CA2215544A1 - Process for producing butanediol - Google Patents
Process for producing butanediol Download PDFInfo
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- CA2215544A1 CA2215544A1 CA 2215544 CA2215544A CA2215544A1 CA 2215544 A1 CA2215544 A1 CA 2215544A1 CA 2215544 CA2215544 CA 2215544 CA 2215544 A CA2215544 A CA 2215544A CA 2215544 A1 CA2215544 A1 CA 2215544A1
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- butanediol
- diacetoxybutane
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
- C07C29/095—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of esters of organic acids
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/28—Preparation of carboxylic acid esters by modifying the hydroxylic moiety of the ester, such modification not being an introduction of an ester group
- C07C67/283—Preparation of carboxylic acid esters by modifying the hydroxylic moiety of the ester, such modification not being an introduction of an ester group by hydrogenation of unsaturated carbon-to-carbon bonds
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
A process for producing butanediol by hydrolyzing diacetoxybutane, wherein the diacetoxybutane to be hydrolyzed contains not more than 0.5% by weight of diacetoxyoctane. The butanediol thus obtained is usable as a starting material in the production of polyester reins, tetrahydrofuran, etc.
Description
CA 0221~44 1997-09-1~
PROCESS FOR PRODUCING BUTANEDIOL
FIELD OF THE INVENTION
This invention relates to a process for producing butanediol having high purity. More particularly, it relates to an improved process which comprises hydrolyzing diacetoxybutane, which is obtained by acetoxylating and hydrogenating butadiene, to thereby give butanediol.
BACKGROUND OF THE INVENTION
Butanediol is a compound which is useful as a solvent or the starting material in synthesizing polyester resins, ~-butyrolactone, tetrahydrofuran, etc.
A known process for producing butanediol comprises hydrolyzing diacetoxybutane, which is obtained by reacting butadiene with acetic acid and oxygen in the presence of a palladium catalyst to obtain diacetoxybutene, and then hydrogenating the diacetoxybutene using a palladium catalyst or a nickel catalyst, to thereby give butanediol (see, JP-A-52-7909, JP-A-52-133912, JP-A-7-82191, etc.; the term "JP-A" as used herein means an "unexamined published Japanese patent application").
In the above-mentioned method starting from butadiene, a large amount of acetic acid is used in the acetoxylation of butadiene. It is necessary to eliminate the unreacted excess acetic acid and the water which is formed as a by-product.
Furthermore, in the hydrolysis of diacetoxybutane, a large CA 0221~44 1997-09-1~
amount of water is used, and it is therefore necessary to eliminate the unreacted excess water and the acetic acid which is formed as a by-product. Various proposals have been made to recover and reuse the water and acetic acid while maintaining the purity of the product at a satisfactory level (see the patents cited above).
The purity of butanediol is particularly important when, for example, it is used for producing tetrahydrofuran, which is the starting material for the production of polyester resins and polyethers such as polytetramethylene ether glycol, etc. When used in the production of tetrahydrofuran, butanediol must have sufficiently high purity so as not to affect the polymerization reaction, since impurities in the butanediol adversely affect the rate of the polymerization reaction and the molecular weight of the polymer product.
In the above-mentioned prior art method for producing butanediol, diacetoxybutane is hydrolyzed and the reaction product is subjected to distillation. After thus distilling off water, acetic acid and other low-boiling compounds, components containing butanediol are generally obtained as the bottom settlings. These bottom settlings are then further distilled to thereby eliminate remaining low-boiling compounds as the overhead products and diacetoxybutane, hydroxy-acetoxybutane, etc. as the upper side stream. The butanediol is distilled off as the middle side stream, lower side stream CA 0221~44 1997-09-1~
or bottom settlings, and is then rectified to thereby give highly pure butanediol. However, this process does not always result in sufficient elimination of impurities.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an industrially advantageous process for producing butanediol having high purity, which is appropriate as the starting material for producing polyester resin, tetrahydrofuran, etc., the process comprising hydrolyzing diacetoxybutane obtained by acetoxylating butadiene followed by hydrogenation.
The present inventors have conducted extensive studies on processes for producing butanediol having high purity. As a result, they have successfully found that butanediol obtained from butadiene is contaminated with impurities which are difficult to remove by distillation. One such impurity is monoacetoxyoctanol, which is formed by the hydrolysis of diacetoxyoctane contained as an impurity in diacetoxybutane.
When examined by gas-llquid equilibration, it is more difficult to distill off monoacetoxyoctanol than expected on the basis of the difference (about 40~C) between the boiling point of 1j4-butanediol (230~C) and that of monoacetoxyoctanol (estimated as about 270~C).
Accordingly, the present invention provides a process for producing butanediol by hydrolyzing diacetoxybutane, wherein the diacetoxybutane to be hydrolyzed contains not more CA 0221~44 1997-09-1~
than about 0.5% by weight of diacetoxyoctane.
According to the process of the present invention, highly pure 1,4-butanediol contaminated with not more than about 1% by weight of monoacetoxyoctanol (i.e., having a purity of about 99% by weight or more) can be obtained by regulating the content of diacetoxyoctane in diacetoxybutane to not more than about 0.5% by weight, preferably from about 0.01 to about 0.2% by weight, hydrolyzing the diacetoxybutane, subjecting the hydrolysis product to distillation in a conventional manner, thus eliminating water, acetic acid and other low-boiling compounds therefrom, and then distilling the bottom settlings to thereby rectify the butanediol fraction from which the low-boiling compounds have been eliminated.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 schematically shows an example of a preferred apparatus for performing the process of the present invention, wherein each reference numeral has the following meaning:
1 . . . acetoxylation reactor 2 . . . first distillation column 3 . . . second distillation column 4 . . . hydrogenation reactor 5 . . . third distillation column 6 . . . hydrolysis reactor 7 . . . fourth distillation column 8 . . . fifth distillation column CA 0221~44 1997-09-1~
PROCESS FOR PRODUCING BUTANEDIOL
FIELD OF THE INVENTION
This invention relates to a process for producing butanediol having high purity. More particularly, it relates to an improved process which comprises hydrolyzing diacetoxybutane, which is obtained by acetoxylating and hydrogenating butadiene, to thereby give butanediol.
BACKGROUND OF THE INVENTION
Butanediol is a compound which is useful as a solvent or the starting material in synthesizing polyester resins, ~-butyrolactone, tetrahydrofuran, etc.
A known process for producing butanediol comprises hydrolyzing diacetoxybutane, which is obtained by reacting butadiene with acetic acid and oxygen in the presence of a palladium catalyst to obtain diacetoxybutene, and then hydrogenating the diacetoxybutene using a palladium catalyst or a nickel catalyst, to thereby give butanediol (see, JP-A-52-7909, JP-A-52-133912, JP-A-7-82191, etc.; the term "JP-A" as used herein means an "unexamined published Japanese patent application").
In the above-mentioned method starting from butadiene, a large amount of acetic acid is used in the acetoxylation of butadiene. It is necessary to eliminate the unreacted excess acetic acid and the water which is formed as a by-product.
Furthermore, in the hydrolysis of diacetoxybutane, a large CA 0221~44 1997-09-1~
amount of water is used, and it is therefore necessary to eliminate the unreacted excess water and the acetic acid which is formed as a by-product. Various proposals have been made to recover and reuse the water and acetic acid while maintaining the purity of the product at a satisfactory level (see the patents cited above).
The purity of butanediol is particularly important when, for example, it is used for producing tetrahydrofuran, which is the starting material for the production of polyester resins and polyethers such as polytetramethylene ether glycol, etc. When used in the production of tetrahydrofuran, butanediol must have sufficiently high purity so as not to affect the polymerization reaction, since impurities in the butanediol adversely affect the rate of the polymerization reaction and the molecular weight of the polymer product.
In the above-mentioned prior art method for producing butanediol, diacetoxybutane is hydrolyzed and the reaction product is subjected to distillation. After thus distilling off water, acetic acid and other low-boiling compounds, components containing butanediol are generally obtained as the bottom settlings. These bottom settlings are then further distilled to thereby eliminate remaining low-boiling compounds as the overhead products and diacetoxybutane, hydroxy-acetoxybutane, etc. as the upper side stream. The butanediol is distilled off as the middle side stream, lower side stream CA 0221~44 1997-09-1~
or bottom settlings, and is then rectified to thereby give highly pure butanediol. However, this process does not always result in sufficient elimination of impurities.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an industrially advantageous process for producing butanediol having high purity, which is appropriate as the starting material for producing polyester resin, tetrahydrofuran, etc., the process comprising hydrolyzing diacetoxybutane obtained by acetoxylating butadiene followed by hydrogenation.
The present inventors have conducted extensive studies on processes for producing butanediol having high purity. As a result, they have successfully found that butanediol obtained from butadiene is contaminated with impurities which are difficult to remove by distillation. One such impurity is monoacetoxyoctanol, which is formed by the hydrolysis of diacetoxyoctane contained as an impurity in diacetoxybutane.
When examined by gas-llquid equilibration, it is more difficult to distill off monoacetoxyoctanol than expected on the basis of the difference (about 40~C) between the boiling point of 1j4-butanediol (230~C) and that of monoacetoxyoctanol (estimated as about 270~C).
Accordingly, the present invention provides a process for producing butanediol by hydrolyzing diacetoxybutane, wherein the diacetoxybutane to be hydrolyzed contains not more CA 0221~44 1997-09-1~
than about 0.5% by weight of diacetoxyoctane.
According to the process of the present invention, highly pure 1,4-butanediol contaminated with not more than about 1% by weight of monoacetoxyoctanol (i.e., having a purity of about 99% by weight or more) can be obtained by regulating the content of diacetoxyoctane in diacetoxybutane to not more than about 0.5% by weight, preferably from about 0.01 to about 0.2% by weight, hydrolyzing the diacetoxybutane, subjecting the hydrolysis product to distillation in a conventional manner, thus eliminating water, acetic acid and other low-boiling compounds therefrom, and then distilling the bottom settlings to thereby rectify the butanediol fraction from which the low-boiling compounds have been eliminated.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 schematically shows an example of a preferred apparatus for performing the process of the present invention, wherein each reference numeral has the following meaning:
1 . . . acetoxylation reactor 2 . . . first distillation column 3 . . . second distillation column 4 . . . hydrogenation reactor 5 . . . third distillation column 6 . . . hydrolysis reactor 7 . . . fourth distillation column 8 . . . fifth distillation column CA 0221~44 1997-09-1~
9 . . . sixth distillation column.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The content of diacetoxyoctane in diacetoxybutane can be regulated to not more than about 0.5% by weight by one of the following methods:
(a) reacting butadiene with acetic acid and oxygen and recovering diacetoxybutene from the reaction product by distillation wherein, during recovery, the amount of diacetoxyoctadiene in the obtained diacetoxybutene is regulated to a predetermined level (for example about 0.5% by weight or less);
(b) hydrogenating diacetoxybutene and regulating the content of diacetoxyoctane in the obtained diacetoxybutane (i.e., the hydrogenation product) at or below a predetermined level by distillation; and (c) partly or totally combining the procedures for reducing the impurities in the above-mentioned methods (a) and (b) so as to regulate the diacetoxyoctane content in diacetoxybutane at or below a predetermined level. It lS
preferred to distill off diacetoxyoctadiene by method (a) from the viewpoint of simplifying and reducing the overall energy consumption of the process.
Preferred embodiments of the process of the invention are now described below.
CA 0221~44 1997-09-1~
(1) Acetoxylation step comprising reacting butadiene with acetic acid and molecular oxygen to thereby give diacetoxybutene:
The acetoxylation reaction is performed in a reactor 1 (see Fig. 1) by a conventional method which comprises reacting butadiene with acetic acid and molecular oxygen in the presence of a palladium catalyst. As the palladium catalyst, use is preferably made of metallic palladium or salts thereof.
Preferred palladium salts are those selected from the group comprising organic palladium salts such as palladium acetate, and inorganic palladium salts such as palladium chloride and palladium nitrate. The palladium catalyst may either be used alone or in combination with a promoter. Preferred promoters are selected from the group comprising metals such as bismuth, selenium, antimony, tellurium, copper, etc. and metal salts, metal oxides or metal acids thereof such as bismuth oxide, selenic acid, tellurium oxide, antimony chloride, orthotelluric acid, copper chloride, etc. It is preferred that the catalyst is supported on a carrier, with preferred carriers belng selected from the group comprising silica, alumina, active carbon, etc. The palladium content in the catalyst supported on a carrier preferably ranges from about 0.1 to about 20% by weight, while the content of the promoter, if present, preferably ranges from about 0.01 to about 30% by weight.
The acetoxylation reaction may be performed by a number CA 0221~44 1997-09-1~
of different methods. Preferred methods of the reaction include the conventional fixed bed method, fluidized bed method and catalyst-suspending method.
The reaction is preferably carried out within a temper-ature range of from about 40 to about 180~C, more preferably from about 60 to about 150~C. Preferably, the reaction is performed under atmospheric pressure or higher, more preferably not more than about 300 kg/cm2 (29.4 MPa), and most preferably from about 30 to about 150 kg/cm2 (2.94 - 14.7 MPa).
Since the acetoxylation reaction product thus obtained in the reactor contains the unreacted butadiene, etc., it is preferably degassed and then distilled to thereby give diacetoxybutene.
Preferably, distillation of the acetoxylation reaction product is carried out in the following manner, described with reference to Figure 1. First, water and acetic acid are distilled off as the overhead products from first distillation column 2. The bottom settlings from column 2 are then supplied to second distillation column 3, where diacetoxybutene is obtained from the column top while high-boiling fractions containing diacetoxyoctadiene are drawn out from the bottom.
It may be preferred to supply the bottom settlings distillation column 3 to a thin film evaporator to thereby elevate the separation efficiency of the high-boiling fractions (as described in detail in JP-A-6-321861).
CA 0221~44 1997-09-1~
The amount of diacetoxyoctadiene contained in the diacetoxybutene recovered from the top of column 3 is at least partially dependent on the content of diacetoxyoctadiene in the diacetoxybutene supplied to distillation column 3 and the operation conditions of distillation column 3. Preferably, the diacetoxybutene supplied to distillation column 3 contains about 3% by weight of diacetoxyoctadiene. Distillation column 3 is preferably operated at a theoretical plate number of from about 5 to about 10, under a column top pressure of from about 5 to about 200 mmHg (0.7 to 26.7 kPa), at a column bottom temperature of not more than about 190~C, a reflux ratio of from about 0.1 to about 1 and a distilling ratio of from about 70 to about 99%.
The diacetoxybutene drawn from the top of column 3 preferably contains from about 0.1 to about 2.5% by weight of diacetoxyoctadiene. When the process of the invention also includes distilling off diacetoxyoctane contained in the diacetoxybutane, the distillation conditions following the acetoxylation are set so that the diacetoxyoctadiene content is regulated to from about 1.0 to about 2.5% by weight, preferably not more than about 1.5% by weight. When diacetoxyoctadiene alone is distilled off such that the process does not include a diacetoxyoctane removal step, the distillation conditions following acetoxylation are preferably set so that the diacetoxyoctadiene content is regulated to not more than about CA 0221~44 1997-09-1~
0.5% by weight, preferably not more than about 0.1% by weight.
In order to sharply reduce the amounts of impurities contained in the diacetoxybutene, it may be preferred to vary one or more of the distillation conditions. For example, it may be preferred to increase the theoretical plate number or the reflux ratio and lower the distillation ratio. More particularly speaking, distillation column 3 may preferably be operated at a theoretical plate number of from about S to about 20, a reflux ratio of from about 0.1 to about lO and a distillation ratio from the column top of from about 70 to about 97%.
(2) Hydrogenating the reaction product obtained in the acetoxylation step to thereby give diacetoxybutane:
The diacetoxybutene obtained from the top of distillation column 3 in the acetoxylation step is subjected to hydrogenation to thereby form diacetoxybutane. The hydrogenation reaction is preferably carried out by bringing the diacetoxybutene into contact with hydrogen in the presence of a precious metal catalyst such as a palladium, nickel or ruthenium catalyst and reacting within a temperature range of from about 40 to about 180~C, preferably under atmospheric pressure or higher, more preferably up to about 150 kg/cm2 (14.7 MPa).
The hydrogenation reaction may be performed by a number of different methods including, for example, the CA 0221~44 1997-09-1~
conventional fixed bed method, fluidized bed method or catalyst-suspending method.
The hydrogen used in the hydrogenation reaction may preferably either have high purity or be diluted with another gas exhibiting no undesirable effect on the reaction. Hydrogen is preferably employed in an amount of from about 1 to about 50 mol, more preferably from about 2 to about 20 mol, per mol of diacetoxybutene.
The hydrogenation product is degassed to thereby eliminate the unreacted hydrogen therefrom and is then subjected to distillation in the third distillation column 5 to thereby give diacetoxybutane. In this distillation step, the diacetoxybutane is obtained as the overhead product while high-boiling fractions containing diacetoxyoctane, which is the hydrogenation product of diacetoxyoctadiene, are obtained as the bottom settlings.
Distillation column 5 is preferably operated at a theoretical plate number of from about 5 to about 10, under a column top pressure of from about 5 to about 200 mmHg (0.7 to 26.7 kPa), at a column bottom temperature of not more than about 190~C, a reflux ratio of from about 0.1 to about 1 and a distillation ratio from the column top of from about 70 to about 99%.
The diacetoxyoctane content in the diacetoxybutane supplied to distillation column 5 is at least partially CA 0221~44 1997-09-1~
dependent on the operation conditions of distillation column 3.
Under the said conditions, the diacetoxyoctane content is about 0.1 to 2.5% by weight prior to distillation in column 5. When the diacetoxyoctadiene content is reduced at or below 0.5% by weight in distillation column 3, the diacetoxyoctane content is less than about 0.5% by weight, and more preferably not more than about 0.1% by weight. When only a portion of the diacetoxyoctadiene is eliminated in distillation column 3, the diacetoxyoctane content is preferably from about 1.0 to about 2.5% by weight, and more preferably not more than about 1.5% by weight.
If the diacetoxyoctadiene content in distillation column 3 is more than 2.5% by weight, the content has to be reduced at or below 0.5% by weight by the distillation in distillation column 5.
When the procedure for eliminating diacetoxyoctadiene in distillation column 3 is combined with the procedure for eliminating diacetoxyoctane in distillation column 5, the predetermined level to which the content of diacetoxyoctadiene or diacetoxyoctane is reduced in each column is appropriately determined by taking the balance between the distillation loads in columns 3 and 5 into consideration. For example, it is preferred that the amount of diacetoxyoctadiene eliminated in distillation column 2 exceeds 50% of the total amount eliminated.
CA 0221~44 1997-09-1~
When distillation column 3 is operated under the preferred conditions described above, the diacetoxybutane drawn from the top of column 5 contains from about 1.0 to about 2.5%
by weight of diacetoxyoctane. In the process of the present invention, the operation conditions of distillation column 5 are preferably set so that the diacetoxyoctane content is regulated to not more than about 0.5% by weight, and more preferably not more than about 0.2% by weight.
More particularly speaking, distillation column 5 is preferably operated at a theoretical plate number of from about 5 to about 20, a reflux ratio of from about 0.1 to about 10 and a distillation ratio from the column top of from about 70 to about 97%.
When the diacetoxyoctane content in the diacetoxybutane exceeds 0.5% by weight, the butanediol obtained by hydrolyzing it contains the same content of monoacetoxyoctanol which is difficult to remove by distillation.
(3) Hydrolyzing hydrogenation product to thereby give butanediol:
Preferably, the hydrolysis reaction is performed by bringing diacetoxybutane into contact with water in the presence of a solid acid catalyst such as a cation exchange resin within a temperature range of from about 30 to about 110~C, and more preferably from about 40 to about 90~C, under such a pressure as to prevent boiling or serious bubbling due CA 0221~44 1997-09-1~
to dissolved gases, etc. in the course of the reaction, i.e., preferably from about atmospheric pressure to about 10 kg/cm ~G
~0.098 to 1.08 MPa).
In this reaction, water is preferably employed in an amount of from about 2 to about 100 mol, preferably from about 4 to about 50 mol, per mol of diacetoxybutane. When water is used in an excessively small amount, the reaction ratio is lowered. On the other hand, it is not preferred to use too much water, since increased heat energy would be required to recover butanediol from the reaction product.
The reaction may be carried out by a number of different methods which, for example, are conducted either batchwise or continuously. When an ion exchange resin is used in the hydrolysis reaction, it may be in a suspended state.
Alternatively, the reactants may be passed through a column packed with the ion exchange resin. From an industrial viewpoint, it is preferred to employ a continuous fixed bed method.
When the reaction is performed by using a suspended bed, the ion exchange resin is preferably employed in an amount of from about 0.1 to about 50% by weight, and more preferably from about 1 to about 10% by weight, based on the weight of the liquid (water and the diacetoxybutane).
When using the continuous fixed bed method, the reaction may be carried out by continuously supplying water and CA 0221~44 1997-09-1~
diacetoxybutane to a reactor 6 packed with the ion exchange resin, which is preferably kept at a predetermined temperature, and simultaneously drawing out the butanediol thus formed as a mixture with acetic acid and the excess water.
The diacetoxybutane and water may be supplied either separately or as a mixture thereof. It is also possible to supply these materials as a homogeneous liquid phase which further contains butanediol (i.e., the reaction product), together with impurities such as monohydroxyacetoxybutane, etc.
When using the fixed bed method, it is preferred to supply these materials in the form of a homogeneous liquid phase so as to accelerate the smooth progress of the reaction.
The liquid product formed by the reaction contains the desired butanediol together with acetic acid, water, partial hydrolyzates and some by-products such as teterahydrofuran.
After the completion of the reaction, the catalyst is filtered off from the reaction mixture and the filtrate is distilled to thereby give butanediol.
The distillation is preferably effected in the following manner. In the fourth distillation column 7, water and acetic acid are eliminated as the overhead products. Then the bottom settlings are supplied to the fifth distillation column 8 from which the unreacted diacetoxybutane and its isomers are eliminated as the overhead products. Next, the bottom settlings, comprising 1,4-butanediol as the major CA 0221~44 1997-09-1~
component thereof, are supplied to the sixth distillation column 9. From the top of distillation column 9, the desired 1,4-butanediol product is obtained, while high-boiling compounds are drawn out as the bottom settlings. The 1,4-butanediol product preferably contains not more than about 1%
by weight, and more preferably from about 0 to about 0.5% by weight, of monoacetoxyoctanol.
To further illustrate the present invention, the following Examples will be given wherein all "parts" and "%
are by weight.
(Reference Example 1) Acetoxylation reaction Into an acetoxylation reactor were supplied 170 part/hr of 1,3-butadiene, 3,000 part/hr of acetic acid and 530 part/hr of oxygen. In the presence of a catalyst comprising 3% of palladium and 0.6% of tellurium supported on active carbon, the mixture was reacted under 9 MPa at 100~C and degassed to thereby give a reaction product containing 14.2% of diacetoxybutene and 0.6% of diacetoxyoctadiene.
This reaction product was supplied to distillation column 2 at a rate of 3,100 part/hr. Thus, water and most of the acetic acid were distilled off from the column top at a rate of 252 part/hr, while bottom settlings containing 84.5% by weight of diacetoxybutene and 3.2% by weight of diacetoxy-octadiene were drawn off at a rate of 580 part/hr.
CA 0221~44 1997-09-1 (Example 1) The bottom settlings obtained in the above Reference Example 1 were supplied to distillation column 2 (practical plate number: 20) at a rate of 580 part/hr and distilled therein under a column top pressure of 2.7 kPa at a reflux ratio of 0.5. Thus a solution containing 86.3% of diacetoxy-butene and 1.0% of diacetoxyoctadiene was distilled off from the column top at a rate of 550 part/hr.
The diacetoxybutene fraction thus obtained was supplied to a hydrogenation reactor packed with a palladium catalyst and a ruthenium catalyst and hydrogenated therein under a hydrogen gas stream at 70~C and a reaction pressure of 5 kPa. Thus a reaction mixture containing 86.5% of diacetoxybutane and 1.0%
of diacetoxyoctane was obtained.
Next, the reaction mixture was subjected to gas/liquid separation and then supplied to distillation column 5 (practical plate number: 20) at a rate of 550 part/hr and distilled therein under a column top pressure of 2.0 kPa at a reflux ratio of 0.25. Thus a solution containing 87.1% of diacetoxybutane and 0.2% of diacetoxyoctane was distilled off from the column top at a rate of 520 part/hr.
The hydrogenation reaction mixture thus obtained was supplied to a hydrolysis reactor packed with a strongly acidic ion exchange resin (Diaion SK-lB ; manufactured by Mitsubishi Chemical Corporation) at a rate of 520 part/hr together with CA 0221~44 1997-09-1~
-500 part/hr of water. Then hydrolysis was effected at a temperature of 50~C to thereby give a reaction mixture containing 10.2% of 1,4-butanediol and 0.04% of monoacetoxy-octanol.
This reaction mixture was supplied to the distillation column 7 at a rate of 1,020 part/hr. Then water and most of the acetic acid were distilled off from the column top at 660 part/hr, while the bottom settlings containing 28.9% of 1,4-butanediol and 0.1% of monoacetoxyoctanol were drawn out from the column bottom at a rate of 360 part/hr. Then the bottom settlings were supplied to distillation column 8. After distilling off the unreacted diacetoxybutane from the column top, the bottom settlings of distillation column 8 were supplied to distillation column 9. The high-boiling compounds were drawn out from the column bottom and 1,4-butanediol with a purity of 99.3% was obtained from the column top. This 1,4-butanediol contained 0.4% of monoacetoxyoctanol.
(Example 2) Distillation was performed in the same manner as described in Example 1 but the reflux ratio of distillation column 3, into which the bottom settlings obtained in Reference Example 1 were supplied, was adjusted to 5. Thus a distillate containing 87.1% of diacetoxybutene and 0.1% of diacetoxy-octadiene was obtained from the column top.
The diacetoxybutene fraction thus obtained was CA 0221~44 1997-09-1~
subjected to hydrogenation in the same manner as in Example 1 to thereby give a reaction mixture containing 87.3% of diacetoxybutane and 0.1% of diacetoxyoctane.
After gas/liquid separation, the hydrogenation reaction mixture thus obtained was not supplied to distillation column 5 as in Example 1, but rather was hydrolyzed under the same conditions as those employed in Example 1. Thus a reaction mixture containing 10.4% of 1,4-butanediol and 0.02% of monoacetoxyoctanol was obtained.
This reaction mixture was supplied successively to distillation columns 7, 8 and 9 in the same manner as in Example 1. From the top of distillation column 9, 1,4-butanediol with a purity of 99.5% was obtained. This product contained 0.2% of monoacetoxyoctanol.
(Comparative Example 1) Distillation was performed in the same manner as described in Example 1, but the reflux ratio of distillation column 3 was adjusted to 0.05. Thus a distillate containing 85.0% of diacetoxybutene and 1.7% of diacetoxyoctadiene was obtained from the column top.
The diacetoxybutene fraction thus obtained was subjected to hydrogenation in the same manner as in Example 2.
The hydrogenation reaction mixture containing 85.1% of diacetoxybutane and 1.6% of diacetoxyoctane was then subjected to gas/liquid separation. After gas/liquid separation, the CA 0221~44 1997-09-1~
-reaction mixture was not supplied to distillation column 5 as in Example 2, but rather was hydrolyzed under the same conditions as those employed in Example 1 to thereby give a reaction mixture containing 9.9% of 1,4-butanediol and 0.3% of monoacetoxyoctanol.
This reaction mixture was supplied successively to distillation columns 7, 8 and 9 in the same manner as in Example 1. From the top of distillation column 9, 1,4-butanediol with a purity of 95.1% was obtained. This product contained 3.2% of monoacetoxyoctanol.
The process of the present invention makes possible the industrial production of highly pure 1,4-butanediol containing not more than 1% by weight of monoacetoxyoctanol, which is suitable as a starting material for producing polyester, teterahydrofuran, etc.
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The content of diacetoxyoctane in diacetoxybutane can be regulated to not more than about 0.5% by weight by one of the following methods:
(a) reacting butadiene with acetic acid and oxygen and recovering diacetoxybutene from the reaction product by distillation wherein, during recovery, the amount of diacetoxyoctadiene in the obtained diacetoxybutene is regulated to a predetermined level (for example about 0.5% by weight or less);
(b) hydrogenating diacetoxybutene and regulating the content of diacetoxyoctane in the obtained diacetoxybutane (i.e., the hydrogenation product) at or below a predetermined level by distillation; and (c) partly or totally combining the procedures for reducing the impurities in the above-mentioned methods (a) and (b) so as to regulate the diacetoxyoctane content in diacetoxybutane at or below a predetermined level. It lS
preferred to distill off diacetoxyoctadiene by method (a) from the viewpoint of simplifying and reducing the overall energy consumption of the process.
Preferred embodiments of the process of the invention are now described below.
CA 0221~44 1997-09-1~
(1) Acetoxylation step comprising reacting butadiene with acetic acid and molecular oxygen to thereby give diacetoxybutene:
The acetoxylation reaction is performed in a reactor 1 (see Fig. 1) by a conventional method which comprises reacting butadiene with acetic acid and molecular oxygen in the presence of a palladium catalyst. As the palladium catalyst, use is preferably made of metallic palladium or salts thereof.
Preferred palladium salts are those selected from the group comprising organic palladium salts such as palladium acetate, and inorganic palladium salts such as palladium chloride and palladium nitrate. The palladium catalyst may either be used alone or in combination with a promoter. Preferred promoters are selected from the group comprising metals such as bismuth, selenium, antimony, tellurium, copper, etc. and metal salts, metal oxides or metal acids thereof such as bismuth oxide, selenic acid, tellurium oxide, antimony chloride, orthotelluric acid, copper chloride, etc. It is preferred that the catalyst is supported on a carrier, with preferred carriers belng selected from the group comprising silica, alumina, active carbon, etc. The palladium content in the catalyst supported on a carrier preferably ranges from about 0.1 to about 20% by weight, while the content of the promoter, if present, preferably ranges from about 0.01 to about 30% by weight.
The acetoxylation reaction may be performed by a number CA 0221~44 1997-09-1~
of different methods. Preferred methods of the reaction include the conventional fixed bed method, fluidized bed method and catalyst-suspending method.
The reaction is preferably carried out within a temper-ature range of from about 40 to about 180~C, more preferably from about 60 to about 150~C. Preferably, the reaction is performed under atmospheric pressure or higher, more preferably not more than about 300 kg/cm2 (29.4 MPa), and most preferably from about 30 to about 150 kg/cm2 (2.94 - 14.7 MPa).
Since the acetoxylation reaction product thus obtained in the reactor contains the unreacted butadiene, etc., it is preferably degassed and then distilled to thereby give diacetoxybutene.
Preferably, distillation of the acetoxylation reaction product is carried out in the following manner, described with reference to Figure 1. First, water and acetic acid are distilled off as the overhead products from first distillation column 2. The bottom settlings from column 2 are then supplied to second distillation column 3, where diacetoxybutene is obtained from the column top while high-boiling fractions containing diacetoxyoctadiene are drawn out from the bottom.
It may be preferred to supply the bottom settlings distillation column 3 to a thin film evaporator to thereby elevate the separation efficiency of the high-boiling fractions (as described in detail in JP-A-6-321861).
CA 0221~44 1997-09-1~
The amount of diacetoxyoctadiene contained in the diacetoxybutene recovered from the top of column 3 is at least partially dependent on the content of diacetoxyoctadiene in the diacetoxybutene supplied to distillation column 3 and the operation conditions of distillation column 3. Preferably, the diacetoxybutene supplied to distillation column 3 contains about 3% by weight of diacetoxyoctadiene. Distillation column 3 is preferably operated at a theoretical plate number of from about 5 to about 10, under a column top pressure of from about 5 to about 200 mmHg (0.7 to 26.7 kPa), at a column bottom temperature of not more than about 190~C, a reflux ratio of from about 0.1 to about 1 and a distilling ratio of from about 70 to about 99%.
The diacetoxybutene drawn from the top of column 3 preferably contains from about 0.1 to about 2.5% by weight of diacetoxyoctadiene. When the process of the invention also includes distilling off diacetoxyoctane contained in the diacetoxybutane, the distillation conditions following the acetoxylation are set so that the diacetoxyoctadiene content is regulated to from about 1.0 to about 2.5% by weight, preferably not more than about 1.5% by weight. When diacetoxyoctadiene alone is distilled off such that the process does not include a diacetoxyoctane removal step, the distillation conditions following acetoxylation are preferably set so that the diacetoxyoctadiene content is regulated to not more than about CA 0221~44 1997-09-1~
0.5% by weight, preferably not more than about 0.1% by weight.
In order to sharply reduce the amounts of impurities contained in the diacetoxybutene, it may be preferred to vary one or more of the distillation conditions. For example, it may be preferred to increase the theoretical plate number or the reflux ratio and lower the distillation ratio. More particularly speaking, distillation column 3 may preferably be operated at a theoretical plate number of from about S to about 20, a reflux ratio of from about 0.1 to about lO and a distillation ratio from the column top of from about 70 to about 97%.
(2) Hydrogenating the reaction product obtained in the acetoxylation step to thereby give diacetoxybutane:
The diacetoxybutene obtained from the top of distillation column 3 in the acetoxylation step is subjected to hydrogenation to thereby form diacetoxybutane. The hydrogenation reaction is preferably carried out by bringing the diacetoxybutene into contact with hydrogen in the presence of a precious metal catalyst such as a palladium, nickel or ruthenium catalyst and reacting within a temperature range of from about 40 to about 180~C, preferably under atmospheric pressure or higher, more preferably up to about 150 kg/cm2 (14.7 MPa).
The hydrogenation reaction may be performed by a number of different methods including, for example, the CA 0221~44 1997-09-1~
conventional fixed bed method, fluidized bed method or catalyst-suspending method.
The hydrogen used in the hydrogenation reaction may preferably either have high purity or be diluted with another gas exhibiting no undesirable effect on the reaction. Hydrogen is preferably employed in an amount of from about 1 to about 50 mol, more preferably from about 2 to about 20 mol, per mol of diacetoxybutene.
The hydrogenation product is degassed to thereby eliminate the unreacted hydrogen therefrom and is then subjected to distillation in the third distillation column 5 to thereby give diacetoxybutane. In this distillation step, the diacetoxybutane is obtained as the overhead product while high-boiling fractions containing diacetoxyoctane, which is the hydrogenation product of diacetoxyoctadiene, are obtained as the bottom settlings.
Distillation column 5 is preferably operated at a theoretical plate number of from about 5 to about 10, under a column top pressure of from about 5 to about 200 mmHg (0.7 to 26.7 kPa), at a column bottom temperature of not more than about 190~C, a reflux ratio of from about 0.1 to about 1 and a distillation ratio from the column top of from about 70 to about 99%.
The diacetoxyoctane content in the diacetoxybutane supplied to distillation column 5 is at least partially CA 0221~44 1997-09-1~
dependent on the operation conditions of distillation column 3.
Under the said conditions, the diacetoxyoctane content is about 0.1 to 2.5% by weight prior to distillation in column 5. When the diacetoxyoctadiene content is reduced at or below 0.5% by weight in distillation column 3, the diacetoxyoctane content is less than about 0.5% by weight, and more preferably not more than about 0.1% by weight. When only a portion of the diacetoxyoctadiene is eliminated in distillation column 3, the diacetoxyoctane content is preferably from about 1.0 to about 2.5% by weight, and more preferably not more than about 1.5% by weight.
If the diacetoxyoctadiene content in distillation column 3 is more than 2.5% by weight, the content has to be reduced at or below 0.5% by weight by the distillation in distillation column 5.
When the procedure for eliminating diacetoxyoctadiene in distillation column 3 is combined with the procedure for eliminating diacetoxyoctane in distillation column 5, the predetermined level to which the content of diacetoxyoctadiene or diacetoxyoctane is reduced in each column is appropriately determined by taking the balance between the distillation loads in columns 3 and 5 into consideration. For example, it is preferred that the amount of diacetoxyoctadiene eliminated in distillation column 2 exceeds 50% of the total amount eliminated.
CA 0221~44 1997-09-1~
When distillation column 3 is operated under the preferred conditions described above, the diacetoxybutane drawn from the top of column 5 contains from about 1.0 to about 2.5%
by weight of diacetoxyoctane. In the process of the present invention, the operation conditions of distillation column 5 are preferably set so that the diacetoxyoctane content is regulated to not more than about 0.5% by weight, and more preferably not more than about 0.2% by weight.
More particularly speaking, distillation column 5 is preferably operated at a theoretical plate number of from about 5 to about 20, a reflux ratio of from about 0.1 to about 10 and a distillation ratio from the column top of from about 70 to about 97%.
When the diacetoxyoctane content in the diacetoxybutane exceeds 0.5% by weight, the butanediol obtained by hydrolyzing it contains the same content of monoacetoxyoctanol which is difficult to remove by distillation.
(3) Hydrolyzing hydrogenation product to thereby give butanediol:
Preferably, the hydrolysis reaction is performed by bringing diacetoxybutane into contact with water in the presence of a solid acid catalyst such as a cation exchange resin within a temperature range of from about 30 to about 110~C, and more preferably from about 40 to about 90~C, under such a pressure as to prevent boiling or serious bubbling due CA 0221~44 1997-09-1~
to dissolved gases, etc. in the course of the reaction, i.e., preferably from about atmospheric pressure to about 10 kg/cm ~G
~0.098 to 1.08 MPa).
In this reaction, water is preferably employed in an amount of from about 2 to about 100 mol, preferably from about 4 to about 50 mol, per mol of diacetoxybutane. When water is used in an excessively small amount, the reaction ratio is lowered. On the other hand, it is not preferred to use too much water, since increased heat energy would be required to recover butanediol from the reaction product.
The reaction may be carried out by a number of different methods which, for example, are conducted either batchwise or continuously. When an ion exchange resin is used in the hydrolysis reaction, it may be in a suspended state.
Alternatively, the reactants may be passed through a column packed with the ion exchange resin. From an industrial viewpoint, it is preferred to employ a continuous fixed bed method.
When the reaction is performed by using a suspended bed, the ion exchange resin is preferably employed in an amount of from about 0.1 to about 50% by weight, and more preferably from about 1 to about 10% by weight, based on the weight of the liquid (water and the diacetoxybutane).
When using the continuous fixed bed method, the reaction may be carried out by continuously supplying water and CA 0221~44 1997-09-1~
diacetoxybutane to a reactor 6 packed with the ion exchange resin, which is preferably kept at a predetermined temperature, and simultaneously drawing out the butanediol thus formed as a mixture with acetic acid and the excess water.
The diacetoxybutane and water may be supplied either separately or as a mixture thereof. It is also possible to supply these materials as a homogeneous liquid phase which further contains butanediol (i.e., the reaction product), together with impurities such as monohydroxyacetoxybutane, etc.
When using the fixed bed method, it is preferred to supply these materials in the form of a homogeneous liquid phase so as to accelerate the smooth progress of the reaction.
The liquid product formed by the reaction contains the desired butanediol together with acetic acid, water, partial hydrolyzates and some by-products such as teterahydrofuran.
After the completion of the reaction, the catalyst is filtered off from the reaction mixture and the filtrate is distilled to thereby give butanediol.
The distillation is preferably effected in the following manner. In the fourth distillation column 7, water and acetic acid are eliminated as the overhead products. Then the bottom settlings are supplied to the fifth distillation column 8 from which the unreacted diacetoxybutane and its isomers are eliminated as the overhead products. Next, the bottom settlings, comprising 1,4-butanediol as the major CA 0221~44 1997-09-1~
component thereof, are supplied to the sixth distillation column 9. From the top of distillation column 9, the desired 1,4-butanediol product is obtained, while high-boiling compounds are drawn out as the bottom settlings. The 1,4-butanediol product preferably contains not more than about 1%
by weight, and more preferably from about 0 to about 0.5% by weight, of monoacetoxyoctanol.
To further illustrate the present invention, the following Examples will be given wherein all "parts" and "%
are by weight.
(Reference Example 1) Acetoxylation reaction Into an acetoxylation reactor were supplied 170 part/hr of 1,3-butadiene, 3,000 part/hr of acetic acid and 530 part/hr of oxygen. In the presence of a catalyst comprising 3% of palladium and 0.6% of tellurium supported on active carbon, the mixture was reacted under 9 MPa at 100~C and degassed to thereby give a reaction product containing 14.2% of diacetoxybutene and 0.6% of diacetoxyoctadiene.
This reaction product was supplied to distillation column 2 at a rate of 3,100 part/hr. Thus, water and most of the acetic acid were distilled off from the column top at a rate of 252 part/hr, while bottom settlings containing 84.5% by weight of diacetoxybutene and 3.2% by weight of diacetoxy-octadiene were drawn off at a rate of 580 part/hr.
CA 0221~44 1997-09-1 (Example 1) The bottom settlings obtained in the above Reference Example 1 were supplied to distillation column 2 (practical plate number: 20) at a rate of 580 part/hr and distilled therein under a column top pressure of 2.7 kPa at a reflux ratio of 0.5. Thus a solution containing 86.3% of diacetoxy-butene and 1.0% of diacetoxyoctadiene was distilled off from the column top at a rate of 550 part/hr.
The diacetoxybutene fraction thus obtained was supplied to a hydrogenation reactor packed with a palladium catalyst and a ruthenium catalyst and hydrogenated therein under a hydrogen gas stream at 70~C and a reaction pressure of 5 kPa. Thus a reaction mixture containing 86.5% of diacetoxybutane and 1.0%
of diacetoxyoctane was obtained.
Next, the reaction mixture was subjected to gas/liquid separation and then supplied to distillation column 5 (practical plate number: 20) at a rate of 550 part/hr and distilled therein under a column top pressure of 2.0 kPa at a reflux ratio of 0.25. Thus a solution containing 87.1% of diacetoxybutane and 0.2% of diacetoxyoctane was distilled off from the column top at a rate of 520 part/hr.
The hydrogenation reaction mixture thus obtained was supplied to a hydrolysis reactor packed with a strongly acidic ion exchange resin (Diaion SK-lB ; manufactured by Mitsubishi Chemical Corporation) at a rate of 520 part/hr together with CA 0221~44 1997-09-1~
-500 part/hr of water. Then hydrolysis was effected at a temperature of 50~C to thereby give a reaction mixture containing 10.2% of 1,4-butanediol and 0.04% of monoacetoxy-octanol.
This reaction mixture was supplied to the distillation column 7 at a rate of 1,020 part/hr. Then water and most of the acetic acid were distilled off from the column top at 660 part/hr, while the bottom settlings containing 28.9% of 1,4-butanediol and 0.1% of monoacetoxyoctanol were drawn out from the column bottom at a rate of 360 part/hr. Then the bottom settlings were supplied to distillation column 8. After distilling off the unreacted diacetoxybutane from the column top, the bottom settlings of distillation column 8 were supplied to distillation column 9. The high-boiling compounds were drawn out from the column bottom and 1,4-butanediol with a purity of 99.3% was obtained from the column top. This 1,4-butanediol contained 0.4% of monoacetoxyoctanol.
(Example 2) Distillation was performed in the same manner as described in Example 1 but the reflux ratio of distillation column 3, into which the bottom settlings obtained in Reference Example 1 were supplied, was adjusted to 5. Thus a distillate containing 87.1% of diacetoxybutene and 0.1% of diacetoxy-octadiene was obtained from the column top.
The diacetoxybutene fraction thus obtained was CA 0221~44 1997-09-1~
subjected to hydrogenation in the same manner as in Example 1 to thereby give a reaction mixture containing 87.3% of diacetoxybutane and 0.1% of diacetoxyoctane.
After gas/liquid separation, the hydrogenation reaction mixture thus obtained was not supplied to distillation column 5 as in Example 1, but rather was hydrolyzed under the same conditions as those employed in Example 1. Thus a reaction mixture containing 10.4% of 1,4-butanediol and 0.02% of monoacetoxyoctanol was obtained.
This reaction mixture was supplied successively to distillation columns 7, 8 and 9 in the same manner as in Example 1. From the top of distillation column 9, 1,4-butanediol with a purity of 99.5% was obtained. This product contained 0.2% of monoacetoxyoctanol.
(Comparative Example 1) Distillation was performed in the same manner as described in Example 1, but the reflux ratio of distillation column 3 was adjusted to 0.05. Thus a distillate containing 85.0% of diacetoxybutene and 1.7% of diacetoxyoctadiene was obtained from the column top.
The diacetoxybutene fraction thus obtained was subjected to hydrogenation in the same manner as in Example 2.
The hydrogenation reaction mixture containing 85.1% of diacetoxybutane and 1.6% of diacetoxyoctane was then subjected to gas/liquid separation. After gas/liquid separation, the CA 0221~44 1997-09-1~
-reaction mixture was not supplied to distillation column 5 as in Example 2, but rather was hydrolyzed under the same conditions as those employed in Example 1 to thereby give a reaction mixture containing 9.9% of 1,4-butanediol and 0.3% of monoacetoxyoctanol.
This reaction mixture was supplied successively to distillation columns 7, 8 and 9 in the same manner as in Example 1. From the top of distillation column 9, 1,4-butanediol with a purity of 95.1% was obtained. This product contained 3.2% of monoacetoxyoctanol.
The process of the present invention makes possible the industrial production of highly pure 1,4-butanediol containing not more than 1% by weight of monoacetoxyoctanol, which is suitable as a starting material for producing polyester, teterahydrofuran, etc.
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
Claims (8)
1. A process for producing butanediol, comprising hydrolysis of diacetoxybutane, wherein the diacetoxybutane to be hydrolyzed contains not more than about 0.5% by weight of diacetoxyoctane.
2. The process as claimed in Claim 1, wherein said diacetoxybutane is obtained by hydrogenation of diacetoxybutene.
3. The process as claimed in Claim 1, wherein said diacetoxybutane is obtained by acetoxylation of butadiene to produce diacetoxybutene, followed by hydrogenation of said diacetoxybutene.
4. The process as claimed in Claim 3, wherein said acetoxylation of butadiene is performed by reacting said butadiene with acetic acid and molecular oxygen in the presence of a palladium catalyst to thereby produce said diacetoxybutene.
5. The process as claimed in Claim 1, wherein the content of said diacetoxyoctane in said diacetoxybutane to be hydrolyzed is not more than 0.2% by weight.
6. The process as claimed in Claim 2 or 3, wherein said diacetoxybutene contains not more than about 0.2% by weight of diacetoxyoctadiene.
7. The process as claimed in any one of Claims 1 to 6, wherein said butanediol is 1,4-butanediol.
8. The process as claimed in Claim 7, wherein said 1,4-butanediol contains not more than about 1% by weight of monoacetoxyoctanol.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25145596 | 1996-09-24 | ||
| JP8-251455 | 1996-09-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2215544A1 true CA2215544A1 (en) | 1998-03-24 |
Family
ID=17223088
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2215544 Abandoned CA2215544A1 (en) | 1996-09-24 | 1997-09-15 | Process for producing butanediol |
Country Status (4)
| Country | Link |
|---|---|
| KR (1) | KR19980024923A (en) |
| CA (1) | CA2215544A1 (en) |
| DE (1) | DE19741729A1 (en) |
| TW (1) | TW380131B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11040334B2 (en) | 2017-02-13 | 2021-06-22 | Daicel Corporation | Catalyst for reduction reaction of 3,4-dihydroxytetrahydrofuran, and method for producing 3,4-dihydroxytetrahydrofuran reduced product |
-
1997
- 1997-09-02 TW TW86112630A patent/TW380131B/en not_active IP Right Cessation
- 1997-09-15 CA CA 2215544 patent/CA2215544A1/en not_active Abandoned
- 1997-09-22 DE DE1997141729 patent/DE19741729A1/en not_active Withdrawn
- 1997-09-24 KR KR1019970048547A patent/KR19980024923A/en not_active Application Discontinuation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11040334B2 (en) | 2017-02-13 | 2021-06-22 | Daicel Corporation | Catalyst for reduction reaction of 3,4-dihydroxytetrahydrofuran, and method for producing 3,4-dihydroxytetrahydrofuran reduced product |
Also Published As
| Publication number | Publication date |
|---|---|
| TW380131B (en) | 2000-01-21 |
| KR19980024923A (en) | 1998-07-06 |
| DE19741729A1 (en) | 1998-03-26 |
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