TECHNICAL FIELD :

The present invention relates to a process for the production of aldehydes from alpha-olefins . More specifically, the invention relates to a process for producing aldehydes from alpha-olefins by use of rhodium-containing catalysts . BACKGROUND ART:

Various processes for the production of aldehydes

10 from alpha-olefins are known. For example, a process using cobalt catalyst has been used commercially to form aldehydes, i.e. , the socalled "cobalt oxo process". In this cobalt oxo process, .a cobalt catalyst is mixed with alpha-olefin, carbon monoxide, and hydrogen in a ligand ^x5 phase. Under high temperature and pressure, a hydroformyla- tion reaction occurs to form aldehydes containing one more carbon atom than the olefin. The cobalt catalyst is then separated from the reaction mixture by chemical reaction and the catalyst is subsequently regenerated prior to

20 recycle back to the original "reaction vessel for further treatment with fresh alphs-olefin, hydrogen and carbon monoxide. The aldehyde is then separated by distillation. . This aldehyde is converted subsequently to a dimer aldehyde, e.g., butyraldehyde from propylene is converted

²⁵ to 2-ethyl hexanal , by aldol condensation. In this process, only normal mono-aldehydes are useful for the aldol condensation step.

The cobalt oxo process is, however, subject to a number of disadvantages. The process requires high

30 temperatures and pressures. Moreover, a number of side reactions occur resulting in a relatively high

proportion of undesirable branched chain mono-alde¬ hydes, a high proportion of paraffin and unwanted alcohols. Furthermore, the cobalt catalyst tends to decompose during the process, and typically 10%-20% of the cobalt is lost with each pass of the catalyst through the reaction system.

One commercial multi-step process for the manufacture of higher alcohols is via hydroformylation of high purity, lower molecular weight olefins. In this process, olefin containing n -carbon atoms is converted to an aldehyde with n+1 carbon atoms, followed by external condensation t aldehydes containing 2 (n+1) carbon atoms. For example, (1) high purity propylene may be distilled from a steam cracked material, (2) this propylene is hydroformylated to butyraldehydes,

(3) n-butyraldehyde is then separated from the mixture of isomers and subsequently, (4) n-butylaldehyde is condensed to 2-ethyl hexenal, (5) 2-ethyl nexenal is then hydrogenated to the saturated aldehyde, and finally (6) 2-ethyl hexenal is reduced to the desired 2-ethyl hexanol (2-EH) containing eight carbon atoms. 2-EH is a major raw material ^" for the preparation of phtalic acid esters which are used as plasticizers and the like. Another commercial multi-step process for the manufacture of higher oxoalcohols is via hydroformy¬ lation of higher olefins. In this process, lower molecular weight olefins must be first polymerized. For example, catalytic or steam cracked propylene/butene-1 mixtures are polymerized to the desired extent, the higher molecular weight c--C _{1 T} olefins are then distilled to obtain feedstocks having the desired olefin in purified form and these feedstocks are subjected to hydroformylation individually to C -C. .

7 J.4- aldehydes. These aldehydes- are then hydrogenated to the

corresponding oxo alcohols. Only cobalt catalyst is used commercially for this route because higher olefins obtained via polymerization step are branched, which branched olefins cannot be easily and economi- cally hydroformylated using rhodium catalysts.

Cobalt and rhodium are both used commercially as catalysts in the hydroformylation step for the first multi-step process described above. However, the high cost of high purity feed for this process, in addition to the limited commercial availability of pure feed, has restricted its use in the manufacture of 2-ethyl hexanol starting with propylene feed. Although 3-methylpentanol may be manufactured from pure ethylene feed in a similar fashion, the high cost of ethylene has made this route economically unattractive.

In general , the multi-step rhodium based oxo process has had severe problems when using liquid phase reaction conditions with a homogeneous rhodium catalytic complex because of the difficulties encountered in separating aldehyde product from the liquid phase reaction media. In part, these problems arise because the normal aldehydes of interest, e.g. , C -C, aldehydes, require elevated temperatures for sufficient volatili¬ zation so that they can be removed from the liquid reaction media by distillation, stripping or the like. In these same temperature ranges, the rhodium based oxo processes of the prior art suffer from destabliza- tion, decomposition, deactivation or loss of selectivity. Attempts to separate catalyst solution and recycle it to the reactor have met with difficulties in conducting the vacuum distillation necessary for such separation because of the deactivation or decomposition of the catalysts during such a step.

- _- -

Moreover, these multi-step rhodium based oxo processes rely on low conversion to prevent degrada¬ tion of the rhodium catalyst. Comparisons illustrated in German Patent 2,802,923 (1978) showed that catalyst tested at reaction temperatures and in the absence of olefin for 25 hours lost 27-42% of its activity. Netherlands Patent 7704989 reported that its rhodium oxo process for butyraldehyde operates in the 22-37% conversion range, while the German patent reported that their rhodium process operates at about 30% conver¬ sion level, it is clear that the conventional rhodium processes operate commercially at economically unattrac¬ tive low conversion levels of 20-40% in order to maintain catalytic activity. A limited product slate of C aldehydes and 2-ethyl hexanol coupled with the high cost of pure feed and recycling because of low conversion per pass are the major disadvantages of these multi-step rhodium oxo processes.

Many methods and catalyst systems using rhodium based catalysis have been described which produce aldehydes from alpha-olefins. Many of these methods and systems are summarized in Advances in Organometallic Chemistry, "Hydroformylation", Vol. 17, pp. 1-60 (1979) by R. G. Pruett. As one example, Pruett et al . in U.S. Patent No. 3,527,809 disclose a process in which an alpha-olefin is contacted with carbon monoxide and hydrogen in the presence of a rhodium-containing complex catalyst and tertiary organo- containing ligands. The temperature range, total gas pressure and partial pressures exerted by the hydrogen and carbon monoxide are also said to be factors in the reaction process.

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A similar process is disclosed in Slaugh et al. U.S. Patent No. 3,239,566, in which olefinic compounds are converted to saturated aldehydes and/or alcohols having one more carbon atom than the olefinic compounds by reacting the olefinic compounds in liquid phase with carbon monixide and hydrogen in the presence of a catalyst comprising ruthenium and/or rhodium in complex combination with carbon monoxide and a phosphorous- containing ligand, e.g. , a tertiary organo phosphorous compound such as-trialkyl phosphine.

British Patent No. 1,387,657 discloses a process for hydroformylation of an olefin containing up to five carbon atoms in which the olefin is catalyti- cally reacted with hydrogen and carbon monoxide in a primary reaction zone so that an aldehyde or aldehyde and alcohol is produced and some olefin remains unconverted. The aldehyde or aldehyde and alcohol produced is withdrawn from the reaction mixture as vapor along with other gases, including unconverted olefin. The gases thus withdrawn are separated. Part of the separated gases, including some unconverted olefin, are then recycled to the primary reaction zone, the other part of the unconverted olefin is hydroformy- lated in a secondary reaction zone and further aldehyde dor aldehyde and alcohol product is separated from the secondary reaction zone without further recycling of the remaining separated gases. Other variations of such processes are described in British Patent No. 1,228,201 and Wilkinson U.S. Patent No. 4,108,905. Similarly, U.S. Patent No. 3,511,880 discloses a process in which an olefin is converted to n+1 aldehydes by hydroformylation in the presence of carbon monoxide and hydrogen in a liquid phase reaction medium containing a Group VIII noble metal, a biphyllic ligand and, for example, an alkali metal hydroxide.

Hughes et al . U.S. Patent No. 3,821,311 teaches a single-stage process in which an alpha-olefin is reacted with hydrogen, carbon monoxide and a liquid solution phase comprising (a) a hydroxylic organic solvent, (b) a rhodium complex, (c) a triaryl phos- phine, triaryl arsine or triaryl stibine and (d) an aldol condensation catalyst, such as KOH. The desired product is said to be a saturated aldehyde containing

2n+2 carbon atoms. As illustrated in the figure for this patent, in the Hughes et al. process, the reaction is run in a hydroformylation/aldol reactor. The reaction mixture is then charged into a vacuum distillation column for separation of the product from the lower boiling components and from the residue containing the catalyst, ligand, and the higher boiling components, the residue is recycled back to the reaction vessel for further reaction with new or recycled alpha-olefin, H and CO. this process is subject to a number of important disadvantages. For example, because the Rh-catalyst leaves the reaction vessel losses of catalyst occur. Moreover, the distillation requires high vacuum and low temperatures in order to avoid catalyst decomposition. Thus, loss of vacuum will cause a temperature rise and decomposition of catalyst. Also, this process requires the removal of the high boiling by-products, e.g. , the trimer aldehyde, prior to recycling of the solution containing the catalyst and ligand back to the hydroformylation reactor. Furthermore, it is well established that the rhodium-containing catalyst used by the patentee deactivates in the absence of olefin, see Netherlands Patent No. 78-00856. Since during the vacuum distil¬ lation step of this process the catalyst is separated from olefin, deactivation of the catalyst is expected

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to occur. Still further, recycling of the solution containing the catalyst and ligand will most likely require heating in order to avoid precipitation of these elements and clogging of the recycle system. U.S Patent No. 3,278,612 to Greene discloses a p ^rocess for the production of Cn+.1, and C2„n+.2_ alcohols from C olefins in the presence of certain complex transition metal-phosphorouscontaining catalytically active materials, including certain cobalt, rhodium and ruthenium complexes, in systems containing certain organic Lewis bases, i.e. , electron-sharing doners, such as amines.

None of the above prior art processes provides a one-step reaction for the production of the aldehydes containing 2n+2 carbon atoms from the alpha-ole ins containing n carbon atoms in which one can readily recover the product as a vapor. Such a one-step reaction process is highly desirable since the higher molecular weight materials are, in many cases, the ultimate product which is sought from the hydroformylation process. With most of the prior art processes, the aldehyde containing n+1 carbon atoms are first separated from the reaction mixture and subse¬ quently an aldol condensation with the n+1 aldehyde is conducted for form the aldehyde containing 2n+2 carbon atoms. If desired, hydrogenation to the alcohol can then also be carried out.

Most of these prior techniques employ a tripenyl phosphine based rhodium-containing complex catalyst, and they are therefore also subject to a number of other disadvantages. Under the more extreme reaction conditions set forth in the prior art patents, the triphenyl phosphine based rhodium catalysts are subject to some degree of decomposition, expecially

at higher temperatures, e.g. , about 125-135°C. Since rhodium is extremely expensive, even a small amount of decomposition is very undesirable. Also, even at lower temperatures, the rhodium catalysts are subject to deactivation because of the presence of acid.

While rhodium based catalyst systems have generally provided more efficient production of aldehyde than cobalt, e.g. , the reaction rate with Rh-based catalyst can be about 1000 times as fast as with a Co-based catalyst, rhodium is much more expensive than cobalt and is likely to increase in cost as more and more processes switch from cobalt to rhodium. Moreover, any deactivation or decomposition of the Rh-catalyst is extremely disadvantageous. Thus, methods which produce the desired aldehyde product in one step while "decreasing rhodium decomposition or deactivation are extremely desirable both from an efficiency and from an economic point of view.

DISCLOSURE OF INVENTION:

It has now been found that higher aldehydes can be produced in a one-stage reaction in which at least one alphaolefin containing n carbon atoms, wherein n is an integer of 2 or greater, is reacted in the liquid phase with a mixture of carbon monoxide and hydrogen in the presence of complex rhodium-containing catalyst, free ligand and Lewis base to thereby form aldehyde containing 2n+2 carbon atoms, wherein the reaction is conducted at a temperature and pressure sufficient to remove at least part of the product from the reaction mixture by vaporization or stripping, i.e. , by product flash-off. It has also been found that n+1 aldehydes having an improved normal to iso isomer ration and that improved stabilization of a rhodium

based catalyst are provided by a process in which at least one alpha-olefin containing n carbon atoms, wherein n is an integer of 2 or more, is reacted in the liquid phase with a mixture of carbon monoxide and hydrogen in the presence of complex rhodium-containing catalyst not containing halogen, free ligand and Lewis base to thereby form the aldehyde containing n+1 carbon atoms, wherein the reaction is conducted at a temper¬ ature and pressure sufficient to remove at least part of the product from the reaction mixture by vaporiza¬ tion or stripping. In these processes, up to about 60% of the olefin is converted to aldehyde product in one pass through the reactor system.

These processes have a number of distinct advantages over the prior art. For example, the first of these processes provides a one-stage reaction of the production of aldehydes containing 2n+2 carbon atoms by a product flash-off technique. With both processes, the rhodium catalyst does not have to leave the reactor vessel and, accordingly, there is less chance of lost of the rhodium catalyst or of poisoning of the catalyst because the rhodium is "protected" by a continuous olefin partial pressure. Moreover, the presence of the Lewis base has been found to stabilize the rhodium catalyst, resulting in less chance of a catalyst deactivation caused by acid and water present in the reaction mixture. Furthermore, the presence of base has been found to result in an increase in the normal to iso isomer ratio of the product of the processes of the invention. Still further, the processes of this invention allow for the presence of olefin at all times. Therefore, even the tripenyl phosphine based rhodium catalysts will be suitable for use in the present processes. Still further, when the reac- tion is run about 140°C, aldehydes containing 8 or more

carbon atoms not previously obtainable by product flash-off techniques can now be produced from such vaporization or stripping processes.

The alpha-olefins suitable for use in the present invention include those containing from 2 to 12 carbon atoms, e.g. , ethene, propene, butene-1, pentene-1, hexene-1 and octene- 1. Mixtures of such olefins can also be used. In a preferred embodiment, the alpha-olefin can be a mixture of propene and butine-1; a mixture of ethene and propene; and/or a mixture of propene and pentene-1.

It has further been found in accordance with this invention that the presence of acid in the hydroformylation reaction mixture causes deactivation of the rhodium-containing catalyst. For example, the CO partial pressure has a detrimental effect on the rhodium-containing catalyst activity. During the hydroformylation reaction, the water from the conden¬ sation of the aldehydes to the trimer glycol ester by-product can react with CO to produce formic acid.

Also, hydrolysis of the trimer-glycol ester by-product can yield acidic compounds. We have found that by including base in the reaction mixture, such deacti¬ vation is lessened or avoided. Suitable bases for includsion in the reaction mixture of the present invention include Lewis bases, e.g. , inorganic bases such as KOH and organic bases such as triethanol amine. Of course, if the aldol condensation reaction is desired to produce the aldehydes containing 2n+2 carbon atoms from the olefin starting materials via the aldol condensation reaction, the base should be an effective basic aldol condensation catalyst. Suitable such aldol cndensa- tion catalysts include the alkali metal and alkaline earth metal oxides and hydroxides such as KOH, NaOH and

Sr(OH) and stronger organic bases such as tetrabutyl phosphonium acetate, which if used can also act as the solvent for the reaction mixture.

The concentration of the base in the reaction mixture can vary greatly and should be in an amount effective to stabilize the rhodium-containing catalyst or if desired, in an amount effective to catalyze the aldol condensation t the aldehyde dimer product. If only stabilization of the catalyst is desired, of course, a lower concentration of the base is desira¬ ble. If the dimer aldehyde is the product desired, a higher concentration of base is normally chosen.

With the process of the invention for preparing monomer aldehydes containing n+1 carbon atoms, any rhodium-containing catalyst not containing halogen which is stable at the desired reaction temperature and conditions can be used. For example, using the product flash-off technique to prepare butyraldehyde from propylene in the presence of base, a temperature of only about 90°.C. at appropriate pressure is required and therefore any rhodium-containing catalyst not containing halogen known in the art to be stable at this temperature will be appropriate. Such non-halogen containing rhodium catalysts provide higher n/i isomer ratios than those catalysts which contain halogen, which n/i ratios are even further improved in the presence of the Lewis base.

Similarly, with the process of the present invention for producing dimer aldehydes containing 2n+2 carbon atoms, any rhodium-containing catalyst thermally stable at the desired reaction temperature will be suitable. Of course, rhodium-containing catalysts not containing halogen are also preferred in the process of the invention.

Of course, the rhodium-containing catalysts in the processes of the present invention should also have a sufficient reaction rate with the olefin at the desired temperature to make the reaction process economically feasable. Preferably, the rhodium-contain¬ ing catalyst should also be one that will produce a high normal to iso isomer ratio for the product of the process, e.g. , a normal to iso molar ratio of at least about 5/1 and preferably from about 5/1 to about 90/1.

If it is desired to operate at higher temperatures , a rhodium-containing catalyst which is thermally stable at the desired reaction temperatures must be used. For example, if the product desired from the product flash-off technique is 2-ethyl-hexanal , the reaction temperature should be about 130°C. at an appropriate pressure, and accordingly, the rhodium- containing catalyst should be stable at this tempera¬ ture. Preferably rhodium-containing catalysts for operating the process of the invention in the tempera¬ ture range of from about 100°C. to 125°C. include, for example, RhHC0(PPh ) and RhHCO(AsPh ) in which Ph represents a phenyl group. The preferred catalysts are, however, those which exhibit high thermal stability. These thermally stable catalysts include

[Rh(C0),(PPh„ -)A] ⁺ BPh *-,¥-, and the hydrocarbylsilyl alkyl diaryl phosphine complexes disclosed in ^' copending U.S. patent application serial no. 11,230, filed on February

12, 1979, the disclosure of which is incorporated herein by reference. A catalyst prepared using Ph P

(CH 2_)nP ⁺ Ph2(CH2P)BPh4 ^~ w,herein n i.s an i.nt.eger of_ t.wo or more, as the ligand is also suitable higher temperature reactions. The concentration of rhodium- containing catalyst in the reaction mixture can vary greatly,- e.g. , from about 10 ppm to about 10,000 ppm. preferably from about 20 ppm to about 5,000 ppm.

The product flash-off processes of the present invention can employ any organic solvent in which the base is sufficiently soluble to allow the desired reaction t occur. Suitable solvents include tributyl phosphate, pentadiol , tetrabutyl phosphonium acetate, trimer glycol ester (i.e. , the timer by¬ product of the aldol condensation reation) and diethylene glycol.

The reaction mixture employed in the processes of the present invention also preferably contains free ligand. This ligand is not necessarily the same ligand that is attached to the complex rhodium-containing catalyst. Thus, suitable ligands include any ligands that are capable of complexing with rhodium to form a rhodium-containing catalyst which is stable at the temperature at which the reaction will be run. Suitable such ligands for the higher temperature product flash- off process of the present invention include [Rh(CO) ,(PPh, ό) A] ⁺ BPh4 ^~ Ph __P(CH )T).P ⁺ Ph A(CH AP)Bph - ^" an.d Ph A,-P(CH A_) D.SiR _^ wherein

Ph represents a phenyl group; n is an integer of 2 or more, preferably, from 2 to 6; and R is an alkyl group. For conducting the product flash-off process of the present invention at temperatures lower than 125°C , other well-known ligands which will complex with the rhodium may be used, e.g. , triphenyl phosphine and tripenyl arsine. The concentration of the ligand in the reaction mixture can vary depending upon the concentration of the catalyst to form a desirable range of ligand to catalyst molar ratios. The ligand to rhodium molar ratio can vary from about 2/1 to about 2000/1 and preferably from about 2/1 to about 1000/1.

Carbon monoxide and hydrogen can be fed into the reaction vessel at various pressures depending upon the product that is desired from the reaction. The molar ratio of hydrogen to carbon monoxide is a factor which helps determine the product produced by the product flash-off technique of the present invention. Thus, the molar ratio of H to CO in the process of the present invention can vary from about .5/1 to about 50/1 and preferably from about 2/1 to about 15/1. 0 Of course, more hydrogen will be required for a simple hydroformylation than for a hydroformylation-aldol condensation process since excess hydrogen is necessary to react with the enal form which is produced by the latter process. This is illustrated by the following

15 reaction formulas:

Hydroformylation: RCH=CH ₂ +H ₂ +C0 ^Rh - ^cata l ^st RCH ₂ CH ₂ CH0

Combined hydroformylation and aldolization:

CH R RCH=CH ₂ =H ₂ +Co ^Rh - ^cata ly ^{st "i} RCH ₂ CH ₂ CH=C-CH0(enal)

CH ₂ R

RCH=CH2_+1.5 H2„C0 —-|-RCH2,,CH2CH2CH-CH0.

~ ~ The temperature range used in the processes of the present invention varies depending upon the reactants used, the termal stability of the rhodium- containing catalyst, and the product desired from the reaction. Of course, with the product flash-off

25 technique, the temperature should be sufficient to remove at least part of the product from the reaction mixture by vaporization or stripping at a desired process pressure condition. Typical temperature

ranges for the process of the present invention are from about 90 to 200°C, preferably 100 to 200°, such as from about 120 to about 180°C. As an exmaple , using the product flash-off technique of the present invention to produce 2-propyl-heptanal as the desired product, a temperature of about 140°C. and pressure about 150 psi can be used.

As with the temperature, the pressure ranges for the processes of the present invention can vary depending upon the reactants ^" used and the products which are desired therefrom. Generally, using the product flash-off technique of the invention, a lower pressure is desired, e.g. , a pressure of from about 50 psi to about 700 psi and preferably from about 50 psi to about 400 psi. Of course, the combined temper¬ ature and pressure conditions for the product flash-off technique should be such that the desired aldehyde product will be stripped or vaporized by the feed gases at a rate corresponding to the product's formation. In summary, the product flash-off processes of the present invention can be controlled to produce either the aldehydes containing n+1 carbon atoms or the aldehydes containing 2n+2 carbon atoms by employing a proper concentration of rhodium and/or basic aldol catalyst. For example, lower rhodium catalyst concentra¬ tions with a relatively higher base concentration produce predominantly aldehydes containing 2n+2 carbon atoms, while higher rhodium catalyst concentrations with a relatively low base concentration produce predominantly aldehyde containing n+1 carbon atoms. Of course, any factors that affect the ratio of the hydroformylation reaction or aldol condensation reaction will also have an effect on the product that is formed. For example, the rhodium catalyzed hydro- formylation rates are increased with higher hydrogen

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pressures and decreased with higher CO partial pressures and higher ligand concentrations. On the other hand, the rate of aldol condensation is affected by the solvent used. Therefore, any changes in this factors will have an effect on the product produced.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic representation of an apparatus for performing a "product flash-off" process in accordance with the present invention.

° BEST MODE OF CARRYING OUT THE INVENTION:

Referring to Figure 1, a product flash-off technique in accordance with the present invention is illustrated. In this process, reactor 1 contains a liquid reaction medium 2 which includes base, an 5 appropriate rhodium-containing catalyst and free ligand. The reaction medium 2 is maintained at a temperature sufficient to vaporize or strip any of the desired product that is formed at the reaction pressure. CO and H are introduced through line 3 and alpha-olefin through line 4 into the reactor 1. The CO, H and alpha- olefin are dispersed in the reaction medium by use of a sparger 5. The reaction medium 2 is also stirred vigorously with stirrer 6. As the alpha-olefin disperses through the reaction medium, it is converted into the desired product, and along with unreacted CO, H and olefin, the product is directed through line 7 to a condensor 8. In the condenser 8, the condensable product is condensed before entering gas-liquid separator 9. The non-condensable gases, such as unreacted CO, H,

2 and alpha-olefin, are withdrawn from the top of the separator 9 and recycled back via line 10 and compressor

11 for reintroduction into -the reactor 1. A small portion of non-condensable gases is purged through a valve

12.

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If a solvent is used which is immiscible with the desired aldehyde, the condensable product, including the desired aldehyde, is continuously discharged from the base of the separator 9 and passes to a secondary liquid-liquid separator 14 via line 13. The solvent, upon settling, is separated by phase separation and discharged from the separator by line 15. The solvent containing the major portion of the water produced by the reaction is dried in a bed 17 via pump 16 to remove its water. The solvent is combined with make-up solvent introduced by line 18, which solvent is recovered from the aldehyde product. The aldehyde product is collected from the liquid-liquid separator 14 via line 19. If a solvent is used which is miscible with the desired aldehyde, the condensable product is trans¬ ferred via line 13 to a distillation column (not shown) where separation of aldehyde and solvent is conducted. The solvent recovered from the distillation is recycled back to reactor 1 and steps 14-17 are eliminated. The following examples are presented for the purpose of illustrating,- but not limiting, the process of the present invention.

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Example 1

0.097 grams of HRh[Ph PC H Si(CH ) ] 3.95 grams of Ph PC H Si(CH ) , lg of KOH, and 68 cc diethylene glycol are charged to the 300 cc autoclave. The reactor is sealed, and the air in the autoclave is flushed out with nitrogen, while the contents of the autoclave are stirred with a turbine sparger at 1500 revolutions per-minute and heated to a temperature of 120°C. Synthesis gas with-a molar ratio of 1.5 H /CO is introduced into the reactor via the olefin charge line, forcing the olefin charge (20.3 grams of butene-1) into the reactor. The synthesis gas is diverted from the charging cylinder when 700 psig pressure is attained in the autoclave. Preblended synthesis gas at 1/1 H /CO ratio from a storage reservoir is then admitted directly into the reactor.

The reaction mixture is analyzed by gas chromatography. The molar ratio of normal to iso product, the percent dimer conversion, and the mole percents of n-pentanal (n-C aide) , 2-propyl- heptanal (n-C anal), 2-propyl-heptenal (n-C enal) , iso- pentanal (i-C aide), and 2-propyl-methyl-hexenal

(x-C ) were calculated from the data obtained, The results are set forth below in Table I.

TABLE I Selectivity, Mole Percent

Molar Ratio n-C ₅ ^n"C 10 ⁿ - ^c ιo Dimer

-- ^C 5 ^X"C 10 n/i aide anal enal aide aide Conv.

46 . 0 13 . 8 20 . 8 55 . 7 9 . 3 0 . 2 76 . 7%

^■ RIX

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Example 2

The procedure of Example 1 is repeated using RhHC0(PPh ) as a catalyst, a reaction temperature of 100°C. , and an olefin feed of about 20 g. The solvent (60-70 cc. ) , reaction time, and olefin charge are varied as indicated in columns 2-4 of Table II below. The results are analyzed as in Example 1 and are set forth in columns 5-7_ of Table II.

These results demonstrate that satisfactory conversion to dimer aldehydes along with high se¬ lectivity toward the normal products can be obtained by the process of the present invention in a variety of solvents.

^TjREA T

Reaction Olefin Monomer aldehydes Dimer Aldehydes

Run Solvent Time Change Dimer n+1 2n+2

Tributyl*

35 minutes butene-1 67.8(C ) 32.1(C ₁₀ ) 32.1 phosphate

b 1 ,3-pentadiol 35 minutes hexene-1/ 22.6(C ) 21.9(C ₁₀ ) 53.6 bu ene-1** 23.7(C _? ) 21.0(C ₁₂ ) 10.7(C ₁ )

e c 1-3-pentadiol 45 minutes butene-1 11 .6 (C ) 88.4( C ₁₍₎ ) 88.4 l d Tnmer-g °lycol ester 3 „ 5 _c minutes , butene-1 52 ■ κc ₅ ) 47.9(C ₁₀ ) 47.9

e diethylene 60 minutes propylene 17.9(C ₄ ) 82.1(C ₈ ) 82.1 glycol

* r /CO feed at a molar ratio of 1/1 with an olefin charge of 38 grams. -""Molar ratio of C ~/C, ^~ of 0.82, total amount heχene-1 added 29 grams. σ. vo o O

O

Ft

Example 5

A 300 cc capacity autoclave is charged with 20.3 grams of butene-1, 73.2 grams of diethylene glycol (DEG) , 1 gram of KOH, 3.95 grams of diphenyl phosphino ethyl trimethyl silane and 0.097 grams of tris-(di¬ phenyl phosphino ethyl trimethyl silane) rhodium carbonyl hydride. The air in the autoclave is flushed out with nitrogen, while the contents of the autoclave are stirred with a turbine sparger at 1500 rpm. The reactor is then heated to about 140°C. Without agitation, the autoclave is pressurized with a 4/1-H /CO molar ratio synthesis gas (CO and H ) to about 500 psig. The agitation is resumed and simultan¬ eously a preblended synthesis gas having a H /CO molar ratio of 1.5/1.0 is admitted to the reactor. The run is concluded after 8 minutes starting from the time when synthesis gas valve is opened to allow gas flow to reactor. The progress of the oxonation is monitored on the basis of the amount of CO and H consumed. After 8 minutes, the H /CO feed valve is shut off and the autoclave is immediately cooled with dry ice to about 0°C. Prior to depressing the_ autoclave, a large gas sample is taken. The autoclave is then vented and the reactor content containing two organic layers is removed from the autoclave and transferred to a glass separator. The lower layer containing almost 99.7% of DEG solvent used is separated from the upper layer. Analyses of vapor and liquid product samples are carried out using gas chromatography. The results of these analyses are summarized below in Table III. The data demonstrate that butene-1 is efficiently converted to 2-propyl heptanal/2-propyl heptenal in high reactivity and selectivity. The - selectivity to the branched chain aldehyde product

(isopentanal and 4-methyl-2-propyl hexanal) is only about 2 percent. The normal (n-pentanal or n-pentenal based derivatives) to iso (branched-chain aldehydes ratio is 44 to 1. Also, the catalyst showed no signs of any decomposition.

P

<N

O

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CO

_* r> Zable__III

H &££££_££ _£ f__E_x m£l£_3_

U ( .

Aldehyde X £££_£l __L____Σ_ ∑ grams grams grams mo 1 7 ₀ butane 0.1114 0.177 0.250 butene-1 0.4003 0.831 2.025 t-2-butene 0.1547 0.307 0.196 c-2-butene 0.2355 0.432 0.213 i-pentanal 0.0741 0.273 2.1 to _ n-pentana 1 .0.2307 2.106 14.1 iso-C aldehyde* 0.0092 0.1 2-propyl heptanal 1.2549 0.760 13.4 2-propyl heptenal 5.8563 2.550 70.3

C m trimer 0 0

DEG 0.2196 72.98 ligand 1_1_1 _° __ 11

Sum 12.25 80.67 2.684 100

©

Example 4

The same procedure outlined in Example 3 is repeated except that propylene is used in place of butene-1. Charges to the autoclave are: propylene 22 grams, diethylene glycol 116.8 grams, KOH 1 gram, diphenyl phosphino ethyl trimethyl silane 5.846 grams and tris-(diphenyl phosphino ethyl trimethyl silane) rhodium carbonyl hydride 0.144 grams. The calculated rhodium concentration in solution is 102 ppm. The reaction temperature and pressure are respectively

130°C. and 700 psi. The results are summarized in Table IV.

i £i l_Pha_s_ Aldehyde

M££££_i;- Z££ __._L— .iiiΣ_ Va_££ _Pha_ £ §._ __._i£.__.__._i_-.__.Σ grams grams grams mol % propane 0.0120 0.0539 0.4719 propylene 0.0318 0.2014 1.7135 iso butyra 1dehyde 0.0179 0.5185 2.5 n-butyra 1dehyde 0.0401 1.4930 7.1 l 4-methyl 2-ethyl 0.0854 0.3179 2.1 u", pentanal l 4-methyl 2-ethyl ^• 0.1970 1.0933 6.8 pentanal

2-ethyl hexanal 1.7839 6.7908 44.7

2-ethyl hexanal 1.2655 4.9703 33.0

C. _ trimer 0.2149 0.6149 3.8

DEG 2.220 114.580

Silane Ligand 5.390 0.456

Sum 1Ϊ725 ^~ 8 ^~ Ϊ3l70 ^~ 9 2.185 100

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Example 5

The same procedure outlined in Example 3 is again repeated except that a mixed feed of propylene and butene-1 is used rather than just butene-1. Charges to the autoclave are: propylene 8.7 grams, butene-1

11.3 grams, diethylene glycol 73.2 grams, KOH 1 gram, diphenyl phosphino ethyl trimethyl silane 4.188 grams and tris- (diphenyl phosphino ethyl trimethyl silane) 0.096 grams. The rhodium concentration in solution is 101 ppm. The reaction time is 13 minutes. The reaction temperature and pressure are respectively 140°C. and 700 psi. The results are summarized in Table V.

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© CO CO

P Table V H

R £££ _C£n£ _£f_Tx £_l _j

Liquid Phase Aldehyde

^U £E'er Lay_er Lower La _j er Va£or Phase Selecti i y grams grams grams mole % propane 0.0077 0.0351 0. .3131 propylene 0.0489 0.2314 1 .5282 butane 0.1164 0.0847 0, .0872 bu ene-1 0.2240 0.2459 0 .3029 1

^ butene-2 0.0509 0.0516 0 .0185 c-but ene-2 O.0800 0.0780 0 .0185 i-butana 1 0.0113 0.1945 1.7 n-butana 1 0.0107 0.4521 3.8 i-pentanal 0.0207 0.1678 1.3 n-pentana 1 1.0647 0.7172 5.3

4-methyl-2- — — _ ethyl-pentanal ~~ 1 4-methy1-2 0.0560 0.1185 1.6 e hyl-pentenal O

4-methy1-2- 0.0193 0.1 propy1-pentanal

2-propyl-hexanal 0.2502 0.1596 3.5 and 2-ethy1-heptana 1

2-propyl-hexanal 1.9582 1.7680 31.0 and 2-ethy1- heptanal

4-methyl-2 propyl 1.0167 0.1 hexanal ,

_I 2-propy1-heptana 1 0.6639 0.2137 6.6 e 2-propy 1-heptana 1 1.7968 1.0549 21.6

I

DEG 0.805 72.395

Silane Ligand 1_111 _0 193

Sum 11.471 79.277 2.268 100

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Example 6

Following the same procedure used in Example

3, the autoclave is charged with 20.2 grams of butene-1 , 74.1 grams of diethylene glycol, 1 gram of KOH, 3.14 grams of phosphinophosphonium ligand having the chemical formula of:

[Ph ₂ P(CH ) ₂ P ⁺ Ph ₂ (CH ₂ Ph) ]BPh ^"

and 0.103 grams of RhH(CO) (AsPh ) , with Ph indicating a phenyl group. The rhodium concentration in solution is 102 ppm and ligand to rhodium molar ratio is 40 to 1. The run is carried out at 120°C. and 700 psig until 100% conversion, based on carbon monoxide consumption, is reached (35 minutes). The data (solvent and ligand free basis) are summarized in Table VI below.

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R£a££££_C_£n n£ _£f_]Ex m£l£_£ -_. . £ .--. £_ -S!._JLi£ ^_l.£ _^ i

Liquid Phase Aldehyde ^u E£ ^er L ^{a er} Lower Layer Va£or Phase Selectivity grams grams grams mo1 % butane 0.704 0.327 0.2673 butene-1 0.102 0.069 0.2076 t-2-but ene 0.189 0.120 0.0393 c-2-butene 0.257 0.167 0.0393 iso-pentanal 0.259 0.589 3.3 o t n-pentana 1 ,0.289 1.713 7.7

4-methyl 2-propyl 1 0.057 0.054 0.5 hexanal

2-propyl heptanal 1 4.469 2.205 28.3

2-propyl heptenal 1 9.557 4.435 6_0__L2.

Sum 15.88 9.68 0.553 100

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Example 7

An autoclave is charged with 110 cc. of diethylene glycol, 0.095 g. of [Rh(CO) *,D(PPh _* „5) A_ ] ⁺ BPh4 ^~ ,

1 gram KOH, and 3.9 grams of triphenyl phosphine. The reactor is sealed, purged three times with nitrogen, and heated to 120°C. Twenty grams of butene-1 are charged to reactor without stopping agitation by the pressure of synthesis gas blended to give a 4/1 ratio of H /CO. The synthesis gas is diverted from the charging cylinder when 700 psig pressure is attained in the reactor. Synthesis gas is then admitted directly into the reactor. A temperature of 120°C. and 700 psig of synthesis gas is maintained substantially throughout the reaction period of 35 minutes. The reaction mixture is analyzed for n-pentanal, iso-pentanal , 2-propyl heptanal, 2-propyl heptenal, 2-propyl-methyl-hexenal, % conversion and % dimer conversion and the results are summarized in Table VII below..

Table VII

Selectivity , Mole p ^' ercent

n-C O- iso-C O_ n-C, L O.. n-C, i U _ x-C, 1 U „ Dimer

Conv.% aide aide anal enal aide Conv.%

35.5 0 1.4 44.4 47.3 7.0 98.6

-^^-^ -^

Example 8

A 2 liter stainless steel reactor equipped with agitator, sparge inlet and appropriate outlet arrangments for continuous hydroformylation operation is charged with the following materials:

Table VIII Contents charged Per 1 Liter of Liquid Reactant Volume

amount

2-propyl heptanal 380 g diethylene glycol 461 g

C, l b _ trimer 59 g

Potassium hydroxide 1.23 g diphenyl phosphino ethyl trimethyl silane 33.8 g rhodium, as metal*- 14.7 ppm ligand/rhomium molar ratio 976

*The rhodium used is tris-(diphenyl phosphino ethyl trimethyl silane) rhodium carbonyl hydride.

The reactor is pressurized to about 250 psig and heated to about 140°C.

A mixture of butene-1 (150 cc/hour) , hydrogen

(38.1 cubic feet/hour) and carbon monoxide (9.6 cubic feet/hour) is fed continuously via the sparge inlet to the liquid reaction medium maintained at the above temperature and pressure. Reactor effluent gases containin unreacted feeds, product aldehydes and solvent leave the top of the reactor and pass through a condenser where product and solvent are condensed to 10-15°C. before entering to a gas-liquid separator.

Condensable product is continuously discharged at a rate 8 to 10 g/hour from the base of the separator and is collected in a receiver. A thirty (30) hour cut of the continuous run is taken and analyzed using gas chromatographic techniques. The results from the analysis are set forth below in Table IX.

-Table IX Component Area Percent

V ^s 2.3

Isopentanal 1.5 n-pentanal 2.3

4-methyl-3-propyl-hexanal 0.2

2-propyl-heptanal 40.3

4-methyl-2-propyl-hexanal 0.2

2-propyl-heptenal 36.4

DEG 2.1

Glycol Ester 2.9

Ligand and high boiling Prod. 1.7 n/i 53.6

% conversion to dimer aldehyde 95%

_OM?I

Example 9

In the same run, as set forth in Example 8, but at a slightly lower pressure, the rhodium concentra tion is increased from 14.7 ppm to 100 ppm (ligand/rhodium ratio of 143). The conversion rate of olefin to liquid oxo product is 6 to 7 times faster. Gas chromatography of the liquid sample showed 21.6% monoaldehydes and 62.2% dimer aldehydes, with a selectivity toward dimer aldehydes of 83.8%. ^'

The results in Examples 8 and 9 demonstrate that the process of the present invention provides a one stage reaction by which aldehydes containing 2n + 2 carbon atoms can be prepared from the alpha-olefins containing n carbon atoms. Also, the example demonstrates that the catalyst was thermally stable.

Example 10

A stainless steel reactor equipped with an agitator, sparge inlet and appropriate outlet arrangements for continuous hydroformylation operation is charged with the components listed in Table X below:

Table X Contents Charged per 100 Liter of Liquid Reactant Volume

kg

2-propyl heptanal 38.52 diethylene glycol 39.53

C-. _ trimer 0.66 potassium hydroxide 2.16 diphenyl phosphino ethyl trimethyl silane 3.64 rhodium, as metal* 240ppm *τhe rhodium used is tris-(diphenyl phosphino ethyl trimethyl silane) rhodium carbonyl hydride.

QM IF

The reactor is pressurized to about 300 psig and heated to about 140°C.

A mixture of gaseous butene-1 , hydrogen and carbon monoxide together with recycle gases is fed continuously via the sparge inlet to the liquid reaction medium maintained at the above temperature and pressure. Reactor effluent gases are withdrawn therefrom, and include unreacted feeds, product aldehydes and solvent. These gases leave the top of-the reactor and pass through a condenser, where product and solvent are condensed before entering a gas-liquid separator. Non-condensable gases are withdrawn from the top of the separator and recycled to the reactor via a compressor. A small portion of these gases is purged through a valve. The condensable product withdrawn from the separator is continuously discharged from the base of the separator and passed to a secondary liquid-liquid separator, where the solvent DEG, upon settling, is separated by phase separation (DEG is the bottom layer). The aldol product is collected. The discharge DEG removed from separator, containing major portion of product water, is dried in a bed via a pump to remove the water therein. This dried DEG is then combined with make-up DEG recovered from aldehyde product, prior to returning to the reactor. Rates and weight compositions of feed, product and recycled streams are detailed below in Table XI.

As shown in Table IX, for 85 kg of liquid reactant charged, the production rates of C, _ aldehydes (a mixture of 2-propyl heptenal and 2-propyl heptanal) and C aldehydes are, respectively, about 70 and 3.2 kg per hour. Overall conversion to aldehydes from butene-1 is about 95%, with almost no iso-aldehyde formed.

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Table XI

Feed and Product Rates and Compositions

Per 85 kg of Liquid Reactant I (Table 5) Charged

Analysis of Steam Olefin(l) Syn Gaj 3(2) Reactor(3) Non-Condensabl( _ Purge Recycle Condensable DEG

Composition Wt. ° Feed Feed Effluent Gases(4) Gas(5) Gas(6) Liquid(7) Feed(8)

10.8 19.87 20.84 20.8 20.8 0.028

^H 2

CO 89.1 69.56 72.94 72.9 72.9 0.097

Butene-1 100 5.77 5.96 5.96 5.96 1.88

C Aldehyde 0.24 0.093 0.09 0.09 3.27

C. Aldehydes 3.27 - - - . 70.40

Trimer 0.038 - - '- 0.83

H„0 0.531 0.16 0.16 0.16 8.12

DEG 100

Rate Kg/hour 44.8 26.6 1744 1663 2.9 1660 81.0 12.5

Example 11

As shown by the following example, the presence of acidic compounds during the hydroformylation reactions causes deactivation of the complex rhodium-containing catalyst. In some cases, water from the condensation reaction of aldehydes reacts with CO to give formic acid. In other cases, hydrolysis of the rimer aldehyde by-product of the condensation reactions can yield acidic compounds. While these acidic conditions should be avoided, in the event of deactivation conditions, the complex rhodium catalyst can be regenerated by the addition of base.

A continuous hydroformylation reaction using butene-1 was run in a 2 liter autoclave, with 20% trimer aldehyde, n-pentanal, RhHC0(PPh ) catalyst (about 170 ppm) and triphenyl phosphine ligand in a molar ratio to the catalyst of 210/1. The reaction was conducted at a temperature of about 97.5°C. and a pressure of about 114 psia. The H /CO ratio varied from 8/1 to 10/1. A series of. such runs were made. The acid value (i.e. , the amount of KOH needed to neutralize any acid present) -of the reaction mixture in each case was measured initially and after a certain reaction time as indicated in columns 1-4 of Table XII below. Analyses of the samples taken from the reactors were found to contain formic acid and valeric acid. The above results deomonstrate that acid deactivates the catalyst, but that activity can be regenerated by treatment with base.

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Table XII

Reaction

Duration Acid Value mg KOH/g Rh

Run Hours Charge Reactor Sample Activity a 80 4.1 5.3 Active b 154 5.3 8.7 Non-active c 66 4.1 7.9 Non-active d 154 1.4* 3.4 Active

* e 294 1.2* 0.9 Active f 650 1.4* 0.3 Active

*fresh distilled pentanal used.

The catalyst from run c above was recovered and used in a series of batch hydroformylation reactions in a 300 cc reactor at a pressure of about 300 psi and a temperature of about 100°C. The H /CO was pressur¬ ized into the react at a molar ratio of 4/1 and during the run was fed at a molar ratio of 1/1. In certain instances, the system is treated with KOH prior to conducting the hydroformylation reaction. The acid value before and after the run, the reaction rate and the normal to iso product molar ration was measured. The results are set forth below in Table XIII.

Table XIII

Acid Number mg KOH/gm

Rate*

Run No. Treate :d Before After Min -1 n/i g No 8.45 12.13 0 0 h Yes 1.23 0.60 0.16 5. .5 i No 8.45 10.41 0 0 j Yes 0.67 - 0.60 0.12 0. ,8 k (Fresh) — — 0.10 8. ,9

1 (Fre :sh) 0.12

^based on H /CO consumption

O

The activity of the catalyst at the end of the reaction time is indicated in Column 5 of the Table.

Example 12

COMPARATIVE ACCELERATED EXPOSURE TEST A series of side by side tests were run to demonstrate the temperature instability of RhH(CO) (PPh ) at higher temperatures to show that the presence of base increases the normal to'iso isomer ratio of the product produced by the process of the invention. The test procedure is basically the same as that described for Examples 1-33 of Netherlands Patent No. 78-00856, which corresponds to U.S. Application No. 762,336 filed January 27, 1977 of Bryant et al .

A first 250 ml stainless steel vessel is charged with 0.089g of RhH(CO) ) (PPH ) in which Ph repre¬ sents a phenyl group, 3.57g of triphenyl phosphine, 75.Og (67ml) of diethylene glycol, and 1.Og of KOH. A second such vessel is charged with the same materials, except the KOH is omitted. Both vessels are heated to the same selected temperature as indicated in column 3 of Table XIV below by use of an oil bath. A mixture of H and CO in a molar ratio of 1/1 is introduced into each vessel to a total pressure of 85 psig. A slight CO/H gas flow is maintained in each vessel , i.e. , about 1 bubble/sec. A series of such comparative exposures are conducted at the various selected tempera¬ tures indicated in column 3 of Table XIV below. The time for each exposure test is indicated in column 2 of Table XIV.

ACTIVITY TEST

After the exposure indicated in columns 2 and 3, the contents of each vessel are cooled to ambient temperature and transferred to a 300 cc autoclave, and a hydroformylation or a combined hydroformylation/aldol

OMPI

condensation reaction is conducted. The temperature of the autoclave is increased to 120°C. Butene-1 and H /CO mixture in a molar ratio of 1.5/1 and a total pressure of 600 psig are added to the autoclave. The rhodium concentration is 100 ppm and the ligand to rhodium molar ratio is about 140/1 in each instance. The reaction rates (activity) relative to a non-exposed system (i.e. , exposure A in Table XIV) is determined and the results are set forth in columns 4 and 5 of Table XIV. In some instances, the n/i ratio of the product of each process is also determined.

Table XIV

Exposure Activity

1 2 3 4 5

Time(hrs) Temp(C° ) w/KOH w/out KOH

A 0 1.0 1.0

B 24 100 . .75 .34

C 24 110 - .74 .38

D 24 120 .671 .36

E 24 130 .302 .104

F 4 115 NA .70

G 24 115 NA .20

The results demonstrate a substantial improve¬ ment in the activity of the catalyst due to the presence of the base. For example, at 130°C. a 300% improvement in activity was obtained with the base present, while at 100°C. a 220% improvement is observed with the base. Also, in each case where the n/i ratio was measured, it was higher for the sample containing base. For example,

with exposure C, the n/i ratio was 6.2 for the sample containing the base while it was only 5.1 for the sample not containing base, indicating that the presence of the base increases the n/i ratio of the product.

It will be understood that the embodiments described above are merely exemplary and that persons skilled in the art may make many variations and modifica¬ tions without departing from the spirit and scope of the invention. All such modifications and variations are intended to be included within the scope of the invention as defined by the appended claims.

INDUSTRIAL APPLICABILITY

The process of the present invention can be used to produce dimeraldhydes which are particularly suited for use as intermediates in the production of plasticizers.

OMPI_