Ind. Eng. Chem. Res. 1991,30,1389-1390 Baldyga, J.; Bourne, J. R. Simplification of micromixing calculations. Chem. Eng. J. 1989,42,83. Bourne, J. R.; Tovstiga, G. Measurement of the diffusivity of 1naphthol in water with a rotating disc. Chem. Eng. Commun. 1985,36, 67. Bourne, J. R.; Hilber, C.; Tovstiga, G. Kinetics of azo coupling reactions between 1-naphthol and diazotized sulphanilic acid. Chem. Eng. Commun. 198637,293. Bourne, J. R.; Ravindranath, K.; Thoma, S. A. Control of product distributions in mixing-controlled reactions. J. Org. Chem. 1988, 53, 6166. Bourne, J. R.; Kut, Oe. M.; Lenzner, J.; Maire, H. Kinetic of the diazo coupling between 1-naphthol and diazotized sulfanilic acid. Znd. Eng. Chem. Res. 1990,29, 1761. Lips, M. Ph.D. Thesis 9240, ETH ZOrich, 1990.
1389
Maire, H. Ph.D. Thesis 9272, ETH Ztirich, 1990. *Author to whom correspondence should be addressed. Present address: Department of Chemical Engineering, Swiss Federal Institute of Technology Ztirich, UniversitSltastr. 6, CH-8092 Ztirich, Switzerland.
John R. Bourne,* Horst Maire Technisch-Chemisches Laboratorium, ETH CH-8092 Zurich, Switzerland Received for review November 2, 1990 Revised manuscript received February 5, 1991 Accepted February 22,1991
Enhancement of Rate and Selectivity in Hydroformylation of Allyl Alcohol through Solvent Effect+ Enhancement in the rate and selectivity in hydroformylation of allyl alcohol using HRh(CO)(PPha)S catalyst has been demonstrated through the solvent effect. of 1X l0-S and 1.67 X lo4 mol/cm8, respectively. The total pressure of CO/H2 (in a ratio of 1:l)was 61.36 atm. The effect of linear alcohols as solvents on the rate and selectivity was investigated. The results are presented in Table I. It was observed that the rate of hydroformylation increased with increasing carbon number of the normal alcohol used as a solvent. The increase in the initial rate of hydroformylation was nearly 2 times when the solvent was changed from ethanol to octanol. There was a consistent increase in the rate as the carbon number was OHCCHSHpCH20H changed from C2to Cg. In addition to the enhancement (9 CH,=CHCHpOH + CO + Hp in the rates, the solvents also strongly influenced the seCH3CHCH20H lectivity of the desired product (I) in particular. The I normal/iso ratio increased from 1.7 when ethanol was used CHO as solvent to 15 when octanol was used. This finding has I1 important implications, since 4-hydroxybutyraldehyde (I) OHCCH&H&H@H + 4 HO(CHp)40H (ii) can be converted to commercially useful products such as 1,4- butanedid 1,4-butanediol. In order to explain the observed trends, the mechanism The major disadvantage of this route is the formation of hydroformylation proposed earlier (Evans et al., 1968b) of 2-methyl-3-hydroxypropionaldehyde(11)along with the can be considered. When coordinating solvents, like aldesired product 4-hydroxybutyraldehyde (I). Therefore, cohols, are used, they can take part in the catalytic cycle improvingthe selectivity of I becomes important. In earlier by coordination to the metal. Wilkinson and co-workers reporta (Shimizu, 1976; Smith, 1978; Tamura and Kumano, have reported the existence of alcohol coordinated species 1980) on the selectivity studies for different catalyats and (Evans et al., 1968a). It is well-known that factors which promoters, the normal/iso ratios (I/II) observed were lower tend to reduce the electron density on the metal enhance than 4. the rate as well as the normal/iso aldehyde ratio (Moser In this paper, we wish to report improved selectivity and et al., 1987). The electron density on the Rh center will rates in the hydroformylation of allyl alcohol using HRhbe highest for the ethanol coordinated species and reduce (CO)(PPh,), catalyst through solvent effect. It has been as the carbon number of the alcohol increases. This exshown that by using linear alcohols as solvent, the rate as plains the observed enhancement in the rate of hydrowell as the normal/iso ratio improves substantially for formylation and normal/iso aldehyde selectivity observed hydroformylation. with higher alcohols as solvents. Besides the electronic effect, the steric hindrance at the metal center will also Experimental Section vary with the coordinated alcohol. As a result, the formation of the terminal alkyl-Rh species will be favored The details regarding the experimental procedure folwhen larger sizes of alcohol molecules are coordinated. lowed were the same as reported in our earlier work This will also enhance the normal/iso ratio. Another factor (Deehpande and Chaudhari, 1989). The catalyst HRhthat could also have an effect on selectivity is hydrogen (CO)(PPh,), was prepared according to the procedure bonding. The hydrogen on the alcohol can have bonding described in the literature (Evans et al., 1968b). with the oxygen of allyl alcohol, thus hindering formation of the branched aldehyde. In order to confirm this, the Results and Discussion hydroformylation of 1-hexene was studied. When the hydroformylation of 1-hexene was carried out The hydroformylation of allyl alcohol was studied at 70 in different alcohol solvents, almost the same trend was OC and HRh(CO)(PPh,), and allyl alcohol concentrations oaa8-58a5pi /2630-13a~$02.50/0 0 1991 American Chemical Society
Introduction The hydroformylation of allyl alcohol is a subject of keen academic as well as commercial interest (Shimizu, 1976; Matsumoto et al., 1978a,b;Pittman and Honnick, 19801, since it can provide an alternative route for the manufacture of 1,4-butanediol,which is commercially synthesized from acetylene (Appleyard and Gartahore, 1946). The hydroformylation route for 1,Cbutanediol is
-c' -
1390 Ind. Eng. Chem. Res., Vol. 30,No. 6, 1991 Table I. Effect of Solvent on Conversion and Selectivity in Hydroformylation of Allyl Alcoholo selectivity, 9% init rate x lo', no. solvent conversion, % time, min mol/(cm%) I I1 1 ethanol 98.6 180 3.56 62.69 37.31 2 1-butanol 99.2 91 4.17 73.92 23.77 99.1 82 4.76 81.05 15.83 3 1-pentanol 4 1-hexanol 99.3 63 5.38 87.87 8.62 5 1-heptanol 99.4 50 5.84 88.56 6.64 6 1-octanol 99.2 46 6.21 89.35 5.88 OCatalyst HRh(CO)(PPh& 1 X atm; temperature = 70 O C .
lo4 mol/cms; allyl alcohol, 1.67 x
n/iso ratio 1.7 3.1 5.1 10.2 13.3 15.2
mol/cms; partial pressure of CO = partial pressure of Ha = 30.68
Table 11. Effect of Solvent on Conversion and Selectivity in Hydroformylation of l-Hexenea and l-Deceneb no. olefin solvent conversion, % time, min rate x 107, mol/(cm3.s) 1 I-hexene ethanol 98 96 3.47 2 1- hexene butanol 96 84 4.79 3 1- hexene heptanol 94 50 6.94 4b 1-decene ethanol 88 230 0.186 56 1-decene heptanol 94 0.711 208
n/iso ratio 1.04 1.41 2.54 1.13 4.54
OCatalyst HRh(CO)(PPhd3, 2.00 X lo4 mol/cms; 1-hexene, 8.00 X lo-' mol/cms; partial pressure of CO = partial pressure of Hz = 13.6 atm; temperature = 70 "C. 1-Decene, 5.23 X lo-' mol/cms; catalyst, 1.00 X lo4 mol/cms; temperature = 50 "C; partial pressure of CO = partial pressure of Hz = 13.6 atm.
observed. The results are presented in Table 11. The enhancement in rate was almost 2-fold when the solvent was changed from ethanol to heptanol. The selectivity toward the normal isomer also increased from 1.04 to 2.54 with a change in solvent. This effect is less pronounced compared to that with allyl alcohol. Similar results were obtained with 1-decenewas used as the substrate (Table 11). The normal/iso ratio increased from 1.13 in ethanol to 4.54 in 1-heptanol. Likewise the rate was also enhanced from 1.81 X 10-8 to 7.1 X 10-8mol/(cm%), a Cfold increase, as expected. The higher rates observed with increasing chain length of solvent alcohol are likely to be due to the electronic effects discussed above. Another factor that can affect the rates is the solubility of hydrogen in reaction media as the hydroformylation of allyl alcohol is linearly dependent on H2 concentration (Deshpande and Chaudhari, 1989). The solubility of H2in octanol was found to be marginally higher than in ethanol; for example, the solubility values for ethanol and octanol were 3.50 X 10" and 3.62 X 10-8mol/(cm3*atm),respectively, at 30 OC. Hence it can be concluded that the kinetic trend observed cannot be attributed to an enhancement in solubility of hydrogen. Conclusions The results obtained in hydroformylation of allyl alcohol as well as linear olefins (1-hexeneand 1-decene) indicate that both the hydrogen-bonding effect and the interaction at the metal center can cause a dramatic change in the activity and selectivity. However, these effecta need further investigations not only with different substrates (substituted and unsubstituted), but also using catalysts wherein different substituted phosphine derivatives are used, in order to fully explain the observed behavior.
w t m NO.I, 2671471-0; 11,38433-80-6; H2CSCHCH2OH,
107-18-6; HRh(CO)(PPh&, 17186-29-4; HzC..=CH(CH&CHS, 592-41-6; H&..=CH(CH2)7CHB, 872-05-9; OHC(CH2)&H3, 11171-7; OHC(CH.J&Ha, 112-44-7; H&CH(CHO)(CH.J&HS, 92554-2; HaCCH(CHO)(CHa),CH3, 19009-56-4.
Literature Cited Appleyard, C. J. S.; Gartahore, J. F. C. Manufacture of 1,4Butanediol at I. G. LUDWIGSHAFEN including manufacture of 1,4butanediol and tetrahydrofuran, precautions in handling acetylene, and semitechnical preparations of 1,4-butanediol. BIOS Rep. 1946, No. 22,367. Deshpande, R. M.; Chaudhari, R. V. Hydroformylation of Allyl alcohol Using Homogenous HRh(CO)(PPhs), Catalyst: A Kinetic Study. J. Catal. 1989,115,326. Evans, D.; Yagupsky, G.; Wilkinson, G. The Reaction of Hydridocarbonyl tris(tripheny1phoaphine)rhodium with Carbon Monoxide, and of the Reaction products, Hydridocarbonyl bis(triphenylphosphine) rhodium and Dimeric species, with hydrogen. J. Chem. SOC.,A 1968a, 2260. Evans, D.; Osbom, J. A.; Wilkinson, G. Hydroformylationof Alkenea by use of Rhodium Complex Catalyst. J. Chem. SOC.,A 1968b, 3133. Mataumoto, M.; Shimizu, T.; Moriya, S.; Fuchigami, Y.; Tsurumaru, H.; Tamura, M. 4-Hydroxybutyraldehyde. Japanese Patent 7866713, 1978a. Mataumoto, M.; Shimizu, T.; Moriya, S.; Fuchigami, Y.; Tsurumaru, H.; Tamura, M. Extraction of 4Hydroxybutyraldehvde. Jawese Patent 7868715, 1978b. Moeer, W. R.; Papile, C. J.; Brannon, D. A.; Duwell, R. A.; Weininger, S.J. The mechanism of phosphine Modified Rhodium Catalyzed Hydroformylation studied b y CIR-FTIR. J. Mol. Catal. 1987,41, 271. Pittman, C. U., Jr.; Honnick, W. D. Rhodium Catalyzed Hydroformylation of Allyl alcohol. A Potential Route to 1,4-Butanediol. J . Org. Chem. 1980,45, 2132. Shimizu, T. Butanediols. German Patent 2538364,1976. Smith, W. E. Butanediol or substituted butanediols. German Offen. 2758473, 1978. Tamura, M.; Kumano, S. New Process for l,4-butanediol via allyl alcohol. Chem. Econ. Eng. Rev. 1980, 12 (9), 32. Author to whom correspondence should be addreseed. NCL Communication No. 4906.
Raj M.Deshpande, Sunil 8. Divekar R a g h u r a j V. Gholap, Raghunath V. Chaudhari* Chemical Engineering Division National Chemical Laboratory f i n e 411 008, India Received for review September 27, 1990 Accepted February 14,1991
