2,369,182
Patented Feb. 13, 1945
UNITED. STATES PATENT ‘OFFICE,
v CONTROLLED OXIDATION OF UNSATU
RATED ORGANIC COMPOUNDS
Frederick F. Rust and William E. Vaughan,
Berkeley, Calif., assignors to Shell Development ‘
Company, San Francisco, Calif., a corporation
. of Delaware
No Drawing. Application March 27, 1943,
I
-
Serial No. 480,862
12 Claims.
7
This invention relates to the controlled oxida
(Cl. 260—533)
treated. Finally, it is desirable to obtain unsatu
rated carboxylic acids from unsaturated organic
tion of unsaturated organic compounds, and more
particularly pertains to the catalytic controlled
oxidation of unsaturated organic compounds to
produce valuable oxygenated products, such as
‘ compounds, and particularly unsaturated car
boxylic acids containing the > same number of
unsaturated carboxylic acids, saturated and/or
rial, rather than the aforesaid mixtures predom
inating in saturated oxygenated compounds con
unsaturated ketones, and the like, which contain
carbon atoms per molecule as the primary mate
taining varied numbers of carbon atoms per
the same number of carbon atoms per molecule
molecule.
'
as the primary. material treated. In one of its
It is the main object of the present invention
more speci?c embodiments, the invention is di 10
to provide a novel process whereby predeter
rected to the catalytic oxidation of unsaturated
mined unsaturated oxygenated organic com
aliphatic and/or alicyclic hydrocarbons to pro
pounds, and particularly unsaturated carboxylic
duce unsaturated carboxylic acids, saturated
acids, may be obtained. Another object is to pro
and/or unsaturated ketones, and other unsatu
rated oxygenated hydrocarbons having the same 15 vide a process for the production ‘of unsaturated
number of carbon atoms per molecule as the un
carboxylic acids having the same number of car
saturated hydrocarbon subjected to oxidation.
bon atoms per molecule as the'starting organic
The oxidation of various organic compounds
has been effected for a number of years both
material treated. Still another object of the in
vention is to provide a process whereby unsatu- -
non-catalytically and in the presence of cata 20 rated organic compounds, particularly unsatu
rated aliphatic and/or alicyclic hydrocarbons,
lysts. As a general rule, most if not all of these
may be catalytically and directionally treated to
oxidations resulted in considerable decomposition,
produce economic yields of unsaturated oxygen
i. e. cleavage of the carbon-to-carbon bonds of
ated compounds, especially unsaturated car
the organic starting material. Also, the products
of reaction of such oxidations usually contained 25 boxylic acids. A still further object is to provide
a. novel process for the controlled catalytic ox
various percentages of hydrocarbons which had
idation of aliphatic and/or‘ alicyclic unsaturated
been oxidized to a greater or' lesser extent. For
‘' hydrocarbons having three or more carbon atoms
instance, the catalytic oxidation of aliphatic hy
per molecule to form the corresponding unsatu
drocarbons, whether they be saturated or unsatu
.rated, in accordance with the teachings of the 30 rated carboxylic acids, as well as other valuable
oxygenated compounds, such as the saturated or
prior art, formed mixtures containing various
percentages of aldehydes, alcohols, acids, acetals,
unsaturated ketones and‘ peroxides‘ having the
esters, ketones and other oxygenated compounds.
These various oxygenated compounds contained
same number of carbon atoms per molecule as
the starting organic material treated. The ‘term
varied numbers of carbon atoms per molecule due 35 “ketone,” as employed herein, refers to organic‘
compounds having one or more carbonyl groups,
to the carbon-to-carbon scission as well as to
and therefore includes diketones.
‘
\
other side-reactions, such as polymerization or
It has now been discovered that the above and
condensation. Also, the oxidation of unsaturated
other objects may be attained by eiiecting~ the
hydrocarbons according to the prior art processes
formed saturated oxygenated compounds which 40 partial oxidation in the ‘presence of hydrogen
bromide. More speci?cally stated, the invention
usually contained a lesser number of carbon
resides in the partial and controlled oxidation of
atoms vper molecule than the unsaturated hydro
unsaturated organic compounds, particularly. of
carbons subjected to oxidation.
unsaturated aliphatic and/or alicyclic hydrocar
Although most of the oxygenated organic com
pounds iormed as a result of the partial oxida 45 bons, in the presence 01 a catalyst consisting of
or comprising a hydrogen bromide, or of a com
tion of hydrocarbons according to the known
pound capable of yielding hydrogen bromide un
processes are generally more valuable than the
der the operating conditions. In one of its more
primary materials subjected to such oxidation,
speci?c embodiments, the invention resides in the
it is frequently desirable to obtain predominantly
production of unsaturated carboxylic acids and,
carboxylic acids and/or ketones rather than mix
to a certain degree, oi ketones, peroxides and/or
tures containing them and large amounts of other
various more or less oxygenated substances. Also,
halo-substituted derivatives, by the partial, con
trolled oxidation of hydrocarbons containing at
it is often desirable to obtain oxygenated com
pounds having the same number 01 carbon atoms
least one unsaturated double bond, by subjecting
this primary material, in the. presence of a hy
per molecule as the starting organic material
/
l
2
2,369,182
bustion and therefore decomposition of the fear
bon structure of the starting organic material.
on the character of the unsaturated hydrocar
bon treated. For instance, unsaturated hydro
carbons containing a terminal methyl radical,
particularly when such radical is directly at
tached to an unsaturated carbon atomof sec
ondary character, tend to produce unsaturated
carboxylic acids, whereas unsaturated hydrocar
yielding it under the employed operating condi
tions, besides retarding the explosion or com
plete combustion of the starting unsaturated or
of the carbon structure occurs. This upper tem
30 perature will at least in part depend on the spe
ci?c organic substance treated as well as on the
drogen bromide, or a substance capable of yield
ing hydrogen bromide under the operating con
ditions, to the action of oxygen under temper
ature and pressure conditions which are below
those vcapable of causing the spontaneous com- ,
bons which do not have such a terminal methyl
The above—outlined invention is predicated on
radical may form oxygenated compounds pre
the discovery that the presence of hydrogen bro
mide, during the oxidation of the above-men 10 dominating in or containing saturated ketonic
compounds. Also, unsaturated aliphatic hydro
tioned and hereinbelow more fully described un
carbons containing a, saturated tertiary carbon
saturated organic compounds (particularly when
atom directly linked to an unsaturated carbon
the reaction is e?ected in the vapor phase and
‘atom may form the corresponding tertiary al
under the hereinbelow outlined operating con
ditlons), controls the oxidation reaction so as to 15 kenyl hydro-peroxide and/or di(tertiary alkenyl)
peroxide. For example, whereas butene-1, when
cause the oxygen to react with a saturated car
subjected to the controlled oxidation in accord
bon atom instead of affecting the unsaturated
ance with the process of the present invention,
or double bond of the starting organic material.
produces 3-oxy-butene-1, isopropyl ethylene may
For example, when propylene is subjected to oxi
dation in accordance with the present process, 20 form 3-methyl-3-hydroperoxy-butene-1, and the
corresponding~di(tertiary alkenyl) peroxide.
the resultant reaction mixture will contain oxy
It was stated above that the non-explosive,
genated compounds predominating in acrylic
slow and controlled oxidation of the above-de
acid, thus clearly illustrating the directional
scribed class of unsaturated organic compounds
catalytic effect of hydrogen bromide during the
partial and controlled oxidation of the mentioned 25 is e?ected in accordance with the process of the
present invention at elevated temperatures which
unsaturated organic compounds in the presence
are below those at which spontaneous combus
of hydrogen bromide. Also, the presence of the
tion or substantial degradation or decomposition
hydrogen bromide or of compounds capable of
ganic material, apparently inhibits decomposi
tion of the carbon structure of such organic ma
terials, so that the resultant mixture predomi
proportions thereof and or of the oxygen and
hydrogen bromide present in the mixture sub
jected to the elevated temperatures. For in
nates in oxygenated compounds containing the 35 stance, generally speaking, other conditions be
ing equal, an increase in the hydrogen bromide
same number of carbon atoms per molecule as
content of a mixture will usually lower the tem
the starting organic material subjected to oxi
perature at which spontaneous combustion will
dation in accordance with the present process.
occur. Also, it must be noted that excessively
The unsaturated organic compounds which
may be oxidized according to the process of the 40 high temperatures, even though they may be be
low the explosive region, should be avoided be
present invention include aliphatic and alicyclic
cause of certain undesirable side-reactions, such
hydrocarbons which contain one or more ole?nic
as excessive conversion of hydrogen bromide to
linkages between carbon atoms which may be of
alkyl or alkenyl bromides. Generally, it may be
primary, secondary or tertiary character. In‘ or
der to produce unsaturated carboxylic acids, 45 stated that for the lower boiling unsaturated
aliphatic and alicyclic hydrocarbons, the upper
these'unsaturated hydrocarbons should contain 7
temperature limit is in the neighborhood of 225°
at least three carbon atoms per molecule. Ex
0., although with shorter contact periods this
amples of hydrocarbons which may be oxidized
temperature may be raised to approximately 250°
according to the present process are ethylene,
propylene, butene-l, butene-2, isobutylene, pen
tene-l, pentene-2, 3-methyl-butene-1, 2-methyl
butene - 1, 2 - methyl - butene - 2, hexene' - 2, 4
methyl-pentene-2, hexene-3, octene-2, cyclopen~
tene, cyclo-hexene, 3-methyl cyclohexene, hexa
diene-2,4, and their homologues and alkylated
derivatives. Halogenated unsaturated organic
‘ C., or even somewhat higher.
Some of the more
readily oxidizable unsaturated compounds may
be economically oxidized in accordance with the
present process at temperatures as low as about
150° C. With further decrease in the operating
temperature‘ the output of the product per unit
time will decrease so that at temperatures of
below about 100° C. the controlled oxidation in
compounds containing one or more halogen (i. e.
the presence of the aforementioned catalysts may
chlorine, bromine, iodine and/or fluorine) atoms
become uneconomical.
and one or more ole?nic linkages, may also be
The reaction may be effected in the liquid~or
oxidized according to this process. Examples of tit)
such halogenated hydrocarbons are allyl halides,
z-halo-propylene, crotyl halides, 3-halo-cyclo
vapor phase, or in a two-phase liquid-vapor
system. Since it is di?lcult to maintain a de
sirable relatively high oxygen concentration
when .the reaction is conducted in the liquid
compounds, such as the unsaturated alcohols of 65 phase, it is generally preferred to effect the
oxidation according to the present invention in
the type of allyl alcohol, as well as acids, keto
the vapor phase. Some of the relatively higher
acids, and the like, may also be used as the start
boiling compounds cannot be effectively main
ing materials. However, the present invention
tained in the vapor phase and in contact with
is particularly applicable to the controlled oxida
tion of the lower homologues of the aforemen 70 su?icient concentrations of oxygen and of hy
drogen bromide without causing the spon
tioned unsaturated hydrocarbons. In this con
taneous combustion of such a mixture. The
nection it must be noted that the character of
oxidation of .such unsaturated organic" com
the oxygenated compound formed as a result of
pounds of the de?ned class may be readily ef
the oxidation in accordance with the process of
the present invention will at least in part depend 76 fected in the presence of inert diluents or car
pentene, 3-halo-cyclohexene, and the like, and
their homologues. Other unsaturated organic
9,869,189
3
riers such as steam, nitrogen, carbon dioxide
and even methane, which latter is relatively
stable at the temperatures at which the above
.mentloned unsaturated organic compounds may
be oxidized e?ectively according to the present
invention. Although nitrogen is a, highly suit
the reactants, i. e. oxygen and the unsaturated
able ‘diluent, the use of steam is generally con
sidered to be most advantageous because hy
drogen bromide may then be removed from the
reaction zone may also vary, and is at least in part
dependent on the other operating conditions,
organic compound, at various points along the
reaction-‘zone. Such operation may be fre
quently desirable to control the operating con
ditions, e. g. temperature, in the reaction zone.
The residence time of the reactants in the,
such as the specific unsaturated organic material '
reaction mixture as'an overhead fraction in the 10 treated. the ratio thereof to the oxygen and/or
form of its constant boiling mixture of hydrogen ' "the catalyst, the presence or absence of inert
bromide and water.
-
diluents, the operating temperatures and pres
‘
‘sures, etc. In a continuous system, it has been
found that satisfactory yields of the desired un
The volumetric ratios of oxygen to the un
saturated organic starting material may varyv . -
within relatively wide limits. It may be gen-' 15 saturated carboxylic acids and/or of the ketones,.___
may be obtained with space velocities of be
erally stated that satisfactory yields of the de-'
sired, oxygenated product or products may be ' tween about 12 and about 20, although higher
obtained ‘by using at least equivolumetric quan-"
» or lower space velocities may also be employed. '
tities of these two substances. An increase in the
amount of orwgen in the treated mixture usually 20
increases the yield of the desired unsaturated»
carboxylic acids. However, any undue increase '
in the ratio of oxygen to the starting mate-,
rial is generally dangerous because of excessive
explosion hazards. On the other hand, the use 25
of oxygen-to-hydrocarbon or oxygen-to-organic
compound ratios which are considerably below
ical, although operable, it being noted that
the lowering of the oxygen-to-starting mate-
rial ratio usually causes a faster consumption
of oxygen per unit of time. Since the hydrogen
bromide apparently acts as an explosion retard
ant or inhibitor it is possible to employ mixtures
vume of reaction space per hour.
i
Instead of using individual unsaturated or
ganic compounds, e. ‘g. individual unsaturated
aliphatic or alicyclic hydrocarbons, it is possible
to employ mixtures thereof. Also, instead of
using pure or substantially pure oxygen for the ‘
"oxidation in accordance with the present proc
equivolumetric'will normally lower the output of
the desired product or products per unit of time
because of the presence of less oxygen per unit
of space. This renders the process less econom
The term “space velocity” as employed‘ refers to
the volume ‘of the vapors of the unsaturated‘
organic material conveyed through a unit vol
"ess, it is possible to employ oxygen-containing
so
mixtures such as air, or even substances capable
of yielding molecular oxygen under the operating
conditions. Furthermore, although the ex
' -amples presented hereinbelow are directed
speci?cally to the use of hydrogen bromide as
35 the catalyst, the process of the present inven
tion may also be realized by using substances
capable of yielding hydrogen bromide under the
which contain excess quantities of oxygen. . This
' operating conditions employed.
yields of the desired oxygenated product or
The invention is illustrated by the following
speci?c examples, it being understood that there
products.
isno intention of being limited by any details. -
in turn results in the production of higher '
'
‘
The amount of hydrogen bromide, as the: I thereof, since many variations may be made
catalyst may also vary within relatively wide '- within thescope of the claimed invention.
limits, although optimum amounts orpercent
Example I
ages may be readily determined for each in 45
A
Pyrex
glass
reactor
was employed and was
dividual starting material treated and for the‘
provided with a vapor bath 'to maintain the re
speci?c operating conditions employed. Gener
actants at- a constant and desired temperature
ally speaking, the percentage of oxygen. which
throughout the reaction. A 2:211 vaporous mix
will react to form the desired oxygenated prod-_
uct or products will vary with a change in the 50 ture of propylene, oxygen and hydrogen bromide,
respectively,'was conveyed through thereactor
hydrogen bromide concentration in the mixture
at a space velocity of about 15, while the reaction
subjected to treatment. This is particularly true
temperature was maintained at about 224° C. An
in the case of the lower hydrogen bromide con
analysis of the reaction mixture showed that
centrations, i.e, when relatively small percent
ages of the hydrogen bromide are employed. 55 the yield, as based on the consumed propylene,
Very high hydrogen bromide concentrations will
was as follows:
Per cent
cause excessive dilution and thus decrease the
Organic acids
‘
18.5
output of the desired product or products.
Carbonylic compounds __________________ __ 5.3
The oxidation in accordance with the proc
18.5
ess of the present invention may be effected at sov Allyl bromide
atmospheric pressures although higher or lower
The organic acids predominated in acrylic acid,
pressures may also be employed. In fact, it is
while the principal carbonylic compound formed
generally preferable to employ superatmospheric
pressures because more of the mixture subjected
was found to be bromo-acetone.
Example II
unit of reaction space per unit of time. 1
A 2:2:1 vaporous mixture of butene-Z, oxygen
The invention may be executed in a batch,
' and hydrogen bromide, respectively, was conveyed
intermittent or continuous manner. vWhen
through the reactor mentioned in the previous
operating in a continuous system' all of the re
example. The reactor was maintained at a tem
70
actants as well as the diluents, if any of the
perature of about 217° C., while the space ve
latter are used, and the catalyst may be first
locity ‘employed was equal to about 15. It was
mixed, and the mixture then conveyed through
found that the yield of crotonic acid was equal to
the whole length of the reaction zone. In the
to treatment may be conveyed through a given 65
about 16%, the yield of diacetyl was about 2.3%,
alternative, it is possible to introduce at least a
and
the yield of unsaturated bromides was about
75
part of the catalyst and/or of one or both of
.
‘4
' 2,889,182
‘25%. These percentages are based on the con
oxygenated products which comprises subjecting
sumed butylene. In addition to the above reac
a vaporous mixture containing an unsaturated
aliphatic hydrocarbon and oxygen to the action‘
tion products, minor amounts of crotonaldehyde
‘and acetaldehyde were also found in the reac
‘ tion products.
of hydrogen bromide at a temperature of between
about 100° C. and the spontaneous combustion
~ ‘
Example III
temperature of the mixture, and~efiecting the
E
reaction for a period of time 'suiiicient to cause
A vaporous mixture consisting of one part of
the controlled catalytic oxidation of the unsat
cyclohexene, one part of hydrogen bromide, four
urated aliphatic hydrocarbon.
'
'
.
‘parts of oxygen, and four parts of nitrogen (em 10
6. A process for the production of cyclohex
,ployed as a diluent) was conveyed through the
above-mentioned reactor at a space velocity of
I slightly over 15%. The reaction temperature was
‘maintained at about 193° C. An analysis of the
‘reaction products showed that about 6.3% of the 15
‘ cyclohexene introduced was converted to a ketone
I identi?ed as A’cyclohexenone.
enone which comprises subjecting a vaporous
mixture containing cyclohexene and oxygen to
the action oi‘ hydrogen bromide at a temperature
of about 200° C. and for a period of time sum
cient to e?ect the controlled catalytic oxidation
of the cyclohexene and recovering cyclohexenone
from the resultant reaction mixture.
7. The process according to .claim 6 wherein
an inert diluent is employed as a carrier for the
The alkenyl bromides, which are formed as a
‘result of side reactions between the starting or
ganic material and the hydrogen bromide cata
cyclohexene.
lyst are valuable compounds and ?nd a wide use 20
8. A process for the production of cyclohex
in the various chemical industries. However, if
enone which comprises subjecting a vaporous
desired, they may be subjected to further oxida
mixture containing cyclohexene and oiwgen to
the action of hydrogen bromide at an elevated
temperature which is below the spontaneous com
lbrominated and/or unhalogented oxygenated 25 bustion temperature of the mixture, effecting the
tion in accordance with the process of the pres
;ent invention to produce added amounts of
1 products, e. g. substituted or unsubstituted unsat
‘ urated carboxylic acids.
We claim as our invention:
reaction for a period of time su?icient to cause
the controlled catalytic oxidation of the cyclo
hexene and recovering cyclohexenone from the
1. A process for the production of acrylic acid
resultant reaction mixture.
30
and allyl bromide which comprises subjecting a
9. A process for the production of desirable
vaporous mixture containing substantially equi
oxygenated products and unsaturated halogenat
‘volumetric quantities of propylene and oxygen,
ed products which comprises subjecting a va
‘at substantially atmospheric pressure and at a
porous mixture containing an'unsaturated alicy.
temperature of about 225° C., to the action of 35 clic hydrocarbon and oxygen to the action of
}
hydrogen bromide catalyst for a period of time
hydrogen bromide at an elevated temperature
sufficient to e?ect the controlled catalytic oxida ‘ 1 which is below the spontaneous combustion tem
tion of the propylene, and recovering acrylic acid
perature of the mixture, and eifecting the re
and allyl bromide from the reaction mixture thus
action for a period of time suilicient to cause the
formed.
40 controlled catalytic oxidation of the unsaturated
2. A process for the production of acrylic acid
alicyclic hydrocarbon. '
which comprises subjecting a vaporous mixture 10. In a process for the production of desir
of propylene and oxygen to the action of hydro
able oxygenated products and unsaturated halo
gen bromide at a temperature of between about
genated products, the steps of subjecting vapors
100° C. and the temperature at which sponta 45 of a compound selected from the class consisting
of unsaturated aliphatic and alicyclic hydrocar
neous combustion occurs, e?'ecting the reaction
for a period of time su?icient to cause the con
bons to the action of oxygen in the presence of
trolled catalytic oxidation of the propylene, and
hydrogen bromide, and effecting the reaction at
recovering acrylic acid from the reaction mix
a temperature of between about 100° C. and the
50 spontaneous combustion temperature of the mix
ture thus formed.
3. A process for the production of crotonic acid
ture.
and of diacetyl which comprises subjecting a va—
11. In a process for the production of desirable
porous mixture containing substantially equi
products, the step of subjecting vapors of an un
volumetric quantities of butene-2 and of oxygen,
saturated organic compound containing an ole
at substantially atmospheric pressure and at a
?nic linkage between two carbon atoms of all
temperature of about 200° C., to the action of
phatic characterto the action of oxygen in the
hydrogen bromide for a period of time sui?cient
presence of hydrogen bromide and at a temper
to effect the controlled catalytic oxidation of the
ature of between about 100' C. and the temper
_ butylene, and separately recovering crotonic acid
ature at which spontaneous combustion and the
‘ and diacetyl from the resultant reaction mixture. 60 resultant decomposition of the carbon structure
of the starting unsaturated organic compound oc
4. A process for the production of crotonic acid
' which comprises subjecting a vaporous mixture
our.
containing butene-2 and oxygen to the action of
12. In a process for effecting controlled oxida
, hydrogen bromide at a temperature of between
tion and for the production of desirable oxygen
about 100° C. and the temperature at which spon
65 ated products, the step of subjecting an unsat- .
taneous combustion occurs, effecting the reaction
‘ for a period of time su?icient to cause the con
trolled catalytic oxidation of the butylene and
recovering crotonic acid from the resultant re
action mixture.
5. A process for the production of desirable
to
urated organic compound to the action of oxygen
and of hydrogen bromide at a temperature of
between about 100° C. and the temperature at
which spontaneous combustion occurs.
FREDERICK F. RUST.
WILLIAM E. VAUGHAN.
vCERTIFICA'I'E OF CORRECTION.
- Patent No. 2,569,182.
February 15-, 1915.
I FREDERICK F; RUST, ET AL.
It-is hereby certified that error appears in the. printed specification
of the above numbered patent requiring correction as follows: Page 1;, sec
and column, lines 21;. and 25, aiid‘lines 56 angi 37, tlaims 8 and 9 respec-i
tively, for "an elevated temperature which is below'f read --—,a temperature
of between about 100° 0'. and"; and that the said Letters Patent should be
read with this eorreetion therein that 'the same may confom to the record
of the case in the Patent Office.
'
v
Signed and sealed this 27th day of'November,. A. D. "1914.5.
- Leslie Frazer
(SeaI)
First Assistant Commissioner oi’ Patents.