mixtures of butenes and propyl
enes, and similar materials are used as charge
The utility of the ole?n-carboxylic acid reaction
as a method for the production of esters has not ‘
been fully realized heretofore, possibly because of
the lack of economical processes for the prepara
inafter. This reaction, which leads to the forma
tion of esters, has not heretofore been described
in the art. While the mechanism of the reaction
is not clearly understood, it might appear that
a step-wise reaction occurs which involves the
hydrolysis of the nitrile to an acid in the ?rst step
and the subsequent addition of the acid to the
double bond of the ole?n in the second step.
However, I have found that the substitution of the
corresponding carboxylic acid, which is the inter
mediate in such reaction, for the particular nitrile
the presence of appropriate oxidizing agents. 40 does not result in the production of an ester under
the same reaction conditions. The exact mech
They may also be produced from alkyl chlorides,
tion of acids. Acids are readily obtained by the
oxidation of alcohols, aldehydes and ketones in
ethers and esters by suitable reactions. The hy=
drolysis of nitriles has also been used as a source
anism of the reaction is not obvious nor has it
been determined as yet, but the ultimate result
may possibly and probably does conform to the
of acids. Catalytic oxidation of crude petroleum,
petroleum distillates and residues, shale oils and 45 following equation:
tars, also yields acids as products. Ole?ns yield
acids when treated with carbon monom‘de and
‘i it
steam or when oxidized in the presence of ozone.
In most instances, however, all such general
methods for the production of acids suffer from 50
R-CN + X-o=o-Y + 21110 —-> R—C—O—C-C-Y + NH:
H n
in which R is an alkyl or alkenyl radical and X
and Y are hydrogen or the same or di?erent alkyl
conditions, or relative non~availability of starting
materials. Furthermore, the number of process
In accordance with a preferred embodiment of
steps involved in the preparation and isolation of
certain acids imposes serious limitations from an 55 the process of the present invention, controlled
proportions of the selected nitrile and ole?n are
economic viewpoint,
such limitations as low yields, severe reaction
brought into intimate contact with an aqueous
solution of an inorganic acid such as sulfuric
acid, phosphoric acid and the like at a suitable
temperature. During the course of the reaction
the mixture is vigorously agitated, after which it
is passed to a quiescent zone where an aqeuous
tion at the reaction temperature. Inert diluents
are preferably used only in such cases where they
are advantageous in holding the operating pres
sure within a convenient range.
In the practice of the process of the present
invention, it is ordinarily preferred to have a.
bottom layer separates and is discarded. The
ester is recovered from the water-insoluble layer,
preferably by washing said layer free of acid com
molecular excess of one of the organic reactants.
Accordingly, the ratio of ole?n to nitrile is usually
kept at about 2 to 1. However, successful re
ponents with an aqueous sodium or potassium 10 sults have been obtained when the nitrile is used
in excess.
bicarbonate solution, drying with any suitable
The quantity of 65 per cent sulfuric acid em
conventional drying agent, and subjecting the
ployed is adjusted to give a molecular excess of
resulting dried material to distillation.
sulfuric acid (H2804) with respect to the nitrile.
The reactants which are used in the process of
One of the functions of the acid, besides that of
the present invention comprise ole?nic hydrocar
acting as catalyst, appears to be that of absorb
bons and nitriles in the presence of a solution of
ing and reacting with any ammonia, if such is
an acid such as sulfuric acid. Low-molecular
formed in the reaction. Other inorganic acids
weight ole?ns such as ethylene, propylene, b-utyl
enes and amylenes, as well as branched mono
are used at suitable concentrations which can be
ole?ns having higher molecular weights, such as
readily determined by experiment and are like
those containing up to about 16 carbon atoms or
more, may be used. These ole?ns may be derived
from any convenient source, such as by thermal
and catalytic cracking of petroleum gases and dis—
wise used in stoichiometrical excess of the nitrile.
Water appears to be essential and is preferably
added with the acid but not in such amounts as to
dilute the acid so that the acid is no longer an
tillates, polymerization reactions and the like.
effective catalyst in the reaction.
Aliphatic as well as cycloaliphatic ole?ns may be
reacted in accordance with the process of the in
vention. While relatively pure ole?ns are or
which may be used as catalysts in the reaction are
Other acids
phosphoric acid, benzenesulfonic acid and the
like. Preferably the acids used are such as do
not form compounds with the ole?n that are more
dinarily preferred, it is often advantageous to
carry out the reaction with mixtures of ole?nic 30 stable than any of those possibly formed with
sulfuric acid or that react with the ole?n in other
manners. For this reason, hydrochloric acid,
nitric acid, and certain other acids are usually not
formed and the uses for which they are intended.
The nitriles may be either saturated or unsat
The time of contact between catalyst and re
urated and may be prepared by any of the meth
actants is subject to rather wide variation and
ods known to the art. Typical nitriles are pro
is dependent on the nature of the ole?n and nitrile
pionitrile, butyronitrile, acrylonitrile, pentene
as well as on the other reaction conditions. In
nitriles and the like. The nitriles may contain
some instances, maxmum yields are realized with
halogen or other substituents, for example, 2 and
a reaction time of a few hours, while in other
3-chloropropionitriles and 2, 3 and ‘l-chloro
instances, involving more refractory intermedi
butyro-nitriles. When sulfuric acid is used in the
ates, several days may be required.
present process, a solution containing about 65
The process of the present invention is illus
per cent acid is preferred.
trated in the following speci?c examples. How
Reaction temperatures are ordinarily main
tained at a level preselected to give an adequate 45 ever, since numerous other process modi?cations
and variations will be obvious to those skilled in
reaction rate but, in general, relatively low tem
the art in the light of the foregoing disclosure,
peratures, which favor ester formation, are used.
no undue limitations are thereby intended.
They may vary from approximately 40° to ap
materials, with or without subsequent puri?ca
tion of the esters, depending upon the esters
proximately 200° C. with temperatures between
Example I
the range of approximately 40° to approximately ‘
100° C. being generally preferred. The higher tem
peratures may be required when ole?ns having low
The preparation of an alkyl propicnate was
effected from propionitrile (ethyl cyanide) and
1016011131’ weights are used. With ole?ns in the
range of decenes (C10H20) and higher, tempera
tures in the range of approximately 45° to ap- >
proximately 55° C. are most generally applicable.
The temperature chosen will be dependent upon
the ole?n feed and is an important factor in
the present process since it has been found that
ester formation does not occur at any substan
tial rate above certain limits.
Reaction pressures are governed largely by the
nature of the ole?n used in the process and may
extend from atmospheric pressure to about 300
pounds per square inch or higher. If normally
gaseous ole?ns, such as ethylene or propylene,
are used, an inert saturated hydrocarbon diluent,
such as normal pentane, is preferably employed
in admixture with the ole?n in the ratio of about
15 per cent of ole?n to 85 per cent diluent, and
an ole?nic polymer consisting essentially of do
decenes (0121124) in the presence of sulfuric acid.
A mixture of 772 g. (approximately 4 mols) of the
polymer, 110.4 g. (approximately 2 mols) of pro
pionitrile and 318 ml. of 65 per cent sulfuric acid
(approximately 3 mols) was stirred for 141 hours
While the temperature was held at 45° to 55° C.
GO Upon standing, three layers separated. The aque
ous bottom layer was discarded. The top and
middle layers were separately washed free of acid
components with an aqueous sodium bicarbonate
solution and were dried over calcium chloride.
Distillation of the top layer revealed that it con
sisted only of unchanged polymer. Fractionation
of the middle layer yielded 73.5 g. of a propion
ate ester having a boiling range of 117° to 131° C.
at a pressure of 1 mm. of mercury and a refrac
tive index (nD2O) of 1.4607.
The yield of ester
the pressure is maintained in the range of ap
based on the nitrile charged was 16 per cent.
proximately 225 to approximately 300 pounds per
An attempt was made to improve the yield of
ester by conducting the reaction at 80° to 90° C.
square inch. In all cases, liquid-phase operation
is preferred, and su?icient pressure is employed
to maintain the reactants in a lique?ed condi
for 141 hours.
aqueous layer and an organic
layer separated. The latter contained no ester
but was composed of ole?n polymers comparable
of concentrated
1 mol) and
a solution
acid and
63 g. of water.
to those of the charge.
The mixture was stirred and heated at reflux tern
A further attempt to prepare the ester was
made in essentially the same manner except that
perature for 70 hours, after ‘which the two organic
layers which separated were washed with sodium
bicarbonate until free of acidic constituents and
then dried. Fractionation of the dried top layer
yielded 20 per cent of the theoretical amount oi’
propionic acid was substituted for propionitrile.
The temperature was held at 45° to 55° C. for
144 hours. Distillation of the organic layer sub
sequent to the removal of acidic components
ester based on the nitrile charged.
yielded only unchanged ole?n polymers.
Example II
An ester was prepared from propionitrile and
an ole?nic polymer consisting predominantly of
dodecenes in which a molar excess of the nitrile
Many modi?cations and variations of the inven~
tion may be made without departing from the
scope thereof and therefore no limitations are
intended other than those de?ned in the ap
pended claims.
was used. The general procedure described in
I claim:
1. A process for the production of an ester
Example I was followed. The reaction mixture
of a carboxylic acid which comprises: reacting a
consisted of 1 mol of ole?n polymer, 2 mols of
nitrile with an ole?n in the presence of water
propionitrile and 2.5 mols of 65 per cent sulfuric
and a strong acid selected from the group con
acid and it was agitated for 143 hours at a tem~
perature of 45° to 55° C. Distillation of the mid 20 sisting of sulfuric acid, phosphoric acid, and
benzenesulfonic acid; maintaining the tempera
dle layer gave a 20 per cent yield of ester based
ture of the reactants in the range from 40° to
on the ole?n polymer charged.
200° 0.; and maintaining the reactants under
The yield was slightly better in this example
pressure su?icient to maintain them in liquid
than in Example I, in which the nitrile was used
in excess of the ole?n. This may possibly be the
2. A process for the production of an ester of
result also of the use of the higher ratio of water
a carboxylic acid which comprises: reacting a
(in the acid) to nitrile.
Example III
nitrile with an ole?n in the presence of an
reaction Zone was maintained at about 300 to
ous solution of sulfuric acid having a concen
aqueous solution of sulfuric acid; maintaining
An ester of an unsaturated acid (an ethyl 30 a stoichiometric excess of sulfuric acid over
penteneoate) was prepared from trans-S-pen
ole?n; maintaining the temperature of the reac-.
tants in the range from 40° to 200° 0.; and main
tenenitrile (CH3—CH:CH——CH2—-CN) and eth
ylene in the presence of sulfuric acid. One mol
taining the reactants under pressure sufficient to
of the nitrile and a mixture of 2 mols of ethylene
maintain them in liquid phase.
in 4.4. mols of n-pentane were charged simul
3. A process for the production of an ester of
taneously to a reaction zone containing 1.5 mole
a carboxylic acid which comprises: reacting a
of 65 per cent sulfuric acid. The pressure in the
nitrile with an ole?n in the presence of an aque
350 pounds per square inch and the temperature
tration of approximately 65' per cent I'I2SO4;
was held at 90° to 100° C. while the mixture was 40 maintaining the temperature of the reactants in
continuously agitated. The emulsion was trans
the range from 40° to 200° C.; and maintaining
ferred to a separator where the aqueous bottom
the reactants under pressure sufficient to main
layer was drawn off, after which the organic
tain them in liquid phase,
layer was stabilized and subsequently washed with
4. A process for the production of a dodecyl
aqueous sodium bicarbonate. Distillation yielded 45 ester of a carboxylic acid which comprises react
ing a nitrile corresponding to said carboxylic
an ester fraction corresponding to 17 per cent of
acid with an ole?n polymer consisting essentially
the nitrile charged.
of dodecenes in the presence of aqueous sulfuric
Example IV
acid having a concentration of approximately
A mixture of 336 g. (approximately 2 mols) of 50 65% H2804 at a temperature within the range
an ole?nic polymer consisting predominantly of
of approximately 40° to approximately 100° C.
dodecenes, 81 g. (approximately 1 mol) of trans
under pressure su?icient to maintain liquid phase.
3-pentene-nitrile and 159 1111 (approximately 1.5
5. A process for the production of an ester of
mols) of 65 per cent sulfuric acid was stirred at
penteneoic acid which comprises reacting a pen
45° to 55° C. for 169 hours. These are the same 55 tenenitrile and an ole?n in the presence of aque—
relative proportions as were used in Example I
ous sulfuric acid and at a temperature within the
and the procedure of Example I was otherwise
range of approximately 40° to approximately
followed. In contrast to the reaction with pro
100° C. under pressure sufficient to maintain liquid
pionitrile in Example I, however, only two layers
separated on standing. The organic layer yielded 60
6. A process for the'production of a cyclohexyl
a light yellow, viscous liquid having a boiling
ester of a carboxylic acid which comprises react
range of 140° to 154° C. at a pressure of 2 mm.
ing cyclohexene and the nitrile of the said car
boxylic acid in the presence of aqueous sulfuric
of mercury. The yield of this ester, based on
the nitrile charged, was about 20 per cent of
acid and at a temperature within the range of
65 approximately 40° to approximately 100° C. under
the theoretical.
Example V
pressure sufficient to maintain liquid phase.
Cyclohexyl propionate was prepared from a
mixture of 246 g. (approximately 3 mols) of
cyclohexene, 55.2 g. of propionitrile (approxi
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