CA1126752A - Preparation of butanedicarboxylic acid esters - Google Patents
Preparation of butanedicarboxylic acid estersInfo
- Publication number
- CA1126752A CA1126752A CA319,539A CA319539A CA1126752A CA 1126752 A CA1126752 A CA 1126752A CA 319539 A CA319539 A CA 319539A CA 1126752 A CA1126752 A CA 1126752A
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- Canada
- Prior art keywords
- butadiene
- catalyst
- stage
- tertiary nitrogen
- nitrogen base
- Prior art date
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/36—Preparation of carboxylic acid esters by reaction with carbon monoxide or formates
- C07C67/38—Preparation of carboxylic acid esters by reaction with carbon monoxide or formates by addition to an unsaturated carbon-to-carbon bond
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
O.Z. 0050/033014 Abstract of the Disclosure: In a process for the prepara-tion of butanedicarboxylic acid esters by a) reacting butadiene or hydrocarbon mixtures containing butadiene with carbon monoxide and a C1-C4-alkanol in the presence of a tertiary nitrogen base and a cobalt carbonyl catalyst at from 80 to 150°C under superatmospheric pressure, b) removing the greater part of the tertiary nitrogen base together with any excess hydrocarbon and c) reacting the resulting pentenoic acid ester, in the presence of the catalyst remaining in the reaction mixture, and in the presence of the remaining amount of tertiary nitrogen base, with carbon monoxide and a C1- to C4-alkanol at from 140 to 200°C under superatmospheric pressure, to give the butanedicarboxylic acid ester, the improvement wherein the reaction mixture in stage c) is substantially free from dissolved butadiene or butadiene bonded to the catalyst.
Butanedicarboxylic acid esters may be used for the preparation of polymers.
Butanedicarboxylic acid esters may be used for the preparation of polymers.
Description
7~ ~
O.Z. 0050/0~014 Preparation of butanedicarboxylic acid este~s -~ ., ~
The present invention relates to a process for the preparation of butanedicarboxylic acid esters by reacting butadiene, or a hydrocarbon ~ixture containing butadiene, with carbon monox~de and an alkanol in the presence of a - cobalt carbonyl catalyst and a tertiary nitrogen base.
~ erman Laid-Open Application DOS 2,037,782 discloses a process for the preparation of adipic acid wherein buta-diene is reacted with carbon monoxide and water under super-atmospheric pressure at an elevated temperature in the pre-sence of a rhodium compound as the catalyst. The yieldsof dicarboxylic acids achieved with this process do not offer encouragement to carry out the process industrially.
According to a different process, described in German Pub-lished Application DAS 1,518,216, butadiene is converted to dicarboxylic acids in the presence of cobalt carbonyl, pyridine and water, at 430 bar and 210C The yield achieved is from 50 to 7C~ of theory, based on butadiene.
In addition, 3ulletin of the Chemical Society of Japan, 46 (1973), 524 - 530 disc~oses that dimethyl adipate is obtained by reacting butadiene with carbon monoxide and methanol in -the presence of cobalt carbonyl and pyridine and then carbonylating the resulting methyl pentenoate with the same catalys-t, the temperature being raised to 200C in the second stage. However, the yields of dimethyl adipate are only from 47 to 51l,''.
It is an object of the present invention to increase the yield of butanedicarboxylic acids obtained by carbonyla-'~
~Z675;2 tion of butadiene and in particular to improve the effec-tiveness of carb~nylation of the pentenoic acid ester obtained as an intermediate.
We have found that this object is achieved by providing a process for the preparation of butanedicarboxylic acids by a) reacting butadiene or hydrocarbon mixtures containing butadiene with carbon monoxide and a Cl-C4-alkanol in the presence o~ a ter-tiary nitrogen base and a cobalt carbonyl catalyst at from 80 to 150C under superatmospheric pressure, b) removing the greater part of the tertiary nitrogen base - together with any excess hydrocarbon and c) reacting the resulting pentenoic acid ester9 without removing the catalyst and in the presence of the remaining amount of tertiary nitrogen base, with carbon monoxide and a Cl- to C4-alkanol at from 140 to 200C under superatmospheric pressure, to give the butanedicarboxylic acid ester, wherein the reaction mixture in stage c) is s~bstantially free from dissolved butadiene or butadiene bonded to the catalyst.
The novel process has the advantage that it is possible to increase the yields of butanedicarboxylic acid esters without removing the catalyst, and in particular that it is possible to render more effective the stage wherein pentenoic acid esters are carbonylated to give butanedi-carboxylic acid es-ters.
The starting material is pure 1,3-butadiene or a hydrocarbon mixture containing butadiene. Such hydro-- 3 - O.Z~ C050~033014 carbon mixtures for example contain, in addition to buta-diene, saturated-hydrocarbons of 3 to 5 carbon atoms and mono-unsaturated olefins of ~ to 5 carbon atoms. The butadiene content should as a rule be more than 10% by weight. In industry, C4-cuts, in particular, are used as the starting mixture. This definition embraces all mix-tures of predominantly non-branched C4-hydrocarbons which contain more than l~o by weight of 1,3-butadiene (butadiene) and more than 15% by weight of butenes. Depending on the origin of the mixture, the individual components are normally present in the following proportions in the mixtures:
butadiene 10 - 70, on average 40 - 60, % by weight isobutene 15 - 40, on average 20 - 35, % by weight but-l-ene 10 - 40, on avsrage 10 - 25, % by weight but-2-ene 5 - 20, on average 5 - 15, % by weight butane 1 - 10, on average 1 - 10~ % by weight butynes 0.1 - 3, on average 0.1 - 3, % by weight Such C4-cuts are obtained, for example, on dehydro genation of butane or butene and as by-~roducts for thQ produc-tion of ethylene~ by thermal cracking of naphtha or higherhydrocarbon cuts.
Suitable Cl-C4-alkanols are methanol, ethanol, propanol, butanol and isobutanol. The use of methanol is particularly preferred~ Advantageously, the alkanol is used in excess, especially in an amount of from 1.5 to 5 ~s~
_ 4 _ O.Z 0050/03~014 moles per mole of butadiene.
The reaction is preferably carried out at from 120 ~ , ~
to 140C un~er pressures of ~rom 600 to 1,200 bar. As a rule, from 0.01 to 0.1 gram atom of cobalt, in the form of a cobalt carbonyl complex, is used per mole of butadiene.
Carbon monoxide is advantageously employed in excess, for example in from 1.5 to lO times the stoichio-metrically required amount.
Suitable tertiary nitrogen bases advantageously have a PKa of from 3 to ll, with theproviso that theyareprefer-ably lower-boiling than the pentenoic acid ester to be pre-pared. Preferably, N-heterocyclic compounds,eg. pyridine (PKa 5.3), methylpyridines, eg. 3-picoline (PKa 6.o) and isoquinoline (PKa 5.4), and trialkylamines, eg. trimethyl-amine (PKa ll.0), are used. Pyridine is of particular - importance industrially. It has proved especially advan-tageous to use from 20 to 50 moles of pyridine per mole of cobalt carbonyl catalyst.
The cobalt catalystsused in stage a) are either pro-duced in situ from cobalt salts, eg. salts of fatty acids, such as formates, acetates, propionates or butyrates, or, advantageously, are introduced as préformed cobalt carbonyl.
In particular, it has proved advantageous to introduce the cobaltcarbonyl catalystinto the reaction mixtureas a solution in butadieneor aC4-cut. Such a solution is obtained, for example, by reacting an aqueous solution of a cobalt salt of a fatty acid with a mixture of carbon monoxide and hydrogen in the presence of active charcoal at from 100 to 170C
under a pressure of from 100 to 400 bar. The resulting - -_ 5 _ O.Z; 0050,/033014 cobalt carbonyl is then extracted from the aqueous solution by means of butadiene or a C4-cut.
The reaction mixture obtained in stage a) contains unconverted butadiene, with or without other hydrocarbons, tertiary nitrogen bases, cobalt carbonyl catalysts, uncon-- verted alkanols, the pentenoic acid ester formed as the desired product, by-products, eg. esters of valeric acid, vinylcyclohexene, butenylketones and butylketones, and butadiene polymers.
It is an essential feature of the invention that in stage c) the reaction mixture is substantially ~ree from dissolved butadiene or butadiene bonded to the catalyst.
Advantageously, at least 50%, mors especially 80%, of the cobalt catalyst should, in stage c), not be in the form of a ~r-allyl complex with butadiene.
This can easily be checked in that, if conversion in stage a) is incomplete, ie. butadiene is present, the IR spectrum of the catalyst is essentially characterized by the cobalt carbonyl bands at 2,010 and 2,080 cm 1, whilst the band at 1,930 cm 1 is less pronounced. As the butadiene content is progressively reduced, the bands at 2,010 and 2,080 cm 1 disappear, whilst the carbonyl band at 1,930 cm 1 becomes the main carbonyl band. This indicates that the cobalt carbonyl complex which contains bonded butadiene has been virtually completely converted to a pure cobalt carbonyl complex which only retains small amounts of bonded butadiene A suitable composition of catalyst, appropriate ~or stage c), is obtained, for e~ample, by converting, in stage a), at least; 99% by weight o~ the butadiene employed.
~;2 675~Z
- 6 - O.Z. 0050~0~3014 Thereafter the pressure of the resulting reaction mixture is released and tertiary nitrogen bases contained in the ~ ., mixture are very largely removed, as are any excess hydro-carbons. This removal is effected, for example, by dis-tillation or other separation processes, eg. ex~raction, Advantageously, tertiary nitrogen bases and any excess hydrocarbon are removed by distillation under reduced pres-sure. Advantageously, the tertiary nitrogen bases are removed to the point where their content is only from 2 to 10 moles per mole of cobalt carbonyl catalyst.
Since it is frequently inappropriate to convert at least 99% of the butadiene, especially if a butadiene-containing hydrocarbon is used, a catalyst which is effective in stage c) is in such cases obtained by removing the free butadiene from the reaction mixture obtained ~n stage aj, after releasing the pressure, by, for example, distillation, with or without other hydrocarbons which may be present.
`~ In removing this butadiene care is taken, however, that the entire amount of tertiary nitrogen base remains in the reac-tion mixture. The latter is then treated with carbon monoxide at from 100 to 160C under a pressure of from 50 to 200 bar. The treatment time is as a rule from 5 to 60 minutes. ~uring this treatment the cobalt carbonyl catalyst is converted to a form appropriate forstage c).
Following this after-treatment, the greater part of the tertiary nitrogen bases contained in the reaction mixture is then removed as explained above, until the amount remaining is as stated above.
It is to be noted that during distillation the tem-æ
- 7 - O.Z. Oo~o/o~o perature in the bottom should not exceed 75C, so as to avoid decompositlo~n of the cobalt catalyst.
The pentenoic acid ester remaining in the reaction mixture thus obtained is reacted with carbon monoxide and a Cl-C4-alkanol, if necessary after addition of an appropr~te fresh amount of alkanol, at from 140 to 200C under a pressure of from lO0 to 400 bar in the presence of the cobalt catalyst present in the reac-tion mix-ture and of the tertiary nitrogen base. As mentioned above,from 2to lO moles of tertiary nitrogen base are present in the reaGtion mixture per mole of cobalt catalyst.
Advantageously, the reaction is carried out at from 150 to 180C under a pressure of from lO0 to 400 bar, The amount of al~anol present is, for example, from 1.5 to 4 moles per mole of pentenoic acid ester. It has also proved advan-tageous to add a few per cent by volume of hydrogen, eg.
from 0.2 to 4% by volume, to the carbon monoxide, in order to increase the rate of reaction. After releasing the pressure, excess alkanol and free tertiary nitrogen base are distilled from the reaction mixture obtained. This does not remove the tertiary nitrogen bases bonded chemically to the catalyst ~from 1 to 2 moles per gram atom of cobalt).
To avoid decomposition of the cobalt complex9 with undesir-able formation of metallic cobalt, it has proved advantageous to pass a slow stream o~ carbon monoxide, or of a gas con-taining carbon monoxide, into the bottom of the column.
~12f~52 - 8 - O.Z. 0050/G~3014 The reaction mixture which is left, and which con-tains catalyst, butanedicarboxylic acid ester and by-products, is treated with an oxidizing agent, eg. molecular oxygen or a ga~ containing the latter, eg. air, in an aqueous acid medium, advantageously at a pH of from 3 to ~, and advantageously at from 80 to 160C. After the treat-ment, the mixture is separated into an organic phase and an aqueous phase, for example by decanting. Fractional dis-tillation of the organic phase gives the residual tertiary nitrogen base, the unconverted pentenoic acid ester, which is recycled to the carbonylation reaction, and a mixture of butanedicarboxylic acid esters (80 - 85% by weight of adipic acid esters, 11 - 15% by weight of 2-methylglutaric acid esters and 3 - 6% by weight of 2-ethylsuccinic acid esters) The ester mixture can be used to prepare diols or poly-esters. The adipic acid ester obtainable from the ester mixture by fractional distillation may be used for the preparation of adipic acid. The aqueous phase containing cobalt salts, with or without free acid, is advantageously recycled, being used as a starting solution for the prepara-tion of the cobalt catalyst.
The adipic acid esters and/or adipic acid obtained according to the invention may be used for the preparation of polymers.
The Examples which follow illustrate the process of the invention.
EXAMP~E 1 a) Per hour, 310 ml of a C4-cut, which contains 43% by weight of butadiene (1,57 moles) and 3.7 g of cobalt in the .
- 9 - o ~ z ~ 0050~03301L~
form of cobal~ carbonyl compounds are in-troduced into the bottom of a high-pressure vessel of 1.9 liters capacity.
In addition, 124 g (1,57 moles) of pyridine, 100 g (3.14 moles) of methanol and 60 liters (S.T.P.) of carbon monoxide are introduced per hour. The carbonylation takes place at 140C and 600 bar. The product taken off at the top of the high-pressure vessel is let down, resulting in the removal, in the gaseous form, of excess C4-hydrocarbons, in addition to excess carbon monoxide. The excess hydro-carbons contain virtually no butadiene so that, based on butadiene, the reaction is quantitative.
b) Per hour,about 52 g of methanol and 100 g of pyridine as well as hydrocarbons are distilled from the material dis-charged, the distillation being carried out under reduced pressure so as not to damage the catalyst. The distilla-tion bottom temperature is kept to a maximum of 65C.
c) The distillation residue thus obtained, which con-tains 3.7 g of cobalt as the carbonyl complex, 165 g (1.44 moles) of pentenoic acid esters and 22.8 g (0.228 mole) of pyridine is fed, together with 92 g (2.88 moles) of methanol and 55 liters (S.T.P.) o~ carbon monoxide, con-taining 2% by volume of hydrogen, continuously into the bottom of a further high-pressure vessel of 1.7 liters capacity. The carbonylation is carried out at 170C
under a pressure of 150 bar. Gas-chromatographic analysis of the products discharged shows that 95% by weight of the methyl pentenoate employed has been converted, the selec-tivity in respeci of dimethyl adipate being 76%.
- 10 - O.Z. OC50/0~,014 - ~COMPARATIVE EXAMPLE
. i; ~
- The procedure described in Example l is followed, but in s~age 1 a) ~he reaction is carried out a~ a lo~er ~emp~a~e, viz. 120C , the conversion achieved, based on butadiene, being only 80%, according to gas-chromatographic analysis.
Thereafter the procedure followed is entirely as described in Example l; the material discharged from stage c) shows, according to gas-chromatographic analysis, a conversion of 56% by weight of the methyl pentenoate employed, the selec-tivity being 77% -in respe-ct of dimeth~l-adipate.
The lowering of the conversion of methyl pentenoate shows clearly that the catalyst has not been adequately converted into the active form ~or stage c).
a) The procedure followed is as in Example 1, but the reaction is carried out at 130C and 600 bar, so that only 90% of the butadiene is converted. A~ter releasing the pressure, the C4-hydrocarbons and unconverted butadiene are separated off. The reaction product is then treated, ln the presence of the entire pyridine and methanol, in a further high-pressure vessel of 0.4 liter capacity, for 60 minutes at 140C under a CO pressure of lOO bar. This results in over 95~ conversion of the catalyst, which was - pre~iously quantitatively present in a chemically bonded form, as the ~-allyl complex, into butadiene-free cobalt carbonyl.
. ~ ~
~ O.Z. 0050/033014 b) After letting down to atmospheric pressure, about 100 g of pyridine;and 52 g of methanol are distilled off per hour, under reduced pressure (bottom temperature 65C).
c) The distillation resiclue thus obtained, which con-tains the cobalt carbonyl catalyst, 165 g (1.44 moles) of pentenoic acid ester and 22.8 g (0.288 mols) of pyridine is fed, together with 92 g (2.88 moles) of methanol and 55 liters (S.T.P,) of carbon monoxide, continuously into the bottom of a further high-pressure vessel of 1,7 liters capacity. The carbonylation is carried.out at 170C and 150 bar. Gas-chromatographic analysls of the products discharged shows that 98.5~ of the methyl pentenoate employed has been converted, the selectivity in respect of dimethyl adipate being 77.~%.
_ . .
O.Z. 0050/0~014 Preparation of butanedicarboxylic acid este~s -~ ., ~
The present invention relates to a process for the preparation of butanedicarboxylic acid esters by reacting butadiene, or a hydrocarbon ~ixture containing butadiene, with carbon monox~de and an alkanol in the presence of a - cobalt carbonyl catalyst and a tertiary nitrogen base.
~ erman Laid-Open Application DOS 2,037,782 discloses a process for the preparation of adipic acid wherein buta-diene is reacted with carbon monoxide and water under super-atmospheric pressure at an elevated temperature in the pre-sence of a rhodium compound as the catalyst. The yieldsof dicarboxylic acids achieved with this process do not offer encouragement to carry out the process industrially.
According to a different process, described in German Pub-lished Application DAS 1,518,216, butadiene is converted to dicarboxylic acids in the presence of cobalt carbonyl, pyridine and water, at 430 bar and 210C The yield achieved is from 50 to 7C~ of theory, based on butadiene.
In addition, 3ulletin of the Chemical Society of Japan, 46 (1973), 524 - 530 disc~oses that dimethyl adipate is obtained by reacting butadiene with carbon monoxide and methanol in -the presence of cobalt carbonyl and pyridine and then carbonylating the resulting methyl pentenoate with the same catalys-t, the temperature being raised to 200C in the second stage. However, the yields of dimethyl adipate are only from 47 to 51l,''.
It is an object of the present invention to increase the yield of butanedicarboxylic acids obtained by carbonyla-'~
~Z675;2 tion of butadiene and in particular to improve the effec-tiveness of carb~nylation of the pentenoic acid ester obtained as an intermediate.
We have found that this object is achieved by providing a process for the preparation of butanedicarboxylic acids by a) reacting butadiene or hydrocarbon mixtures containing butadiene with carbon monoxide and a Cl-C4-alkanol in the presence o~ a ter-tiary nitrogen base and a cobalt carbonyl catalyst at from 80 to 150C under superatmospheric pressure, b) removing the greater part of the tertiary nitrogen base - together with any excess hydrocarbon and c) reacting the resulting pentenoic acid ester9 without removing the catalyst and in the presence of the remaining amount of tertiary nitrogen base, with carbon monoxide and a Cl- to C4-alkanol at from 140 to 200C under superatmospheric pressure, to give the butanedicarboxylic acid ester, wherein the reaction mixture in stage c) is s~bstantially free from dissolved butadiene or butadiene bonded to the catalyst.
The novel process has the advantage that it is possible to increase the yields of butanedicarboxylic acid esters without removing the catalyst, and in particular that it is possible to render more effective the stage wherein pentenoic acid esters are carbonylated to give butanedi-carboxylic acid es-ters.
The starting material is pure 1,3-butadiene or a hydrocarbon mixture containing butadiene. Such hydro-- 3 - O.Z~ C050~033014 carbon mixtures for example contain, in addition to buta-diene, saturated-hydrocarbons of 3 to 5 carbon atoms and mono-unsaturated olefins of ~ to 5 carbon atoms. The butadiene content should as a rule be more than 10% by weight. In industry, C4-cuts, in particular, are used as the starting mixture. This definition embraces all mix-tures of predominantly non-branched C4-hydrocarbons which contain more than l~o by weight of 1,3-butadiene (butadiene) and more than 15% by weight of butenes. Depending on the origin of the mixture, the individual components are normally present in the following proportions in the mixtures:
butadiene 10 - 70, on average 40 - 60, % by weight isobutene 15 - 40, on average 20 - 35, % by weight but-l-ene 10 - 40, on avsrage 10 - 25, % by weight but-2-ene 5 - 20, on average 5 - 15, % by weight butane 1 - 10, on average 1 - 10~ % by weight butynes 0.1 - 3, on average 0.1 - 3, % by weight Such C4-cuts are obtained, for example, on dehydro genation of butane or butene and as by-~roducts for thQ produc-tion of ethylene~ by thermal cracking of naphtha or higherhydrocarbon cuts.
Suitable Cl-C4-alkanols are methanol, ethanol, propanol, butanol and isobutanol. The use of methanol is particularly preferred~ Advantageously, the alkanol is used in excess, especially in an amount of from 1.5 to 5 ~s~
_ 4 _ O.Z 0050/03~014 moles per mole of butadiene.
The reaction is preferably carried out at from 120 ~ , ~
to 140C un~er pressures of ~rom 600 to 1,200 bar. As a rule, from 0.01 to 0.1 gram atom of cobalt, in the form of a cobalt carbonyl complex, is used per mole of butadiene.
Carbon monoxide is advantageously employed in excess, for example in from 1.5 to lO times the stoichio-metrically required amount.
Suitable tertiary nitrogen bases advantageously have a PKa of from 3 to ll, with theproviso that theyareprefer-ably lower-boiling than the pentenoic acid ester to be pre-pared. Preferably, N-heterocyclic compounds,eg. pyridine (PKa 5.3), methylpyridines, eg. 3-picoline (PKa 6.o) and isoquinoline (PKa 5.4), and trialkylamines, eg. trimethyl-amine (PKa ll.0), are used. Pyridine is of particular - importance industrially. It has proved especially advan-tageous to use from 20 to 50 moles of pyridine per mole of cobalt carbonyl catalyst.
The cobalt catalystsused in stage a) are either pro-duced in situ from cobalt salts, eg. salts of fatty acids, such as formates, acetates, propionates or butyrates, or, advantageously, are introduced as préformed cobalt carbonyl.
In particular, it has proved advantageous to introduce the cobaltcarbonyl catalystinto the reaction mixtureas a solution in butadieneor aC4-cut. Such a solution is obtained, for example, by reacting an aqueous solution of a cobalt salt of a fatty acid with a mixture of carbon monoxide and hydrogen in the presence of active charcoal at from 100 to 170C
under a pressure of from 100 to 400 bar. The resulting - -_ 5 _ O.Z; 0050,/033014 cobalt carbonyl is then extracted from the aqueous solution by means of butadiene or a C4-cut.
The reaction mixture obtained in stage a) contains unconverted butadiene, with or without other hydrocarbons, tertiary nitrogen bases, cobalt carbonyl catalysts, uncon-- verted alkanols, the pentenoic acid ester formed as the desired product, by-products, eg. esters of valeric acid, vinylcyclohexene, butenylketones and butylketones, and butadiene polymers.
It is an essential feature of the invention that in stage c) the reaction mixture is substantially ~ree from dissolved butadiene or butadiene bonded to the catalyst.
Advantageously, at least 50%, mors especially 80%, of the cobalt catalyst should, in stage c), not be in the form of a ~r-allyl complex with butadiene.
This can easily be checked in that, if conversion in stage a) is incomplete, ie. butadiene is present, the IR spectrum of the catalyst is essentially characterized by the cobalt carbonyl bands at 2,010 and 2,080 cm 1, whilst the band at 1,930 cm 1 is less pronounced. As the butadiene content is progressively reduced, the bands at 2,010 and 2,080 cm 1 disappear, whilst the carbonyl band at 1,930 cm 1 becomes the main carbonyl band. This indicates that the cobalt carbonyl complex which contains bonded butadiene has been virtually completely converted to a pure cobalt carbonyl complex which only retains small amounts of bonded butadiene A suitable composition of catalyst, appropriate ~or stage c), is obtained, for e~ample, by converting, in stage a), at least; 99% by weight o~ the butadiene employed.
~;2 675~Z
- 6 - O.Z. 0050~0~3014 Thereafter the pressure of the resulting reaction mixture is released and tertiary nitrogen bases contained in the ~ ., mixture are very largely removed, as are any excess hydro-carbons. This removal is effected, for example, by dis-tillation or other separation processes, eg. ex~raction, Advantageously, tertiary nitrogen bases and any excess hydrocarbon are removed by distillation under reduced pres-sure. Advantageously, the tertiary nitrogen bases are removed to the point where their content is only from 2 to 10 moles per mole of cobalt carbonyl catalyst.
Since it is frequently inappropriate to convert at least 99% of the butadiene, especially if a butadiene-containing hydrocarbon is used, a catalyst which is effective in stage c) is in such cases obtained by removing the free butadiene from the reaction mixture obtained ~n stage aj, after releasing the pressure, by, for example, distillation, with or without other hydrocarbons which may be present.
`~ In removing this butadiene care is taken, however, that the entire amount of tertiary nitrogen base remains in the reac-tion mixture. The latter is then treated with carbon monoxide at from 100 to 160C under a pressure of from 50 to 200 bar. The treatment time is as a rule from 5 to 60 minutes. ~uring this treatment the cobalt carbonyl catalyst is converted to a form appropriate forstage c).
Following this after-treatment, the greater part of the tertiary nitrogen bases contained in the reaction mixture is then removed as explained above, until the amount remaining is as stated above.
It is to be noted that during distillation the tem-æ
- 7 - O.Z. Oo~o/o~o perature in the bottom should not exceed 75C, so as to avoid decompositlo~n of the cobalt catalyst.
The pentenoic acid ester remaining in the reaction mixture thus obtained is reacted with carbon monoxide and a Cl-C4-alkanol, if necessary after addition of an appropr~te fresh amount of alkanol, at from 140 to 200C under a pressure of from lO0 to 400 bar in the presence of the cobalt catalyst present in the reac-tion mix-ture and of the tertiary nitrogen base. As mentioned above,from 2to lO moles of tertiary nitrogen base are present in the reaGtion mixture per mole of cobalt catalyst.
Advantageously, the reaction is carried out at from 150 to 180C under a pressure of from lO0 to 400 bar, The amount of al~anol present is, for example, from 1.5 to 4 moles per mole of pentenoic acid ester. It has also proved advan-tageous to add a few per cent by volume of hydrogen, eg.
from 0.2 to 4% by volume, to the carbon monoxide, in order to increase the rate of reaction. After releasing the pressure, excess alkanol and free tertiary nitrogen base are distilled from the reaction mixture obtained. This does not remove the tertiary nitrogen bases bonded chemically to the catalyst ~from 1 to 2 moles per gram atom of cobalt).
To avoid decomposition of the cobalt complex9 with undesir-able formation of metallic cobalt, it has proved advantageous to pass a slow stream o~ carbon monoxide, or of a gas con-taining carbon monoxide, into the bottom of the column.
~12f~52 - 8 - O.Z. 0050/G~3014 The reaction mixture which is left, and which con-tains catalyst, butanedicarboxylic acid ester and by-products, is treated with an oxidizing agent, eg. molecular oxygen or a ga~ containing the latter, eg. air, in an aqueous acid medium, advantageously at a pH of from 3 to ~, and advantageously at from 80 to 160C. After the treat-ment, the mixture is separated into an organic phase and an aqueous phase, for example by decanting. Fractional dis-tillation of the organic phase gives the residual tertiary nitrogen base, the unconverted pentenoic acid ester, which is recycled to the carbonylation reaction, and a mixture of butanedicarboxylic acid esters (80 - 85% by weight of adipic acid esters, 11 - 15% by weight of 2-methylglutaric acid esters and 3 - 6% by weight of 2-ethylsuccinic acid esters) The ester mixture can be used to prepare diols or poly-esters. The adipic acid ester obtainable from the ester mixture by fractional distillation may be used for the preparation of adipic acid. The aqueous phase containing cobalt salts, with or without free acid, is advantageously recycled, being used as a starting solution for the prepara-tion of the cobalt catalyst.
The adipic acid esters and/or adipic acid obtained according to the invention may be used for the preparation of polymers.
The Examples which follow illustrate the process of the invention.
EXAMP~E 1 a) Per hour, 310 ml of a C4-cut, which contains 43% by weight of butadiene (1,57 moles) and 3.7 g of cobalt in the .
- 9 - o ~ z ~ 0050~03301L~
form of cobal~ carbonyl compounds are in-troduced into the bottom of a high-pressure vessel of 1.9 liters capacity.
In addition, 124 g (1,57 moles) of pyridine, 100 g (3.14 moles) of methanol and 60 liters (S.T.P.) of carbon monoxide are introduced per hour. The carbonylation takes place at 140C and 600 bar. The product taken off at the top of the high-pressure vessel is let down, resulting in the removal, in the gaseous form, of excess C4-hydrocarbons, in addition to excess carbon monoxide. The excess hydro-carbons contain virtually no butadiene so that, based on butadiene, the reaction is quantitative.
b) Per hour,about 52 g of methanol and 100 g of pyridine as well as hydrocarbons are distilled from the material dis-charged, the distillation being carried out under reduced pressure so as not to damage the catalyst. The distilla-tion bottom temperature is kept to a maximum of 65C.
c) The distillation residue thus obtained, which con-tains 3.7 g of cobalt as the carbonyl complex, 165 g (1.44 moles) of pentenoic acid esters and 22.8 g (0.228 mole) of pyridine is fed, together with 92 g (2.88 moles) of methanol and 55 liters (S.T.P.) o~ carbon monoxide, con-taining 2% by volume of hydrogen, continuously into the bottom of a further high-pressure vessel of 1.7 liters capacity. The carbonylation is carried out at 170C
under a pressure of 150 bar. Gas-chromatographic analysis of the products discharged shows that 95% by weight of the methyl pentenoate employed has been converted, the selec-tivity in respeci of dimethyl adipate being 76%.
- 10 - O.Z. OC50/0~,014 - ~COMPARATIVE EXAMPLE
. i; ~
- The procedure described in Example l is followed, but in s~age 1 a) ~he reaction is carried out a~ a lo~er ~emp~a~e, viz. 120C , the conversion achieved, based on butadiene, being only 80%, according to gas-chromatographic analysis.
Thereafter the procedure followed is entirely as described in Example l; the material discharged from stage c) shows, according to gas-chromatographic analysis, a conversion of 56% by weight of the methyl pentenoate employed, the selec-tivity being 77% -in respe-ct of dimeth~l-adipate.
The lowering of the conversion of methyl pentenoate shows clearly that the catalyst has not been adequately converted into the active form ~or stage c).
a) The procedure followed is as in Example 1, but the reaction is carried out at 130C and 600 bar, so that only 90% of the butadiene is converted. A~ter releasing the pressure, the C4-hydrocarbons and unconverted butadiene are separated off. The reaction product is then treated, ln the presence of the entire pyridine and methanol, in a further high-pressure vessel of 0.4 liter capacity, for 60 minutes at 140C under a CO pressure of lOO bar. This results in over 95~ conversion of the catalyst, which was - pre~iously quantitatively present in a chemically bonded form, as the ~-allyl complex, into butadiene-free cobalt carbonyl.
. ~ ~
~ O.Z. 0050/033014 b) After letting down to atmospheric pressure, about 100 g of pyridine;and 52 g of methanol are distilled off per hour, under reduced pressure (bottom temperature 65C).
c) The distillation resiclue thus obtained, which con-tains the cobalt carbonyl catalyst, 165 g (1.44 moles) of pentenoic acid ester and 22.8 g (0.288 mols) of pyridine is fed, together with 92 g (2.88 moles) of methanol and 55 liters (S.T.P,) of carbon monoxide, continuously into the bottom of a further high-pressure vessel of 1,7 liters capacity. The carbonylation is carried.out at 170C and 150 bar. Gas-chromatographic analysls of the products discharged shows that 98.5~ of the methyl pentenoate employed has been converted, the selectivity in respect of dimethyl adipate being 77.~%.
_ . .
Claims (6)
1. In a process for the preparation of butanedicarboxylic acid esters by a) reacting butadiene or hydrocarbon mixtures containing butadiene with carbon monoxide and a C1-C4-alkanol in the presence of a tertiary nitrogen base and a cobalt carbonyl catalyst at from 80 to 150°C under superatmospheric pressure, b) removing the greater part of the tertiary nitrogen base together with any excess hydrocarbon and c) reacting the resulting pentenoic acid ester, in the presence of the catalyst remaining in the reaction mixture, and in the presence of the remaining amount of tertiary nitrogen base, with carbon monoxide and a C1- to C4-alkanol at from 140 to 200°C under superatmospheric pressure, to give the butanedicarboxylic acid ester, the improvement wherein the reaction mixture in stage c) is substantially free from dissolved butadiene or butadiene bonded to the catalyst.
2. A process as claimed in claim 1, wherein from 20 to 50 moles of tertiary nitrogen base are used per mole of cobalt carbonyl catalyst in stage a).
3. A process as claimed in claim 1, wherein from 2 to 10 moles of tertiary nitrogen base are used per mole of cobalt catalyst in stage c).
4. A process as claimed in claim 1, wherein, in stage c), at least 50% of the cobalt catalyst is not in the form of a .pi. -allyl complex with butadiene.
5. A process as claimed in claim 1, wherein the con-version, based on butadiene, in stage a) is maintained at not less than 99 mole %.
O.Z. 0050/033014
O.Z. 0050/033014
6. A process as claimed in claim 1, wherein, in stage b), the mixture remaining after removal of the hydrocarbons is treated with carbon monoxide under a pressure of from 50 to 200 bar, at from 100 to 160°C, whilst maintaining a molar ratio of cobalt catalyst to pyridine of 1 : 20 - 50.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2802580.1 | 1978-01-21 | ||
| DE19782802580 DE2802580A1 (en) | 1978-01-21 | 1978-01-21 | PROCESS FOR THE MANUFACTURING OF BUTANDICARBON ACID ESTERS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1126752A true CA1126752A (en) | 1982-06-29 |
Family
ID=6030044
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA319,539A Expired CA1126752A (en) | 1978-01-21 | 1979-01-12 | Preparation of butanedicarboxylic acid esters |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0003306B1 (en) |
| JP (1) | JPS54112819A (en) |
| CA (1) | CA1126752A (en) |
| DE (2) | DE2802580A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4692549A (en) * | 1986-06-27 | 1987-09-08 | E. I. Du Pont De Nemours And Company | Carboalkoxylation of butadiene to form dialkyl adipate |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2713195C3 (en) * | 1977-03-25 | 1980-01-10 | Basf Ag, 6700 Ludwigshafen | Process for the preparation of butanedicarboxylic acid esters |
-
1978
- 1978-01-21 DE DE19782802580 patent/DE2802580A1/en not_active Withdrawn
-
1979
- 1979-01-12 CA CA319,539A patent/CA1126752A/en not_active Expired
- 1979-01-15 EP EP79100108A patent/EP0003306B1/en not_active Expired
- 1979-01-15 DE DE7979100108T patent/DE2961623D1/en not_active Expired
- 1979-01-22 JP JP492679A patent/JPS54112819A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| EP0003306B1 (en) | 1981-12-30 |
| JPS54112819A (en) | 1979-09-04 |
| JPS6136739B2 (en) | 1986-08-20 |
| EP0003306A1 (en) | 1979-08-08 |
| DE2961623D1 (en) | 1982-02-18 |
| DE2802580A1 (en) | 1979-07-26 |
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