U.S. patent application number 09/883538 was filed with the patent office on 2001-11-08 for method for producing trimethylhydroquinone.
This patent application is currently assigned to Nippon Petrochemicals Company Limited. Invention is credited to Kiyota, Noboru, Konishi, Tomohiro, Matsumura, Yasuo, Suyama, Kazuharu.
Application Number | 20010039366 09/883538 |
Document ID | / |
Family ID | 26417847 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010039366 |
Kind Code |
A1 |
Suyama, Kazuharu ; et
al. |
November 8, 2001 |
Method for producing trimethylhydroquinone
Abstract
An inexpensive method for producing trimethylhydroquinone free
from the problem of the disposal of waste catalyst, which method
comprises the steps of: (1) reacting isophorone in the presence of
an acid catalyst and recovering .beta.-isophorone by distiiulation,
(2) oxidizing the .beta.-isophorone in the presence of amorphous
carbon and a base to obtain 4-oxoisophorone, (3) reacting the
4-oxoisophorone with an acid anhydride in a liquid phase or with a
carboxylic acid in a vapor phase in the presence of a solid acid
catalyst to obtain trimethylhydroquinones, and (4) hydrolyzing the
trimethylhydroquinones to obtaining trimethylhydroquinone.
Inventors: |
Suyama, Kazuharu;
(Nerima-ku, JP) ; Kiyota, Noboru; (Yokohama-shi,
JP) ; Konishi, Tomohiro; (Kawasaki-shi, JP) ;
Matsumura, Yasuo; (Yokohama-shi, JP) |
Correspondence
Address: |
HOLLANDER LAW FIRM, P.L.C.
SUITE 305
10300 EATON PLACE
FAIRFAX
VA
22030
|
Assignee: |
Nippon Petrochemicals Company
Limited
|
Family ID: |
26417847 |
Appl. No.: |
09/883538 |
Filed: |
June 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09883538 |
Jun 18, 2001 |
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09573624 |
May 17, 2000 |
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09573624 |
May 17, 2000 |
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09123318 |
Jul 28, 1998 |
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6211418 |
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Current U.S.
Class: |
568/771 |
Current CPC
Class: |
C07C 67/00 20130101;
C07C 69/017 20130101; C07C 69/16 20130101; C07C 39/08 20130101;
C07C 67/00 20130101; C07C 67/00 20130101 |
Class at
Publication: |
568/771 |
International
Class: |
C07C 039/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 1997 |
JP |
9-221044 |
Mar 10, 1998 |
JP |
10-76712 |
Claims
What is claimed is:
1. A method for producing trimethylhydroquinone comprising the
steps (1) to (4) of: (1) reacting isophorone in the presence of an
acid catalyst and recovering .beta.-isophorone by distillation; (2)
oxidizing said .beta.-isophorone in the presence of amorphous
carbon and a base to obtain 4-oxoisophorone; (3) reacting said
4-oxoisophorone with at least one member selected from the group
consisting of acid anhydrides and carboxylic acids in the presence
of a solid acid catalyst to obtain at least one compound
represented by the following general formula [I]: 3wherein each of
R.sub.1 and R.sub.2 is a hydrogen atom or an acyl group and both
may be the same or different ones; and (4) hydrolyzing the compound
having an acyl group or groups in the reaction product obtained in
said step (3), thereby obtaining trimethylhydroquinone.
2. The method for producing trimethylhydroquinone in claim 1,
wherein the reaction in said step (3) is done in a liquid phase
using said acid anhydride.
3. The method for producing trimethylhydroquinone in claim 1,
wherein the reaction in said step (3) is done in a vapor phase
using said carboxylic acid.
4. The method for producing trimethylhydroquinone in claim 1,
wherein said oxidation in said step (2) is done using molecular
oxygen.
5. The method for producing trimethylhydroquinone in claim 1,
wherein said solid acid catalyst in said step (3) is an acidic ion
exchange resin catalyst.
6. The method for producing trimethylhydroquinone in claim 1,
wherein said solid acid catalyst in said step (3) is silica-alumina
catalyst.
7. The method for producing trimethylhydroquinone in claim 2,
wherein said acid anhydride is acetic anhydride.
8. The method for producing trimethylhydroquinone in claim 3,
wherein said carboxylic acid is acetic acid.
9. The method for producing trimethylhydroquinone in claim 1,
wherein the reaction product in said step (3) is at least one
member selected from the group consisting of trimethylhydroquinone,
4-acetoxy-2,3,6-trimethylp- henol, 4-acetoxy-2,3,5-trimethylphenol
and trimethylhydroquinone diacetate.
10. The method for producing trimethylhydroquinone in claim 1,
wherein the compound having an acyl group or groups in said step
(4) is at least one member selected from the group consisting of
4-acetoxy-2,3,6-trimethylphe- nol, 4-acetoxy-2,3,5-trimethylphenol
and trimethylhydroquinone diacetate.
11. A method for producing trimethylhydroquinone comprising:
oxidizing .beta.-isophorone in the presence of amorphous carbon and
an oxidation-resistant nitrogen-containing heterocyclic base to
obtain 4-oxoisophorone and to separate 4-oxoisophorone by
distillation to obtain highly pure 4-oxoisophorone; reacting said
highly pure 4-oxoisophorone in a liquid phase with an excess of an
acid anhydride in the presence of a solid acid catalyst to obtain
at least one compound represented by the following formula [I]:
4wherein R.sub.1 and R.sub.2 may be the same or different and are
selected from hydrogen or an acyl group; recovering at least part
of unreacted acid anhydride; and hydrolyzing compounds having at
least one acyl group in the obtained reaction product represented
by formula [I], thereby obtaining trimethylhydroquinone.
12. A method for producing trimethylhydroquinone as claimed in
claim 11, wherein said solid acid catalyst is selected from the
group consisting of acid ion exchange resin, silica-alumina,
alumina, silica, zeolite, natural clay minerals or an inorganic
acid supported on a porous inorganic carrier.
13. A method for producing trimethylhydroquinone as claimed in
claim 11, wherein said oxidation of .beta.-isophorone is conducted
in the presence of molecular oxygen as an oxidizing agent.
14. A method for producing trimethylhydroquinone as claimed in
claim 11, wherein said acid anhydride is acetic anhydride.
15. A method for producing trimethylhydroquinone as claimed in
claim 11 wherein the reaction product represented by the formula
[I] is at least one compound selected from trimethylhydroquinone,
4-acetoxy-2,3,6-trimeth- ylphenol, 4-acetoxy-2,3,5-trimethylphenol
or trimethylhydroquinone diacetate.
16. A method for producing trimethylhydroquinone as claimed in
claim 11 wherein the compound having at least one acyl group is
selected from 4-acetoxy-2,3,6-trimethylphenol,
4-acetoxy-2,3,5-trimethylphenol or trimethylhydroquinone
diacetate.
17. A method for producing trimethylhydroquinone as claimed in
claim 11, wherein said .beta.-isophorone is obtained by reacting
isophorone in the presence of an acid catalyst and recovering
.beta.-isophorone by distillation.
18. A method for producing trimethylhydroquinone 20 comprising:
oxidizing .beta.-isophorone in the presence of amorphous carbon and
an oxidation-resistant nitrogen-containing heterocyclic base to
obtain 4-oxoisophorone and to separate 4-oxoisophorone by
distillation to obtain highly pure 4-oxoisophorone; reacting said
highly pure 4-oxoisophorone with at least one member selected from
acid anhydrides or carboxylic acids in the presence of a solid acid
catalyst to obtain at least one compound represented by the
following formula [I]: 5wherein R.sub.1 and R.sub.2 may be the same
or different and are selected from hydrogen or an acyl group; and
hydrolyzing compounds having at least one acyl group in the
obtained reaction product represented by formula [I], thereby
obtaining trimethylhydroquinone.
19. A method for producing trimethylhydroquinone as claimed in
claim 18, wherein said oxidation of .beta.-isophorone is conducted
in the presence of molecular oxygen as an oxidizing agent.
20. A method for producing trimethylhydroquinone as claimed in
claim 18, wherein said amorphous carbon is an activated carbon.
21. A method for producing trimethylhydroquinone as claimed in
claim 18, wherein said oxidation-resistant nitrogen-containing
heterocyclic base is pyridine.
22. A method for producing trimethylhydroquinone as claimed in
claim 18, wherein the reaction product represented by formula [I]
is at least one compound selected from trimethylhydroquinone,
4-acetoxy-2,3,6-trimethylph- enol, 4-acetoxy-2,3,5-trimethylphenol
or trimethylhydroquinone diacetate.
23. A method for producing trimethylhydroquinone as claimed in
claim 18 wherein the compound having at least one acyl group is
selected from 4-acetoxy-2,3,6-trimethylphenol,
4-acetoxy-2,3,5-trimethylphenol or trimethylhydroquinone
diacetate.
24. A method for producing trimethylhydroquinone as claimed in
claim 18, wherein said .beta.-isophorone is obtained by reacting
isophorone in the presence of an acid catalyst and recovering
.beta.-isophorone by distillation.
25. A method for producing 4-oxoisophorone comprising: oxidizing
.beta.-isophorone in the presence of amorphous carbon and an
oxidation-resistant nitrogen-containing heterocyclic base to obtain
4-oxoisophorone.
26. A method for producing 4-oxoisophorone as claimed in claim 25
wherein said method further comprises a step for separating
4-oxoisophorone by distillation to obtain highly pure
4-oxoisophorone.
27. A method for producing 4-oxoisophorone as claimed in claim 25
wherein said heterocyclic base comprises pyridine.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] This invention relates to a method for producing
trimethylhydroquinone from isophorone. The trimethylhydroquinone is
a useful substance as an intermediate compound for preparing
vitamin E.
[0003] (2) Prior Art
[0004] The following methods are mainly known for preparing
trimethylhydroquinone.
[0005] In one of them, 2,3,6-trimethylphenol is sulfonated with
sulfuric acid and it is then oxidized with manganese dioxide
(Japanese Laid-Open Patent Publication No. 62-108835). This method
is not desirable because a large quantity of heavy metal waste is
produced, which have a large influence on environment. In addition,
the 2,3,6-trimethylphenol as a starting material is expensive, so
that the cost for the production of trimethylhydroquinone is
high.
[0006] Another method relates to chloro-oxidation of
2,4,6-trimethylphenol (Japanese Patent Publication No. 5-68456).
Because quite toxic chlorine is used as an oxidizing agent in this
method, the process is dangerous to be worked. In addition, when
organic chlorine compounds are generated as by-products, the cost
for the disposal of waste is expensive.
BRIEF SUMMARY OF THE INVENTION
[0007] It is, therefore, the object of the present invention to
provide an improved method for producing trimethylhydroquinone
without difficulty, which method can be worked in a low cost and
which is free from the problem in the disposal of waste
catalyst.
[0008] That is, the primary aspect of the present invention is a
method for producing trimethylhydroquinone comprising the steps of
(1) to (4):
[0009] (1) Reacting isophorone in the presence of an acid catalyst
and recovering .beta.-isophorone by distillation;
[0010] (2) oxidizing the above .beta.-isophorone in the presence of
amorphous carbon such as activated carbon and a base to obtain
4-oxoisophorone;
[0011] (3) reacting the above 4-oxoisophorone with at least one
member selected from the group consisting of acid anhydrides and
carboxylic acids in the presence of a solid acid catalyst to obtain
at least one compound represented by the following general formula
[I]: 1
[0012] wherein each of R.sub.1 and R.sub.2 is a hydrogen atom or an
acyl group and both of R.sub.1 and R.sub.2 may be the same or
different; and
[0013] (4) hydrolyzing the compound having an acyl group or groups
in the reaction product obtained in the step (3), thereby obtaining
the trimethylhydroquinone.
[0014] In the above step (3), when an acid anhydride is used, the
reaction is carried out in a liquid phase. On the other hand, when
a carboxylic acid is used, the reaction is carried out in a vapor
phase.
[0015] A second aspect of the present invention is that the acid
anhydride in the step (3) is acetic anhydride.
[0016] A third aspect of the present invention is that the solid
acid catalyst used in the step (3) is an acidic ion exchange
resin.
[0017] A fourth aspect of the present invention is that the product
in the step (3) is at least one member selected from the group
consisting of trimethylhydroquinone,
4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol
and trimethylhydroquinone diacetate.
[0018] A fifth aspect of the present invention is that the compound
having an acyl group or groups are at least one member selected
from the group consisting of 4-acetoxy-2,3,6-trimethylphenol,
4-acetoxy-2,3,5-trimethylp- henol and trimethylhydroquinone
diacetate.
[0019] According to the method of the present invention, the
trimethylhydroquinone can be produced easily in a low cost without
causing the problem of the disposal of waste catalyst.
DETAILED DESCRIPTION OF THE INVENTION
[0020] In the following, each preparation step will be described in
more detail.
[0021] Step (1)
[0022] [Reaction of Isophorone in the Presence of an Acid Catalyst
to Obtain .beta.-isophorone by Distillation]
[0023] In this step, isophorone is reacted by adding an acid
catalyst and .beta.-isophorone having a lower boiling point is
obtained by distillation. More particularly, it is possible to
produce .beta.-isophorone by reacting isophorone in the presence of
an acid catalyst, and then, the .beta.-isophorone is recovered by
distillation. In another mode of reaction, the distillation is
carried out while reacting isophorone in the presence of an acid
catalyst, thereby recovering the .beta.-isophorone. Because the
boiling point of .beta.-isophorone is lower than that of
isophorone, they can be separated by distillation without
difficulty.
[0024] In other words, the reaction to convert the isophorone to
.beta.-isophorone is an equilibrium reaction, so that when the
.beta.-isophorone is removed from the reaction system in the
progress of reaction, the equilibrium is shifted to one side, as a
result, the yield of .beta.-isophorone can be raised. Accordingly,
the so-called reactive distillation is preferable in this step (1),
in which the distillation is performed simultaneously with the
reaction of isophorone in the presence of an acid catalyst.
[0025] More particularly, when an acid catalyst in a liquid state
or in a solid state, the reaction can be done such that the mixture
of an acid catalyst and isophorone is put into an appropriate
distillation apparatus and distillation is carried out to take out
.beta.-isophorone from the distillation apparatus. With the mode of
reaction like this, the duration of distillation is the same as the
duration of reaction.
[0026] When the reactive distillation is employed, any of solid
acids and high boiling point liquid acids can be used as the acid
catalyst. The high boiling point liquid acids are exemplified by
organic acids such as adipic acid and p-toluenesulfonic acid,
inorganic acids such as phosphoric acid and sulfuric acid, which
have boiling points higher than those of starting materials and
reaction products. The solid acids are exemplified by synthetic
solid acid catalysts, natural clay solid acid catalysts, and other
solid acid catalysts which are prepared by supporting inorganic
acids on porous inorganic carrier substances.
[0027] Preferable solid acid catalysts are exemplified by synthetic
solid acid catalysts such as silica-alumina, alumina, silica and
zeolites, and natural clay minerals such as acid clay and activated
clay. When zeolite is used as a solid acid catalyst, those
containing hydrogen-zeolite such as HX-type zeolite, HY-type
zeolite USY-type zeolite, mordenite and ZSM-5 are preferalby
employed. Furthermore, it is possible to reduce the deposition of
carbon to a catalyst by causing the catalyst to support an alkali
metal such as sodium or potassium.
[0028] Besides the above catalysts, it is possible to use by
supporting one or a combination of inorganic acids such as
phosphoric acid, and heteropoly-acids of phosphotungstic acid,
silicotungstic acid and silicomolybdic acid on an appropriate
porous inorganic substance. More particularly, supported acid
catalysts in which an inorganic acid is supported on a porous
inorganic substance such as alumina, magnesia, silica and activated
carbon, can be used.
[0029] Among the above-mentioned solid acid catalyst, synthetic
solid acid catalysts, especially silica-alumina, HY-type zeolite,
USY-type zeolite, mordenite and ZSM-5 are preferably used in view
of their durability.
[0030] The duration of reaction is selected in the range of 1
minute to 200 hours in a batch-wise process.
[0031] The pressure of distillation for recovering
.beta.-isophorone is preferably lower than 1 MPa and it is not
inevitable to carry out reduced pressure distillation. If
appropriate, however, it is also possible to employ the reduced
pressure distillation in view of the fact that low temperature
operation is desirable in order to avoid the isomerization of
.beta.-isophorone. The type of distillation is not limited. When
distillation is done simultaneously with the reaction, it is
possible to distill together with the acid using a packed column
filled with a packing such as Dickson rings. In this case, the
reflux ratio is not limited, for example, it is selected in the
range of 1:1 to 100:1. For the distillation, any of continuous
distillation and batch-wise distillation can be employed. The
composition of isophorone and .beta.-isophorone in the distillate
varies according to the conditions of reflux ratio and the kind of
packing.
[0032] The .beta.-isophorone obtained in the above step (1) is fed
to the succeeding oxidation step. Because isophorone is hardly
oxidized in the oxidation reaction in the step (2), it is possible
to use the reactant of low purity .beta.-isophorone which is
obtained in the step (1). However, in order to facilitate the
refining in the subsequent process, it is preferable to raise the
purity of .beta.-isophorone by removing isophorone. In view of this
point, the purity of .beta.-isophorone to be fed into the step (2)
is in the range of 50 to 100%. When the purity of .beta.-isophorone
is low, it is possible to raise the purity by the re-distillation
in an ordinary manner without catalyst. Because .beta.-isophorone
is liable to be isomerized to isophorone, the above-mentioned
re-distillation is preferably done under reduced pressure.
[0033] Step (2):
[0034] [Oxidation of .beta.-isophorone in the Presence of Amorphous
Carbon such as Activated Carbon and a Base, and Preferably using a
Gas Containing Molecular Oxygen, to Obtain 4-axoisophorone]
[0035] In this step, .beta.-isophorone is oxidized in the presence
of amorphous carbon such as activated carbon and a base, and
preferably using a gas containing molecular oxygen to obtain
4-oxoisophorone. The amorphous carbons such as activated carbons
used in this step are not limited and they are exemplified by those
of coconut shell origin, coal tar origin, pitch origin and charcoal
origin. Furthermore, carbon black can also be used.
[0036] The specific surface area of the activated carbon is in the
range of 30 to 2,000 m.sup.2/g. The use quantity of the activated
carbon is 0.002 to 100 parts by weight, preferably 1 to 50 parts by
weight, and more preferably 5 to 30 parts by weight, per 100 parts
by weight of .beta.-isophorone. When the quantity of activated
carbon is less than 0.002 parts by weight, the oxidation is hardly
caused. On the other hand, when the quantity of activated carbon is
more than 100 parts by weight, the handling of reactants is
troublesome because the ratio of solid substance is too large in
batch-wise operation.
[0037] The bases preferably used in the method of the present
invention are nitrogen-containing bases, especially amines and
nitrogen-containing heterocyclic bases. The amines are exemplified
by triethylamine, trimethylamine, tri-n-propylamine,
triisopropylamine, tri-n-butylamine, tri-n-hexylamine,
trioctylamine, benzyldimethylamine, diethylamine, di-n-butylamine,
and dioctylamine.
[0038] The nitrogen-containing heterocyclic bases are exemplified
by pyridine, aminopyridine, chloropyridine, dichloropyridine,
cyanopyridine, dimethylaminopyridine, piperidinopyridine, pyridine
methanol, propylpyridine, pyrrolidinopyridine, 2,6-lutidine,
3,5-lutidine, 2,4-lutidine, 2,5-lutidine, 3,4-lutidine,
2,4,6-collidine, 1,3-di(4-piperidyl)propane, picoline, pipecoline,
pyridazine, pyrimidine, dichloropyridazine,
1,8-diazabicyclo[5.4.0]-7-undecene (DBU),
1,5-diazabicyclo[4.3.0]-5-nonene (DBN), pyrazine, methylpyrazine,
dimethylpyrazine, cyanopyrazine, pyrazole, dimethylpyrazole,
methylpyrazolone, piperazine, methylpiperazine, dimethylpiperazine,
morpholine, quinoline, isoquinoline, tetrahydroquinoline,
imidazole, methylimidazole, phenylimidazole, quinaldine,
triethylenediamine, piperidine, methylpiperidine, pyrrolidine,
phenanthroline, and melamine.
[0039] Aliphatic amine such as triethylamine can also be used.
However, the most part of triethylamine or the like is consumed by
oxidation during the reaction. When the amine is oxidized, amine
oxide is produced and it is further decomposed into low molecular
weight aldehyde and secondary amine. The boiling point of the
decomposition product of low molecular weight aldehyde is close to
the boiling points of reactants and reaction solvent, so that
difficulty is caused in the recovery of them by distillation.
Furthermore, it is inevitable to recycle the reaction solvent in
order to put the method into industrial practice economically,
however, the above decomposition product is disadvantageously
accumulated during the recycling operation.
[0040] Meanwhile, this problem can be solved by using an
oxidation-resistant base, i.e., a difficultly oxidizable base such
as a nitrogen-containing base. For this reason, an acid-resistant
nitrogen-containing heterocyclic base, more preferably, pyridine is
used in the method of the present invention.
[0041] In this oxidation reaction, it cannot be avoided that the
methyl group on the allyl position of .beta.-isophorone is oxidized
to produce a by-product of 5,5-dimethyl-3-oxo-1-cyclohexene
carbaldehyde as represented by the following structural formula
[II]. 2
[0042] The boiling point of this compound is quite close to that of
4-oxoisophorone, so that the separation from the 4-oxoisophorone is
difficult. When aliphatic amine such as triethylamine is used, the
selectivity to produce the above aldehyde is as large as 12%,
however, when a nitrogen-containing heterocyclic base such as
pyridine is used, the selectivity is seriously reduced to a value
as small as about 1%. In other words, it is quite advantageous that
the isolation and refining of 4-oxoisophorone can be done
economically without difficulty by using a nitrogen-containing
heterocyclic base, preferably pyridine, as the base.
[0043] Therefore, in this step, it is advantageous that the
contamination of reaction system due to the oxidative decomposition
and the generation of undesirable by-product can be avoided by
using the nitrogen-containing heterocyclic base, preferably
pyridine as a base.
[0044] The use quantity of the base is 0.1 to 1,000 moles,
preferably 1 to 100 moles, and more preferably 2 to 50 moles, per
100 moles of .beta.-isophorone. When the quantity of a base is less
than 0.1 mole, the oxidation hardly occurs. Even when more than
1,000 moles of a base is added, no problem is caused in the
reaction, however, the effect of excess addition can not be
expected any more. However, the base can be added in excess also as
a solvent.
[0045] The oxidation can be attained using an optional oxidizing
agent and it is done preferably using molecular oxygen. The
molecular oxygen may contain an inert gas such as nitrogen.
Accordingly, the oxidation in this step can be carried out by using
air. For example, the oxidizing step can be done by blowing an
oxygen-containing gas such as air into the reaction system.
[0046] The reaction temperature is selected in the range of 0 to
200.degree. C., preferably 20 to 140.degree. C., and more
preferably 30 to 120.degree. C. When the temperature is lower than
0.degree. C., the reaction hardly proceeds, so that a very long
reaction time is required. On the other hand, when the temperature
is higher than 200.degree. C., undesirable results occur in that
.beta.-isophorone is isomerized to isophorone and much
polymerization product is formed to reduce the yield of
4-oxoisophorone.
[0047] The mode of reaction may be any of batch-wise and
continuous. The continuous flow type reaction is desirable for
industrial production. When the continuous flow type reaction is
done, any type of fixed bed, moving bed and fluidized bed systems
can be employed.
[0048] The duration of reaction is not especially limited. For
example, in the case of batch-wise system, it is selected in the
range of 1 minute to 168 hours.
[0049] The pressure of reaction is in the range of 0.1 to 10 MPa.
When the pressure is lower than 0.1 MPa, the reaction rate is too
low. On the other hand, the pressure above 10 MPa does not cause no
trouble, however, it is not economical because a large scale
pressure-resistant reactor must be used. A preferable reaction
pressure is in the range of 0.5 to 6 MPa and more preferably it is
in the range of 0.6 to 4 MPa. With the pressure in these ranges,
the evaporation of reactants and solvent can be reduced
effectively. When no pressure is applied, the loss of materials
increases due to the evaporation and entrainment of contents with
the blowing of the oxygen-containing gas.
[0050] After the reaction, highly pure 4-oxoisophorone is obtained
from the reaction mixture by a suitable measure such as
distillation, crystallization, re-crystallization, or high pressure
crystallization, as occasion demands.
[0051] When the .beta.-isophorone obtained in the step (1) using
isophorone is fed as a reactant for this step, the
.beta.-isophorone sometimes contains the isophorone which was not
reacted in the step (1). However, because this unreacted isophorone
is hardly oxidized in the conditions of the step (2), when the
reactant containing the isophorone is used, it can be recovered in
this step and the recovered isophorone can be used as a feed
material for the step (1).
[0052] In the next step (3), 4-oxoisophorone obtained in the step
(2) is reacted with a carboxylic acid or a carboxylic acid
unhydride in a vapor phase or in a liquid phase in the presence of
a solid acid catalyst to obtain trimethylhydroquinone, its esters
or their mixture.
[0053] More particularly, this step (3) may be any one of the
following measures (3A) and (3B). That is, the step (3A) in which
4-oxoisophorone is reacted with an acid anhydride in a liquid phase
and the step (3B) in which 4-oxoisophorone is reacted with a
carboxylic acid in a vapor phase. In the purpose to produce
trimethylhydroquinone in the method of the present invention, any
of them can be employed.
[0054] In the first place, the step (3A) to react with an acid
anhydride in a liquid phase will be described, and then the step
(3B) to react with a carboxylic acid in a vapor phase will be
described.
[0055] Step (3A):
[0056] [Both of 4-oxoisophorone and an Acid Anhydride are Brought
into Contact with a Solid Acid Catalyst in a Liquid Phase to Obtain
at Least One Compound as Represented by the General Formula
[I]]
[0057] The acid anhydrides are exemplified by carboxylic anhydrides
such as acetic anhydride, formic anhydride, propionic anhydride,
butyric anhydride, isobutyric anhydride, valeric anhydride,
isovaleric anhydride, and oxalic anhydride. Among them, acetic
anhydride is preferable.
[0058] The ratio of coexisting acid anhydride is more than 2 moles
per 1 mole of 4-oxoisophorone, and the acid anhydride is used in
excess to some extent, however, it is not necessary to use in a
large excess. In the following, an example using acetic anhydride
is described.
[0059] The acetic anhydride serves as a solvent as well as a
reactant. Because the reaction in this step is carried out in
liquid state, the reaction can be done with an appropriate solvent.
When acetic anhydride which serves as a reactant as well as a
solvent is employed, the liquid phase reaction can be carried out
without another solvent, so that any other solvent is not always
fed. However, it is of course possible to use an additional
solvent. When acetic acid is used in place of the acetic anhydride,
even though their chemical structures resemble each other, the
selectivity for trimethylhydroquinone is very low.
[0060] It is preferable to carry out the reaction without the
existence of oxygen substantially in order to avoid the oxidation
of trimethylhydroquinone. Accordingly, it is possible to displace
the air in the reaction system with an inert gas or to supply a
small amount of inert gas into a reaction system, not only in a
flow type reaction system but also in a reaction system of any
other type, in order to prevent the reaction system from the
invasion of oxygen. As the inert gas to be fed, nitrogen is
preferable.
[0061] A solid acid catalyst is used in this step. Usable solid
acid catalysts are exemplified by synthetic solid acid catalysts
such as acidic ion exchange resin, silica-alumina, alumina, silica
and zeolite, and natural clay minerals such as acid clay and
activated clay. The acidic ion exchange resins are exemplified by
strongly acidic ion exchange resin and weakly acidic ion exchange
resin. When a zeolite is used as a solid acid catalyst, it is
possible to use those containing hydrogen-zeolite such as HX-type
zeolite, HY-type zeolite and hydrogen-faujasite. Besides them, it
is possible to use one or mixture of inorganic acids such as
phosphoric acid, and heteropoly-acids of phosphotungstic acid,
silicotungstic acid and silicomolybdic acid supported on an
appropriate porous inorganic carrier such as alumina, magnesia,
silica or activated carbon.
[0062] Among the above solid acid catalysts, the acidic ion
exchange resin is preferably used in view of its durability of
catalytic activity. More preferable one is strongly acidic ion
exchange resin catalyst. The usable strongly acidic ion exchange
resin has acid groups of sulfonic acid which are connected to
several resin structures such as cross-linked polystyrene skeletal
structure. As a commercially available product, Amberlyst 15E
(trade name, made by Japan Organo, Ltd.) can be used.
[0063] The advantage to use the solid acid catalyst in the method
of the present invention depends upon the fact that the reaction
process can be simplified and the recovery of acid anhydride and
carboxylic acid is easy. In the following, the process of the
present invention is compared with the case in which sulfuric acid
is used.
[0064] When sulfuric acid is used, it is necessary to neutralize
the aqueous liquid in order to remove catalyst after reaction. In
this process, unreacted acid anhydride is converted into carboxylic
acid by hydrolysis. Furthermore, because the carboxylic acid is
soluble in water, an additional step is required to recover pure
carboxylic acid.
[0065] Meanwhile, when solid acid catalyst is used, the catalyst
can be separated without difficulty after reaction, so that neither
the addition of water nor the neutralization is necessary. Because
no water is added, the unreacted acid anhydride is not subjected to
hydrolysis and the acid anhydride can be recovered as it stands.
The liquid obtained by the reaction is a mixture of
trimethylhydroquinones, unreacted feed materials, acid anhydride
and carboxylic acid produced by the reaction, so that this reaction
mixture can be refined by distillation or any other measure.
[0066] By using the solid acid catalyst as described above, the
treating process can be simplified and the recovery of unreacted
substances and the refining of reaction product are made easy to
produce economical advantages.
[0067] The reaction temperatures are determined in accordance with
the kind of used catalyst, the duration of contact between
reactants and catalyst, and the ratio of dilution of reactants to
reaction medium. It can be selected in the range of -40 to
300.degree. C., preferably 0 to 300.degree. C., and more preferably
10 to 150.degree. C. The reaction temperature above 300.degree. C.
is not desirable because side reactions increase and the coking of
catalyst is intensive to reduce seriously the selectivity. The
reaction temperature below -40.degree. C. is not desirable either
in economical viewpoint because the rate of intended reaction is
low.
[0068] The mode of reaction may be any of batch-wise and
continuous. The continuous flow type reaction is desirable for
industrial production. When the continuous flow type reaction is
done, any type of fixed bed, moving bed and fluidized bed systems
can be employed.
[0069] The pressure of reaction is not especially limited as far as
the reaction phase is maintained in liquid. The pressure may be 1
MPa or lower, preferably lower than 0.5 MPa, and more preferably
lower than 0.2 MPa.
[0070] The contact time between reactants and a catalyst both in
batch-wise reaction and continuous flow reaction is in the range of
1 second to 100 hours, preferably 1 minute to 50 hours. When the
contact time is shorter than 1 second, the degree of conversion is
low. If the contact time is longer than 100 hours, side reactions
occur, for example, the produced trimethylhydroquinone is
polymerized, as a result, the selectivity is lowered.
[0071] As described above, the products in the above reaction are
any one of or the mixture of trimethylhydroquinone,
4-acetoxy-2,3,6-trimethylphen- ol, 4-acetoxy-2,3,5-trimethylphenol
and trimethylhydroquinone diacetate. When the reaction product is a
mixture of the above compounds, its composition varies with
reaction conditions. However, any of the
4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol
and trimethylhydroquinone diacetate other than the
trimethylhydroquinone, can be converted into trimethylhydroquinone
by means of ordinarily known hydrolysis.
[0072] It is possible to obtain highly pure intended product from
the reaction mixture by distillation, crystallization,
re-crystallization or pressurized crystallization as occasion
demands.
[0073] When unreacted 4-oxoisophorone exists, it can be recovered
easily by distillation and be reused. The 4-oxoisophorone does not
pertain substantially to the reaction under the conditions of the
next step (4), so that it is serviceable as a inert solvent.
Accordingly, the reaction mixture of this step (3) can be fed to
the next step (4) without removing the unreacted 4-oxoisophorone
and, after the hydrolysis in the step (4), the 4-oxoisophorone may
be recovered.
[0074] Step (3B):
[0075] [Both of 4-oxoisophorone and a Carboxylic Acid are Brought
into Contact with a Solid Acid Catalyst in a Vapor Phase to Obtain
at Least One Compound as Represented by the General Formula
[I]]
[0076] The carboxylic acid in this step serves as a reactant. In
addition, when the reaction is done in a flow reaction system, it
serves also as a reaction medium. The carboxylic acids used herein
are exemplified by acetic acid, formic acid, propionic acid,
butyric acid, isobutyric acid, valeric acid, isovaleric acid,
oxalic acid, adipic acid, malonic acid and fumaric acid. Among
them, acetic acid, formic acid and propionic acid are preferable,
and the acetic acid is more preferable. In the following, the
example using the acetic acid will be described.
[0077] Because the acetic acid is used in excess, it serves as a
reaction medium as well as a reactant in a flow type reaction
system as described above. In the flow type reaction system, steam
is generally used as a medium. The steam is advantageous because it
is inexpensive and it condenses when it is cooled to facilitate the
recovery of reaction product. It is to be noted, however, that the
use of steam is not appropriate because the selectivity for
4-oxoisophorone to the compound represented by the formula [I]
(hereinafter referred to as "trimethylhydroquinones") is low.
[0078] As other mediums, nitrogen flow and hydrogen flow are
exemplified. They are, however, expensive. In addition, they cannot
be condensed by cooling them, so that reaction products are
entrained in the gas flow in the form of mist, which makes the
recovery of product difficult. Accordingly, this method is not
suitable for the industrial mass production.
[0079] When acetic acid is used, the recovery of reaction product
is easy because the acetic acid condenses when it is cooled.
Further important point is that the selectivity for
trimethylhydroquinones can be improved by the use of acetic acid.
When acetic anhydride, a derivative of acetic acid, is used as a
medium, the selectivity for trimethylhydroquinone is quite
worse.
[0080] In order to avoid the oxidation of trimethylhydroquinone, a
small amount of inert gas may be fed to the reaction system not
only in the flow system but also in any other reaction system. The
inert gas is preferably nitrogen.
[0081] When the acyl group or groups in the foregoing formula [I]
are an acetyl group or groups, the reaction product in this step is
at least one of trimethylhydroquinone,
4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol
and trimethylhydroquinone diacetate.
[0082] A solid acid catalyst is used in this step. Preferable solid
acid catalysts are exemplified by synthetic solid acid catalysts
such as silica-alumina, alumina, silica and zeolite, and natural
clay minerals such as acid clay and activated clay. When a zeolite
is used as a solid acid catalyst, it is possible to use those
containing hydrogen-zeolite such as HX-type zeolite, HY-type
zeolite and hydrogen-faujasite. It is preferable to use HY-type
zeolite, USY-type zeolite, mordenite and ZSM-5. Furthermore, it is
possible to reduce the deposition of carbon to catalyst by causing
the catalyst to support an alkali metal such as sodium or
potassium.
[0083] In addition, it is possible to use one or the mixture of
inorganic acids such as phosphoric acid, and heteropoly-acids of
phosphotungstic acid, silicotungstic acid and silicomolybdic acid
supported on an appropriate porous inorganic carrier.
Carrier-supported acid catalysts are exemplified by those in which
an inorganic acid is supported on a porous inorganic substance such
as alumina, magnesia, silica or activated carbon.
[0084] Among the above solid acid catalysts, the synthetic solid
acid catalysts such as silica-alumina, HY-type zeolite, USY-type
zeolite, mordenite and ZSM-5 are preferably used in view of their
durability as catalysts. In view of the selectivity in the
reaction, the silica-alumina is especially preferred.
[0085] The reaction temperatures are determined in accordance with
the kind of used catalyst, the duration of contact between
reactants and catalyst, and the ratio of dilution of reactants to
reaction medium. It can be selected in the range of 100 to
600.degree. C., preferably 200 to 500.degree. C., and more
preferably 250 to 400.degree. C. The reaction temperature above
600.degree. C. is not desirable because side reactions increase and
the coking of catalyst is intensive to reduce seriously the
selectivity. The reaction temperature below 100.degree. C. is not
desirable either in economical viewpoint because the rate of
intended reaction is low.
[0086] During the reaction in this step, the activity of catalyst
is gradually reduced by the coking with the long time use of
catalyst, however, the initial catalytic activity can be recovered
by decoking with air at a high temperature of, for example,
500.degree. C.
[0087] The mode of reaction may be any of batch-wise and
continuous. The continuous flow type reaction is desirable for
industrial production. When the continuous flow type reaction is
employed, any type of fixed bed, moving bed and fluidized bed
systems can be employed.
[0088] In this step, the reaction is carried out in a vapor phase.
The liquid phase reaction is not desirable because the
polymerization of reactants or products markedly increases.
[0089] The pressure of reaction is not especially limited as far as
the reaction is in a vapor phase. The pressure may generally be 1
MPa or lower, preferably lower than 0.5 MPa, and more preferably
lower than 0.2 MPa.
[0090] The contact time between reactants and a catalyst in the
continuous flow reaction is in the range of 0.001 second to 100
seconds, preferably 0.01 second to 5 seconds. When the contact time
is shorter than 0.001 second, the degree of conversion is too low.
If the contact time is longer than 100 seconds, the side reaction
such as the polymerization of produced trimethylhydroquinones
increases, as a result, the selectivity is lowered. In the
batch-wise reaction, the contact time is in the range of 10 minutes
to 10 hours.
[0091] The gas which is taken out from a reactor is immediately
cooled into a liquid. If necessary, it is possible to recover by
passing the gas through an absorbing liquid such as a hydrocarbon.
A highly pure intended product can be obtained by distillation,
crystallization, re-crystallization or pressurized crystallization
as occasion demands.
[0092] When unreacted 4-oxoisophorone exists, it can be recovered
easily by distillation and reused. The 4-oxoisophorone does not
pertain substantially to the reaction under the conditions of the
next step (4), so that the reaction mixture in this step can be fed
to the next step (4) without removing the unreacted 4-oxoisophorone
and, after the hydrolysis in the step (4), the 4-oxoisophorone may
be recovered.
[0093] Step (4):
[0094] [To Obtain the Intended Trimethylhydroquinone by Hydrolyzing
the Reaction Product of the Step (3A) or Step (3B)]
[0095] In the foregoing step (3A) or step (3B), the
trimethylhydroquinone intended in the present invention is
obtained. In many cases, however, the trimethylhydroquinone is
produced in the form of its esters. Accordingly, the
trimethylhydroquinone can, be obtained by hydrolyzing these
compounds.
[0096] An example of the compound of formula [I] in which the acyl
group is acetyl group will be described. In this case, as described
above, the compounds as represented by the formula [I] are
4-acetoxy-2,3,6-trimethyl- phenol, 4-acetoxy-2, 3,
5-trimethylphenol and trimethylhydroquinone diacetate.
[0097] The trimethylhydroquinone can easily be obtained by
hydrolyzing these compounds having acyl groups. In this step, a
catalyst is used for hydrolyzing these compounds having acyl
groups. As the catalyst, any of acid catalyst and base catalyst can
be used.
[0098] The solid acids of proton acids and Lewis acids are used as
the acid catalysts. The proton acids are exemplified by sulfuric
acid, hydrochloric acid, nitric acid, phosphoric acid, perchloric
acid, and carboxylic acids such as formic acid, acetic acid and
adipic acid. The sulfuric acid is especially preferable. The Lewis
acids are exemplified by aluminum chloride, boron trifluoride,
boron trifluoride ether complex, iron chloride and zinc chloride.
The solid acid catalysts are exemplified by synthetic solid acid
catalysts such as silica-alumina, alumina, silica and zeolites, and
natural clay minerals such as acid clay and activated clay. When
zeolite is used as a solid acid catalyst, it is possible to use
those containing hydrogen-zeolite such as HX-type zeolite, HY-type
zeolite or hydrogen-faujasite. Preferably, HY-type zeolite,
USY-type zeolite, mordenite or ZSM-5 are used. Furthermore, it is
possible to reduce the deposition of carbon to catalyst by causing
the catalyst to support an alkali metal such as sodium or
potassium.
[0099] Besides the above ones, it is possible to use by supporting
one or a combination of inorganic acids such as phosphoric acid,
heteropoly-acids of phosphotungstic acid, silicotungstic acid and
silicomolybdic acid on an appropriate porous inorganic substance.
More particularly, acid-supported catalysts in which an inorganic
acid is supported on a porous inorganic substance such as alumina,
magnesia, silica or activated carbon, can be used.
[0100] Among the above-mentioned solid acid catalysts, synthetic
solid acid catalysts, especially silica-alumina, HY-type zeolite,
USY-type zeolite, mordenite and ZSM-5 are preferably used.
[0101] Meanwhile, the base catalysts are exemplified by inorganic
acids such as sodium hydroxide, potassium hydroxide, calcium
hydroxide barium hydroxide, sodium hydrogen carbonate and potassium
hydrogen carbonate, alkoxides such as sodium methoxide and sodium
ethoxide, amines such as triethylamine and pyridine, and
ammonia.
[0102] In order to avoid the oxidation of trimethylhydroquinone
produced by the hydrolysis in this step, the reaction can be
carried out without the substantial existence of oxygen. For the
purpose of eliminating the existence of oxygen, the reaction is
done in the environment of an inert gas such as nitrogen. When the
temperature of hydrolysis is high, the effect of protection with
the inert gas is large. In the industrial practice, nitrogen is
desirable as an inert gas.
[0103] The mode of reaction may be any of batch-wise and
continuous. The use of a solid acid as a catalyst facilitates the
flow type reaction.
[0104] As the medium for flow type reaction, steam is commonly
used. The steam is inexpensive and the recovering of reaction
product is made easy because the steam is condensed by cooling.
[0105] In accordance with the kind of used catalyst, contact time
between catalyst and reactants, and the ratio of dilution of
reactants and medium, the reaction temperature is selected in the
range of 0 to 600.degree. C., preferably 50 to 300.degree. C., and
more preferably 100 to 250.degree. C. The reaction temperature
higher than 600.degree. C. is not desirable because the side
reactions increase and the coking of catalyst occurs seriously to
lower the selectivity. The reaction temperature below 0.degree. C.
is not desirable in economical viewpoint because the rate of
reaction is too low.
[0106] During the reaction in this step, the activity of catalyst
is gradually reduced by the coking with the long time use of
catalyst, however, the initial catalytic activity can be recovered
by decoking with air at a high temperature of, for example,
500.degree. C.
[0107] In a flow type reaction, as far as the reactant and reaction
product are in a vapor phase, the pressure of reaction is not
especially limited. The pressure of reaction is generally 1 MPa or
lower, preferably lower than 0.5 MPa and more preferably lower than
0.2 MPa.
[0108] The contact time between reactants and a catalyst in
continuous flow reaction in a vapor phase is in the range of 0.001
second to 100 seconds, preferably 0.01 second to 5 seconds. When
the contact time is shorter than 0.001 second, the degree of
conversion is too low. If the contact time is longer than 100
seconds, the side reaction such as the polymerization of produced
trimethylhydroquinone increases. In the batch-wise reaction, the
contact time is in the range of 10 minutes to 10 hours.
[0109] In the flow type reaction, the gas which is taken out from a
reactor is immediately cooled into a liquid. If necessary, it is
possible to recover by passing the gas through an absorbing liquid
such as a hydrocarbon.
[0110] It is possible to obtain highly pure intended product from
the reaction mixture by distillation, crystallization,
re-crystallization or pressurized crystallization as occasion
demands.
[0111] When the feed material to this step (4) contains
4-oxoisophorone, it can be recovered by distillation of a filtrate.
The recovered 4-oxoisophorone can be used as a feed material to the
step (3).
[0112] The method of the present invention comprises the
combination of 4 steps and it is possible to produce
trimethylhydroquinone without difficulty from inexpensive
isophorone.
[0113] The present invention will be described in more detail with
reference to several examples, in which the unit "%" means "percent
by weight" unless otherwise indicated.
EXAMPLE 1
Step (1)
[0114] To 2 liter flask were fed 1,106 g of isophorone and 76 g of
adipic acid and a distillation column (50 cm in length and filled
with 3 mm Dickson rings) was attached. Distillation was carried out
under ambient pressure at a reflux ratio of 60:1. When the flow
rate of effluent was 7.6 g/h, .beta.-isophorone of 95% purity (by
gas chromatography) and 184.degree. C. in boiling point was
obtained. Further, when the flow rate of effluent was 12.1 g/h,
.beta.-isophorone of 93% purity and 184.degree. C. in boiling point
was obtained.
EXAMPLE 2a
Step (2)
[0115] To a 200 ml autoclave were fed 50.0 g of .beta.-isophorone,
5.0 g of activated carbon (for chromatography use, made by Wako
Pure Chemical Industries, Ltd.), 11.1 g of pyridine and 63.3 g of
acetone. These contents were heated to 100.degree. C. and air was
introduced through a blowing tube with stirring. The flow rate of
air was regulated to 400 ml/min (as of atmospheric pressure) and
the internal pressure was regulated to 3.0 MPa. The concentration
of oxygen in the waste gas was measured with an oxygen analyzer.
After the reaction for 4 hours, the reaction mixture was cooled to
a room temperature and excess air was released. Removing the
catalyst by filtration, 124 g of filtrate was obtained. This was
analyzed by gas chromatography with an internal standard of
isobutylbenzene, the degree of conversion of .beta.-isophorone was
99.8% and the selectivity for 4-oxoisophorone was 73.8%. The
results are shown in the following Table 1.
EXAMPLE 2b
[0116] The reaction was carried out in the like manner as in
Example 1a except that the reaction temperature was 60.degree. C.
The results are also shown in the following Table 1.
EXAMPLES 2c to 2i
[0117] The reaction was carried out in the like manner as in
Example 1a except that the reaction temperatures and the kinds of
bases were changed. The results are also shown in the following
Table 1.
1 TABLE 1 Conversion Selectivity Selectivity Recovery Base of
.beta.-Iso- of 4-Oxo- of of Example Qty. Temp. Time phorone
isophorone Aldehyde Base No. Name (mole) (.degree. C.) (h) (%) (%)
(%) (%) 2a Pyridine 39 100 4 99.8 73.8 1.3 90.7 2b Pyridine 39 60 4
36.1 67.9 1.9 95.8 2c TEA 39 40 4 100.0 67.9 12.1 67.9 2d TEA 39 30
1 48.7 60.2 11.9 76.2 2e TEA 6.8 60 4 99.6 65.9 8.4 46.2 2f TEA 2
60 4 90.8 75.0 4.7 4.8 2g TPA 39 60 4 100.0 69.1 9.7 80.8 2h TBA 39
60 4 99.2 65.9 8.8 75.8 2i BMA 6.8 60 4 99.3 71.3 4.3 42.4 Notes
Qty.: The quantity per 100 moles of .beta.-isophorone TEA:
Triethylamine TPA: Tri-n-propyl amine TBA: Tri-n-butylamine BMA:
Benzyldimetylamine Aldehyde: 5,5-dimethyl-3-oxo-1-cyclohexene
carbaldehyde (Formula [II])
EXAMPLE 3Aa
Step (3A)
[0118] To a 100 ml three-necked flask were fed 1 g of strongly
acidic ion exchange resin catalyst (trade name: Amberlyst 15E made
by Japan Organo Ltd.), 10.2 g of 4-oxoisophorone and 15.0 g of
acetic anhydride, and reaction was carried out at 50.degree. C. for
7.5 hours under nitrogen atmosphere at an atmospheric pressure with
stirring. The reaction mixture was then cooled and analyzed by gas
chromatography to obtain the result that the degree of conversion
of reactant was 93.9% and the selectivity for
trimethylhydroquinones was 90.0%. By comparing the retention time
in gas chromatography and the result in mass spectrometry with
those of separately synthesized standard sample, the reaction
product was identified as trimethylhydroquinone diacetate. The
results are shown in the following Table 2A.
EXAMPLES 3Ab AND 3Ac
[0119] The reaction was carried out in the like manner as in
Example 3Aa except that the reaction temperatures and the
quantities of acetic anhydride were changed. The results are also
shown in the following Table 2A.
2TABLE 2A Qty. of Conversion Exam- Acid Catalyst Acetic of 4-oxo-
Selectivity ple Qty. Anhydride Temp. Time isophorone TMHQ's TMHQ
TMHQ-Ac TMHQ-2Ac No. Name (wt. parts) (mole) (.degree. C.) (h) (%)
(%) (%) (%) (%) 3Aa Amberlyst 10 220 50 8 93.9 90.0 0 0 90.0 3Ab
Amberlyst 10 750 50 8 100 98.5 0 0 98.5 3Ac Amberlyst 10 300 100 8
98.4 89.5 0 0 89.5 Notes Amberlyst: All Amberlysts were Amberlyst
15E Qty. of Catalyst: Parts by weight per 100 parts by weight of
4-oxoisophorone Qty. of Acetic Anhydride: Moles per 100 moles of
4-oxoisophorone TMHQ: Trimethylhydroquinone TMHQ's: Total of
trimethylhydroquinones TMHQ-Ac: Trimethylhydroquinone acetate
TMHQ-2Ac: Trimethylhydroquinone diacetate
EXAMPLE 3Ba
Step (3B)
[0120] A stainless steel tube of 1 m in length and 12 mm in inner
diameter was filled will 15 ml of silica-alumina catalyst (trade
name: N633L made by Nikki Chemical Corp.), the particle size of
which was previously adjusted to 16 to 20 mesh. The reaction was
carried out at 300C under atmospheric pressure with feeding 52.5 g
of 4-oxoisophorone at a flow rate of 10.5 ml/h and acetic acid at a
flow rate of 30 ml/h to the catalyst phase through respective
preheating tubes. The contact time with the catalyst was 0.6
second. The reaction mixture was cooled and analyzed by gas
chromatography to obtain results that the degree of conversion of
reactant was 58% and the selectivity for trimethylhydroquinones was
75.4%. By comparing the retention time in gas chromatography and
the result in mass spectrometry with those of separately
synthesized standard sample, the reaction product was identified as
trimethylhydroquinones. The results are shown in the following
Table 2B.
EXAMPLE 3Bb AND 3Bc
[0121] The reaction was carried out in the like manner as in
Example 3Ba except that the reaction temperatures were changed to
250.degree. C. and 350.degree. C., respectively. The results are
also shown in the following Table 2B.
EXAMPLES 3Bd TO 3Bg
[0122] The reaction was carried out in the like manner as in
Example 3Ba except that the catalysts were changed to HY-type
zeolite (made by Catalyst & Chemical Industries Co., Ltd.),
USY-type zeolite (made by Tosoh Corp.), H-mordenite (made by Tosoh
Corp.) and ZSM-5 were used, respectively. The results are also
shown in the following Table 2B.
3TABLE 2B Conversion Exam- of 4-oxo- Selectivity ple Temp.
isophorone TMHQ's TMHQ TMHQ-Ac TMHQ-2Ac Recovery No. Medium Solid
Acid (.degree. C.) (%) (%) (%) (%) (%) (%) 3Ba Acetic acid
Silica-alumina 300 58.0 75.4 5.6 35.9 33.9 94 3Bb Acetic acid
Silica-alumina 250 17.7 69.7 0 26.7 43.0 93 3Be Acetic acid
Silica-alumina 350 80.6 65.0 12.2 34.5 18.3 94 3Bd Acetic acid
HY-type zeolite 400 45.8 60.4 4.2 28.3 27.9 95 3Be Acetic acid
USY-type zeolite 500 50.2 58.8 3.7 29.5 25.6 94 3Bf Acetic acid
H-mordenite 450 26.5 35.1 18.6 14.0 2.5 95 3Bg Acetic acid ZSM-5
350 25.5 57.5 17.6 30.4 9.5 95 Notes TMHQ: Trimethylhydroquinone
TMHQT's: Total of trimethylhydroquinones TMHQ-Ac:
Trimethylhydroquinone acetate TMHQ-2Ac: Trimethylhydroquinone
diacetate
EXAMPLE 4a
Step (4)
[0123] To a 500 ml flask was fed 10.0 g of reactant mixture
containing 8.64% of trimethylhydroquinone diacetate, 6.24% of a
mixture of 4-acetoxy-2,3,6-trimethylphenol and
4-acetoxy-2,3,5-trimethylphenol, and 75.7% of 4-oxoisophorone, and
the flask was displaced with nitrogen. Then, 50.0 g of water, 1.0 g
of 97% sulfuric acid and 11.3 g of acetic acid were added to the
above reactants and they were stirred at 100.degree. C. for 2 hours
under atmospheric pressure. The reaction mixture was cooled to a
room temperature and 30 ml of hexane was added. The deposited
crystals were filtered off to obtain 0.941 g of
trimethylhydroquinone at a yield of 90.0%. The purity of these
crystals was 100% according to the gas chromatographic analysis.
With the retention time in gas chromatography and the
identification with a standard sample by the results of IR
absorption and MS analysis, it was confirmed that the crystals were
trimethylhydroquinone.
EXAMPLE 4b
[0124] A stainless steel tube of 1 m in length and 12 mm in inner
diameter was filled will 15 ml of silica-alumina catalyst (trade
name: N633L made by Nikki Chemicai Corp.), the particle size of
which was previously adjusted to 16 to 20 mesh. After displacing
the reaction phase with nitrogen, reaction was carried out at
200.degree. C. under atmospheric pressure with feeding 10.5 g of
33% solution of trimethylhydroquinone diacetate in toluene at a
feed rate of 10.5 ml/h and 30 ml/h of water to the catalyst phase
through respective preheating tubes. The contact time with the
catalyst was 0.5 second. The reaction mixture was cooled and
analyzed by gas chromatography to obtain results that the degree of
conversion of reactant was 100% and the selectivity for
trimethylhydroquinone was 95%.
[0125] In accordance with the method of the present invention as
described above, it was made possible to produce inexpensively and
in a high yield the trimethylhydroquinone which is useful as a raw
material for preparing vitamin E, from inexpensive reactants
through simplified process. In addition, it can be produced easily
without causing the problem in waste treatment.
* * * * *