CA1048533A - Dehydroformylation of acetoxybutyraldehydes - Google Patents
Dehydroformylation of acetoxybutyraldehydesInfo
- Publication number
- CA1048533A CA1048533A CA74209308A CA209308A CA1048533A CA 1048533 A CA1048533 A CA 1048533A CA 74209308 A CA74209308 A CA 74209308A CA 209308 A CA209308 A CA 209308A CA 1048533 A CA1048533 A CA 1048533A
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- mixture
- acetoxybutyraldehyde
- produce
- allyl acetate
- acetate
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Abstract
ABSTRACT OF THE DISCLOSURE
Dehydroformylation of isomeric acetoxybutyraldehydes, with minimal dehydroacetoxylation, can be accomplished at a temperature in the range of 120-250° C. in a nonoxidizing atmosphere in the presence of an essentially neutral noble metal catalyst to produce allyl acetate, 1-propenyl acetate or mixtures thereof. This reaction permits recycle of the undesired isomeric acetoxybutyraldehyde products of the hydroformylation of allyl acetate or 1-propenyl acetate to the desired 4-acetoxybutyraldehyde which is an intermediate in the production of 1,4-butanediol useful in making polyesters.
Dehydroformylation of isomeric acetoxybutyraldehydes, with minimal dehydroacetoxylation, can be accomplished at a temperature in the range of 120-250° C. in a nonoxidizing atmosphere in the presence of an essentially neutral noble metal catalyst to produce allyl acetate, 1-propenyl acetate or mixtures thereof. This reaction permits recycle of the undesired isomeric acetoxybutyraldehyde products of the hydroformylation of allyl acetate or 1-propenyl acetate to the desired 4-acetoxybutyraldehyde which is an intermediate in the production of 1,4-butanediol useful in making polyesters.
Description
- ` ' RD--6386 -~0~8533 This invention provides a proces~ for producing allyl acetate, l-propenyl acetate or mixtures thereof by dehydro-formylating 4-acetoxybutyraldehyde, 2-acetoxybutyraldehyde, 3-acetoxy-2-methylpropionaldehyde or mixture~ thereof. This invention also provides an improved process for hydroformylating those products to 4-acetoxybutyraldehyde and an improved process for making 1,4-butanediol from propylene, acetic acid and oxygen.
In my Canadian application A, Serial No. 203,212 filed June 24, 1974 and a3signed to the same as~ignee as the present invention, I have disQlosed and claimed a proce~ for making butanediols by oxidatively coupling propylene and acetic acid to produce allyl acetate which is then hydroformylated to produce the mixture of three i~omerlc acetoxybutyraldehydos.
Hydrogenation of the mixture produces a mixture of isomeric acetoxybutanols which can also contain some of the diesters and free diols. In my Canadian application B, Serial No. 195,892, filed March 25, 1974 and assigned to the same assignee a~ the pr-sent inv-ntion, I have disclos-d and claimed a process wherein the hydrogenation i~ accompllshed during the hydroformylation reaction. De-Esterification of the acetoxybutanol mixture produce~ the desired butanediols which can be separated by distillation.
In my Canadian application C, Serial No. ~oq, 307 filed ~ ~ e~b~r /~,lq~7and assigned to the same as~ignee as the present invention, I have disclosed and claimed that hydro-formylation of l-propenyl acetate under hydroformylating condi-tions in the presence of a cobalt hydroformylation catalyst yields essentially the same isomeric mixture of acetoxybutyralde-hyde~ as is obtained from allyl acetate.
Prior to my di~covery, the prior art, see for example J. Am. Chem. Soc. 70, 383 (1948) and 71, 3054 (1949), reported that the hydroformylation of allyl acetate led to only one product, 4-acetoxybutyraldehyde, in es~entially a 70-75% yield.
Although my work confirm~ this yield, I have also found that the balance of the allyl acetate has been converted to two lsomer3 of the 4-acetoxybutyraldehyde, ~pec~fically, 2-a~etoxybutyral-dehyde and 3-acetoxy-2-methylpropionaldehyde in approximately equ~molar amount~. r Although, a~ ~hown ~n my Canadian application3 A and B re~erred to above, these two isomers can be converted to their corre~ponding butaned~ols, specifically 1,2-butanediol and 2-methy~-1,3-propanediol, neither of the~e two products are a3 de~irable as 1,4-butanediol, which forms polye~ters with dlcarboxylic acids, such as terephthalic acid, which are comm~rcially much more de~irable than the polyester~ obtained from th- other two isomers. It would be highly desirable, therefore, to be able to obtain higher yield~ of the 4-acetoxy-butyraldehydo $ther by docreasing the production of the other two isomers or by converting the latt~r into the de~irod isomer.
Insofar as I am aware, the only attempt to rocycl~
an undesirable by-product of a hydroformylation reaction is de~cribed in Briti~h patent 1,241,646, its corresponding counter-parts in other foreign countrie~, and in articles written by the inventors and coworkers, see for example, Angew Chem., Internat. Bdit. 9, 169 (1970) and 11, 155 (1972), Ind. Eng.
Chem. 62 [4] 33 (1970). me~e referonces describe that in the hydroformylation of propylene to n-butyraldehyde, i~obutyraldehyde is obtained as a less desired product. mi9 latter product is dehydroformylat-d to propylene, carbon monoxide and hydrogen which can then be recycled in the hydroformylation reaction to increase the yield of the n-butyraldehyde in the over-all reaction. Other related art in thi~ area teaches the production of saturated aliphatic compounds arising from the hydrogen interaction with the dehydroformylation product to hydrogonate 1C~48533 ~he olefinic double bond. Th~s latter reaction i~ called decarbonylation becau~e, in effect, only carbon monoxide i~
romoved from the ~tarting product.
One of the convenient mean~ for converting a compound contain~ng an alcoholic hydroxyl group to an olefin is to make the acetate ester of the compound which is then thermolyzed or pyrolyzed to produce the olefin and acetic ac~d. For convenience, this ester thormolysis reaction, as applied to acetato e~ters, will be called dehydroacetoxylation since a hydrogen is removed from one carbon atom and the acetoxy group ~ -from the ad~acent carbon atom to form acetic acid and create an olefinic double bond in the initial compound. Since the isomoric acetoxybutyraldehyde~, to which this invention i~
directed, are acetate esters as well a~ aldehydes, they could undergo (a) the dehydroacetoxylation reaction to produce unsaturated aldehydes, (b) both the dehydroacetoxylation reaction and the hydrogenation reaction to product saturated aldehydes, (c) th- dohydroformylation reaction to produce un~aturated eJter~, (d) the dehydroformylation and hydrogenation reaction to produce ~aturated esters or (e) any combinat~on of (a) through (d). It was indeed surprising to find that the dehydroformylation reaction could be effected with the other reactions occurring to a minimal extent.
I have found an indirect method of converting the two isomers, 2-acetoxybutyraldehyde and 3-acetoxy-2-methyl-propionylaldehyde, to 4-acetoxybutyraldehyde~ In the presence ~ -of a Group VIII noble metal catalyst, any one of these three isomers or a mixture containing any two or all three of them can be dehydroformylated at a temperature in the range of 120-250C~ in a nonoxidizing atmosphere and in the pre~ence of an essentially neutral noble metal catalyst to produce allyl acetate, l-propenyl acetate or mixtures thereof. Dehydro-' :. ,. :. .
10~8533 formylation of those i~omers leads to allyl acetate from 4-acetoxybutyraldehyde, l-propenyl acetate from 2-acetoxybutyr-aldehyde and a mixture of allyl acetate, l-propenyl acetate and variable amounts methacrolein and acetic acid from the le~s thermally stable 3-acetoxy-2-methylpropionaldehyde.
The amount o~ the methacrolein and acetic acid produced i6 dependent on the activity of the catalyst and the temperature used. Of the noble metal catalysts, those from platinum, rhodium and palladium are more active than the other Group VIII
noble metals for promoting the dehydroormylation reaction.
Platinum causes more hydrogenation of tho desired un~aturated ester~ to saturated esters. Rhodium is ~atisfactory but much more expensive than palladium which i~ the preferred cataly~t when it is desired to minimize the amount of unsaturated aldehyde or ~aturated ester by-products.
As I have dlsclosed in my above-referenced Canadian application C, l-propenyl acetate can be hydroformylated to giv~ the same three isomeric acetoxybutyraldehydes in essentially the same proportion a~ is obtained upon hydroformylation of allyl ac-tate. Therefore, the significance of my discovery of the dohydroformylation reaction described above i8 that, by separating some or all of the 4-acetoxybutyraldehyde from the balance of the mixture containing the other two isomers, the latter can be dehydroformylated to furnish feedstock for the hydroformylation reaction. By alway~ recycling the two undesired isomers in this matter, the feed~tock of the hydroformylation reactions, in offoct, is all converted essentially to the desired 4-acetoxybutyr-aldehyde, which can then be readily hydrogenated to produce 4-acetoxy-l-butanol, which, ~n turn, can be de-esterified to produce 1,4-butanediol.
Not only ha~ my discovered of this dehydroformylation reaction provided a proces~ useful in itself for utilizing the '; .
~ V48533 i~omeric acetoxybutyraldehydes, made by any other proces~es, but has also provided improveme~t~ in the hydroformylation reaction to increa~e the yield of 4-acetoxybutyraldehyde in the process described in my above-referenced Canadian application A for making butanediol~ from propylene, acetic acid and oxygen wherein the hydroformylation reaction is aD important intermediate step~
By being able to con~ert all of the hydroformylated products to 4-acetoxybutyraldehyde, the butanediol will all be the desired 1,4-butanediol.
The dehydroformylation reaction can be carried out as a liquid phase, vapor phase or liquid-vapor phase reaction.
Since the products of the reaction are lower boiling than the feedstock, the liquid phase reaction can be carried out at atmospheric pressure at a temperature in the range from the boiling point of the lowest boiling of the dehydroformylated products up to the boiling point of the lowe~t boiling component of the f-edstock. ~oth allyl acetate and l-propenyl acetate, which has two isomeric forms, boil in the rang- of 100-106 C.
Therefore, the min~mum temperature that the dehydroformylation reaction could be carried out at would be about 110 C. ~owever, at this temperature, the rate of the dehydroformylation reaction i8 ~0 slow that it is preferred to use temperatures of at least 120 C. and pre~erably 140 C.
The maximum temperature for the reaction is determined by the lowest boiling component present in llquid phase. The lowost boiling isomer which would be present in the feedstock is 2-acetoxybutyraldehyde which has a boiling point of 168C.
which represents, therefore, the maximum tomperaturo that can be used for the dehydroformylation reaction when carried out ~0 in the liquid phase at at spheric pressure when th$s component is pr~sent and as long as it remains unreacted. When it is dehydroformylated any remaining isomers can be dehydroformylated 1~)48533 at higher temperatures up to their boiling point. Higher temperatures can be obtained by increa~ing the pres~ure.
Gonerally, however, it would be more desirable in this case to carry out the reaction either in the vapor pha8e or th-liquid-vapor phase to save the expense of the more expensive equipment required when carrying out roactions under pressure.
Whon carrying out the reaction in the liquid phase, the noble metal catalyst with or without a support, but proferably havlng a large surface area , i~ suspended, generally with ~tirring in the feedstock. Since all the components of the feeastock are liquid, no ~olvent needs to be u~ed. However, if do~ired, a solvent could used but it generally should have a boiling point high-r than any of the component~ of the feed-stock and be nonreactive with either the components of the feodstock or the dehydroformylated product~. Pref-rably, no ~olvent is used since the reaction i~ simplified.
m. liquid phase reaction i3 carried out in a dis-tillation apparatus wh$ch pormits the d-hydroformylat~d product~
to dL~till as they are formed. If desired, a fractionatlng column can be u~ed to in~ure separation of any feedstock vapors from the vapors of the dehydroformylatèd products. In order to products. In order to minlmize side reaction~, it is preferable to keep the residence time of the feedstock in the di~tillation apparatus to a minimum. This is most easily accomplished by maintaining a relatively small volume of the feed~tock in contact with the catalyst in the boiler section and a~dding additional feedstock at a rate commensurate with the dehydro-formylation reaction to maintain a relatively constant volume in the boiler of the distillation apparatus. Furthermore, by maintaining a high proportion of cataly~t in contact with this volume in the boiler ~ection, the rate of dehydroformylatlon reaction will be increased, there~y al~o decrea~ing the ~ RD-6386 11)4~533 re~idence time of the feedotock in the boiler section. A~
will be readily apparent, an amount of catalyst ~hould not be 80 great as to interfere with heat transfer or distillation of the liquid phase.
In carrying out the dehydroformylation reaction in the vapor pha~e at atmo~pheric pre~sure, it is self evident that the minimum temperature to be used would be governed by the highe8t bolling point of the components of the ~eedstock.
Of the various isomeric acetoxybutyraldehydes to be dehydro-formylated, the highest boiling is 4-acetoxybutyraldehyde which has ~ boiling point of 190 C~ This mean~ that in carrying out the dehydroformylation reaction in the vapor phase at atmospherlc pre~sure, the temperature should be at least 190C.
Lower temperatures than this can be used by carrying out the vapor phase reaction at subatmospheric pressure. However, generally, th-re 18 no incentive to do this ~ince at the lower temperatures, the reaction might ~ust as w ll be carried out in the liquid phase rathsr than the vapor pha-e.
In carrylng out the vapor phase reaction, the vapor~ of the foedstock, produced preferably in a flash-type distillation apparatus, are introduced to the reactor containing the noble metal catalyst at the desired temperature.
To aid in the tran~port o the vapors from the distillation apparatus to the catalyst bod, an inert gas, such as nitrogen or a mixture of carbon monoxide and hydrogen is used a~ a carrier gas to sweep the vapors of the feedstoc~ from the distillation apparatus into the heated tube containing the noble metal catalyst. The vapors issuing from the reactor are then condensed and separated, gonerally by distillation into their various components~
For the vapor phase reaction, the noble metal catalyst is preferably deposited on a neutral support which should, li~e .. . . . . .
. .
--': .... . . .: . , . , . . " , 1~J4~533 the noble metal, have a large ~urface area. The support should be of ~uch a granular ~ize as to permit the vaporQ of the reactants and product~ to readily pass through without the particles them~elves being ~wept from the reactor. Porous carbon pellet~ of 4-14 mesh size are an ideal suppQrt on whlch the noble metal is carrled. In choos~ng the temperature to use, one must balance the degree of conversion against the yield of de~ired product. Generally, it i~ better to use the lower temperature and increase the vapor contact time wlth the catalyst bed or to increase the a unt of catalyst deposited on the support rather than to increase the reaction temperature.
Too high a reaction temperature leads to breakdown of the feed-stock into noncondensable products in addition to the carbon monoxide and hydrogen generated by the dehydroformylation reaction. Should one encounter large yields of noncondensable gases over and above that g-nerated by the carbon monoxlde in the hydrogen, one should then decrea~o th~ temperature at which the dehydroformylation reaction i8 being performed. Such technigues are well known to those ~killed in the art and would be readily ascertained.
In carrying out the dehydroformylation reactlon under liquid-vapor pha~e conditions, the liquid feed product i9 lntroduced to the catalyst bed at a temperature sufficiently high that the feedstock i9 converted to the vapor on contact with the cataly~t bed. Becau~e of the cooling effect resulting from the vaporization of the liquid feed, the catalyst bed is generally kept at a temperature higher than would normally be used for the vapor phase reaction in order that the cooling effect will be compensated for and the reaction be carried out at the temperature which would normally be used for the vapor phase reaction. Generally in carrying out thi~ type of reaction, an inert carrier gas is also provided to insure carrying ., ... - - . .. . . . . . ~.~ ... ..
~L~)4~S;~3 the vapors through the cataly~t bed to the exit port where they are condensed and again separated as di~cus~ed above for the vapor pha~e reaction.
~ n carrying out the dehydroformylation of the iso-meric acetoxybutyraldehydes by any of the abo~e techniques, the particular conditions and catalyQt~ sale~ted are dependent on the particular i~omer~ or mixture~ of i~omers to be dehydro-formylated. Both 4-acetoxybutyraldehyde and 2-acetoxybutyraldehyde are much more thermally ~table than the 3-acetoxy-2-methylprop-ionaldehyde. The fir~t two isomer~ are easier to dehydro-formylate than the third i~omer. Both 4-acetoxybutyraldehyde boiling point 190, 90/20 m~.) and 2-acetoxybutyraldehyde (boiling point 168, 70 /20 mm.) ~an be readily di~tilled in an inert atmospher- at atmo~pheric pre3sure with no detectable dehydroacetoxylation to the corr0~ponding olefinic aldehyde.
In contrast, 3-acetoxy-2-~ethylpropionaldehyde (boiling point ca.
180, ca. 80/20 mm.) will always dehydroacetoxylate to produce ~ignificant quantitie~ of methacrolein and ac~tic acid when diatilled under atmo~pheric pres~ure. The degree to which thl~ dehydroacetoxylation reaction occurs i8 dependent on the rosidence time in the distillation boiler at khe distillation temperature.
Neither the allyl acetate nor the l-propenyl acetate which are the products of the dehydroformylation of these ~someric acetoxybutyraldehydes will dehydroacetoxylate.
Therefore, if 3-acetoxy-2-methylpropionaldehyde i~ to be dehydroformylated either neat or a~ an ingredient in the mixture with the other two isomers, the dehydroacetoxylation reaction can be minimized and the yield of dehydroformylated product maximized by choo~ing those reaction conditions and cataly~ts which cau~e the highest rate for the dehydroformylation reaction. Since this reaction does not occur in the absence _ g _ : , . .:
` 1048533 RD-6386 of the noble metal catalyst, it i~ desirable to choo~e those reaction conditions which minimize both the time thi~ isomer is at an elevated temperature and its contact time with the catalyQt bed. Also it i8 desirable to have the cataly~t be the mo~t active catalyst and in it~ most active form ~o that the dehydroformylation reaction is complsted in as short time as possible. As pointed out above, palladium would be the cataly~t to u~e. To make it in its most active form, it should have as high ~urface area as pos~ible and preferably be on an essentially neutral, porous catalyst support having a large sur-face area.
In addition to the hydrogenation and dehydroacetoxyla-tion reactions discus~ed above, aldol type condensations, oxidation and carbonization reactions can also occur. The aldol condensation reactions can be controlled by maintaining es~entially neutral conditions in the dehydroformylation reaction. This means that the acetoxybutyraldehyde feedstock should be free of any acids or bases and that the cataly~t and its 9upport~, if used, should likewise be essentially neutral.
It, of course, Ls recognized that when 3-acetoxy-2-methylprop-ionaldehyde is one of tho reactants that the dehydroacetoxylation reaction cannot be completely prevented and therefore the products ~ssuing from the dehydroformylation reactor would contain some acetic acid. However, at this point in the reaction, there is little if any unconverted acetoxybutyraldehyde i~omers left unreacted unless the contact time with the cataly~t bed at the particular temperature has been insufficient to provide high yields of the dehydroformylated products.
Oxidation is easily controlled by using an inert atmosphere which excludes oxygen. Since both carbon monoxide and hydrogen will be products of the dehydroformylation reaction and it would be desirable to reu~e this in a further hydro-formylation reaction, it i9 preferred that the inert atmosphere be of carbon monoxide and hydrogen. However, in this caoe, reaction conditions ~hould be chosen which will minimize hydro-genation of the olefinic compounds to saturated compounds. If desired, in otarting up a reaction, other inert gases, for example nitrogen, can be used to initially establish an inert atmosphere which is then permitted to be replaced by the carbon monoxide and hydrogen atmosphere qenerated by the dehydro-formylation reactlon. The carbonization reaction is best control-led by insuring that no overheating occurs on the catalyst bed and that the temperature not exceed the temperature at which the deoired rate of the dehydroformylation reaction occurs. This can readily be determined by monitoring the temperature throughout the length of the catalyst bed to detect runaway conditlons and/or by the amount of uncondenoible ga~es exiting from the reactor. Generally, the lowest tomperature that can be uoed and yet attain the desired rate of dehydroformylation is de~irable in order to attain the highest conversion rate with minimum by-product ormation.
Not only does the activity of a particular catalyst depend upon its method of preparation but once prepared on it~
past history. As it io continued to be used, it will naturally lose some of its activity, but the desired rsaction rate can be maintained by increasing the reaction bed temperature or by regenerating the catalyot by art recognized technlques. Within the above parameters, the temperature which I have found most satisfactory is in the range of 125-250 C., preferably 140-220C.
When only 4-acetoxybutyraldehyde, 2-acetoxybutyraldehyde or mix-tures of theoe two isomers are to be dehydroformylated, their thermal stability perm~ts ~lower reaction rate and aatalyst of lower activity to be uoed than when the 3-acetoxy-2-methylpropion-aldehyde isomer is present.
.
:. . . ~. ',: , ~48533 In preparing the noble metal catalyst, any of the well-known techni~ues known in the art can be u3ed. A salt of the noble metal can be precipitated as the hydroxide or oxide which can then either be prereduced in a reducing atmo~phere or reduced on the initial introduction of the aldehyde isomer~
to be dehydroformylated. To prepare the supported cataly~t, a porous neutral support, i.e. one having neither an acidic nor basic reaction, for example carbon black, can be impregnated in the usual way with a soluble noble metal salt whicb is then reduced in the s~me way as described above for the noble metal oxide or hydroxide.
As more fully detailed in my above referenced Canadian applications, hydroformylation of allyl acetate, 1-propenyl acetate or mixture~ theroof under hydroformylating conditions in the presence of a cobalt hydroformylating catalyst leads to a mixture of 4-acetoxybutyraldehyde~ as the predominant product, and its two isomers 2-acetoxybutyraldehyde and 3-acetoxy-2-methylpropionaldehyde. Hydrogenat$on of this isomeric mixture lead~ to a mixture comprising the monoacetate esters of 1,4-butanediol, 1,2-butanodiol and 2-methyl-1,3-propanediol, respectively. Some trans~sterification can occur during the hydrogenation reaction so that the mixture also can contain some of the diacetates of theso butanediols as well as some of the free butanediolJ. However, during the de-esterification process under de-esterification conditions, all of the esters are converted to the free butanediols so that the degree to which the trans-esterification reaction has occurred presents no processing problem. Of the three butanediols produced, the most commercially important one is 1,4-butanediol which forms polye~ter~ with dicarboxylic acids such as terphthalic acid, which are commercially much more desirable than polyesters obtained from the other two i~omer~ Since thi~ butanediol -~ ~ . . . . . .
:: . . . . .. . . . . .
1~)48533 is the result of the hydrogenation and de-e~terification of the 4-acetoxybutyraldehyde, it i~ obvious that the 4-acetoxy-butyraldehyde is a much more desirable product of the hydro-formylation reaction.
The mixture o~ the isomer$c butyralaehydes produced ~ -in the ~bove-described hydroformylation reaction could be readily separated by fractional distillation into the three components if it were not for the thermal instability of the 3-acetoxy-2-methylprop$onaldehyde. However, I have found that by fla~h distillation at a temperature above that of the two lowest boiling i~omers, 2-acetoxybutyraldehyde and 3-acetoxy-
In my Canadian application A, Serial No. 203,212 filed June 24, 1974 and a3signed to the same as~ignee as the present invention, I have disQlosed and claimed a proce~ for making butanediols by oxidatively coupling propylene and acetic acid to produce allyl acetate which is then hydroformylated to produce the mixture of three i~omerlc acetoxybutyraldehydos.
Hydrogenation of the mixture produces a mixture of isomeric acetoxybutanols which can also contain some of the diesters and free diols. In my Canadian application B, Serial No. 195,892, filed March 25, 1974 and assigned to the same assignee a~ the pr-sent inv-ntion, I have disclos-d and claimed a process wherein the hydrogenation i~ accompllshed during the hydroformylation reaction. De-Esterification of the acetoxybutanol mixture produce~ the desired butanediols which can be separated by distillation.
In my Canadian application C, Serial No. ~oq, 307 filed ~ ~ e~b~r /~,lq~7and assigned to the same as~ignee as the present invention, I have disclosed and claimed that hydro-formylation of l-propenyl acetate under hydroformylating condi-tions in the presence of a cobalt hydroformylation catalyst yields essentially the same isomeric mixture of acetoxybutyralde-hyde~ as is obtained from allyl acetate.
Prior to my di~covery, the prior art, see for example J. Am. Chem. Soc. 70, 383 (1948) and 71, 3054 (1949), reported that the hydroformylation of allyl acetate led to only one product, 4-acetoxybutyraldehyde, in es~entially a 70-75% yield.
Although my work confirm~ this yield, I have also found that the balance of the allyl acetate has been converted to two lsomer3 of the 4-acetoxybutyraldehyde, ~pec~fically, 2-a~etoxybutyral-dehyde and 3-acetoxy-2-methylpropionaldehyde in approximately equ~molar amount~. r Although, a~ ~hown ~n my Canadian application3 A and B re~erred to above, these two isomers can be converted to their corre~ponding butaned~ols, specifically 1,2-butanediol and 2-methy~-1,3-propanediol, neither of the~e two products are a3 de~irable as 1,4-butanediol, which forms polye~ters with dlcarboxylic acids, such as terephthalic acid, which are comm~rcially much more de~irable than the polyester~ obtained from th- other two isomers. It would be highly desirable, therefore, to be able to obtain higher yield~ of the 4-acetoxy-butyraldehydo $ther by docreasing the production of the other two isomers or by converting the latt~r into the de~irod isomer.
Insofar as I am aware, the only attempt to rocycl~
an undesirable by-product of a hydroformylation reaction is de~cribed in Briti~h patent 1,241,646, its corresponding counter-parts in other foreign countrie~, and in articles written by the inventors and coworkers, see for example, Angew Chem., Internat. Bdit. 9, 169 (1970) and 11, 155 (1972), Ind. Eng.
Chem. 62 [4] 33 (1970). me~e referonces describe that in the hydroformylation of propylene to n-butyraldehyde, i~obutyraldehyde is obtained as a less desired product. mi9 latter product is dehydroformylat-d to propylene, carbon monoxide and hydrogen which can then be recycled in the hydroformylation reaction to increase the yield of the n-butyraldehyde in the over-all reaction. Other related art in thi~ area teaches the production of saturated aliphatic compounds arising from the hydrogen interaction with the dehydroformylation product to hydrogonate 1C~48533 ~he olefinic double bond. Th~s latter reaction i~ called decarbonylation becau~e, in effect, only carbon monoxide i~
romoved from the ~tarting product.
One of the convenient mean~ for converting a compound contain~ng an alcoholic hydroxyl group to an olefin is to make the acetate ester of the compound which is then thermolyzed or pyrolyzed to produce the olefin and acetic ac~d. For convenience, this ester thormolysis reaction, as applied to acetato e~ters, will be called dehydroacetoxylation since a hydrogen is removed from one carbon atom and the acetoxy group ~ -from the ad~acent carbon atom to form acetic acid and create an olefinic double bond in the initial compound. Since the isomoric acetoxybutyraldehyde~, to which this invention i~
directed, are acetate esters as well a~ aldehydes, they could undergo (a) the dehydroacetoxylation reaction to produce unsaturated aldehydes, (b) both the dehydroacetoxylation reaction and the hydrogenation reaction to product saturated aldehydes, (c) th- dohydroformylation reaction to produce un~aturated eJter~, (d) the dehydroformylation and hydrogenation reaction to produce ~aturated esters or (e) any combinat~on of (a) through (d). It was indeed surprising to find that the dehydroformylation reaction could be effected with the other reactions occurring to a minimal extent.
I have found an indirect method of converting the two isomers, 2-acetoxybutyraldehyde and 3-acetoxy-2-methyl-propionylaldehyde, to 4-acetoxybutyraldehyde~ In the presence ~ -of a Group VIII noble metal catalyst, any one of these three isomers or a mixture containing any two or all three of them can be dehydroformylated at a temperature in the range of 120-250C~ in a nonoxidizing atmosphere and in the pre~ence of an essentially neutral noble metal catalyst to produce allyl acetate, l-propenyl acetate or mixtures thereof. Dehydro-' :. ,. :. .
10~8533 formylation of those i~omers leads to allyl acetate from 4-acetoxybutyraldehyde, l-propenyl acetate from 2-acetoxybutyr-aldehyde and a mixture of allyl acetate, l-propenyl acetate and variable amounts methacrolein and acetic acid from the le~s thermally stable 3-acetoxy-2-methylpropionaldehyde.
The amount o~ the methacrolein and acetic acid produced i6 dependent on the activity of the catalyst and the temperature used. Of the noble metal catalysts, those from platinum, rhodium and palladium are more active than the other Group VIII
noble metals for promoting the dehydroormylation reaction.
Platinum causes more hydrogenation of tho desired un~aturated ester~ to saturated esters. Rhodium is ~atisfactory but much more expensive than palladium which i~ the preferred cataly~t when it is desired to minimize the amount of unsaturated aldehyde or ~aturated ester by-products.
As I have dlsclosed in my above-referenced Canadian application C, l-propenyl acetate can be hydroformylated to giv~ the same three isomeric acetoxybutyraldehydes in essentially the same proportion a~ is obtained upon hydroformylation of allyl ac-tate. Therefore, the significance of my discovery of the dohydroformylation reaction described above i8 that, by separating some or all of the 4-acetoxybutyraldehyde from the balance of the mixture containing the other two isomers, the latter can be dehydroformylated to furnish feedstock for the hydroformylation reaction. By alway~ recycling the two undesired isomers in this matter, the feed~tock of the hydroformylation reactions, in offoct, is all converted essentially to the desired 4-acetoxybutyr-aldehyde, which can then be readily hydrogenated to produce 4-acetoxy-l-butanol, which, ~n turn, can be de-esterified to produce 1,4-butanediol.
Not only ha~ my discovered of this dehydroformylation reaction provided a proces~ useful in itself for utilizing the '; .
~ V48533 i~omeric acetoxybutyraldehydes, made by any other proces~es, but has also provided improveme~t~ in the hydroformylation reaction to increa~e the yield of 4-acetoxybutyraldehyde in the process described in my above-referenced Canadian application A for making butanediol~ from propylene, acetic acid and oxygen wherein the hydroformylation reaction is aD important intermediate step~
By being able to con~ert all of the hydroformylated products to 4-acetoxybutyraldehyde, the butanediol will all be the desired 1,4-butanediol.
The dehydroformylation reaction can be carried out as a liquid phase, vapor phase or liquid-vapor phase reaction.
Since the products of the reaction are lower boiling than the feedstock, the liquid phase reaction can be carried out at atmospheric pressure at a temperature in the range from the boiling point of the lowest boiling of the dehydroformylated products up to the boiling point of the lowe~t boiling component of the f-edstock. ~oth allyl acetate and l-propenyl acetate, which has two isomeric forms, boil in the rang- of 100-106 C.
Therefore, the min~mum temperature that the dehydroformylation reaction could be carried out at would be about 110 C. ~owever, at this temperature, the rate of the dehydroformylation reaction i8 ~0 slow that it is preferred to use temperatures of at least 120 C. and pre~erably 140 C.
The maximum temperature for the reaction is determined by the lowest boiling component present in llquid phase. The lowost boiling isomer which would be present in the feedstock is 2-acetoxybutyraldehyde which has a boiling point of 168C.
which represents, therefore, the maximum tomperaturo that can be used for the dehydroformylation reaction when carried out ~0 in the liquid phase at at spheric pressure when th$s component is pr~sent and as long as it remains unreacted. When it is dehydroformylated any remaining isomers can be dehydroformylated 1~)48533 at higher temperatures up to their boiling point. Higher temperatures can be obtained by increa~ing the pres~ure.
Gonerally, however, it would be more desirable in this case to carry out the reaction either in the vapor pha8e or th-liquid-vapor phase to save the expense of the more expensive equipment required when carrying out roactions under pressure.
Whon carrying out the reaction in the liquid phase, the noble metal catalyst with or without a support, but proferably havlng a large surface area , i~ suspended, generally with ~tirring in the feedstock. Since all the components of the feeastock are liquid, no ~olvent needs to be u~ed. However, if do~ired, a solvent could used but it generally should have a boiling point high-r than any of the component~ of the feed-stock and be nonreactive with either the components of the feodstock or the dehydroformylated product~. Pref-rably, no ~olvent is used since the reaction i~ simplified.
m. liquid phase reaction i3 carried out in a dis-tillation apparatus wh$ch pormits the d-hydroformylat~d product~
to dL~till as they are formed. If desired, a fractionatlng column can be u~ed to in~ure separation of any feedstock vapors from the vapors of the dehydroformylatèd products. In order to products. In order to minlmize side reaction~, it is preferable to keep the residence time of the feedstock in the di~tillation apparatus to a minimum. This is most easily accomplished by maintaining a relatively small volume of the feed~tock in contact with the catalyst in the boiler section and a~dding additional feedstock at a rate commensurate with the dehydro-formylation reaction to maintain a relatively constant volume in the boiler of the distillation apparatus. Furthermore, by maintaining a high proportion of cataly~t in contact with this volume in the boiler ~ection, the rate of dehydroformylatlon reaction will be increased, there~y al~o decrea~ing the ~ RD-6386 11)4~533 re~idence time of the feedotock in the boiler section. A~
will be readily apparent, an amount of catalyst ~hould not be 80 great as to interfere with heat transfer or distillation of the liquid phase.
In carrying out the dehydroformylation reaction in the vapor pha~e at atmo~pheric pre~sure, it is self evident that the minimum temperature to be used would be governed by the highe8t bolling point of the components of the ~eedstock.
Of the various isomeric acetoxybutyraldehydes to be dehydro-formylated, the highest boiling is 4-acetoxybutyraldehyde which has ~ boiling point of 190 C~ This mean~ that in carrying out the dehydroformylation reaction in the vapor phase at atmospherlc pre~sure, the temperature should be at least 190C.
Lower temperatures than this can be used by carrying out the vapor phase reaction at subatmospheric pressure. However, generally, th-re 18 no incentive to do this ~ince at the lower temperatures, the reaction might ~ust as w ll be carried out in the liquid phase rathsr than the vapor pha-e.
In carrylng out the vapor phase reaction, the vapor~ of the foedstock, produced preferably in a flash-type distillation apparatus, are introduced to the reactor containing the noble metal catalyst at the desired temperature.
To aid in the tran~port o the vapors from the distillation apparatus to the catalyst bod, an inert gas, such as nitrogen or a mixture of carbon monoxide and hydrogen is used a~ a carrier gas to sweep the vapors of the feedstoc~ from the distillation apparatus into the heated tube containing the noble metal catalyst. The vapors issuing from the reactor are then condensed and separated, gonerally by distillation into their various components~
For the vapor phase reaction, the noble metal catalyst is preferably deposited on a neutral support which should, li~e .. . . . . .
. .
--': .... . . .: . , . , . . " , 1~J4~533 the noble metal, have a large ~urface area. The support should be of ~uch a granular ~ize as to permit the vaporQ of the reactants and product~ to readily pass through without the particles them~elves being ~wept from the reactor. Porous carbon pellet~ of 4-14 mesh size are an ideal suppQrt on whlch the noble metal is carrled. In choos~ng the temperature to use, one must balance the degree of conversion against the yield of de~ired product. Generally, it i~ better to use the lower temperature and increase the vapor contact time wlth the catalyst bed or to increase the a unt of catalyst deposited on the support rather than to increase the reaction temperature.
Too high a reaction temperature leads to breakdown of the feed-stock into noncondensable products in addition to the carbon monoxide and hydrogen generated by the dehydroformylation reaction. Should one encounter large yields of noncondensable gases over and above that g-nerated by the carbon monoxlde in the hydrogen, one should then decrea~o th~ temperature at which the dehydroformylation reaction i8 being performed. Such technigues are well known to those ~killed in the art and would be readily ascertained.
In carrying out the dehydroformylation reactlon under liquid-vapor pha~e conditions, the liquid feed product i9 lntroduced to the catalyst bed at a temperature sufficiently high that the feedstock i9 converted to the vapor on contact with the cataly~t bed. Becau~e of the cooling effect resulting from the vaporization of the liquid feed, the catalyst bed is generally kept at a temperature higher than would normally be used for the vapor phase reaction in order that the cooling effect will be compensated for and the reaction be carried out at the temperature which would normally be used for the vapor phase reaction. Generally in carrying out thi~ type of reaction, an inert carrier gas is also provided to insure carrying ., ... - - . .. . . . . . ~.~ ... ..
~L~)4~S;~3 the vapors through the cataly~t bed to the exit port where they are condensed and again separated as di~cus~ed above for the vapor pha~e reaction.
~ n carrying out the dehydroformylation of the iso-meric acetoxybutyraldehydes by any of the abo~e techniques, the particular conditions and catalyQt~ sale~ted are dependent on the particular i~omer~ or mixture~ of i~omers to be dehydro-formylated. Both 4-acetoxybutyraldehyde and 2-acetoxybutyraldehyde are much more thermally ~table than the 3-acetoxy-2-methylprop-ionaldehyde. The fir~t two isomer~ are easier to dehydro-formylate than the third i~omer. Both 4-acetoxybutyraldehyde boiling point 190, 90/20 m~.) and 2-acetoxybutyraldehyde (boiling point 168, 70 /20 mm.) ~an be readily di~tilled in an inert atmospher- at atmo~pheric pre3sure with no detectable dehydroacetoxylation to the corr0~ponding olefinic aldehyde.
In contrast, 3-acetoxy-2-~ethylpropionaldehyde (boiling point ca.
180, ca. 80/20 mm.) will always dehydroacetoxylate to produce ~ignificant quantitie~ of methacrolein and ac~tic acid when diatilled under atmo~pheric pres~ure. The degree to which thl~ dehydroacetoxylation reaction occurs i8 dependent on the rosidence time in the distillation boiler at khe distillation temperature.
Neither the allyl acetate nor the l-propenyl acetate which are the products of the dehydroformylation of these ~someric acetoxybutyraldehydes will dehydroacetoxylate.
Therefore, if 3-acetoxy-2-methylpropionaldehyde i~ to be dehydroformylated either neat or a~ an ingredient in the mixture with the other two isomers, the dehydroacetoxylation reaction can be minimized and the yield of dehydroformylated product maximized by choo~ing those reaction conditions and cataly~ts which cau~e the highest rate for the dehydroformylation reaction. Since this reaction does not occur in the absence _ g _ : , . .:
` 1048533 RD-6386 of the noble metal catalyst, it i~ desirable to choo~e those reaction conditions which minimize both the time thi~ isomer is at an elevated temperature and its contact time with the catalyQt bed. Also it i8 desirable to have the cataly~t be the mo~t active catalyst and in it~ most active form ~o that the dehydroformylation reaction is complsted in as short time as possible. As pointed out above, palladium would be the cataly~t to u~e. To make it in its most active form, it should have as high ~urface area as pos~ible and preferably be on an essentially neutral, porous catalyst support having a large sur-face area.
In addition to the hydrogenation and dehydroacetoxyla-tion reactions discus~ed above, aldol type condensations, oxidation and carbonization reactions can also occur. The aldol condensation reactions can be controlled by maintaining es~entially neutral conditions in the dehydroformylation reaction. This means that the acetoxybutyraldehyde feedstock should be free of any acids or bases and that the cataly~t and its 9upport~, if used, should likewise be essentially neutral.
It, of course, Ls recognized that when 3-acetoxy-2-methylprop-ionaldehyde is one of tho reactants that the dehydroacetoxylation reaction cannot be completely prevented and therefore the products ~ssuing from the dehydroformylation reactor would contain some acetic acid. However, at this point in the reaction, there is little if any unconverted acetoxybutyraldehyde i~omers left unreacted unless the contact time with the cataly~t bed at the particular temperature has been insufficient to provide high yields of the dehydroformylated products.
Oxidation is easily controlled by using an inert atmosphere which excludes oxygen. Since both carbon monoxide and hydrogen will be products of the dehydroformylation reaction and it would be desirable to reu~e this in a further hydro-formylation reaction, it i9 preferred that the inert atmosphere be of carbon monoxide and hydrogen. However, in this caoe, reaction conditions ~hould be chosen which will minimize hydro-genation of the olefinic compounds to saturated compounds. If desired, in otarting up a reaction, other inert gases, for example nitrogen, can be used to initially establish an inert atmosphere which is then permitted to be replaced by the carbon monoxide and hydrogen atmosphere qenerated by the dehydro-formylation reactlon. The carbonization reaction is best control-led by insuring that no overheating occurs on the catalyst bed and that the temperature not exceed the temperature at which the deoired rate of the dehydroformylation reaction occurs. This can readily be determined by monitoring the temperature throughout the length of the catalyst bed to detect runaway conditlons and/or by the amount of uncondenoible ga~es exiting from the reactor. Generally, the lowest tomperature that can be uoed and yet attain the desired rate of dehydroformylation is de~irable in order to attain the highest conversion rate with minimum by-product ormation.
Not only does the activity of a particular catalyst depend upon its method of preparation but once prepared on it~
past history. As it io continued to be used, it will naturally lose some of its activity, but the desired rsaction rate can be maintained by increasing the reaction bed temperature or by regenerating the catalyot by art recognized technlques. Within the above parameters, the temperature which I have found most satisfactory is in the range of 125-250 C., preferably 140-220C.
When only 4-acetoxybutyraldehyde, 2-acetoxybutyraldehyde or mix-tures of theoe two isomers are to be dehydroformylated, their thermal stability perm~ts ~lower reaction rate and aatalyst of lower activity to be uoed than when the 3-acetoxy-2-methylpropion-aldehyde isomer is present.
.
:. . . ~. ',: , ~48533 In preparing the noble metal catalyst, any of the well-known techni~ues known in the art can be u3ed. A salt of the noble metal can be precipitated as the hydroxide or oxide which can then either be prereduced in a reducing atmo~phere or reduced on the initial introduction of the aldehyde isomer~
to be dehydroformylated. To prepare the supported cataly~t, a porous neutral support, i.e. one having neither an acidic nor basic reaction, for example carbon black, can be impregnated in the usual way with a soluble noble metal salt whicb is then reduced in the s~me way as described above for the noble metal oxide or hydroxide.
As more fully detailed in my above referenced Canadian applications, hydroformylation of allyl acetate, 1-propenyl acetate or mixture~ theroof under hydroformylating conditions in the presence of a cobalt hydroformylating catalyst leads to a mixture of 4-acetoxybutyraldehyde~ as the predominant product, and its two isomers 2-acetoxybutyraldehyde and 3-acetoxy-2-methylpropionaldehyde. Hydrogenat$on of this isomeric mixture lead~ to a mixture comprising the monoacetate esters of 1,4-butanediol, 1,2-butanodiol and 2-methyl-1,3-propanediol, respectively. Some trans~sterification can occur during the hydrogenation reaction so that the mixture also can contain some of the diacetates of theso butanediols as well as some of the free butanediolJ. However, during the de-esterification process under de-esterification conditions, all of the esters are converted to the free butanediols so that the degree to which the trans-esterification reaction has occurred presents no processing problem. Of the three butanediols produced, the most commercially important one is 1,4-butanediol which forms polye~ter~ with dicarboxylic acids such as terphthalic acid, which are commercially much more desirable than polyesters obtained from the other two i~omer~ Since thi~ butanediol -~ ~ . . . . . .
:: . . . . .. . . . . .
1~)48533 is the result of the hydrogenation and de-e~terification of the 4-acetoxybutyraldehyde, it i~ obvious that the 4-acetoxy-butyraldehyde is a much more desirable product of the hydro-formylation reaction.
The mixture o~ the isomer$c butyralaehydes produced ~ -in the ~bove-described hydroformylation reaction could be readily separated by fractional distillation into the three components if it were not for the thermal instability of the 3-acetoxy-2-methylprop$onaldehyde. However, I have found that by fla~h distillation at a temperature above that of the two lowest boiling i~omers, 2-acetoxybutyraldehyde and 3-acetoxy-
2-methylpropionaldehyde respectively, that these two i~omer~ can be distilled leaving substantially puro 4-acetoxybutyraldehyde in the ~till pot. The amount of 4-acetoxybutyraldehyde which also codi~tills is dependent on the actual maximum temperature used in the flash distillation. The still pot residue can then be ~ractionally di~tilled to produce very pure 4-acetoxybutyral-deh~de which can then be hydrog-nated to 4-acetoxy-1-butanol u~ing any of the well-known hydrogenation catalysts and hydro-genation conditions to produce sub~tantially pure 4-acetoxy-1-butanol. This latter product can be readily de-esterified using any of tho woll-known de-esterification processes to produce 1,4-butanediol and acetic acid. The acetic acid can be recycled to make allyl acetate by oxidatively coupling propylene with acetic acid.
The mixture of isomers resulting from the above-de~cribed flash distillation (to which may be added, if desired, any of the isomeric mixtures removed in the fractional distillation to further purify the 4-acetoxybutyraldehyde a~
described above), may then be sub~ected to the above described dehydroformylation procedure to produce a mixture of allyl acetate and l-propenyl acetate which may also contain some acetic acid and methacrolein as described above. After the . . , , , -- .
~ ~ RD-6386 removal of thege latter two by-product~, the mixture of the allyl acetate and l-propenyl acetate can be hydroformylated as de~cribed in my Canadian application C re~erenced ab~ve to again produce a mixture of the isomeric acetoxybutyraldehydes in which the 4-ac~toxybutyraldehyde predominates. It i9 therefore seen that this proce~ of removing some of the 4-acetoxybutyraldehyde fnDm the mLxture containing the other two i~omers and dehydro-formylating the latter to produce feed~tock for the hydroformyla-tion reaction, effectively recycles the undesired lsomers. ~he combination of this dehydroformylation reaction with the hydro-formylation reaction represents an improvement in the latter reaction 3ince it results in more of the feedstock being converted to the 4-acetoxybutyraldehyde. The higher yield of this isomer also results in a higher yield of 1,4-butanediol.
In carrying out the hydroformylation of the mixture of allyl acetate and l-propenyl acetate obtained by the proce~s of this invention, I can use any of the procedure di~closed in my above-mentioned Canadian application C. In carrying out the overall process whereby ~a) propylene is oxidatively coupled with acetic acid to form allyl acetate, (b) the allyl acetate, l-propenyl acetate, or mixture of allyl acetate and l-propenyl acetate is hydroformylated to produce the isomeric acetoxybutyraldehydes, which are (c) treated according to the process of this invention to produce substantially pure 4-acetoxybutyraldehyde, wh~ch i~ ~d) hydrogenated to produce 4-acetoxy-1-butanol, which is (e) de-esterified to produce 1,4-butanediol and acetic acid in a form which can be recycled to be oxidatively coupled with propylene, I may use any of the procedure~ for the oxidative coupling, hydroformylation, hydro-genation and the de-esterification disclosed in my above-mentioned Canadian application A.
In order that those -~killed in the art may better - 14 _ ~ 4~533 under~tand my invention, the following examples are given by way of illus~ration and not by way of limitation. Temperature~
are given in degree~ Centigrade and pregsures are reported in pound~ per square inch gauge.
Examples 1-4 illustrate carrying out the dehydroformyla-tion reaction in the liquid phase.
2-Acetoxybutyraldehyde was prepared esQentially free of it~ isomers by hydroformylation of l-propenyl acetate using rhodium bi~(trlphenylphosphine) carbonyl chloride rRhCl(CO)2(PPh3)~ as the catalyst. A su~p~naion o~ 1.0 gram of 10% palladium on carbon black (freshly activated under hydrogen) in 6.4 grams of the 2-acetoxybutyraldehyde was heated at 155-190 for two hours, with an insulated 100 m~. vigreaux column and condenser mounted directly above the reaction ves~el.
The distillate collected in that period was 4.6 gram~ of pale yellow liquid boillng in the 85-103 range. (Gas was also evolved.) Quantitative VPC analysis (propionic acid lnternal standard) showed the presence of 2.9 grams of l-propenyl acetate (59% yield, trans : ci~ ratio about 3:1), 0.92 gram of propyl acetate (18%), 0.72 grams of acetic acid (24%), and about 0.04 gram of unidentified low~r boiling substrate~. No allyl acetate was detected.
RXAMP~E 2 4-Acetoxybutyraldehyde wa~ prepared by the dicobalt octacarbonyl-catalyzed hydro~ormylation of allyl acetate and i~olated from its isomeric by-product~ by repeated di~tillation.
A auspension of 1~0 gram of 10% palladium on acetyl~ne black in 10.0 grams of 4-acetoxybutyraldehyde wa~ heated at 140-180 for one hour a~ in Example 1. Gas was evolved, and 6.1 grams of pale yellow liquid was collected at 80-106 . Quantitative VPC
analysis showed the pre~ence of 2.1 grams of allyl acetate (27% yield), 0.94 gram of propyl acetate (12%), and 1.9 gram~
of acetic acid (41%). No l-propenyl acetate was detected.
A su~pen~ion of 1.0 gram~ o~ 5% platinum on carbon (activated under hydrogen) ln 4~1 grams of 2-acetoxybutyraldehyde was heated at 155-180 for four hour~. Collect~d a~ in the above examples was 1.2 grams of distillate boiling over the 88-120 rangs. Analy~i~ by VPC and NMR showed the presence of 0.45 gram of l-propenyl acetate (14% yield, tran4 : ci8 ratio about 2tl), about 0.1 gram of propyl acetate (3%), and about 0.5 gram of acetlc acid (26%). A large amount of qtarting aldehyde remained unconverted in the ~till pot.
A suspen~ion of 1.0 gram of 5% rhodium on carbon in 10.0 grams of 2-acetoxybutyraldehyde was heated at 145-180 for two hours. Gas wa~ evolved. Collected as in the above case~ was 5.2 grams of di~tillate which boiled in the 80-108 range. VPC analysis showed the presence o 2.8 grams of 1-propenyl acetate (36% yield, tran~ : Ci9 ratio about
The mixture of isomers resulting from the above-de~cribed flash distillation (to which may be added, if desired, any of the isomeric mixtures removed in the fractional distillation to further purify the 4-acetoxybutyraldehyde a~
described above), may then be sub~ected to the above described dehydroformylation procedure to produce a mixture of allyl acetate and l-propenyl acetate which may also contain some acetic acid and methacrolein as described above. After the . . , , , -- .
~ ~ RD-6386 removal of thege latter two by-product~, the mixture of the allyl acetate and l-propenyl acetate can be hydroformylated as de~cribed in my Canadian application C re~erenced ab~ve to again produce a mixture of the isomeric acetoxybutyraldehydes in which the 4-ac~toxybutyraldehyde predominates. It i9 therefore seen that this proce~ of removing some of the 4-acetoxybutyraldehyde fnDm the mLxture containing the other two i~omers and dehydro-formylating the latter to produce feed~tock for the hydroformyla-tion reaction, effectively recycles the undesired lsomers. ~he combination of this dehydroformylation reaction with the hydro-formylation reaction represents an improvement in the latter reaction 3ince it results in more of the feedstock being converted to the 4-acetoxybutyraldehyde. The higher yield of this isomer also results in a higher yield of 1,4-butanediol.
In carrying out the hydroformylation of the mixture of allyl acetate and l-propenyl acetate obtained by the proce~s of this invention, I can use any of the procedure di~closed in my above-mentioned Canadian application C. In carrying out the overall process whereby ~a) propylene is oxidatively coupled with acetic acid to form allyl acetate, (b) the allyl acetate, l-propenyl acetate, or mixture of allyl acetate and l-propenyl acetate is hydroformylated to produce the isomeric acetoxybutyraldehydes, which are (c) treated according to the process of this invention to produce substantially pure 4-acetoxybutyraldehyde, wh~ch i~ ~d) hydrogenated to produce 4-acetoxy-1-butanol, which is (e) de-esterified to produce 1,4-butanediol and acetic acid in a form which can be recycled to be oxidatively coupled with propylene, I may use any of the procedure~ for the oxidative coupling, hydroformylation, hydro-genation and the de-esterification disclosed in my above-mentioned Canadian application A.
In order that those -~killed in the art may better - 14 _ ~ 4~533 under~tand my invention, the following examples are given by way of illus~ration and not by way of limitation. Temperature~
are given in degree~ Centigrade and pregsures are reported in pound~ per square inch gauge.
Examples 1-4 illustrate carrying out the dehydroformyla-tion reaction in the liquid phase.
2-Acetoxybutyraldehyde was prepared esQentially free of it~ isomers by hydroformylation of l-propenyl acetate using rhodium bi~(trlphenylphosphine) carbonyl chloride rRhCl(CO)2(PPh3)~ as the catalyst. A su~p~naion o~ 1.0 gram of 10% palladium on carbon black (freshly activated under hydrogen) in 6.4 grams of the 2-acetoxybutyraldehyde was heated at 155-190 for two hours, with an insulated 100 m~. vigreaux column and condenser mounted directly above the reaction ves~el.
The distillate collected in that period was 4.6 gram~ of pale yellow liquid boillng in the 85-103 range. (Gas was also evolved.) Quantitative VPC analysis (propionic acid lnternal standard) showed the presence of 2.9 grams of l-propenyl acetate (59% yield, trans : ci~ ratio about 3:1), 0.92 gram of propyl acetate (18%), 0.72 grams of acetic acid (24%), and about 0.04 gram of unidentified low~r boiling substrate~. No allyl acetate was detected.
RXAMP~E 2 4-Acetoxybutyraldehyde wa~ prepared by the dicobalt octacarbonyl-catalyzed hydro~ormylation of allyl acetate and i~olated from its isomeric by-product~ by repeated di~tillation.
A auspension of 1~0 gram of 10% palladium on acetyl~ne black in 10.0 grams of 4-acetoxybutyraldehyde wa~ heated at 140-180 for one hour a~ in Example 1. Gas was evolved, and 6.1 grams of pale yellow liquid was collected at 80-106 . Quantitative VPC
analysis showed the pre~ence of 2.1 grams of allyl acetate (27% yield), 0.94 gram of propyl acetate (12%), and 1.9 gram~
of acetic acid (41%). No l-propenyl acetate was detected.
A su~pen~ion of 1.0 gram~ o~ 5% platinum on carbon (activated under hydrogen) ln 4~1 grams of 2-acetoxybutyraldehyde was heated at 155-180 for four hour~. Collect~d a~ in the above examples was 1.2 grams of distillate boiling over the 88-120 rangs. Analy~i~ by VPC and NMR showed the presence of 0.45 gram of l-propenyl acetate (14% yield, tran4 : ci8 ratio about 2tl), about 0.1 gram of propyl acetate (3%), and about 0.5 gram of acetlc acid (26%). A large amount of qtarting aldehyde remained unconverted in the ~till pot.
A suspen~ion of 1.0 gram of 5% rhodium on carbon in 10.0 grams of 2-acetoxybutyraldehyde was heated at 145-180 for two hours. Gas wa~ evolved. Collected as in the above case~ was 5.2 grams of di~tillate which boiled in the 80-108 range. VPC analysis showed the presence o 2.8 grams of 1-propenyl acetate (36% yield, tran~ : Ci9 ratio about
3:1), 0.8 gram of propyl acetate (10%), and 1.2 grams of acetic acid (26%).
Example~ 5-8 illustrate one method of carrying out the dehydroformylation reaction in the liquid-vapor phase.
Since the feedstock immediately volatilized from the catalyst bed in these examples, the actual reaction temperature is probably nearer that of the boiling point of the feedstock than it i~ that of the catalyst bed temperature.
A 5.0 gram bed of 10% palladium on carbon was heated at about 300 and activated under hydrogen. After the hydrogen atmosphere was replaced with nitrogen, a m~xture of 11.6 grams of 2-acetoxybutyraldehyde, 3.2 gram~ of 3-acetoxy-2-methyl-propionaldehyde, 4.4 gram~ of 4-acetoxybutyraldehyde and 0.8 gram ,. . . ~ , ~ .
~D-6386 of aceti~ acid wa~ dropped slowly (over 30 minute9) onto the hot catalyst. An in~ulated lO0 mm. Vigreaux column and condenser were mounted directly above the reaction vesQel. Ga~
was evolved. The di~tillate, 13.4 gram~ collected at 60-110 in one hour total reaction time contained, a~ found by VPC
and NMR analysis, 4~1 grams of l-propenyl aceta~e (46% yield ; based on 2-acetoxybutyraldehyde, 27% yield based on all aldehydes), 1.8 grams of allyl acetate (53% yield based on
Example~ 5-8 illustrate one method of carrying out the dehydroformylation reaction in the liquid-vapor phase.
Since the feedstock immediately volatilized from the catalyst bed in these examples, the actual reaction temperature is probably nearer that of the boiling point of the feedstock than it i~ that of the catalyst bed temperature.
A 5.0 gram bed of 10% palladium on carbon was heated at about 300 and activated under hydrogen. After the hydrogen atmosphere was replaced with nitrogen, a m~xture of 11.6 grams of 2-acetoxybutyraldehyde, 3.2 gram~ of 3-acetoxy-2-methyl-propionaldehyde, 4.4 gram~ of 4-acetoxybutyraldehyde and 0.8 gram ,. . . ~ , ~ .
~D-6386 of aceti~ acid wa~ dropped slowly (over 30 minute9) onto the hot catalyst. An in~ulated lO0 mm. Vigreaux column and condenser were mounted directly above the reaction vesQel. Ga~
was evolved. The di~tillate, 13.4 gram~ collected at 60-110 in one hour total reaction time contained, a~ found by VPC
and NMR analysis, 4~1 grams of l-propenyl aceta~e (46% yield ; based on 2-acetoxybutyraldehyde, 27% yield based on all aldehydes), 1.8 grams of allyl acetate (53% yield based on
4-acetoxybutyraldehyde, 12% yield based on all aldehydes), and 2.3 grams of propyl acetate (15% yield based on all aldehydes).
The other products were acetic acid and methacrolein.
The aldehyde mixture de~cribed in Example 5, lO.0 grams, was dropped onto a bed of 3.1 grams of 5% rhodium on carbon maintained at about 300. As in the previous case, gas was evolved and di~tillate was collected (5.1 grams boiling over the 58-108 range). Produced, as shown by vPC and NMR
analysis, were 1.6 gram~ of l-propenyl acetate (36% yield based on 2-acetoxybutyraldehyde, 21% yield based on all aldehydes), 0.55 gram of allyl acetate (32% yield based on 4-acetoxybutyralde-hyde, 7% yleld based on all aldehydes), and 0.7 gram of propyl acetate (9% yield based on all aldehyde~), The other products were acetic acid and methacrolein.
The aldehyde mixture described in Example 5, 10.0 grams, was dropped onto a bed of 3.0 gram~ of 5% platinum on carbon maintained at about 300. As in the previou~ cases, gas was evolved and distillate was collected (6.2 grams boiling over the 56-104 range). Produced, as found by VPC and NMR
analysis, were l.0 gram of l-propenyl acetate (22X yield based on 2-acetoxybutyraldehyde, 13% yield ba~ed on all aldehydes), 0.3 gram of allyl acetate (18% yield based on 4-acetoxybutyral-~,.. . ... . . .
~ ' . ........ .
1¢~48533 dehyde, 4% yield based on all aldehydes), and 1.1 grams of propyl acetate (1~% yield ba~ed on all aldehydes~. The other products were acetic acid and methacrolein.
me aldehyde mixture de~cribed in Example 5, 10.0 gram~, was dropped onto a bed of 4.1 gram~ of 5% ruthenium on carbon maintained at about 300. As in the previou~ case~, gas was evolved and di~tillate wa~ collected (5.2 grams boiling over the 60-110 range). Produced as shown by VPC and NMR
analysis, were 0.6 gram of l-propenyl acetate (13X yield based on 2-acetoxybutyraldehyde, 8% yield based on all aldehydes), 0.3 gram of allyl acetate (18% yield based on 4-acetoxybutyral-dehyde, 4% yield based on all aldehydes), and 0.8 gram of propyl acetate (10% yield based on all aldehydes).
me yield of methacrolein in Examples 5-8 increased as the total yield of aldehyde rever~ion products decreased.
EXAMP~E 9 A heavy wall 16 mm. I.D. x 70 cm. effective length glass tube was charged with 22 grams of 0.2% palladium on 6-14 mosh carbon and heated at 200-220. Then 25.0 grams of the aldehyde mixture described in Example S was evaporated and passed through the tube with a slow nitrogen carrier 3tream over 30 minutes. A pale yellow liquid (12.4 grams) was condensed and collected. As found by VPC and NMR analysis, it contained about 3 grams of l-propenyl acetate, about one gram of allyl acetate, and about O.S gram of propyl acetate. The other materials were `-acetic acid, methacrolein and the aldehyde starting materlals (about 20% unconverted).
The above examples have clearly demonstrated the best mode known to me of carrying the various aspect~ of my invention into effect. As will be readily understood by those skilled in the art, variations can be made in practicing my ..
iC)~8S33 invention a~ clearly taught in the balance o~ the ~pecification, by the cross-referenced Canadian applications and by the prior art on conversion of alkenes to unsaturated esters, hydroformula-tion, hydrogenation and de-e3terification without departing from the true intended scope of my invention.
My invention can be used as an independent proce3s for conversion of any one or a ~ixture of any of the isomeric acetoxybutyraldehydes to produce the olefinic unsaturated ester~
which are useful in and of themselves. In this respect, the dehydroformylation of 2-acetoxybutyraldehyde can be u~ed as an alternative process of producing l-propenyl acetate for the present process disclosed in the art. Allyl acetate has a wide variety of use~ as the literature on this compound will ~how.
It has already been discussed and shown above how my process can be used to provide an improvement in other known proce~ses, specifically th~ hydroformylation process and the process for making 1,4-butanediol from propylene and acetic acid. Where desired, advantage can be taken of the thermal instability of the 3-acetoxy-2-methylpropionaldehyde to eliminate it from a mixture with one or more of its isomers by heating the mixture and distilling the methacrolein and acetic acid as the one formed.
The acetic acid can be recycled to make allyl acetate from propylene. The remaining isomers can then be readily isolated and either hydrogenated to monoesters or dehydroformylated a~
described above. These and other modifications of this invention and its uses as will be readily di cerned by those skilled in the art, ba~ed on the teachings of the prior art and the specific teachings of this application, can be employed within the scope of the invention. The invention is intended to include all such modifications and variations as are embraced within the following claims.
The other products were acetic acid and methacrolein.
The aldehyde mixture de~cribed in Example 5, lO.0 grams, was dropped onto a bed of 3.1 grams of 5% rhodium on carbon maintained at about 300. As in the previous case, gas was evolved and di~tillate was collected (5.1 grams boiling over the 58-108 range). Produced, as shown by vPC and NMR
analysis, were 1.6 gram~ of l-propenyl acetate (36% yield based on 2-acetoxybutyraldehyde, 21% yield based on all aldehydes), 0.55 gram of allyl acetate (32% yield based on 4-acetoxybutyralde-hyde, 7% yleld based on all aldehydes), and 0.7 gram of propyl acetate (9% yield based on all aldehyde~), The other products were acetic acid and methacrolein.
The aldehyde mixture described in Example 5, 10.0 grams, was dropped onto a bed of 3.0 gram~ of 5% platinum on carbon maintained at about 300. As in the previou~ cases, gas was evolved and distillate was collected (6.2 grams boiling over the 56-104 range). Produced, as found by VPC and NMR
analysis, were l.0 gram of l-propenyl acetate (22X yield based on 2-acetoxybutyraldehyde, 13% yield ba~ed on all aldehydes), 0.3 gram of allyl acetate (18% yield based on 4-acetoxybutyral-~,.. . ... . . .
~ ' . ........ .
1¢~48533 dehyde, 4% yield based on all aldehydes), and 1.1 grams of propyl acetate (1~% yield ba~ed on all aldehydes~. The other products were acetic acid and methacrolein.
me aldehyde mixture de~cribed in Example 5, 10.0 gram~, was dropped onto a bed of 4.1 gram~ of 5% ruthenium on carbon maintained at about 300. As in the previou~ case~, gas was evolved and di~tillate wa~ collected (5.2 grams boiling over the 60-110 range). Produced as shown by VPC and NMR
analysis, were 0.6 gram of l-propenyl acetate (13X yield based on 2-acetoxybutyraldehyde, 8% yield based on all aldehydes), 0.3 gram of allyl acetate (18% yield based on 4-acetoxybutyral-dehyde, 4% yield based on all aldehydes), and 0.8 gram of propyl acetate (10% yield based on all aldehydes).
me yield of methacrolein in Examples 5-8 increased as the total yield of aldehyde rever~ion products decreased.
EXAMP~E 9 A heavy wall 16 mm. I.D. x 70 cm. effective length glass tube was charged with 22 grams of 0.2% palladium on 6-14 mosh carbon and heated at 200-220. Then 25.0 grams of the aldehyde mixture described in Example S was evaporated and passed through the tube with a slow nitrogen carrier 3tream over 30 minutes. A pale yellow liquid (12.4 grams) was condensed and collected. As found by VPC and NMR analysis, it contained about 3 grams of l-propenyl acetate, about one gram of allyl acetate, and about O.S gram of propyl acetate. The other materials were `-acetic acid, methacrolein and the aldehyde starting materlals (about 20% unconverted).
The above examples have clearly demonstrated the best mode known to me of carrying the various aspect~ of my invention into effect. As will be readily understood by those skilled in the art, variations can be made in practicing my ..
iC)~8S33 invention a~ clearly taught in the balance o~ the ~pecification, by the cross-referenced Canadian applications and by the prior art on conversion of alkenes to unsaturated esters, hydroformula-tion, hydrogenation and de-e3terification without departing from the true intended scope of my invention.
My invention can be used as an independent proce3s for conversion of any one or a ~ixture of any of the isomeric acetoxybutyraldehydes to produce the olefinic unsaturated ester~
which are useful in and of themselves. In this respect, the dehydroformylation of 2-acetoxybutyraldehyde can be u~ed as an alternative process of producing l-propenyl acetate for the present process disclosed in the art. Allyl acetate has a wide variety of use~ as the literature on this compound will ~how.
It has already been discussed and shown above how my process can be used to provide an improvement in other known proce~ses, specifically th~ hydroformylation process and the process for making 1,4-butanediol from propylene and acetic acid. Where desired, advantage can be taken of the thermal instability of the 3-acetoxy-2-methylpropionaldehyde to eliminate it from a mixture with one or more of its isomers by heating the mixture and distilling the methacrolein and acetic acid as the one formed.
The acetic acid can be recycled to make allyl acetate from propylene. The remaining isomers can then be readily isolated and either hydrogenated to monoesters or dehydroformylated a~
described above. These and other modifications of this invention and its uses as will be readily di cerned by those skilled in the art, ba~ed on the teachings of the prior art and the specific teachings of this application, can be employed within the scope of the invention. The invention is intended to include all such modifications and variations as are embraced within the following claims.
Claims (12)
1. The process of producing allyl acetate, 1-propenyl acetate or mixtures thereof which comprises dehydro-formylating 4-acetoxybutyraldehyde, 2-acetoxybutyraldehyde, 3-acetoxy-2-methylpropionaldehyde or mixtures thereof at a temperature in the range of 120-250° C. in a nonoxidizing atmosphere and in the presence of an essentially neutral Group VIII noble metal catalyst,
2. The process of claim 1, wherein the catalyst is palladium, rhodium or mixtures thereof.
3. The process of claim 1, wherein the temperature is in the range of 140-220 C.
4. The process of claim 1, wherein a mixture of the three acetoxybutyraldehydes are dehydroformylated.
5. The process of claim 1, wherein the non-oxidizing atmosphere is a mixture of CO and H2.
6. The process of claim 1, wherein a mixture of the three acetoxybutyraldehydes are dehydroformylated at a temperature in the range of 120-250° C. in an atmosphere of CO and H2 in the presence of palladium, rhodium or mixtures thereof supported on an essentially neutral substrate.
7. In the process of hydroformylating allyl acetate or a mixture of allyl acetate and 1-propenyl acetate under hydroformylating conditions in the presence of a cobalt hydroformylating catalyst to produce a reaction mixture compris-ing 4-acetoxybutyraldehyde, as the predominant product, and its two isomers, 2-acetoxybutyraldehyde and 3-acetoxy-2-methylpropion-aldehyde, the improvement wherein at least some of the 4-acetoxybutyraldehyde is separated from said reaction mixture and wherein the residue from said separation is dehydroformylated to produce feedstock for the hydroformylation step, said dehydroformylation being carried out by the process defined in claim 1, 3 or 6.
8. In the process for producing 1,4-butanediol by oxidatively coupling propylene with acetic acid to produce allyl acetate which is hydroformylated under hydroformylating conditions in the presence of a cobalt hydroformylating catalyst to produce a mixture comprising 4-acetoxybutyraldehyde, as the predominant product, and its isomers, 2-acetoxybutyraldehyde and 3-acetoxy-2-methylpropionaldehyde and hydrogenating the mixture of aldehydes under hydrogenating conditions to produce a mixture comprising the acetate esters of 1,4-butanediol and its two isomers, 1,3-butanediol and 1,2-butanediol which are de-esterified under de-esterification conditions to their corresponding diols, the improvement wherein at least some of the 4-acetoxybutyraldehyde is separated from the mixture containing its two isomers to provide feedstock for the hydrogenation reaction and the mixture containing the isomers is dehydroformylated at a temperature in the range of 120°-250°C.
in a nonoxidizing atmosphere and in the presence of a catalyst selected from the group consisting of a Group VIII noble metal and mixtures thereof or a Group VIII noble metal and mixtures thereof on an essentially neutral support to produce feedstock for the hydroformylation reaction.
in a nonoxidizing atmosphere and in the presence of a catalyst selected from the group consisting of a Group VIII noble metal and mixtures thereof or a Group VIII noble metal and mixtures thereof on an essentially neutral support to produce feedstock for the hydroformylation reaction.
9. The process improvement of claim 8, wherein the mixture containing the isomers is dehydroformylated at temperature in the range of 120°-250°C. in an atmosphere of CO and H2 in the presence of palladium, rhodium or mixtures there-of supported on an essentially neutral support to produce feedstock for the hydroformylation reaction.
10. The process of claim 8, for the production of 1,4-butanediol which comprises:
a) oxidatively coupling propylene and acetic acid to allyl acetate with oxygen in the vapor phase over a solid catalyst comprising a Group VIII noble metal salt at a temper-ature sufficiently high to provide the desired rate of formation of allyl acetate but below the temperature at which substantial degradation of allyl acetate occurs;
(b) hydroformylating the allyl acetate of (a), the mixture from (c) or a mixture of the products of (a) and (c) under hydroformylating conditions to produce a mixture comprising 4-acetoxybutyraldehyde, as the predominant product, and its two isomers 2-acetoxybutyraldehyde and 3-acetoxy-2-methylpropionaldehyde;
(c) separating at least some of the 4-acetoxy-butyraldehyde from the mixture containing its two isomers and dehydroformylating the latter at a temperature in the range of 120°-250°C. in a nonoxidizing atmosphere in the presence of a catalyst selected from the group consisting of a Group VIII
noble metal and mixtures thereof or a Group VIII noble metal and mixtures thereof on an essentially neutral support to produce a mixture of allyl acetate and l-propenyl acetate as feedstock for (b);
(d) hydrogenating the separated 4-acetoxybutyralde-hyde from (c) under hydrogenating conditions to produce 4-acetoxy-1-butanol;
(e) de-esterifying the 4-acetoxy-1-butanol to 1,4-butanediol and acetic acid under de-esterification conditions;
and (f) isolating the 1,4-butanediol from the acetic acid.
a) oxidatively coupling propylene and acetic acid to allyl acetate with oxygen in the vapor phase over a solid catalyst comprising a Group VIII noble metal salt at a temper-ature sufficiently high to provide the desired rate of formation of allyl acetate but below the temperature at which substantial degradation of allyl acetate occurs;
(b) hydroformylating the allyl acetate of (a), the mixture from (c) or a mixture of the products of (a) and (c) under hydroformylating conditions to produce a mixture comprising 4-acetoxybutyraldehyde, as the predominant product, and its two isomers 2-acetoxybutyraldehyde and 3-acetoxy-2-methylpropionaldehyde;
(c) separating at least some of the 4-acetoxy-butyraldehyde from the mixture containing its two isomers and dehydroformylating the latter at a temperature in the range of 120°-250°C. in a nonoxidizing atmosphere in the presence of a catalyst selected from the group consisting of a Group VIII
noble metal and mixtures thereof or a Group VIII noble metal and mixtures thereof on an essentially neutral support to produce a mixture of allyl acetate and l-propenyl acetate as feedstock for (b);
(d) hydrogenating the separated 4-acetoxybutyralde-hyde from (c) under hydrogenating conditions to produce 4-acetoxy-1-butanol;
(e) de-esterifying the 4-acetoxy-1-butanol to 1,4-butanediol and acetic acid under de-esterification conditions;
and (f) isolating the 1,4-butanediol from the acetic acid.
11. The process of claim 9, for the production of 1,4-butanediol which comprises:
(a) oxidatively coupling propylene and acetic acid to allyl acetate with oxygen in the vapor phase over a solid catalyst comprising a Group VIII noble metal salt at a temperature sufficiently high to provide the desired rate of formation of allyl acetate but below the temperature at which substantial degradation of allyl acetate occurs;
(b) hydroformylating the allyl acetate of (a), the mixture from (c) or a mixture of the products of (a) and (c) under hydroformylating conditions to produce a mixture comprising 4-acetoxybutyraldehyde, as the predominant product, and its two isomers 2-acetoxybutyraldehyde and 3-acetoxy-2-methyl-propionaldehyde;
(c) separating at least some of the 4-acetoxybutyralde-hyde from the mixture containing its two isomers and dehydro-formylating the latter at a temperature in the range of 120°-250°C. in an atmosphere of CO and H2 in the presence of palladium, rhodium or mixtures thereof supported on an essentially neutral support to produce a mixture of allyl acetate and l-propenyl acetate as feedstock for (b);
(d) hydrogenating the separated 4-acetoxybutyralde-hyde from (c) under hydrogenating conditions to produce 4-acetoxy-1-butanol;
(e) de-esterifying the 4-acetoxy-1-butanol to 1,4-butanediol and acetic acid under de-esterification conditions;
and (f) isolating the 1,4-butanediol from the acetic acid.
(a) oxidatively coupling propylene and acetic acid to allyl acetate with oxygen in the vapor phase over a solid catalyst comprising a Group VIII noble metal salt at a temperature sufficiently high to provide the desired rate of formation of allyl acetate but below the temperature at which substantial degradation of allyl acetate occurs;
(b) hydroformylating the allyl acetate of (a), the mixture from (c) or a mixture of the products of (a) and (c) under hydroformylating conditions to produce a mixture comprising 4-acetoxybutyraldehyde, as the predominant product, and its two isomers 2-acetoxybutyraldehyde and 3-acetoxy-2-methyl-propionaldehyde;
(c) separating at least some of the 4-acetoxybutyralde-hyde from the mixture containing its two isomers and dehydro-formylating the latter at a temperature in the range of 120°-250°C. in an atmosphere of CO and H2 in the presence of palladium, rhodium or mixtures thereof supported on an essentially neutral support to produce a mixture of allyl acetate and l-propenyl acetate as feedstock for (b);
(d) hydrogenating the separated 4-acetoxybutyralde-hyde from (c) under hydrogenating conditions to produce 4-acetoxy-1-butanol;
(e) de-esterifying the 4-acetoxy-1-butanol to 1,4-butanediol and acetic acid under de-esterification conditions;
and (f) isolating the 1,4-butanediol from the acetic acid.
12. The process of claim 10 or 11 wherein the acetic acid step (f) is recycled to step (a).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA74209308A CA1048533A (en) | 1974-09-16 | 1974-09-16 | Dehydroformylation of acetoxybutyraldehydes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA74209308A CA1048533A (en) | 1974-09-16 | 1974-09-16 | Dehydroformylation of acetoxybutyraldehydes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1048533A true CA1048533A (en) | 1979-02-13 |
Family
ID=4101146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA74209308A Expired CA1048533A (en) | 1974-09-16 | 1974-09-16 | Dehydroformylation of acetoxybutyraldehydes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1048533A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0295548B1 (en) * | 1987-06-15 | 1992-03-18 | BASF Aktiengesellschaft | Method for the production of pentenoic acid esters from esters of formyl-valeric acid |
| US10183899B2 (en) | 2016-11-10 | 2019-01-22 | Chevron Phillips Chemical Company Lp | Normal alpha olefin synthesis using metathesis and dehydroformylation |
| US10723672B2 (en) | 2018-02-26 | 2020-07-28 | Chervon Phillips Chemical Company Lp | Normal alpha olefin synthesis using dehydroformylation or dehydroxymethylation |
| US11123723B2 (en) | 2018-02-26 | 2021-09-21 | The Regents Of The University Of California | Oxidative dehydroxymethylation of alcohols to produce olefins |
-
1974
- 1974-09-16 CA CA74209308A patent/CA1048533A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0295548B1 (en) * | 1987-06-15 | 1992-03-18 | BASF Aktiengesellschaft | Method for the production of pentenoic acid esters from esters of formyl-valeric acid |
| US10183899B2 (en) | 2016-11-10 | 2019-01-22 | Chevron Phillips Chemical Company Lp | Normal alpha olefin synthesis using metathesis and dehydroformylation |
| US10435334B2 (en) | 2016-11-10 | 2019-10-08 | Chevron Phillips Chemical Company Lp | Normal alpha olefin synthesis using metathesis and dehydroformylation |
| US10723672B2 (en) | 2018-02-26 | 2020-07-28 | Chervon Phillips Chemical Company Lp | Normal alpha olefin synthesis using dehydroformylation or dehydroxymethylation |
| US11123723B2 (en) | 2018-02-26 | 2021-09-21 | The Regents Of The University Of California | Oxidative dehydroxymethylation of alcohols to produce olefins |
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