MXPA01007188A - Production of aqueous solutions of mixtures of formyltetrahydrofuran and hydrates thereof - Google Patents

Abstract

Disclosed is a process for the recovery of formyltetrahydrofurans (FTHF's) produced by the rhodium-catalyzed hydroformylation of 2,5-dihydrofuran (2-5-DHF) wherein the FTHFs are recovered as an equilibrium mixture of 2 - and 3-FTHF and their hydrates, 2- and 3-[di(hydroxy)methyl]tetrahydrofuran from a hydroformylation product solution comprising a rhodium catalyst, 2- and 3-FTHF and an organic hydroformylation solvent obtained as a liquid product take-off from a hydroformylation process wherein 3-FTHF is produced by the hydroformylation of 2, 5-DHF. 3-FTHF is a valuable organic intermediate useful, for example, in the preparation of 3-methyltetrahydrofuran and 3-amino-methyltetrahydrofuran.

Description

PRODUCTION OF AQUEOUS SOLUTIONS OF FORMILTETRAHYDROFURAN MIXTURES AND HYDRATES OF THE SAME DESCRIPTION OF THE INVENTION This invention pertains to a process for the recovery of formyltetrahydrofurans (FTHF) produced by rhodium-catalyzed hydroformylation of 2,5-dihydrofuran. (2,5-DHF). More specifically, this invention pertains to the production of an equilibrium mixture of 2- and 3-FTHF and its hydrates 2- and 3- [di (hydroxy) ethyl] tetrahydrofuran (DHMTHF) of a solution comprising a rhodium catalyst, a promoter of phosphine, 2- and 3-FTHF and a hydroformylation solvent obtained as a liquid product separated from a hydroformylation process wherein 3-FTHF is produced by the hydroformylation of 2,5-DHF. 3-FTHF is a valuable organic intermediary useful in the preparation of a variety of pharmaceutical and agricultural products. More specifically, 3-FTHF provides access to unusual 3-substituted tetrahydrofuran derivatives such as 3-hydroxymethyltetrahydrofuran, 3-methylaminotetrahydrofuran, and 3-methyltetrahydrofuran. The hydroformylation reaction is well known in the art as a catalytic method for the conversion of an olefin into an aldehyde product having one more carbon than the initial mono-olefin by the addition of one molecule of hydrogen and carbon monoxide to the double bond carbon-carbon. More commercial hydroformylation facilities employ catalyst systems comprising rhodium and organophosphine compounds such as mono and tertiary (trisubstituted) bisphosphines. For example, U.S. Patent 3,527,809 discloses the hydroformylation of olefins employing a catalyst system comprising rhodium compounds and organ phosphors such as triphenylphosphine (TPP) and reactor pressures below 500 psig. Hydroformylation processes employing catalyst systems comprising rhodium in combination with other organophosphine compounds and operated at low to moderate reactor pressures are described in US Patent 3,239,566 (tri-n-butylphosphine) and US Patent 4,873,213 (tribenzilfosfina). The most extensive use of hydroformylation processes is in the hydroformylation of ethylene and propylene to produce propionaldehyde and isomeric butyraldehydes. These aldehydes of low boiling point can be recovered by means of a gas stripping reactor where the unreacted gases are used to entrain the aldehyde product as a vapor of the high boiling reaction mixture with had in the reactor . Said steam removal process is described in US Pat. No. 4,287,369. This method works well for aldehyde products of relatively low boiling point due to their relatively high vapor pressure at the temperature at which the hydroformylation process is operated. The method becomes progressively more impractical as the boiling point of the aldehyde products increases which requires a substantial increase in the volume of stripping gas flow to eliminate an equivalent amount of product. Another traditional product separation technique involves the distillation of the aldehyde product from a high-boiling residue or "bead" containing the catalyst system. For example, US Pat. No. 4,137,240 describes the hydroformylation of cyclic acrolein acetals using a catalyst system comprising rhodium and triphenyl phosphite. The high-boiling products of the described process were separated from the catalyst bead by vacuum distillation at high temperature, resulting in the formation of metallic rhodium which is especially undesirable since the extremely valuable metallic rhodium can be laminated onto the surface of the equipment. process and get lost from the hydroformylation process. U.S. Patent 4,533,757 describes a variation of vapor stripping described above in relation to the recovery of a high boiling aldehyde., nonanal, of a hydroformylation mixture containing rhodium and triphenylphosphine. According to this patent, a liquid reactor affluent comprising a nonanal solution, catalyst components and a high boiling point solvent is fed to a low pressure relaxation tank. In this tank, the stripping gas from the reactor is sprayed through the catalyst solution to vaporize the aldehyde product and stripping it at the lowest pressure. The lower pressure requires less stripping gas than would be required if one tried at the higher pressure inside the hydroformylation reactor. This method requires the use of significant amounts of energy in the form of recompression of the low pressure stripping gas to recirculate in the reactor. The following patents relate to the use of distillation processes in the isolation of high-boiling aldehydes produced by the hydroformylation of olefins containing a functional group: US Patent 2, 894, 038-hydroformylation of 4-formylcyclohexene using a catalyst rhodium / cobalt; US Patent 3,966,827 hydroformylation of 4-hydroxy-2-methylbutene-1; U.S. Patent 4,275,243 - recovery of 4-hydroxybutyraldehyde. It is evident from the numerous and varied types of aldehydes mentioned that there is a need for a product separation method that does not employ the high temperatures that are required to isolate the high boiling aldehydes by conventional distillation techniques. A number of different techniques for separating the hydroformylation catalysts from the aldehydes has been described in the literature. US Patents 4,144,191 and 4,262,147 describe the use of specific mixture of rhodium / cobalt carbonyl cluster catalysts bonded to amino groups on a polymeric support. This catalyst was specifically designed for the sequential hydroformylation steps "one pot" and reduction using dicyclopentadiene for conversion into tricyclic dimethanol product. U.S. Patent 4,533,757 discloses that this system loses rhodium from the resin support to the oxo product. Another proposal that has been described in the literature is the use of phosphorus organ compounds, soluble in water, functionalized in combination with rhodium. US Patent 3,857,895 discloses the use of aminoalkyl and aminoaryl compounds organophosphine in combination with rhodium. The catalyst solution containing the aldehyde product is extracted with aqueous acid to recover the rhodium and organophosphine catalyst components of an organic solution containing aldehyde. Since the acid must be neutralized to recover the catalyst in a way that the reactor can be readmitted, the process presents salt disposal problems. There are many patents pertaining to the hydroformylation of allyl alcohol wherein an aqueous extraction has been employed to separate the 4-hydroxybutyraldehyde product from the solution containing the catalyst. This special case reflects the substantial solubility in water of both the allyl alcohol feed and the 4-hydroxybutyraldehyde product. Thus, as described in US Pat. No. 4,215,077, it is important that very high conversions of allyl alcohol, preferably above 95 percent, are achieved in the hydroformylation reactor. Another aspect of this specific technology (manufacture of 4-hydroxybutyraldehyde) is the problem of separating the rhodium catalyst from the aqueous extract of 4-hydroxybutyraldehyde. In practice, the aqueous extract is limited to about 10 percent of 4-hydroxybutyraldehyde to suppress the loss of rhodium to the aqueous phase as noted in US Pat. No. 4,567,305 wherein the catalyst system consists of rhodium and triphenylphosphine. U.S. Patent 4,678,857 discloses that 5 mg of rhodium per liter of aqueous phase was extracted into the aqueous phase when the concentration of 4-hydroxybutyraldehyde was 38 percent by weight. A problem inherent in the described extraction process is the separation of the rhodium-containing organic phase from the aqueous extract containing 4-hydroxybutyraldehyde. US Pat. No. 4,678,857 proposes that this problem can be overcome by the use of halogenated aromatics to increase the density differences between the organic layer and the aqueous layer. The brominated aromatic compounds are, in general, undesirable from the point of view of toxicity and as potential catalyst poisons. The use of the aqueous extract of 4-hydroxybutyraldehyde as feedstocks for the catalytic hydrogenation for 1,4-butanediol is disclosed in US Pat. Nos. 4,083,882 and 4,064,145. Once again, the relatively low concentration of 4-hydroxybutyraldehyde in the aqueous solution used in the hydrogenation requires a large amount of energy to remove water from the diluted 1,4-butanediol product. U.S. Patent 5,138,101 discloses the separation of high boiling aldehydes from hydroformylation solutions comprising a high boiling aldehyde, catalyst components comprising rhodium and an organophosphine compound, and a hydroformylation solvent by intimately contacting (extracting) the mixture with a solution comprising a primary alkanol such as methanol and water. The extraction mixture comprising the hydroformylation and alkanol / water solutions is allowed to separate into two phases: a hydroformylation solvent phase containing the catalyst components and an alkanol / water phase containing the aldehyde. The hydroformylation solvent phase can be returned to the hydroformylation reactor and the alkanol / water phase containing aldehyde can be further processed, to recover the aldehyde or to convert the aldehyde to other compounds. An alkanol, particularly methanol, is an essential characteristic of the process described in U.S. 5,138,101. U.S. Patent 4,376,208 describes the hydroformylation of 2,5-hydrophuran which employs a catalyst system comprising a rhodium-triarylphosphine complex in the presence of a tertiary amino cocatalyst. A. Polo, et al., Organometallics, 1_1 3525 (1992), also describes the hydroformylation of dihydrofurans and teaches that the most effective catalysts are rhodium catalysts promoted with trialkylphosphites. In each of these cases, the catalyst system caused the performance of 3-FTHF to be critically dependent on the reaction conditions. One reason for this is that an integral component of the catalyst system was a basic amino, which, in addition to the hydroformylation, promoted the condensation of alcohol of the formyl reaction product. Therefore, even under conditions in which the initial yields of 3-FTHF may be high, the isolated yields are not.

FTHFs, especially 3-? Somero, are valuable intermediates useful in the manufacture of commercial compounds. FTHF can be produced by contacting 2.5-DHF with synthesis gas comprising carbon monoxide and hydrogen in the presence of a rhodium-phosphorus catalyst system and a hydroformylation solvent in accordance with known hydroformylation procedures. Said hydroformylation of 2,5-DHF typically produces 2-FTHF and 3-FTHF in molar ratios of about 0.001: 1 to 3.5: 1. The recovery of the 3-FTHF product presents technical difficulties such as the formation of hemiacetal oligomers, acetal oligomers, and aldol condensation compounds of the hydroformylation products. The formation of these by-products is catalyzed by basic materials such as the phosphine components and the phosphite of the hydroformylation catalyst, or even spontaneously, especially during distillation at high temperatures. Recycling the catalyst system after removing the products by distillation or gas spraying is clogged with the problem of removing these high boiling byproducts without damaging the catalyst. Normally, high-boiling byproducts continue to accumulate until the catalyst becomes blocked and loses activity. At that point, the only alternative is to discard the inactivated catalyst and start with a fresh catalyst charge. The formation and accumulation of high-boiling byproducts, aided by base-catalyzed condensations, makes distillation an impractical method for recovering 3-FTHF from hydroformylation product solutions. The normal formation of high boiling byproducts during the hydroformylation reaction typically amounts to not less than 2 percent of the total product as a result of the low reaction temperature. The high boiling points and the dielectric constants of the FTHF render impractical a recovery by gas spraying at the reaction pressure of 2 megaPascal. Vacuum distillation at a base kettle temperature of up to 130 ° C recovers only 40 to 70 percent of the FTHF. The oligomeric by-products, formed at the distillation temperatures of the base kettle, account for the rest of the material balance. The main part of these oligomers are hemiacetals which, upon heating, they release the free monomer by means of a heat promoted desoligomerization. For example, by heating the base kettle temperature to 185 ° C, the total recovery of FTHF will increase to as much as 80 to 96 percent of the total production. However, many rhodium / phosphine catalyst systems are sensitive to high reaction temperatures as described in US Patent A, 211, 621 and other literature. Beyond 130 ° C, the hydroformylation catalyst begins to decompose with the phosphine suffering a loss of rhodium promoter from side groups and the rhodium metal itself eventually being laminated. It has been found that an equilibrium mixture of the FTHFs and the hydrates thereof, ie, DHMTHF, can be separated from hydroformylation solutions comprising the FTHFs, catalyst components comprising rhodium and a phosphorus organ compound, and a solvent of hydroformylation by intimately contacting (extracting) the mixture with water that is essentially devoid of an alkanol. The extraction mixture comprising the hydroformylation solutions and water is allowed to separate into 2 phases: a hydroformylation solvent phase containing the catalyst components and an aqueous phase containing the 2- and 3-FTHF and the 2- and 3-DHMTHF . The hydroformylation solvent phase can be returned to the hydroformylation reactor without further treatment and the aqueous phase containing the FTHF and its hydrates can be further processed to recover the aldehydes or convert the aldehydes to other compounds. Any FTHF that is not removed during a cycle returns to the hydroformylation reactor together with the hydroformylation solvent and can be recovered in a subsequent extraction. Most of the little oligomeric material that is produced during hydroformylation is also extracted into the aqueous phase, thereby purifying the catalyst solution and extending the number of hydroformylation cycles before a catalyst replacement is necessary. For example, during pilot studies the high-boiling oligomeric content remaining in the recycled catalyst solution after 19 extractions, recoveries, and recirculations to the hydroformylation reactor remained below 0.5 percent. Comparing the methods of recovery by distillation and extraction, the best thing that distillation can do is an 80 to 96 percent recovery of FTHF compared to 99+ percent recovery through extraction. The number of catalyst recirculations before replenishment is necessary is typically from one to 12 with recovery by distillation while at least 60 or more cycles are possible through the use of the extraction process described herein. The decline in catalyst activity before catalyst replacement is several percent per recirculation depending on the severity of distillation versus non-loss conditions through extraction. The only losses during the extraction of the product or the catalyst are physical losses caused by the incomplete separation of the phases and by the discarded slipstreams. The process of the present invention therefore provides a means to produce an aqueous solution, essentially devoid of alacanol containing a mixture of compounds having the formulas: OH (i) (H) which comprises (1) intimately contacting a solution of a hydroformylation product comprising (i) 20 to 80 weight percent of an aldehyde of the formula (I); (ii) hydroformylation catalyst components comprising rhodium and an organophosphorus compound, and (iii) 80 to 20 weight percent of an organic hydroformylation solvent, with water essentially devoid of alkanol; (2) allow mixing of step (1) to separate into a two-phase mixture; and (3) separating the two-phase mixture to obtain (a) a hydroformylation solvent phase containing catalyst components and (b) an aqueous phase containing the compounds of formulas (I) and (II); wherein the ratio by volume of water to solution of hydroformylation product employed in step (1) is 0.1: 1 to 4: 1; the hydroformylation product solution employed in step (1) contains less than 15 weight percent of 2,5-DHF, 2,3-DHF, tetrahydrofuran (THF), or a mixture of any two or more of the same; and the molar ratio of the compound (I) to the compound (II) is from 0.05: 1 to 20: 1. The concentration of compound (II) present depends on the concentration of the aldehyde in the aqueous solution. For example, when the concentration of aldehyde (I) and diol (II) is 90%, the diol constitutes approximately 65% of the total of compounds (I) and (II) and when the concentration of aldehyde (I) and diol ( II) is 50%, the diol constitutes approximately 80% of the total of the compounds between (I) and (II), and when the concentration of aldehyde (I) and diol (II) is 10%, the diol constitutes approximately 98% of the total of the compounds (I) and (II). In fact, the high percentage of compound (II) except for the too low aqueous concentrations emphasizes how strongly FTHFs adhere to water. Not surprisingly, when water is scarce, the aldehyde (I) reacts with the diol (II) to form the hemiacetal of the aldehyde (I). However, the hemiacetal concentration is typically less than 2%, usually not more than 0.5%, of the total FTHF present when the concentration of aldehyde (I) and diol (II) is approximately 60%. The process can be operated in a manner by which essentially none of the components of the catalyst system, for example, a catalytically active rhodium-phosphorus complex compound and additional phosphine or phosphite or excess, is extracted by the aqueous solution. Thus, the operation of the recovery process does not result in any significant loss of catalyst from the hydroformylation production system since the hydroformylation solvent phase containing the catalyst components can be recycled to the hydroformylation reactor. The aqueous phase can be used as the feed for other processes wherein the compounds of formulas (I) and (II) are converted to other compounds such as alkanols by hydrogenation. Alternatively, the aldehyde can be isolated by removing the water by distillation under reduced pressure although the recovery of the dry purified aldehyde (I) is not very efficient for the reasons discussed below. The formation of the diols (II) under abundant aqueous conditions and of hemiacetals under low aqueous conditions is based on a strong tendency of the aldehydes (I) to react with hydroxyl-containing materials in general. But the product of the reaction between the aldehydes (I) and a hydroxyl-containing material is itself a hydroxyl-containing material, albeit with a higher molecular weight. So that a very low water content, ever increasing molecular weight hemiacetal oligomers are formed by incorporating ever increasing percentages of the free aldehydes (I) into the growing oligomer. The consequences of this ever increasing molecular weight of the hemiacetal oligomers are many. First, the temperature in the distillation kettle rises. At these higher temperatures, the formation of the hemiacetal oligomers eventually reverses the release of the free aldehydes (I) and eventually also the water. But the rising temperature also allows impurities to catalyze the irreversible conversion of the hemiacetal oligomers, the free aldehydes (I) and the diols (II) into other materials such as acetal oligomers by the release of water, condensation products of aldol, and esters of Tischenko. To the extent that these irreversible byproducts are formed, the recovery of pure free aldehydes (I) is decreased. The degree of this loss depends on the degree of impurities in the original product, but can vary from 2 percent to as much as 70 percent under typical impurity level conditions. Since the formation of the hemiacetal oligomers is reversible by releasing free aldehydes (I) and water a second consequence of the tendency to form higher molecular weight oligomers is that the distilled product never becomes scrupulously dry. Most of the water released by this desoligomerization evaporates instantaneously through the distillate within the vacuum traps due to a difference of 50 ° C or more in the boiling points between the water and the free aldehydes (I). However, water levels below 200 PPM are difficult to achieve due to the strong tenacity of aldehydes (I) to maintain water. Another related consequence is the problem of separating 2-FHTF from 3-FTHF despite its difference from 25 ° C at boiling points to 25 mm Hg pressure. This separation is easy until the desoligomenzation of the hemiacetal begins to release 2-FTHF, the lowest boiling isomer. While forming, the hemiacetal oligomers incorporate free aldehydes of 2-FTHF and 3-FTHF (I) randomly. Therefore, while they are thermally decomposed, they also liberate free aldehydes of 2-FTHF and 3-FTHF (I) randomly. Thus, the distillate of 3-FTHF, previously released from the lower boiling 2-FTHF by the fractionation process, becomes contaminated again with 2-FTHF. This separation is possible by maintaining the distillation temperature of the base kettle below 110 ° C. Up to this temperature, the desoligomerization of the hemiacetal oligomer is not significant so that the release of the 2-FTHF contaminant is also not significant. However, at this point 30 to 70 percent of the total free aldehydes (I) and diols (II) remain bound in the oligomeric materials. The only alternative to recover 2-FTHF and 3-FTHF for subsequent separation at this point is to collect the combined free aldehydes (I) released by the desoligomerization for subsequent refraction. It is found that the free aldehydes (I) harvested from the desoligomerization at base distillation kettle temperatures of 110 ° C to 185 ° C are suitable for this reprocessing. An additional small amount of material can be collected from base distillation kettle temperatures from 185 ° C to 230 ° C; however, its color becomes increasingly darker yellow and its content of free aldehyde (I) and diol (II) becomes increasingly lower as the temperature of the base kettle rises. The material remaining in the base kettle after this secondary recovery of 2-FTHF and 3-FTHF represents 2 percent to 30 percent of the amount of free aldehydes (I) and diols (II) originally fed. The final consequence of the increasing molecular weight of the oligomers is that avoiding water does not prevent their formation. The affinity of the free aldehydes (I) for hydroxyl-containing materials is caused by a deficiency in electrons that any electron-pair donor can satisfy. In the absence of other electron pair donors, the electron pairs of the carbonyl group of free aldehyde (I) are sufficient to irreversibly lead to apolyacetals. Thus, the distillation of anhydrous free aldehydes (I) does not prevent the formation of oligomers. On the contrary, it increases the loss of free aldehydes (I) by increasing the formation of irreversible oligomers in contrast to hydroxyl-containing materials, which form larger amounts of reversible oligomers. Said in alternative terms, the removal of water by fractional distillation under reduced pressure occurs easily until the water content falls below 10 percent by weight. At this point the distillation mixture in the kettle consists mainly of the free aldehyde [FTHF, compound (I)] and the geminal glycol [DHMTHF, compound (II)]. Any free water that exists is mainly water that is released from the compound (II) by the change of equilibrium to make water and the compound (I). However, as the amount of compounds (I) increases, it competes with the compound (II) for the hydroxyl groups with the changing balance, which releases water. When the compound (I) reacts with the compound (II), it forms the compound (III) with n equal to 2, a hemiacetal, which is also an oligomer of two FTHF units.

When in the hemiacetal form with n equal to 2 or greater than 2, the compound (III) will not release water. Even when in equilibrium with the other components in the system, it must first be decomposed step by step into units of nl of the compound (I) and one unit of the compound (II) before the compound (II) can, in turn, decompose into one more unit of compound (I) and water. Since the compound (III) is itself a diol, it could also add more existing free compound (I) to form another compound (III) with n incremented by 1. In fact, this is exactly what happens, when the concentration of free hydrophilic compounds (I) rises sufficiently high with an insufficient amount of OH groups of water to react. The effect is twofold: first, the FTHF effectively adheres to the water more tenaciously as the elimination of water progresses, and second, the average molecular weight of the hemiacetals increases at the same time.

All compounds (III) that exist in the distillation base kettle eventually contain a somewhat large amount of the free aldehyde originally fed. The incorporation of formyltetrahydrofurans within compound (III) is random consisting of 2-formyltetrahydrofuran and 3-formyltetrahydrofuran in proportion to what originally existed in the bulk solution. The decomposition of the compounds (III), however, is not random with the larger hemiacetal oligomers tending to require higher temperatures to decompose again in the monomeric compound (I) and water. This is the main problem for separating the last traces of water and the free FTHF isomers. With a difference of 23 ° C at the boiling points (boiling point of 2-FTHF, 39-42 ° C / 14 mm, and boiling point 3-FTHF, 62-64 ° C / 14 mm), the two isomers should be easily separated with a distillation column of only a few theoretical plates. However, when almost all 2-FTHF has been removed from the lower boiling point and the 3-FTHF free from the higher boiling point begins to distill, the base kettle temperature is also raised. This rise in temperature causes them to progressively de-oligomerize more of the compounds (III) randomly. With the water and the 2-FTHF recently released in the distillation kettle at temperatures substantially above its boiling points, they evaporate instantaneously into the product contaminating it and making the quantitative separation of the isomers and dehydration very difficult. As mentioned above, the hydroformylation product solution employed in the present invention further comprises at least one of the aldehydes described above, a catalyst system comprising rhodium and an organophosphine compound, and a hydroformylation solvent. The rhodium component of the catalyst system can be provided by any of the various rhodium compounds soluble in the organic reaction medium in which the hydroformylation is carried out. Examples of such soluble rhodium compounds include tris (triphenylphosphine) rhodium chloride, tris (triphenylphosphine) rhodium bromide, tris (triphenylphosphine) rhodium iodide, tris (triphenylphosphine) rhodium fluoride, rhodium 2-ethylhexanoate dimer, rhodium acetate, rhodium propionate dimer, rhodium butyrate dimer, rhodium valerate dimers, rhodium carbonate, rhodium octanoate dimer, dodecacarbonyl tetrahydrate, rhodium 2,4-pentanedionate (III), rhodium (I) dicarbonyl acetonylacetonate, tris (triphenylphosphine) rhodium carbonyl hydride [(Ph3P:) 3Rh (CO) -H], and cationic rhodium complexes such as (cyclooctadiene) bis (tribenzylphosphine) tetrafluoroborate rhodium and rhodium (norbornadiene) bis (triphenylphosphine) hexafluorophosphate. The activity and selectivity of the catalyst system is usually relatively insensitive to the rhodium source. The concentration of rhodium [Rh] in the catalyst solution may be in the range of 0.1 to 100, 000 ppm although very low rhodium concentrations are not desirable since the reaction rates are unacceptably low. The upper limit in the concentration of rhodium is not critical and is dictated mainly by the high cost of rhodium. Thus, the concentration of rhodium [Rh] in the catalyst solution is preferably in the range of 10 to 10,000 and, more preferably, 100 to 5,000 ppm. Examples of the organophosphine or phosphite component of the catalyst system are described in the patents referred to herein, including the references cited therein. Additional organophosphines are described in U.S. Patents 4,742,178; 4,755,624; 4,774,362; 4,871,878; 4,873,213 and 4,960,949. The compounds of phosphite and tertiary phosphine (trisubstituted) can be used as the phosphorus organ compounds of the catalyst system. Examples of said phosphines and phosphites include tributylphosphine, tributylphosphite, butyldiphenylphosphine, butyldiphenylphosphite, dibutylphenylphosphite, tribenzylphosphine, tribenzylphosphite, tricyclohexylphosphine, tricyclohexylphosphite, 1,2-bis (diphenylphosphino) -ethane, 1,3-bis (diphenylphosphino) propane, 1,4- butanbis (dibenzylphosphite), 2, 2'-bis (diphenylphosphinomethyl) -1, 1 'biphenyl, and 1,2-bis (diphenylphosphinomethyl) benzene. Typical phosphine and phosphite ligands can be reprocessed by general formulas I P-R2 P- -R4- I and R3 R3 (IV) (V) R R1 R1 I I I 0 o o 1 P-O-R2 and 'P-O-R -O P i i I I o o o R' _3 «R3 R i 3 (VI) (VII) where R1, R2 and R3 are the same or different and each is hydrocarbyl containing up to 12 carbon atoms and R is a divalent hydrocarbylene group linking the two phosphorus atoms through a chain of 2 to 8 carbon atoms.

Examples of the hydrocarbyl groups that R1, R2 and R3 may represent include alkyl including substituted alkylaryl such as benzyl, cycloalkyl such as cyclohexyl and cyclopentyl, and aryl such as phenyl and phenyl substituted with one or more alkyl groups. Alkylene such as ethylene, trimethylene, and hexamethylene, cycloalkylene such as cyclohexylene and phenylene, naphthylene and bifemlene are examples of the hydrocarbylene groups that R4 can represent. The phosphorus organ component of the catalyst system is preferably a t-substituted monophosphine compound such as those having the formula (I) above. Tpfenilfosfina, triciclohexilfosfma, and, tribenzilfosfina are the most preferred organophosphorus compounds. The ratio of moles of organophosphorus compound to gram atoms of rhodium present in the catalyst system is typically 2: 1 to 10,000: 1 with ratios in the range of 2.5: 1 to 1000: 1 being preferred and 3: 1 to 100 being more preferred. :1. The solvent component of the droformilation product solution can be selected from various alkanes, cycloalkanes, alkenes, cycloalkenes and carbocyclic aromatics which are liquid at standard temperature and pressure and have a density that is at least 0.02 g / mL different from the density of the water extraction solvent used. The solubility of formyltetrahydrofurans in several of the aliphatic and cycloaliphatic solvents is limited, but this does not cause problems during the hydroformylation reaction and subsequent extraction provided sufficient stirring is provided to maintain the two reaction phases entering the reaction phase. extractor in similar proportions. Similarly, several of the alkenes and cycloalkenes may themselves undergo the hydroformylation reaction, but this fact also causes no problem with the condition that the olefin substitution is sufficient to maintain their relatively low hydroformylation with the hydroformylation of 2, 5 dihydrofuran. Specific examples of such solvents include alkanes and cycloalkanes such as dodecanes, decalin, octane, mixtures of iso-octane, cyclohexane, cyclooctane, cyclododecane, methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene, isomers of xylene, tetralin, eumeno, substituted alkyl aromatic compounds such as the isomers of diisopropylbenzene, triisopropylbenzene and tert-butylbenzene; and alkenes and cycloalkenes such as 1,7-octadiene, dicyclopentadiene, 1,5-cyclo-octadiene, octene-1, octene-2,4-vinylcyclohexene, cyclohexene, 1,5,9-cyclododecatriene, pentene-1 and mixtures of unrefined hydrocarbons such as naphtha and kerosene. Generally, solvents having polar functional groups, for example ketones and esters, or atoms other than carbon and hydrogen are not preferred because said solvents process too much water solubility and / or tendency to form emulsions to give satisfactory partition characteristics and / or adversely affect the catalyst system. However, higher molecular weight polar ketones, ethers and polar ester compounds, such as isobutyl isobutyrate and bis (2-ethylhexyl) phthalate have been found to give good results. Preferred hydroformylation solvents have a density in the range of 0.6 to 0.9 and are selected from esters having from 6 to 20 carbon atoms, alkanes having from 5 to 20 carbon atoms, alkylsubstituted benzenes having from 7 to 15 carbon atoms, tetrahydronaphthalene, and decahydronaphthalene. The concentration of FTHF in the hydroformylation product solution is critical, giving acceptable results over wide ranges. For example, the concentration of the FTHF in the hydroformylation product solution may be in the range of 20 to 80 weight percent, preferably 50 to 70 weight percent, based on the total weight of the hydroformylation product solution. Likewise, the concentration of the hydroformylation solvent in the hydroformylation product solution can be varied widely. The practical upper limit depends on the limit of the solvent in relation to the product that one wishes to circulate, being a non-particular advantage or disadvantage for circulating large volumes. At 3 or 4 volumes of solvent per product volume, the preferred upper limit is 80 percent by volume of solvent. The practical lower limit depends on the density of the organic hydroformylation solvent and the aqueous extractant with the proviso that the density of the total organic phase is at least 0.02 g / mL less than the density of the hydroformylation product solution so that the phase of the hydroformylation solvent will be separated from and will rise through the aqueous phase countercurrently. For example, with toluene (d = 0.8669) as the solvent and pure water (d = 1) as the aqueous extractant, the preferred lower practical range is 35 percent by volume of solvent. The hydroformylation solvent preferably constitutes 40 to 70 percent by weight, more preferably 35 to 50 percent by weight of the total volume of the solution of the hydroformylation product. The rhodium and organ phosphorus catalyst components typically constitute less than 10 percent by weight of the hydroformylation product solution. Another factor affecting the selection of the hydroformylation solvent is the solubility or partition of the solvent within the aqueous phase. If the solubility of the hydroformylation solvent in the aqueous phase is greater than that of the catalyst components, the concentration of the catalyst will gradually rise in the recirculation catalyst and supplemental solvent additions will be necessary. If the solubility of the hydroformylation solvent in the aqueous phase is less than the catalyst components, the concentration of the catalyst will gradually fall into the recirculation catalyst and supplemental catalyst additions will be necessary. Since the catalyst system and the organic hydroformylation solvent exhibit some solubility in the aqueous phase, the addition of solvent and catalyst components to the recirculation catalyst is normally necessary during the prolonged operation of the hydroformylation / extraction process. The preferred proportion of supplement is usually from 1 to 5 percent by volume of the volume of total recirculation catalyst per cycle unless an extraordinary amount of emulsion is formed in the counter current extractors or the solvent has an extraordinary solubility in the extractant aqueous. According to the first step of the extraction process of the present invention the hydroformylation product solution described above is intimately contacted with water. The weight ratio of the water solution: hydroformylation product can typically vary from 0.1: 1 to 4: 1. The current ratio depends more on the FTHF content of the reaction mixture than on its total volume. Thus, a weight ratio of 3: 1 to 1: 3 of water to the FTHF content is preferred with a weight ratio of 2: 1 to 1: 2 being most preferred. Within the most preferred solvent concentrations of 45 to 60 percent by volume, the most preferred ratio of water to the total reaction mixture becomes a weight ratio of 1.3: 1 to 1:10. The evidence of the formation of diols (II) and oligomers (III) was demonstrated by the following experiments: FTHFs have high water solubility due to a strong interaction with water in appearance beyond simple dielectric solvent interactions. Thus, a rise in temperature that exceeds 15 ° C during the aqueous extraction of the hydroformylation product solution and significantly higher aqueous product densities than those of pure water (d = 1) or pure 3-formyltetrahydrofuran (d = 1.078) suggests the formation of one or More new high density materials during extraction. The densities of the aqueous solutions of 3-FTHF at 23 ° C are shown in Table I where the concentration of FTHF is the concentration in percent by weight of 3-FTHF in essentially pure water. TABLE I Concentration of FTHF Density 0 1.00 10 1.020 20 1.044 30 1.064 40 1.086 50 1.109 60 1.131 70 1.147 80 1.156 90 1.140 100 1.078 The maximum density shown in Table I corresponds approximately to the composition of 3-DHMTHF. 3-DHMTHF contains the elements of a 3-FTHF molecule (MW = 100.11831) and an H20 molecule (MW = 18.01534). Thus, the equivalent weight percent of 3-FTHF in 3-DHMTHD is then 100.11831 / (100.11831 + 18.01534) = 84.75% by weight compared to a maximum in percent by weight of 3-FTHF versus density chart at 80% in weigh. The confirmation of the formation of 3-DHMTHF when 3-FTHF is added to water comes from proton nuclear magnetic resonance spectroscopy. At room temperature, 50 weight percent of aqueous 3-FTHF solutions show two components: 79 mole percent of 3-DHMTHF and only 21 mole percent of 3-FTHF. Furthermore changing the aqueous concentration directly or using water-miscible solvents reversibly changes the mol 3-DHMTHF: 3-FTHF ratio indicating a rapidly established equilibrium between the two components as well as showing their relative stability. The relative amounts of 3-FTHF and 3-DHMTHF at various concentrations of water / 3-FTHF determined according to proton nuclear magnetic resonance spectroscopy is shown in Table II where the values given for "Water", "3- FTHF "and" Solvent "are percent by weight based on the total weight of the 3 component composition and" Solvent "refers to CD3COCD3 (NMR solvent). TABLE II Composition Percent mol Water 3-FTHF Solvent 3-FTHF 3 -DHMTHF 45.0 55.0 0.0 21.0 79.0 37.6 54.4 8.0 24.9 75.1 36.9 46.6 16.5 28.8 71.2 31.4 43.5 25.1 33.3 66.7 24.1 32.0 43.9 43.4 56.6 19.8 26.2 54.0 51.1 48.9 15.2 20.2 64.6 58.1 41.9 . 4 13.8 75.8 68.8 31.2 6.1 6.3 87.6 78.4 21.6 In Table II the value given for component 3-FTHF is the amount of 3-FTHF dissolved in the composition although in the aqueous solution it exists as 3-FTHF and 3-DHMTHF.

Some of the 3-FTHF in the aqueous solution also exists in the form of an acetal, for example, depending on the concentration of up to about 70 percent mole (at very high concentrations) but usually only about 0.5 percent mole (at the concentration of 50 percent by weight) of 3-FTHF is in the form of an acetal having the structure: (lll) where n is 2. Additional evidence confirming them can be found in the linear dependence (see Table III below of the extraction coefficient (K), defined in the following, on the water concentration in the aqueous phase.

Instead of remaining constant as required by a simple solvation equilibrium between two phases, [3-Formyltetrahydrofuran] solvent ~~ ^ [3- Formyltetrahydrofuran] AQUEOUS-linear dependence on water concentration suggests the following equilibrium: 3-Formyltetrahydrofuran + H20 ~ ^ > - 3-Dihydroxymethyltetrahydrofuran in which the solubility of the two components in equilibrium is different between the two phases. It has been found that the extraction of the catalyst and FTHF is best represented by its partition coefficient. For example, the partition coefficient as defined in the following for the partition of FTHF between an aqueous phase and toluene is 5.9 at room temperature at a water concentration of 50 percent by weight (31 Molar) in the aqueous phase. [3 - FTHF] Aqueous K3FTHF = 5. 9 = [3 - FTHF] toluene In this case, K3FTHF is the partition coefficient for 3-FTHF, [3-FTHF] Aqueous is the concentration of 3-FTHF in the aqueous phase, and [3-FTHF] Toluene is the 3-FTHF concentration in the toluene phase. The linear dependence of the partition coefficient on the concentration of the extraction water can be seen in Table III in which M is the molarity of the water, K (toluene) is the partition coefficient between water and the solvent toluene, and K ( 3fthf) is the partition coefficient between water and the substrate 3-FTHF. TABLE III Dependence of the partition coefficients (K) on the Water Concentration in the Aqueous Phase during the Aqueous Extractions of 3-FTHF / Toluene Solutions.; H20] (AQ) M in Weight K (3fthf: K (toluene) 48. 91218 86.1348 9.118963 0.010161 48. 23674 84.72044 8.997923 0.010402 47. 39479 82.96888 8.847047 0.010717 46. 31643 80.74376 8.653805 0.011141 44. 88637 77.82406 8.397537 0.011746 42. 9 73.8262 8.041581 0.012676 39. 95486 68.01833 7.513811 0.014284 . 11341 58.77008 6.646223 0.017725 42. 77033 73.55831 8.018344 0.012741 41. 42245 70.88316 7.776803 0.013445 39. 74471 67.5938 7.476152 0.014411 37. 60019 63.45289 7.091853 0.015812 34. 76379 58.0822 6.583571 0.018022 . 83304 50.83107 5.879181 0.021992 24. 95611 40.38408 4.826035 0.031122 36. 61842 61.57454 6.915922 0.016527 34. 60081 57.76969 6.554365 0.018164 32. 09317 53.12207 6.104996 0.020581 28. 89352 47.31806 5.531618 0.02448 24. 66307 39.85205 4.773521 0.031727 18. 70812 29.72398 3.706395 0.049514 . 45174 50.12216 5.810853 0.022449 27. 76655 45.29974 5.329666 0.026136 24. 43385 39.4445 4.732446 0.032213 . 18008 32.17144 3.970171 0.043874 1 .44315 22.70328 2.942112 0.074328 4.26191 39.14077 4.701635 0.032585 20.90983 33.39555 4.100942 0.041442 16. 74899 26.4487 3.355318 0.058986 11. 32277 17.68473 2.38294 0.107693 18. 03245 28.56244 3.585315 0.052493 14. 00933 21.96798 2.864371 0.077913 8. 925103 13.88343 1.953279 0.152787 8. 925103 13.88343 1.953279 0.152787 11. 73126 18.29434 2.456142 0.102111 7. 037774 10.90603 1.615069 0.213472 Three equivalent extraction cycles are sufficient to recover the FTHF essentially and quantitatively from the hydroformylation solvent phase. The formation of emulsions during extraction can result in lower extraction efficiencies although the unrecovered FTHFs are simply recirculated with the recirculation catalyst back from the hydroformylation reactor where they remain unchanged and can be recovered during a subsequent aqueous extraction. Since these emulsions may require 2 to 48 hours or more to separate completely, they should be avoided when possible, even when a coalescent is used to assist in their separation. The process of the present invention preferably uses a counter current extractor that minimizes turbulence (which causes the formation of emulsions) and acts as a coalescer so that emulsion formation remains small. The effect of emulsion formation on FTHF extraction is minimal for two reasons. First, the extraction moves the FTHF from the organic phase into the aqueous phase where the counter-current extractor can extract the aqueous phase and its emulsion several times. Thus, even a partition coefficient of 1 is enough to eliminate 88 percent of the product with an extraction equivalent of three cycles. Second, even a 10 percent emulsion (a large number) will only decrease a partition coefficient of 5.9 to 4.8. In this case, the extraction equivalent of three cycles is still sufficient to recover over 99 percent of the FTHF entering the extractor. Because the FTHF and DHMTHF act as secondary extraction solvents, some, for example up to 2 percent by weight, of the rhodium and organophosphorus components of the hydroformylation catalyst system can be extracted into the aqueous extraction phase. The amounts of the catalyst components extracted within the aqueous phase are usually significantly greater when a large amount of emulsion is formed independently of any favorable value for its partition coefficient. In that case, the partition coefficient between the aqueous and toluene phases as defined below is 0.0043 at room temperature with 50 weight percent water [Phosphine] Aqueous K Phosphine = 0.0043 [Phosphine] Toluene in the aqueous phase. In this case, KF? Sfina is the partition coefficient of triphenylphosphine, [Phosphine] Aqueous is the concentration of triphenylphosphine in the aqueous phase [Phosphine] Toiuene is the concentration of triphenylphosphine in the toluene phase. Also in this case the partition coefficient shows a water dependence but only because 3-FTHF and 3-DHMTHF (with their water-dependent concentrations) act as secondary extraction solvents. Rhodium, the other catalyst component exists mainly as rhodium (I) bis (triphenylphosphine) hydrocarbon carbonyl complex and accompanies triphenylphosphine with a similar partition coefficient. The extractions equivalent to three cycles leave 98.7 percent of triphenylphosphine and rhodium in the toluene phase. But the 10 percent emulsion changes the effective partition coefficient to 0.095 so that the triphenylphosphine and rhodium that remains in the toluene phase is now only 76 percent of the amount fed. Catalyst losses of this magnitude as well as the pollution that accompanies the downstream product is not acceptable. In both cases, but especially in the latter, it may be advantageous or even necessary to subject the aqueous extraction phase to a second extraction wherein the aqueous phase obtained from the process described above is intimately contacted with substantially non-contaminated hydroformylation solvent. The second extraction not only recovers in the organic solvent any catalyst components, i.e. rhodium and / or phosphorus organ compound, which are extracted within the aqueous phase in the first or main extraction but eliminates catalyst materials from the aqueous phase which have a detrimental effect on the distillation of the aqueous phase to improve the purity of the desired 3-isomer. Preferably, the secondary extraction is carried out using a countercurrent extraction of the organic hydroformylation solvent and the aqueous extraction phase, using at least 0.05 volumes of organic solvent per volume of the aqueous phase. A more preferred volume ratio of the organic solvent to the aqueous phase is typically in the range of 0.1: 1 to 0.5: 1. The secondary extraction can be carried out at a temperature of 0 to 70 ° C with a range of 15 to 35 ° C preferred. The organic solvent containing the catalyst components as well as the re-extracted FTHFs can then be recycled to the hydroformylation reactor to recover the recovered catalyst components and FTHFs from this extraction. However, to prevent excessive dilution of the hydroformylation catalyst solution with the additional solvent, most of the additional solvent used in the secondary extraction should normally be recovered first for reuse in the secondary extraction. In this example, said subsequent extraction of the aqueous phase with fresh toluene is guaranteed. During the subsequent extraction even if the percentage of emulsion rises to 20 percent (an unlikely event), an equivalent extraction of three cycles is sufficient to recover all but 0.3 percent of the phosphine and rhodium originally fed. Almost all other cases are better than this. And with the high cost of the catalyst components, quasi-quantitative recovery is important. Due to the high water solubility of FTHFs, no other additives are necessary to ensure their early complete extraction in an unmodified aqueous extractant. The high polarity of the FTHF and especially the DHMTHF ensures the extraction of a minimum of the relatively non-polar hydroformylation solvent and catalyst components so that their separation is also almost complete. More specifically, the addition of an alkanol and / or salt modifiers simply serves to increase the solubility of the water in the recirculation catalyst and the hydroformylation solvent and the catalyst components in the aqueous phase. More importantly, said modifiers represent contaminants that must subsequently be removed to obtain a substantially pure final product. It has been found that the initial material, 2,5-dihydrofuran, and its isomer, 2,3-d? H? Drofuran, are excellent solubilizing agents (such as tetrahydrofuran) to dissolve the relatively non-polar hydroformylation solvent within the medium of aqueous extraction and, vice versa, water inside the hydroformylation solvent. Thus, in the hydroformylation reactor, the solubilizing effect of 2,5-dihydrofuran, in initial material, in water within the organic droformilation solvent ensures a homogeneous reaction medium, which is important to avoid reaction complications such as hydrogenation of the initial material in tetrahydrofuran rather than its hydroformylation. Therefore, in order to minimize the need to recover the catalyst components by subsequent extraction with fresh solvent, it is important to avoid high concentrations of these tetrahydrofuran-like materials in the final extractable product. This means conducting the hydroformylation at low temperatures to avoid isomerizing 2, 5-d? H? Drofuran into 2,3-dihydrofuran; using synthesis gas without substantial excess of hydrogen beyond the 1: 1 stoichiometry required to avoid producing excessive amounts of tetrahydrofuran; and, driving the reaction at high conversions to avoid significant amounts of 2,5-dihydrofuran in the hydroformylation product solution. Alternatively, these compounds can be removed by stripping gas at a low temperature or distillation before extraction. As long as these three components remain below 50 percent of all furan derivatives in the product, the extraction will work (ie, it will separate into two phases), albeit with considerable cross-contamination of both extraction phases at the higher end. of this range. A more desirable concentration maintains these three tetrahydrofuran-like components below 35 percent of all furan derivatives in the product. However, the hydroformylation product solution subjected to the extraction according to the present invention contains less than 15 percent by weight, preferably less than 10 percent by weight of 2,5-DHF, 2,3-DHF, THF or a mix of any of the 2 or more of them. It has been found that the solubility of the FTHF in the aqueous extractant is higher at lower extraction temperatures. Thus, no advantage is achieved by using temperatures higher than those of the hydroformylation reaction temperature, for example 50 to 85 ° C, and superior results are obtained when the extraction temperature is lower than that of the hydroformylation reactor especially with exotherms of up to 15 ° C accompanying the solvation / reaction that occurs during the aqueous extraction. The extraction process is preferably carried out at an initial temperature in the range of 0 to 70 ° C and more preferably in the range of 25 to 45 ° C. The range of 25 to 45 ° C is the most practical from the points of view of extraction efficiency, equilibrium reach velocity, and solvation / reaction exotherms. The time during which the solution of the hydroformylation product and the water are in contact, ie before the phase separation, is dependent on the speed at which the phases reach equilibrium. In practice this can vary from one minute or less to impractically long mixing times in excess of three hours. In contrast to the published requirements for high allyl alcohol conversions for the extraction of successful aqueous product during hydroformylation in hydroxybutyraldehyde, it has been found that a low conversion strategy of 2, 5-d? H? Drofuran referred to above is not only operable , but is preferred to produce a product that contains very low levels of unwanted 2-FTHF. Due to the much higher boiling point and the presence of the hydroxyl group, this mode of operation is not suitable in the recovery of aqueous extractive product after the hydroformylation of allyl alcohol. This mode of operation is successful with 2,5-DHF since 2,5-DHF will be hydroformylated only between 3-FTHF but it can also be isomerized into 2,3-DHF which will be hydroformylated into 2-FTHF, but at a very high speed slower than the hydroformylation of 2,5-DHF. The separation of the unreacted DHF from the reaction mixture before the aqueous extraction is simple due to its low boiling points. Thus, stopping the reaction at low conversions of 2,5-DHF keeps the formation of 2-FTHF at a minimum while maintaining the concentrations of 2,3-DHF at low levels. Removing the unreacted DHF from the partially complete reaction allows its separation by subsequent distillation with the removal of unwanted 2,3-DHF and the return of purified 2,5-DHF to the hydroformylation reactor. Using this operation technique while maintaining the conversion of 2.5-DHF below 50 percent decreases the impurity content of 2-FTHF from 10 to 0.1 percent of its value at 95 percent conversion of 2, 5-DHF at a cost of less than 5 percent of material removed as 2,3-DHF. The resulting extracted aqueous product shows a ratio of 3-FTHF to 2-FTHF from 200: 1 to 20,000: 1 under typical reaction conditions. The hydroformylation of 2,5-DHF can be carried out at a temperature in the range of 40 to 180 ° C. However, in order to minimize the isomerization of the 2,5-DHF reactant in 2,3-d? H? Drofuran (2,3-DHF), the hydroformylation will normally be carried out at a temperature in the range of 50 to 85 ° C. The isomerization of the reactant 2,5-DHF in 2,3-DHF leads to the formation of a mixture of 2- and 3-FTHF. Co-production of these isomers presents no problem in their extractive separation, but limits the superior yield of the desired 3-FTHF to 30% because 2,3-DHF produces 2- and 3-FTHF in a ratio of 3: 1. The total pressure used in hydroformylation may be in the range of 0.01 to 35 mPa (1.5 to 5,000 psig) with total pressures in the range of 0.35 to 7 mPa (50 to 1,000 psig) being preferred. The molar ratio of carbon monoxide to hydrogen in the synthesis gas can be from 3: 1 to 0.3: 1 with molar ratios of 2: 1 to 0.5: 1 being more common. As mentioned above, the synthesis gas preferably does not contain a substantial excess of hydrogen to avoid producing excessive amounts of tetrahydrofuran. The process of the present invention is further illustrated by the following examples. The following reference examples describe the hydroformylation processes for the production of the hydroformylation product solutions and formyltetrahydrofurans which are employed in the process of the invention. As used herein, the percent conversion of a reactant is: Reactant Moles Converted X 100 Moles of Reactant Fed and the percentage of selectivity in a particular compound: Moles of Reactant Converted into the Desired Product X 100 Moles of Reactant Converted REFERENCE EXAMPLE 1 To a 300 mL stainless steel autoclave, were charged 150 mL of 2,5-DHF (d = 0.927, 139 g, 1.93 moles), 37.6 mg of rhodium dicarbonyl acetylacetonate (I) (0.147 mmol - mmol), and 95.4 mg of triphenylphosphine (0.364 mmol). The atomic ratio of phosphorus to rhodium was 2.50 and the rhodium concentration was 100 ppm (weight / volume). The autoclave was sealed and the run started loading the system with 2.17 mPa (300 psig) of synthesis gas (ratio of hydrogen to carbon monoxide = 1.01: 1) and stirring rapidly and heating the contents of the autoclave to 70 ° C. During the course of the reaction the synthesis gas pressure was kept at 2.17 mPa (300 psig) by periodic refilling of synthesis gas from a tank. During 42 hours, the pressure drop of the synthesis gas amounted to a total of 45.95 mPa (6650 psig) and, at the end of this time, the uptake was almost over. Gas chromatographic analysis (GC) of a sample of the reaction product mixture showed an initial material conversion of 95.4 percent, a selectivity for 3-FTHF of 94.7% and a selectivity for 2- FTHF of 2.2%. The distillation of this product gave a material that boils at 83.5-85.5 ° C / 32 Torr or 74.0-75.5 ° C / 17 Torr whose GC analysis showed to be 98.9% pure 3-FTHF. During the course of this fractional distillation, the base temperature reached a maximum of 127 ° C and the recovery of the product was only 54%. Gas chromatographic analysis of the distillation residue of the kettle after the end of the distillation showed a multitude of oligomeric by-products caused, presumably, by the condensation of aldol assisted by phosphine of the aldehydes in the product. This example demonstrates the results obtained when the hydroformylation product obtained from 25-DHF is recovered by distillation. REFERENCE EXAMPLE 2 Reference Example 1 was repeated except that the 2,5-DHF reactant was reduced to 75 mL and 75 mL of toluene solvent was added. The time required to achieve 95% conversion of the initial material as measured by GC analysis was 23.0 hours. The selectivities and the ratio of 3-FTHF to 2-FTHF were essentially the same as in Example 1. The recovery of pure 3-FTHF 99.0% by distillation of the products of several of these combined experiments containing a toluene solvent was 49 %.

REFERENCE EXAMPLE 3 Reference Example 2 was repeated except that the synthesis gas pressure was 4.58 mPa (650 psig). The time required to achieve 95% conversion of the initial material as measured by GC analysis was 23.5 hours. The selectivities and the ratio of 3-FTHF to 2-FTHF were essentially the same as in Example 1. REFERENCE EXAMPLE 4 Reference Example 2 was repeated except that the pressure of the synthesis gas was 0.79 mPa (100 psig). The time required to achieve 95% conversion of the initial material as measured by GC analysis was 19.5 hours. The selectivities and the ratio of 3-FTHF to 2-FTHF were essentially the same as in Example 1. REFERENCE EXAMPLE 5 Reference Example 2 was repeated except that the amount of tp-phenylphosphine was increased to give an atomic ratio of phosphorus: rhodium of 12: 1. The time required to achieve 95% conversion of the initial material was 18.0 hours. The selectivity for 3-FTHF was 91.9% and the selectivity for 2-FTHF was 7.9%. REFERENCE EXAMPLE 6 Reference Example 5 was repeated except that the initial charge of 2.5-DHF was 150 mL and the toluene solvent was omitted. The time required to achieve 95% conversion of 2,5-DHF was 39.0 hours. The selectivity for 3-FTHF was 92.7% and the selectivity for 2-FTHF was 7.1%. This example demonstrates that the absence of an inert reaction solvent has no effect on the result of the hydroformylation reaction, even with significant changes in the phosphine component of the catalyst. REFERENCE EXAMPLE 7 Reference Example 5 was repeated except that the triphenylphosphine was replaced with tricyclohexylphosphine. The time required to achieve 95% conversion of 2,5-DHF was 16.5 hours. The GC analysis of the product at this point showed a selectivity of 91.0% for 3-FTHF and a selectivity of 8.2% for 2-FTHF. REFERENCE EXAMPLE 8 Reference Example 5 was repeated except that the triphenylphosphine component of the catalyst was replaced with an equimolar amount of trimethylphosphite. The time required to achieve 95% conversion of 2,5-DHF was 24.0 hours. The GC analysis of the product showed a selectivity of 89.2% for 3-FTHF and a selectivity of 9.1% for 2-FTHF. REFERENCE EXAMPLE 9 Reference Example 5 was repeated except that the ratio of hydrogen to carbon monoxide in the synthesis gas was maintained at 2: 1 more than 1: 1. The time required to achieve 95% conversion of 2,5-DHF was 9.5 hours. The GC of the product showed a selectivity of 65.8% for 3-FTHF and a selectivity of 25.0% for 2-FTHF, and a selectivity of 9.0% for tetrahydrofuran. This example demonstrates the defect of changing the ratio of hydrogen to carbon monoxide in the synthesis gas in the reaction result. REFERENCE EXAMPLE 10 Reference Example 5 was repeated except that the rhodium source was changed to rhodium (II) 2-ethylhexanoate at a rhodium concentration of 100 ppm. The time required to achieve 95% conversion of 2,5-DHF was 18.5 hours. The selectivity for 3-FTHF was 94.0% and the selectivity for 2-FTHF was 3.7%. REFERENCE EXAMPLE 11 Reference Example 10 was repeated except that the rhodium concentration was 200 ppm and the amount of triphenylphosphine was increased to maintain an atomic ratio of phosphorus to rhodium of 12: 1. The time required to achieve 95% conversion of the initial 2,5-DHF material was 8.5 hours. The selectivity for 3-FTHF was 94.1% and the selectivity for 2-FTHF was 2.8%. REFERENCE EXAMPLE 12 Reference Example 10 was repeated except that the rhodium concentration was 400 ppm and the amount of triphenylphosphine was increased to maintain an atomic ratio of phosphorus to rhodium of 12: 1. The time required to achieve 95% conversion of the initial 2,5-DHF material was 7.5 hours. The selectivity for 3-FTHF was 95.3% and the selectivity for 2-FTHF was 1.8%. REFERENCE EXAMPLE 13 Reference Example 2 was repeated except that the solvent was isooctane. The time required to achieve 95% conversion of the initial material as measured by GC analysis was 21.5 hours. The selectivities and ratio of 3-FTHF to 2-FTHF were essentially the same as in Example 1. REFERENCE EXAMPLE 14 Reference Example 2 was repeated except that the solvent was 1,3-diisopropylbenzene. The time required to achieve 95% conversion of the initial material as measured by GC analysis was 19.5 hours. The selectivities and ratio of 3-FTHF to 2-FTHF were essentially the same as in Example 1. REFERENCE EXAMPLE 15 Reference Example 2 was repeated except that the solvent was 2, 2, 4-trimethyl-1 monoisobutyrate, 3-pentanediol. The time required to achieve 95% conversion of the initial material as measured by GC analysis was 23.5 hours. The selectivities and ratio of 3-FTHF to 2-FTHF were essentially the same as in Example 1.

REFERENCE EXAMPLE 16 Reference Example 2 was repeated except that the solvent was bis (2-ethylhexyl) phthalate. The time required to achieve 95% conversion of the initial material as measured by GC analysis was 21.5 hours. The selectivities and ratio of 3-FTHF to 2-FTHF were essentially the same as in Example 1. EXAMPLES 1-36 The extraction examples were carried out under nitrogen in a separatory funnel using a calibrated graduated cylinder to measure the volumes of the extracted phases and an uncorrected thermometer to measure the temperatures of the extraction. The final analyzes were conducted after the initial exotherm had collapsed and all the emulsions had completely separated. Each phase was analyzed by gas chromatography using a capillary column of 20 M x 0.25 mm DB 1701 at a flow rate of 3.5 cc / minute helium. Ethanol was the internal standard for the aliquot of the aqueous phase and n-dodecane was the internal standard for the aliquot of the catalyst phase. In each case, the temperature was checked so that the results coincided within 2 ° C. The quantities of materials used in the Examples 1-36 are shown in Table IV where the values given for 3-FTHF, Toluene and Water are the relative amounts by volume of those materials used in each extraction example wherein the solution of 3-FTHF in Toluene was extracted with the relative amount of water specified. TABLE IV Example No. 3-FTHF Toluene Water 1 10 10 80 2 10 20 70 3 10 30 60 4 10 40 50 5 10 50 40 6 10 60 30 7 10 70 20 10 80 10 9 20 10 70 10 20 20 60 11 20 30 50 12 20 40 40 13 20 50 30 14 20 60 20 15 20 70 10 16 30 10 60 17 30 20 50 18 30 30 40 19 30 40 30 20 30 50 20 21 30 60 10 22 40 10 50 23 40 - 20 40 24 40 30 30 TABLE IV (contd) Example No. 3-FTHF Toluene Water 25 40 40 20 26 40 50 10 27 50 10 40 28 50 20 30 29 50 30 20 30 50 40 10 31 60 10 30 32 60 20 20 33 60 30 10 34 70 10 20 35 70 20 10 36 80 10 10 The results obtained in the extractions of Examples 1-36 are shown in Table V where the values given for Vol are the relative volumes of the phases of Tolueno and Acuosa in each example, the values given for 3-FTHF, Toluene (Tol) and Water are the percentages by weight of each component in the Toluene and Aqueous phases (based on the total weight of each phase) and the values dice for K are the partition coefficients for 3-FTHF calculated from: [3 - FTH F] Aqueous _FTHF = [3 - FTH F] Toluene where K3-FTHF is the partition coefficient for 3-FTHF, [3-FTHF] Aqueous is the concentration of 3-FTHF in the phase aqueous, and [3-FTHF] To? Ueno is the concentration of 3-FTHF in the toluene phase. The calculation of the partition coefficients was made at different initial concentrations of the solvent, water and 3-FTH. To check the consistency of the results, several of these analyzes were repeated and in all cases the repetitions coincided within 10 percent of each other. Where they were repeated, the given analytical values are averages of the plurality of analyzes. The results of these experiments are summarized in Table V below. The purpose of these Examples is to show the consistency of the partition coefficient calculations and the dependence of the partition coefficients on the water concentration.

TABLE V Example Phase of Toluene Fasp Ar-iose No. m 3FTHF Iol Aqua Density Vol 3FTHF Iol Water Density Jl 1 9.4 1.4 98.4 0.2 0.8701 89.1 11.7 0.7 87.6 1.0240 9.7 2 18.6 1.8 98.0 0.2 0.8709 79.8 12.8 1.8 85.4 1.0264 8.2 3 29.6 1.8 98.0 0.2 0.8709 68.8 14.5 1.0 84.5 1.0302 9.5 4 39.6 2.2 97.7 0.1 0.8717 58.9 16.5 1.5 82.0 1.0343 9.1 5 50.6 3.1 96.8 0.1 0.8735 48.0 18.9 1.1 80.0 1.0396 7.4 6 61.6 3.9 95.9 0.2 0.8754 37.2 22.2 0.8 77.0 1.0468 6.8 A 7 71.8 4.3 95.0 0.2 0.8763 27.0 28.2 2.0 69.8 1.0595 7.8 8 83.2 5.0 94.8 0.2 0.8777 15.9 41.2 1.0 57.8 1.0878 10.2 9 8.1 3.5 96.3 0.2 0.8745 88.8 22.9 2.0 75.1 10482 7.8 10 19.9 4.0 95.9 0.1 0.8754 77.2 25.6 0.7 73.6 1.0541 7.8 11 29.8 4.0 95.9 0.1 0.8755 67.3 28.7 1.4 69.9 1.0608 8.7 12 41.1 5.5 94.3 0.2 0.8787 56.2 32.6 1.1 66.3 1.0691 7.2 13 51.8 5.5 94.3 0.2 0.8788 45.7 38.6 0.8 60.6 1.0820 8.6 14 64.5 9.3 90.6 0.1 0.8867 33.3 44.5 0.7 54.8 1.0949 5.9 15 76.2 11.1 88.7 0.2 0.8906 21.8 57.2 2.0 40.8 1.1222 6.5 TABLE V (cont) Example F Faassee of TToolluueennoo Aqueous Phase No, Vol 3FTH F Tol Water Density VQ | 3FTHF IQ! Water Density K_ 16 9.4 6.3 93.6 0.1 0.8803 86.4 34.3 1.0 64.7 1.0729 6.7 17 20.4 6.5 93.3 0.2 0.8809 75.5 38.2 0.7 61.1 1.0811 7.2 18 31.3 8.1 91.8 0.1 0.8841 64.8 42.6 0.9 56.5 1.0907 6.5 19 42.4 9.0 90.9 0.1 0.8860 53.8 48.7 0.8 50.5 1.1040 6.8 20 54.3 11.9 87.9 0.2 0.8923 42.3 56.1 1.7 42.2 1.1199 5.9 21 68.6 17.3 82.5 0.2 0.9036 28.4 66.7 2.5 30.8 1.1427 4.9 in 22 9.5 9.7 90.1 0.2 0.8875 85.1 45.3 1.2 53.5 1.0966 5.8 23 20.5 10.5 89.3 0.2 0.8892 74.3 50.1 1.3 48.6 1.1070 6.0 24 32.0 12.4 87.4 0.2 0.8933 63.0 56.1 1.5 42.4 1.1198 5.7 25 44.4 17.4 82.4 0.2 0.9038 50.9 62.6 2.8 34.6 1.1339 4.5 26 61.1 26.1 73.8 0.1 0.9221 34.9 70.7 4.5 24.8 1.1513 3.4 27 9.6 14.0 85.7 0.3 0.8967 83.9 56.1 1.4 42.5 1.1198 5.0 28 21.4 20.7 79.0 0.3 0.9109 72.3 61.0 2.3 36.7 1.1304 3.7 29 34.8 25.8 74.0 0.2 0.9216 59.3 67.2 3.3 29.4 1.1438 3.2 30 52.6 37.6 62.2 0.2 0.9465 42.3 72.0 7.5 20.5 1.1542 2.3 TABLE V (cont) Example Phase of Toluene Aqueous Phase No. Vol 3FTHF IQ | Water Density Vol 3FTHF Iol Water Density _K_ 31 7.6 21.1 78.6 0.3 0.9117 84.5 65.6 3.3 31.1 1.1403 3.9 32 19.5 29.8 69.9 0.3 0.9302 72.9 70.6 5.6 23.8 1.1512 2.9 33 39.3 52.2 47.5 0.3 0.9774 54.0 71.6 12.4 16.0 1.1533 1.6 34 1.9 40.1 59.2 0.7 0.9523 89.8 71.9 9.2 18.9 1.1540 2.2 35 < One phase > 36 A phase cp co EXAMPLES 37-44 Using the procedures described above for Examples 1-36, the partition coefficients for the extraction of 3-FTHF in water were determined using the hydrocarbon decane, isooctane, p-xylene and 1,3-diisocyanate solvents. propylbenzene (DIPB). The partition coefficients were also determined by the same procedures using the inert organic solvents 1-decanol (alcohol), isobutyl isobutyrate (ester, IBIB), 2, 2,4-trimethyl-1,3-pentanediol monoisobutyrate (alcohol). ester, TMPD-MIB), and dimethyl teftalafo (aromatic diester, DMT). The volume ratios of 3-FTHF: Solvent: Water used in each of Examples 37-44 was 3: 3: 4. The partition coefficients are shown in Table VI where the values specified for solubility of 3-FTHF in solvent are percentages by weight, the values given for Temp are temperatures (° C), 3-FTHF is the partition coefficient for 3-FTHF determined as described above and KSo? Vente is the coefficient for the solvent used in each determined example of its solubility in the two phases and affected by the presence of the 3-FTHF substrate.

Table vi Example 0 Solubility I partition coefficients No. 3-FTHF Solvent Density in solvent emp & £ Q £ 80! Fi -K-FTHF 18 Toluene 0.867 100 24.7 0.01165 6.518 37 p-Xilene 0.852 100 24.1 0.00740 7.022 38 DIPB 0.856 100 24.4 0.01904 5.869 39 n-Dean 0.730 0.93 25.1 0.00661 217.5 40 Isooctane 0.692 2.36 24.7 0.00746 73.91 41 1-Decanol 0.829 100 25.7 0.01695 1.134 42 TMPD-MIB 0.937 100 24.4 0.00481 2.024 43 IBIB 0.844 100 24.2 0.00772 7.715 44 DMT 1,178 100 24.2 0.02526 2,218 EXAMPLES 45-56 Using the procedure described above for Examples 1-36, the partition coefficients were determined for all the solvents tested as well as for triphenylphosphine in toluene all extracted with water. In addition, the effect of 3-FTHF on the partition coefficient of toluene in water was explored using different concentrations of aqueous 3-FTHF as the extraction medium. The results are summarized in Table VII where the CS: S ratio is the volume ratio of Co-Solvent: Solvent, the H20 ratio: (S + CS) is the water volume ratio: Solvent plus Co-Solvent, if there is, DIPB, TMPD-MIB, and IBIB have the meanings given above, DMP is dimethyl phthalate.

The purpose of the experiments of Examples 45-56 is to show the degree of partition of the materials in water limited solubility in water and, in contrast, as 3-FTHF affects this partition. These Examples include materials that could act as solvents for the reaction and extraction. TABLE V) l Example CS: S HzO: (S + CS) Partition coefficient No. Solvent Co-Solvent Relationship Solvent ratio 45 Tolueno - - 1: 1 U.00063 46 Toluene 3-FTHF 1: 1 10: 1 0.00865 47 Toluene 3-FTHF 1: 1 1: 1 0.0117 48 Toluene 3-FTHF 1: 1 1: 10 0.147 49 isooctane - - 1: 1 0.00002 50 n-Dean - - 1: 1 0.00002 51 p-Xilene - - 1: 1 0.00015 52 1,3-DIPB - - 1: 1 0.00006 53 1 -Decano! - - 1: 1 0.00028 54 TMPD-MIB - - 1: 1 0.00008 55 IBIB - - 1: 1 0.00116 56 DMP - - 1: 1 0.00731 EXAMPLE 57 The procedure described in the preceding examples was repeated using a volume ratio of 50: 1 triphenylphosphine: toluene and a volume ratio of 1: 1 of water: triphenylphosphine + toluene. The partition coefficient of tp-phenylphosphine between toluene and water was determined to be 0.00433. EXAMPLES 58-61 Using the procedure of Examples 1-36, the partition coefficient for 3-formyltetrahydrofuran between toluene and water was determined at various temperatures. The results are summarized in Table VIII where the ratios of 3-FTHF: Toluene and H20: FTHF + Toluene are by volume. TABLE VIII Example No Ratio of 3- Ratio of H20 (3- Temperature Coefficient of FTHF Toluene FTHF + Toluene) Partition of 3-FTHF 58 1: 1 0.67: 1 0.2 13.91 59 1: 1 0.67: 1 24 6.53 60 1: 1 0.67: 1 52.6 2.97 61 1: 1 0.67: 1 93.5 1.178 EXAMPLES 62-69 The hydroformylation product solutions produced in the Examples of Reference 2, 5, 10, 11, 12, 13, 14, 15, and 16 were subjected to aqueous extraction according to the present invention using an upstream extractor with an initial water to organic feed ratio of 0.6: 1 (volume : volume) to recover the product. The main extractor was a 2.5-inch diameter, 48-inch-long glass tube that has an internal volume of 3.5 liters and was packed with 1/4 inch Penn State gasket. The secondary extractor was a glass tube that has a diameter of 1,375 inches and a length of 30 inches, an internal volume of 0.7 liters and was also packed with 1/4 inch packing from Penn State. The feed rates were 1-3 liters per hour. This extractor operated on an equivalent of three simple extractions. The temperatures in the extractor varied from the ambient (26.5 ° C) to 47.7 ° C, indicative of the autogenous temperature rise associated with the solvation / reaction extraction. Turbidity and sometimes a pale yellow color in the effluent from this extractor indicated incomplete separation of the aqueous phase from that of the solvent. The catalyst components remained in the solvent phase of reaction. If any portion of this phase remained in or was not removed from the aqueous phase, it would contaminate the final product. Therefore, the aqueous phase obtained from the first extractor was subjected to a second countercurrent extraction with fresh solvent to eliminate this contamination. The feed ratio of aqueous phase to fresh solvent was 10: 1 (volume: volume). The temperature gradient in the second extractor against the current was minimal since the heats of solvation / reaction that accompany the extraction would have emerged mainly in the first extractor. The results of these extractions are shown in Table IX where the solvent and Solv refer to the hydroformylation solvent component of the hydroformylation product solution used in each sample, Isooct refers to isooctane, DIPB and TMPD-MIB has the meanings given above, DOP is bis (2-ethylhexyl) phthalate, HPS refers to the hydroformylation product solution, Rh refers to rhodium, TPP refers to triphenylphosphine, and FTHF refers to 2- and 3-FTHF. The values given for the HPS components are percentages by weight based on the total weight of the HPS and whose sum equals 100 percent, the values given for the components of the aqueous phase produced in the initial aqueous extraction (first) of the HPS are the percentages in relative weight determined by gas chromatographic analysis for volatile organic components [solvent and FTHF], atomic absorption for the rhodium component of the catalyst, and P-31 nuclear magnetic resonance spectroscopy for the phosphine components of the catalyst (the bound and free components). The numbers reported represent the total amount of that material in that aqueous phase with less than 100, this value being the relative amount of that material entering the other phase of solvent. The values given for the components of the aqueous phase (second) produced by subjecting the first aqueous extraction phase to a second countercurrent extraction with fresh solvent are relative percentages by weight determined by the same methods for each component. In this case, the numbers reported are added to the relative numbers of the first extraction with that number less relative to the second number reported being the amount of that material that goes into the other solvent phase. Reporting the values in this form gives the amount of that component at any stage by multiplying the amount in the HPS by the relative percentage of that component in any of the other phases. The purpose of these examples is to show the results of extracting the current reaction mixtures with water to compare them with other methods of product recovery.

TABLE IX Example Components of the Aqueous phase Components of the aqueous HPS components of the first extraction after extraction Nía. Solvent Solv Rh TPP FTHF Solv Rh TPP FTHF -BÍL TP_P_ FTHF 62 Toluene 42.05 0.0046 0.0295 57.92 3.1 2.0 2.4 97.4 0.1 0.03 96.3 63 Toluene 42.00 0.0046 0.1413 57.85 3.3 1.8 2.6 98.2 0.1 0.05 97.0 64 Toluene 41.94 0.0092 0.2821 57.77 4.6 4.3 1.9 98.6 0.1 0.07 97.0 65 Toluene 41.82 0.0183 0.5626 57.60 2.9 1.4 2.2 98.1 0.06 0.06 97.3 66 Isooct 42.05 0.0046 0.0295 57.92 2.1 2.5 2.8 99.2 0.1 0.17 98.8 67 DIPB 42.05 0.0046 0.0295 57.92 3.5 0.4 1.9 97.7 0.05 0.02 96.0 (Ti 68 TMPD- 42.05 0.0046 0.0295 57.92 6.4 5.2 6.7 94.4 0.1 1.4 93.9 MIB 69 DOP 42.05 0.0046 0.0295 57.92 6.2 5.2 2.9 97.1 0.25 0.04 95.1 The invention has been described in detail with particular reference to the preferred embodiments thereof, but it will be understood that variations and modifications may be made within the spirit and scope of the invention.

Claims (3)

1. CLAIMS 1. Process to produce an aqueous solution, essentially devoid of alkanol, containing a mixture of compounds having the formulas:
2. OR 0 (ii) comprising (A) intimately contacting a solution of hydroformylation product comprising (i) 20 to 80 weight percent of an aldehyde of the formula (I), (n) components of the hydroformylation catalyst comprising rhodium and a phosphorus organ compound, and (m) 80 to 20 weight percent of a hydroformylation solvent with water essentially devoid of alkanol; (B) allowing the mixture of step (A) to separate into 2 phases; and (C) separates the two phases to obtain (a) a hydroformylation solvent phase containing catalyst components and (b) an aqueous phase containing the compounds of formulas (I) and (II) characterized in that the ratio by volume of water to hydroformylation product solution employed in step (A) is 0.1: 1 to 4: 1; the hydroformylation product solution employed in step (A) contains less than 15 weight percent of 2,5-dihydrofuran (2,5-DHF), 2,3-dihydrofuran (2,3-DHF), tetrahydrofuran (THF) ), or a mixture of any two or more thereof and the molar ratio of the compound (I) to the compound (II) is 0.05: 1 to 20: 1. 2. The process in accordance with the claim 1, characterized in that the hydroformylation solvent has a density in the range of 0.6 to 0.9 and is selected from esters having from 6 to 20 carbon atoms, alkanes having from 5 to 20 carbon atoms, ketones having from 6 to 20 carbon atoms, dialkyl ethers and cyclic ethers having from 5 to 20 carbon atoms, substituted alkyl benzenes having 7 to 15 carbon atoms, tetrahydronaphthalene, and decahydronaphthalene.
3. 3. The process in accordance with the claim 2, characterized in that the aldehyde of the formula (I) constitutes 50 to 70 weight percent of the total weight of the hydroformylation product solution.