CA1057313A - Process for the continuous production of 2-ethyl hexanol - Google Patents
Process for the continuous production of 2-ethyl hexanolInfo
- Publication number
- CA1057313A CA1057313A CA232,598A CA232598A CA1057313A CA 1057313 A CA1057313 A CA 1057313A CA 232598 A CA232598 A CA 232598A CA 1057313 A CA1057313 A CA 1057313A
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- CA
- Canada
- Prior art keywords
- ethyl
- zone
- hexenal
- condensation
- ethyl hexenal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
- C07C45/67—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton
- C07C45/68—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms
- C07C45/72—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by reaction of compounds containing >C = O groups with the same or other compounds containing >C = O groups
- C07C45/74—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by reaction of compounds containing >C = O groups with the same or other compounds containing >C = O groups combined with dehydration
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
PROCESS FOR THE CONTINUOUS PRODUCTION OF
Abstract of the Disclosure An improvement in a process for preparing 2-ethyl hexanol wherein:
A) One mole of n-butyraldehyde is condensed with another mole of n-butyraldehyde in a condensation zone in the presence of an alkali metal hydroxide wherein there is .
formed 2-ethyl hexenal and higher condensation products;
B) The resultant product is contacted with water to separate alkali metal salts therefrom, an organic phase comprising 2-ethyl hexenal and higher condensation products is separated therefrom and unused alkali metal hydroxide is recycled to the condensation zone;
C) The organic phase is separated in a separation zone into a 2-ethyl hexenal rich fraction and a residual fraction having a major amount of higher condensation product;
D) The 2-ethyl hexenal rich fraction is introduced into a hydrogenation zone containing hydrogen and a hydrogen-ation catalyst and therein hydrogenated to 2-ethyl hexanol, the improvement residing in recycling to the condensation zone at least a portion of the residual fraction containing the major amount of higher condensation product.
Abstract of the Disclosure An improvement in a process for preparing 2-ethyl hexanol wherein:
A) One mole of n-butyraldehyde is condensed with another mole of n-butyraldehyde in a condensation zone in the presence of an alkali metal hydroxide wherein there is .
formed 2-ethyl hexenal and higher condensation products;
B) The resultant product is contacted with water to separate alkali metal salts therefrom, an organic phase comprising 2-ethyl hexenal and higher condensation products is separated therefrom and unused alkali metal hydroxide is recycled to the condensation zone;
C) The organic phase is separated in a separation zone into a 2-ethyl hexenal rich fraction and a residual fraction having a major amount of higher condensation product;
D) The 2-ethyl hexenal rich fraction is introduced into a hydrogenation zone containing hydrogen and a hydrogen-ation catalyst and therein hydrogenated to 2-ethyl hexanol, the improvement residing in recycling to the condensation zone at least a portion of the residual fraction containing the major amount of higher condensation product.
Description
`~ 1057313 :
BACKGROUND OF THE INVENTION ;
Field of the Invention This invention relates to the production of 2-ethyl hexanol by the condensation of n-butyraldehyde in the presence of an alkali metal hydroxide and the conversion of the resul-tant 2-ethyl hexenal to 2-ethyl hexanol by hydrogenation. -~
More particularly, this invention relates to a continuous process for the preparation of 2-ethyl hexanol by such a `
route wherein steps are taken to minimize the deterioration of hydrogenation catalysts used in the hydrogenation zone wherein the 2-ethyl hexenal is hydrogenated to 2-ethyl hexanol.
This invention is particularly directed to a continuous process for preparing 2-ethyl hexanol wherein a portion of a residual organic fraction having a major amount of higher condensation products is recycled to the condensation zone whereby addition-al 2-ethyl hexenal is realized with concomitant reduction in the amount of higher condensation product deposited upon the hydrogenation catalyst in the hydrogenation zone.
N-butyraldehyde has been known to be a starting material for the production of 2-ethyl hexanol and has been used on a commercial scale. The aldehyde is converted into butyraldole by the action of an alkali metal hydroxide. The
BACKGROUND OF THE INVENTION ;
Field of the Invention This invention relates to the production of 2-ethyl hexanol by the condensation of n-butyraldehyde in the presence of an alkali metal hydroxide and the conversion of the resul-tant 2-ethyl hexenal to 2-ethyl hexanol by hydrogenation. -~
More particularly, this invention relates to a continuous process for the preparation of 2-ethyl hexanol by such a `
route wherein steps are taken to minimize the deterioration of hydrogenation catalysts used in the hydrogenation zone wherein the 2-ethyl hexenal is hydrogenated to 2-ethyl hexanol.
This invention is particularly directed to a continuous process for preparing 2-ethyl hexanol wherein a portion of a residual organic fraction having a major amount of higher condensation products is recycled to the condensation zone whereby addition-al 2-ethyl hexenal is realized with concomitant reduction in the amount of higher condensation product deposited upon the hydrogenation catalyst in the hydrogenation zone.
N-butyraldehyde has been known to be a starting material for the production of 2-ethyl hexanol and has been used on a commercial scale. The aldehyde is converted into butyraldole by the action of an alkali metal hydroxide. The
2-ethyl hexenal is formed by cleavage of water from this butyraldol and the 2-ethyl hexenal is subsequently hydrogenated to form 2-ethyl hexanol.
In one process which has been carried out on a commercial scale, n-butyraldehyde is introduced into an aqueous sodium hydroxide solution which is recycled from a separation :
' ~` 1 0 5 7 3 1 3 l ~ zo to a condensntion zone. The qu~ntity of the recycled caustic solution is dependent upon its concentration and is
In one process which has been carried out on a commercial scale, n-butyraldehyde is introduced into an aqueous sodium hydroxide solution which is recycled from a separation :
' ~` 1 0 5 7 3 1 3 l ~ zo to a condensntion zone. The qu~ntity of the recycled caustic solution is dependent upon its concentration and is
3 usually 3 to 30 times the amount of n-butyraldehyde charged.
4 Caustic solution which is consumed during the course of the re~ction i8 replenished by the addition of fresh caustic 6 solution. The aldehyde is condensed in the condensation zone 7 at temperatures of 80 to 140C employing pressures on the order of 1 to 7 kgs./cm2 gauge. The condensation takes place over a period of time between 5 and 60 seconds.
After water i8 separated from the condensation 11 product the resultant raw 2-ethyl hexenal undergoes a treatment 12 or the removal of the alkali metal salts therefrom. The 13 alkali metal ~alts are removed by treatlng the raw 2-ethyl 14 hexènal fraction with water. Thereafter purified 2-hexQnal is charged into a hydrogenation zone containlng hydrogen and - 16 a hydrogenation catalyst. Invariably, the 2-ethyl hexenal 17 which is charged into the hydrogenation zone i8 accompanied 18 by minor a unts of higher boiling products, i.e., higher 19 condensation products which have resulted from the condensation of more than 2 moles of n-butyraldehyde. The subsequent f 21 hydrogenation of the unsaturated aldehyde to form 2-ethyl ; 22 hexanol is carried out in the gaseous phase. For this purpose 23 the raw product is heated in an evaporator to temperatures 24 wh~ch are sufficiently high that the 2-ethyl hexenal can be carried into the hydrogenation reactor by me~ns of recycled 26 hydrogen. However, invariably ~here is present the higher ;; condensation products (higher boiling products) and alkali 28 metal salts which have become entrained in the overhead 1 ~ pro uct from the evaporator. m ese materials are carried into ¦ ~
2 ¦ the hydrogenation reactor along with the 2-ethyl hexenal -3 ¦ material. They have been found to have a marked deteriorating 4 1 effect on the hydrogenation catalyst and the hydrogenation
After water i8 separated from the condensation 11 product the resultant raw 2-ethyl hexenal undergoes a treatment 12 or the removal of the alkali metal salts therefrom. The 13 alkali metal ~alts are removed by treatlng the raw 2-ethyl 14 hexènal fraction with water. Thereafter purified 2-hexQnal is charged into a hydrogenation zone containlng hydrogen and - 16 a hydrogenation catalyst. Invariably, the 2-ethyl hexenal 17 which is charged into the hydrogenation zone i8 accompanied 18 by minor a unts of higher boiling products, i.e., higher 19 condensation products which have resulted from the condensation of more than 2 moles of n-butyraldehyde. The subsequent f 21 hydrogenation of the unsaturated aldehyde to form 2-ethyl ; 22 hexanol is carried out in the gaseous phase. For this purpose 23 the raw product is heated in an evaporator to temperatures 24 wh~ch are sufficiently high that the 2-ethyl hexenal can be carried into the hydrogenation reactor by me~ns of recycled 26 hydrogen. However, invariably ~here is present the higher ;; condensation products (higher boiling products) and alkali 28 metal salts which have become entrained in the overhead 1 ~ pro uct from the evaporator. m ese materials are carried into ¦ ~
2 ¦ the hydrogenation reactor along with the 2-ethyl hexenal -3 ¦ material. They have been found to have a marked deteriorating 4 1 effect on the hydrogenation catalyst and the hydrogenation
5 ¦ reactor.
6 ¦ It has therefore become desirable to minimize the
7 ¦ deleterious effect which has been visited upon the hydrogenatio
8 ¦ catalyst. More especially it has become desirable to provide
9 a means for minimizing the activity deterioration of the lO ¦ hydrogenation catalyst so that it deteriorates to as low an 11 ¦ extent as possible. To minimize this activity decrease it 12 has been proposed to withdraw a fraction containing the higher 13 ¦ condensation products including the alkali metals contained 14 ¦ therein from the sump of the evaporator which i8 arranged 15 ¦ upstream of the hydrogenation reactor. However, to recover 16 ¦ the 2-ethyl hexenal contained in the effluent from the 8ump 17 ¦ it has been necessary to distill the latter in a separate 18 ¦ operation with the addition, if necessary or desired, of alkali 19 ¦ metal hydroxide. The distillate comprising a ~econd 2-ethyl 20 ¦ hexenal fraction has then been sub~ected to hydrogenation.
21 ¦ It will be realized that this additional distillation step is 22 ¦ commercially expensive owing in particular to the fact that 23 ¦ it is necessary to carry the same out in a stainless steel 24 column due to the corrosiveness of the material charged. In 25 ¦ addition it represente losses of valuable product which effect 26 ¦ the overall economy of the process and raise the cost of the 27 ¦ production of the 2-ethyl hexenal.
28 It has therefore become desirable to provide an ' I
alternate and less expensive means for minimizing the activity decrease of the hydrogenation catalyst. More particularly, it has become desirable to provide a process which will provide additional quantities of 2-ethyl hexenal while simultaneously preserving the life of the hydrogenation catalyst. Still more especially it has become desirable to provide a process , which will minimize the amount of higher condensation products realized and maximize the amount of 2-ethyl hexenal produced . from the condensation process.
SUMMARY OF THE INVENTION
In accordance with the present invention it has been found that the hydrogenation catalyst life can be preserved and that more 2-ethyl hexenal can be produced at a given cost ; than heretofore provided. The present process is an improvement in a continuous process for preparing 2-ethyl hexanol wherein:
s A) One mole of n-butyraldehyde is condensed with another mole of n-butyraldehyde in a condensation zone in the presence of an alkali metal hydroxide whereby there is formed 2-ethyl hexenal and higher condensation products;
B~ The resultant product is contacted with water to ;, separate alkali metal salts therefrom and an organic phase comprising 2-ethyl hexenal and higher condensation products is separated therefrom and unused alkali metal hydroxide is recycled to the condensation zone;
- C) The organic phase is separated in a separation ; zone into a 2-ethyl hexenal rich fraction and a residual fraction having from 30 to 60 % by weight of higher condensation product;
` 1057313 1 ;
l D) The 2-ethyl hexenal rich fraction i8 introduced 2 into a hydrogenation zone containing hydrogen and a hydrogen-3 ation catalyst, the improvement residing in recycling to the 4 condensation zone at least a portion of the residual fraction.
In accordance with the invention it has been dis-6 covered that if a portion of the res~dual fraction conta~ning the ma~or amount of higher condensation product ~s recycled 8 to the condensation zone that the same will break up into molecules of lower lecular weight which will be converted into 2-ethyl hexenal. Moreover, the amount of higher con-11 densation product passing through the streams downstream of 12 the condensation product will be reduced so that the amount 13 of higher condensation product deposited on the hydrogenation 14 catalyst will be minimized. It has been found by the technique of the present invention that significantly greater quantities 16 of 2-ethyl hexenal can be realized while minimizing the 17 teleterious effects these higher condensation products have on 18 thehydrogenation catalyst.
19 The continuous process of the present invention is conducted by sub~ecting the n-butyraldehyde to the aldol 21 condensation at a temperature of 80 to 140C in the presence 22 of an alkali metal hydroxide as described above. The product 23 is sub~ected to the action of water to separate alkal~ metal 24 salts therefrom and an organic phase i8 obtaLned. This organic phase com~ri~es the 2-ethyl hexenal together with the higher 26 condensation products. By the term "higher condensation 27 products" there i8 meant those products obtained by the con-28 densation of m~re than 2 moles of n-butyraldehyde. The~e 10573~3 higher condensation products have a higher molecular weight and, accordingly, have higher boiling points. It is these products that deleteriously effect the activity of the hydro-genation catalyst.
The organic phase also contains minor quantities of unreacted n-butyraldehyde, some entrained water and minor quantities of alkali metal. According to the invention this organic phase is subjected to a separation technique designed to separate a phase rich in 2-ethyl hexenal which, in turn, is fed to the hydrogenation zone. The separation technique will also provide a residual phase having a major amount of higher condensation products. By the term "major amount"
there is meant an amount of higher condensation product of between about 30 and 60 % by weight. It is this residual fraction which is recycled to the condensation zone in accordance with the improvement of the invention. G~nerally, ; speaking, the separation can take place by a distillative-type technique such as through the use of an evaporator.
B~ using an evaporator a stream rich in 2-ethyl hexenal can ; 20 be obtained which, in turn, can be used as feed to the hydro-genation zone. Generally speaking, the overhead from the evaporator has between about 96 and 97 % by weight 2-ethyl hexenal. Additionally, the residual product generally con-tains between 40 and 70 % 2-ethyl hexenal (in addition, of course, to the higher condensation products).
In accordance with the improvement of the inven-tion this residual fraction - about 4 to 8 % by weight of 2-ethyl-hexenal fed to the separation zone - is recycled from the ..
`
separation zone e.g. evaporator sump, to the condensation zone. The residue to be returned to this aldol condensation step desirably contains between 40 and 70 % by weight 2-ethyl hexenal which, of course, is in addition to the highercondensation constituents and alkali metal salts.
Surprisingly, it has been found that the higher condensation materials in this residual fraction are largely split in the aldolization step with the formation of 2-ethyl hexenal thus reducing to about one-third the amount which would be produced if the same were not recycled. Thereby, only minor amounts of higher boiling materials become en-trained into the feed to the hydrogenation zone. Conse-quently, about one-third or less higher condensation pro-ducts can become deposited on the catalyst. This signi-ficantly decreases the deterioration of the catalyst and considerably improves its life.
The recycling technique of the present inven-tion has the further advantage that the yield of 2-ethyl hexenal in the aldolization step is improved due to reduced formation of higher condensation products. The yield of 2-ethyl hexenal is increased additionally owing to the fact that it is no longer required to distill the sump residue in a separate operational step to obtain the additional 2-ethyl ~ e~c~
hexenal fraction for-~eet to the hydrogenation zone.
It must further be considered in this connection that the distillation step of the heretofore practice on the sump product was an expensive step owing to the fact that the :
',~ .
;' -~ ' lOS7313 distillation column had to be made of stainless steel to 2 co~bat the corrosiveness of the ms~erial so charged.
3 Finally, it is no longer necessary wi~h the improvemel It 4 of the present invention to take special measures for the com-plete elimination of alkali metal salts from the raw aldoliza-6 tion product. It has been found, surprisingly, that a s~mple 7 scrubbing technique as by contactin~ the aldolization product 8 with water is sufficient. The resultant organic phase con-9 taining the decreased higher condensation product content is compatible with the hydrogenation cataly~t even at the same 11 levels of alkali metal salts.
12 In order to more fully illustrate the nature of the 13 in~ention and the manner of practicing the same the following 14 two examples are presented:
16 Example 1 (presented for purposes of comparison).
17 In the example set forth below there is illustrated 18 the known technique for the production of 2-ethyl hexenal 19 from n-butyraldehyde. In this technique no recycle of evapor-ator sump product to the aldolization step was performed.
21 In a continuously operated aldolization unit there 22 was introduced 5.0 metric tons per hour of n-butyraldehyde and 23 75 liters per hour of a 207o aqueous sodium hydroxide solution.
24 There was also introduced a 3Z by weight aqueous sodium hydroxide aqueous recycle solution. Within a short period of 26 time, 98a8% of the n-butyraldehyde were con~erted at 120 to 27 130C, After the reaction liquor was separated the raw 2-28 ethyl hexenal was treated with water to remove sodium salts '.'' _g_ i 10573~3 1 ¦ adhering thereto and the water was separated. The organic 2 ¦ phase comprising the raw 2-ethyl hexenal was introduced into 3 ¦ an evaporator of a gaseous phase hydrogenation unit positioned ¦ do~mstream of the aldolization unit. The charge to the 5 ¦ evaporation unit had the following composition:
6 ¦ 95.5% by weight 2-ethyl hexenal 7 ¦ 1.3X by weight n-butyraldehyde 8 ~ 1.8Z by weight higher boiling products (largely 9 I higher condensation products)
21 ¦ It will be realized that this additional distillation step is 22 ¦ commercially expensive owing in particular to the fact that 23 ¦ it is necessary to carry the same out in a stainless steel 24 column due to the corrosiveness of the material charged. In 25 ¦ addition it represente losses of valuable product which effect 26 ¦ the overall economy of the process and raise the cost of the 27 ¦ production of the 2-ethyl hexenal.
28 It has therefore become desirable to provide an ' I
alternate and less expensive means for minimizing the activity decrease of the hydrogenation catalyst. More particularly, it has become desirable to provide a process which will provide additional quantities of 2-ethyl hexenal while simultaneously preserving the life of the hydrogenation catalyst. Still more especially it has become desirable to provide a process , which will minimize the amount of higher condensation products realized and maximize the amount of 2-ethyl hexenal produced . from the condensation process.
SUMMARY OF THE INVENTION
In accordance with the present invention it has been found that the hydrogenation catalyst life can be preserved and that more 2-ethyl hexenal can be produced at a given cost ; than heretofore provided. The present process is an improvement in a continuous process for preparing 2-ethyl hexanol wherein:
s A) One mole of n-butyraldehyde is condensed with another mole of n-butyraldehyde in a condensation zone in the presence of an alkali metal hydroxide whereby there is formed 2-ethyl hexenal and higher condensation products;
B~ The resultant product is contacted with water to ;, separate alkali metal salts therefrom and an organic phase comprising 2-ethyl hexenal and higher condensation products is separated therefrom and unused alkali metal hydroxide is recycled to the condensation zone;
- C) The organic phase is separated in a separation ; zone into a 2-ethyl hexenal rich fraction and a residual fraction having from 30 to 60 % by weight of higher condensation product;
` 1057313 1 ;
l D) The 2-ethyl hexenal rich fraction i8 introduced 2 into a hydrogenation zone containing hydrogen and a hydrogen-3 ation catalyst, the improvement residing in recycling to the 4 condensation zone at least a portion of the residual fraction.
In accordance with the invention it has been dis-6 covered that if a portion of the res~dual fraction conta~ning the ma~or amount of higher condensation product ~s recycled 8 to the condensation zone that the same will break up into molecules of lower lecular weight which will be converted into 2-ethyl hexenal. Moreover, the amount of higher con-11 densation product passing through the streams downstream of 12 the condensation product will be reduced so that the amount 13 of higher condensation product deposited on the hydrogenation 14 catalyst will be minimized. It has been found by the technique of the present invention that significantly greater quantities 16 of 2-ethyl hexenal can be realized while minimizing the 17 teleterious effects these higher condensation products have on 18 thehydrogenation catalyst.
19 The continuous process of the present invention is conducted by sub~ecting the n-butyraldehyde to the aldol 21 condensation at a temperature of 80 to 140C in the presence 22 of an alkali metal hydroxide as described above. The product 23 is sub~ected to the action of water to separate alkal~ metal 24 salts therefrom and an organic phase i8 obtaLned. This organic phase com~ri~es the 2-ethyl hexenal together with the higher 26 condensation products. By the term "higher condensation 27 products" there i8 meant those products obtained by the con-28 densation of m~re than 2 moles of n-butyraldehyde. The~e 10573~3 higher condensation products have a higher molecular weight and, accordingly, have higher boiling points. It is these products that deleteriously effect the activity of the hydro-genation catalyst.
The organic phase also contains minor quantities of unreacted n-butyraldehyde, some entrained water and minor quantities of alkali metal. According to the invention this organic phase is subjected to a separation technique designed to separate a phase rich in 2-ethyl hexenal which, in turn, is fed to the hydrogenation zone. The separation technique will also provide a residual phase having a major amount of higher condensation products. By the term "major amount"
there is meant an amount of higher condensation product of between about 30 and 60 % by weight. It is this residual fraction which is recycled to the condensation zone in accordance with the improvement of the invention. G~nerally, ; speaking, the separation can take place by a distillative-type technique such as through the use of an evaporator.
B~ using an evaporator a stream rich in 2-ethyl hexenal can ; 20 be obtained which, in turn, can be used as feed to the hydro-genation zone. Generally speaking, the overhead from the evaporator has between about 96 and 97 % by weight 2-ethyl hexenal. Additionally, the residual product generally con-tains between 40 and 70 % 2-ethyl hexenal (in addition, of course, to the higher condensation products).
In accordance with the improvement of the inven-tion this residual fraction - about 4 to 8 % by weight of 2-ethyl-hexenal fed to the separation zone - is recycled from the ..
`
separation zone e.g. evaporator sump, to the condensation zone. The residue to be returned to this aldol condensation step desirably contains between 40 and 70 % by weight 2-ethyl hexenal which, of course, is in addition to the highercondensation constituents and alkali metal salts.
Surprisingly, it has been found that the higher condensation materials in this residual fraction are largely split in the aldolization step with the formation of 2-ethyl hexenal thus reducing to about one-third the amount which would be produced if the same were not recycled. Thereby, only minor amounts of higher boiling materials become en-trained into the feed to the hydrogenation zone. Conse-quently, about one-third or less higher condensation pro-ducts can become deposited on the catalyst. This signi-ficantly decreases the deterioration of the catalyst and considerably improves its life.
The recycling technique of the present inven-tion has the further advantage that the yield of 2-ethyl hexenal in the aldolization step is improved due to reduced formation of higher condensation products. The yield of 2-ethyl hexenal is increased additionally owing to the fact that it is no longer required to distill the sump residue in a separate operational step to obtain the additional 2-ethyl ~ e~c~
hexenal fraction for-~eet to the hydrogenation zone.
It must further be considered in this connection that the distillation step of the heretofore practice on the sump product was an expensive step owing to the fact that the :
',~ .
;' -~ ' lOS7313 distillation column had to be made of stainless steel to 2 co~bat the corrosiveness of the ms~erial so charged.
3 Finally, it is no longer necessary wi~h the improvemel It 4 of the present invention to take special measures for the com-plete elimination of alkali metal salts from the raw aldoliza-6 tion product. It has been found, surprisingly, that a s~mple 7 scrubbing technique as by contactin~ the aldolization product 8 with water is sufficient. The resultant organic phase con-9 taining the decreased higher condensation product content is compatible with the hydrogenation cataly~t even at the same 11 levels of alkali metal salts.
12 In order to more fully illustrate the nature of the 13 in~ention and the manner of practicing the same the following 14 two examples are presented:
16 Example 1 (presented for purposes of comparison).
17 In the example set forth below there is illustrated 18 the known technique for the production of 2-ethyl hexenal 19 from n-butyraldehyde. In this technique no recycle of evapor-ator sump product to the aldolization step was performed.
21 In a continuously operated aldolization unit there 22 was introduced 5.0 metric tons per hour of n-butyraldehyde and 23 75 liters per hour of a 207o aqueous sodium hydroxide solution.
24 There was also introduced a 3Z by weight aqueous sodium hydroxide aqueous recycle solution. Within a short period of 26 time, 98a8% of the n-butyraldehyde were con~erted at 120 to 27 130C, After the reaction liquor was separated the raw 2-28 ethyl hexenal was treated with water to remove sodium salts '.'' _g_ i 10573~3 1 ¦ adhering thereto and the water was separated. The organic 2 ¦ phase comprising the raw 2-ethyl hexenal was introduced into 3 ¦ an evaporator of a gaseous phase hydrogenation unit positioned ¦ do~mstream of the aldolization unit. The charge to the 5 ¦ evaporation unit had the following composition:
6 ¦ 95.5% by weight 2-ethyl hexenal 7 ¦ 1.3X by weight n-butyraldehyde 8 ~ 1.8Z by weight higher boiling products (largely 9 I higher condensation products)
10 ¦ 1.4X by weight water
11 ¦ The sump of the evaporator was maintained at a
12 ¦ temperature of 165C. Overhead there was withdrawn a product
13 ¦ stream. 96~070 by weight of the raw 2-ethyl hexenal charget
14 ~ was withdrawn from the overhead line of the evaporator by
15 ¦ means of recycled hydrogen and the ~ame was introduced into
16 ~ the hydrogenation reactor. The overhead product from the
17 ¦ evaporator had the following composition:
18 ¦ 1.3Z by weight n-butyraldehyde
19 1 96~970 by weight 2-ethyl hexenal
20 ¦ 0.4X by weight higher boiling product
21 ¦ 1.4% by weight water
22 ¦ The higher boiling products which were withdrawn I from the sump had the following composition:
24 ¦ 65.0% by weight 2-e~hyl hexenal 25 ¦ 35.07. by weight higher boiling products 26 ¦ 25 mg. Na/liter 27 ¦ After processing of the evaporator bottoms by dis-28 ¦ tillation, hydrogenation of the total raw 2-ethyl hexenal and ~, distillation of the raw 2-ethyl hexanol only 2.5 kgs. of 100 kgs. n-butyraldehyde were reacted to form higher boiling products.
Example 2 In this example there is shown the results of a pro-cess similar to that of Example 1 except wherein a portion of the evaporator sump product was recycled to the aldolization , step.
The aldolization was carried out in the manner des-cribed in Example 1. However, additionally, the higher boiling residue from the evaporator in an amount of about 5 %
by weight based on the raw 2-ethyl hexenal charged to the gaseous phase hydrogenation was added to the caustic solution which was recycled to the aldolization step.
The conversion of n-butyraldehyde was 98.8 %.
After the raw 2-ethyl hexenal had been separated from the reac-tion liquor and, by treatment with water and separation of water, largely freed from the sodium salts adhering thereto, it was charged to the gaseous phase hydrogenation.
At a bottom (sump) temperature of 165C, 95.5 % by weight of the raw 2-ethyl hexenal charged to the evaporator was withdrawn from the top of the evaporator and fed in the gaseous phase to the hydrogenation unit containing the hydro-genation catalyst. The composition of the raw 2-ethyl hexenal composition charged to the eYapOrator was as follows:
. 94.4 % by weight 2-ethyl hexenal 1.2 % by weight n-butyraldehyde ,', .`
.'~ - 11 -' i -: ~
~0573~
1 3.1% by weight higher boiling products 2 1.3Z by weight water 3 1.2 mg./l. of sodium 4 The composition of the overhead product from the evalporator that was charged to the hydrogenation zone was 6 as follows 7 1.3Z by weight butanal 8 96~77o by weight 2-ethyl hexenal 9 0.6X by weight higher boiling products 1.4~ by weight water 11 0~1 mg./l of sodium 12 From the sum~ of the evaporator there was withdrawn 13 4.5% by weight, ba~ed on the amount of raw product charged, 14 o~ a mixture composed of:
4770 by weight 2-ethyl hexenal 16 53% by weight higher boiling products 17 21 mg. of Na per liter 18 The same was recycled into the aldolization unit.
19 After hydrogenation to fonm raw 2-ethyl hexanol followed by distillation of the alcohol, only 1.1 kgs. out of 21 100 kgs~ n-butyraldehyde had been converted into higher 22 boiling products whereby the yield of 2-ethyl hexanol was
24 ¦ 65.0% by weight 2-e~hyl hexenal 25 ¦ 35.07. by weight higher boiling products 26 ¦ 25 mg. Na/liter 27 ¦ After processing of the evaporator bottoms by dis-28 ¦ tillation, hydrogenation of the total raw 2-ethyl hexenal and ~, distillation of the raw 2-ethyl hexanol only 2.5 kgs. of 100 kgs. n-butyraldehyde were reacted to form higher boiling products.
Example 2 In this example there is shown the results of a pro-cess similar to that of Example 1 except wherein a portion of the evaporator sump product was recycled to the aldolization , step.
The aldolization was carried out in the manner des-cribed in Example 1. However, additionally, the higher boiling residue from the evaporator in an amount of about 5 %
by weight based on the raw 2-ethyl hexenal charged to the gaseous phase hydrogenation was added to the caustic solution which was recycled to the aldolization step.
The conversion of n-butyraldehyde was 98.8 %.
After the raw 2-ethyl hexenal had been separated from the reac-tion liquor and, by treatment with water and separation of water, largely freed from the sodium salts adhering thereto, it was charged to the gaseous phase hydrogenation.
At a bottom (sump) temperature of 165C, 95.5 % by weight of the raw 2-ethyl hexenal charged to the evaporator was withdrawn from the top of the evaporator and fed in the gaseous phase to the hydrogenation unit containing the hydro-genation catalyst. The composition of the raw 2-ethyl hexenal composition charged to the eYapOrator was as follows:
. 94.4 % by weight 2-ethyl hexenal 1.2 % by weight n-butyraldehyde ,', .`
.'~ - 11 -' i -: ~
~0573~
1 3.1% by weight higher boiling products 2 1.3Z by weight water 3 1.2 mg./l. of sodium 4 The composition of the overhead product from the evalporator that was charged to the hydrogenation zone was 6 as follows 7 1.3Z by weight butanal 8 96~77o by weight 2-ethyl hexenal 9 0.6X by weight higher boiling products 1.4~ by weight water 11 0~1 mg./l of sodium 12 From the sum~ of the evaporator there was withdrawn 13 4.5% by weight, ba~ed on the amount of raw product charged, 14 o~ a mixture composed of:
4770 by weight 2-ethyl hexenal 16 53% by weight higher boiling products 17 21 mg. of Na per liter 18 The same was recycled into the aldolization unit.
19 After hydrogenation to fonm raw 2-ethyl hexanol followed by distillation of the alcohol, only 1.1 kgs. out of 21 100 kgs~ n-butyraldehyde had been converted into higher 22 boiling products whereby the yield of 2-ethyl hexanol was
23 increased by 1.4 kgs. as compared to the yield obtained by
24 Example 1 supra.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a continuous process for preparing 2-ethyl hexanol wherein:
A) One mole of n-butyraldehyde is condensed with another mole of n-butyraldehyde in a condensation zone in the presence of an alkali metal hydroxide whereby there is formed 2-ethyl hexenal and higher condensation products;
B) The resultant product is contacted with water to separate alkali metal salts therefrom and an organic phase comprising 2-ethyl hexenal and higher condensation products is separated therefrom and unused alkali metal hydroxide is recycled to the condensation zone;
C) The organic phase is separated in a separation zone into a 2-ethyl hexenal rich fraction and a residual fraction having from 30 to 60 % by weight of higher condensation product;
D) The 2-ethyl hexenal rich fraction is introduced into a hydrogenation zone containing hydrogen and a hydrogenation catalyst, the improvement which comprises recycling to said condensation zone at least a portion of said residual fraction.
A) One mole of n-butyraldehyde is condensed with another mole of n-butyraldehyde in a condensation zone in the presence of an alkali metal hydroxide whereby there is formed 2-ethyl hexenal and higher condensation products;
B) The resultant product is contacted with water to separate alkali metal salts therefrom and an organic phase comprising 2-ethyl hexenal and higher condensation products is separated therefrom and unused alkali metal hydroxide is recycled to the condensation zone;
C) The organic phase is separated in a separation zone into a 2-ethyl hexenal rich fraction and a residual fraction having from 30 to 60 % by weight of higher condensation product;
D) The 2-ethyl hexenal rich fraction is introduced into a hydrogenation zone containing hydrogen and a hydrogenation catalyst, the improvement which comprises recycling to said condensation zone at least a portion of said residual fraction.
2. A process according to claim 1 wherein said residual fraction comprises 40 to 70% by weight of 2-ethyl hexenal.
3. A process according to claim 1 wherein the amount of residual fraction recycled to the condensation zone is between 4 and 8% by weight of the 2-ethyl hexenal charged to the hydrogenation zone.
4. A process according to claim 1 wherein said 2-ethyl hexenal rich fraction is separated from said fraction having a major amount of higher condensation products by evaporation.
5. A process according to claim 1 wherein the con-densation step of step A is carried out at a temperature be-tween 80 and 140°C at a pressure of 1 to 7 kgs./cm2 gauge for between 5 and 60 seconds.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19742437957 DE2437957B2 (en) | 1974-08-07 | 1974-08-07 | PROCESS FOR THE CONTINUOUS MANUFACTURING OF 2-AETHYLHEXANOL |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1057313A true CA1057313A (en) | 1979-06-26 |
Family
ID=5922623
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA232,598A Expired CA1057313A (en) | 1974-08-07 | 1975-07-31 | Process for the continuous production of 2-ethyl hexanol |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5141309A (en) |
| AT (1) | AT335989B (en) |
| BR (1) | BR7505008A (en) |
| CA (1) | CA1057313A (en) |
| DE (1) | DE2437957B2 (en) |
| FR (1) | FR2282417A1 (en) |
| GB (1) | GB1462328A (en) |
| PL (1) | PL99233B1 (en) |
| RO (1) | RO72483A (en) |
| SE (1) | SE421304B (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS50111966A (en) * | 1974-02-11 | 1975-09-03 | ||
| DE2713434C3 (en) * | 1977-03-26 | 1980-10-23 | Ruhrchemie Ag, 4200 Oberhausen | Process for the production of 2-ethylhexanol |
| US4528405A (en) * | 1983-12-30 | 1985-07-09 | Union Carbide Corporation | Aldol condensation of enolizable aldehydes using a metal carboxylate catalyst |
| DE3530839A1 (en) * | 1985-08-29 | 1987-03-05 | Ruhrchemie Ag | METHOD FOR PRODUCING 2-ETHYLHEXANOL |
| JPS62278816A (en) * | 1986-05-28 | 1987-12-03 | Yagi Antenna Co Ltd | Timer circuit |
| GB9615050D0 (en) * | 1996-07-17 | 1996-09-04 | Exxon Chemical Patents Inc | Recycle and recovery of useful products from heavy aldol by-products |
| JP4003361B2 (en) * | 1998-11-27 | 2007-11-07 | 三菱化学株式会社 | Method for producing alcohol |
| DE10252173B3 (en) * | 2002-11-09 | 2004-06-03 | Celanese Chemicals Europe Gmbh | Process for the recovery of aliphatic C3-C10 alcohols from high boilers |
| DE102009050345A1 (en) | 2009-10-22 | 2011-06-01 | Süd-Chemie AG | Preparing alpha, beta-unsaturated carbonyl compounds, comprises reacting aldehydes and/or ketones in the presence of hydrotalcite catalyst and preparing the hydrotalcite catalyst |
| CN103864587B (en) * | 2012-12-10 | 2016-05-11 | 中国石油天然气股份有限公司 | Method for synthesizing 2-ethyl-2-hexenal |
-
1974
- 1974-08-07 DE DE19742437957 patent/DE2437957B2/en not_active Ceased
- 1974-09-09 AT AT722674A patent/AT335989B/en not_active IP Right Cessation
-
1975
- 1975-07-29 FR FR7523675A patent/FR2282417A1/en active Granted
- 1975-07-30 SE SE7508638A patent/SE421304B/en not_active IP Right Cessation
- 1975-07-31 RO RO7583031A patent/RO72483A/en unknown
- 1975-07-31 CA CA232,598A patent/CA1057313A/en not_active Expired
- 1975-07-31 GB GB3207475A patent/GB1462328A/en not_active Expired
- 1975-07-31 PL PL18243375A patent/PL99233B1/en unknown
- 1975-08-06 BR BR7505008A patent/BR7505008A/en unknown
- 1975-08-07 JP JP9625275A patent/JPS5141309A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| PL99233B1 (en) | 1978-06-30 |
| GB1462328A (en) | 1977-01-26 |
| AU8359875A (en) | 1977-02-03 |
| SE7508638L (en) | 1976-02-09 |
| AT335989B (en) | 1977-04-12 |
| JPS5141309A (en) | 1976-04-07 |
| BR7505008A (en) | 1976-08-03 |
| RO72483A (en) | 1981-06-30 |
| FR2282417A1 (en) | 1976-03-19 |
| SE421304B (en) | 1981-12-14 |
| FR2282417B1 (en) | 1977-12-09 |
| DE2437957A1 (en) | 1976-02-26 |
| ATA722674A (en) | 1976-08-15 |
| DE2437957B2 (en) | 1976-06-16 |
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