Hydroformylation of allyl alcohols

Ma.nufa.cture. Most butanediol is manufactured in Reppe plants via hydrogenation of butynediol. Recendy an alternative route involving acetoxyiation of butadiene has come on stream and, more recendy, a route based upon hydroformylation of allyl alcohol. Woddwide butanediol capacity has climbed steadily for many years. In 1990 it was estimated to be 428,000 metric tons (141), as compared to a Htde more than 70,000 metric tons in 1975... 

Selectivity refers to the fraction of raw material alkene that is converted to product aldehyde, but since hydroformylation typically gives both a linear and branched isomer, selectivity also refers to the relative amounts of each. The linear branched (l b) ratio is highly catalyst dependant. One must simultaneously consider whether the proposed catalyst will give the desired l b selectivity and also whether the proposed catalyst is feasible for use with the catalyst/product separation technologies. For example, water extraction of a polar product, such as in the hydroformylation of allyl alcohol to give 4-hydroxybutanal, would not work well with a sodium salt of a sulfonated phosphine since both are water soluble. 

The desired product in the hydroformylation of allyl alcohol is 4-hydroxybutanal. As with other alkenes, hydro formylation gives both a linear and a branched isomer (Equation 2.1). 

Another route to the diol monomer is provided by hydroformylation of allyl alcohol or allyl acetate. Allyl acetate can be produced easily by the palladium-catalyzed oxidation of propylene in the presence of acetic acid in a process similar to commercial vinyl acetate production. Both cobalt-and rhodium-catalyzed hydroformylations have received much attention in recent patent literature (83-86). Hydroformylation with cobalt carbonyl at 140°C and 180-200 atm H2/CO (83) gave a mixture of three aldehydes in 85-99% total yield. 

Industrial hydroformylation of allyl alcohol employs [RhH(CO)(PPh3)3] as catalyst (Kuraray see also 4.1.1.4). In an aqueous solution K[Ru(EDTA-H)C1] catalyzed both the water gas shift and hydroformylation under 10 bar CO at 100-130 °C. The major product was y-hydroxybutyraldehyde (35%) but large amounts of y-butyrolactone and dihydroftiran were also produced [151]. 

Hydroformylation. Hydroformylation of allyl alcohol is a synthetic route for producing 1.4-bulanediol. a raw material for poly(butylene terephthalate). an engineering plastic. 

An alternative route involving acetoxylation of butadiene and has come on stream, and, more recently, a route based upon hydroformylation of allyl alcohol has also been used. Another process, involving chlorination of butadiene, hydrolysis of the dichlorobutene, and hydrogenation of the resulting butenediol, has been practiced. 

ARCO An intermediate for 1,4-butanediol Rhodium catalyst with chelating phosphorus ligand hydroformylation of allyl alcohol followed by hydrogenation of the resultant aldehyde Reaction 5.9... 

Matsumoto and Tamura (at Kuraray Co.) have demonstrated that the combination of simple bis(diphenylphosp-hino)alkane ligands and PPhs has a very positive effect on catalyst stabihty and the reduction of unwanted side reactions. This is most evident in the hydroformylation of a reactive alkene substrate such as allyl alcohol. The use of HRh(CO)(PPh3)2 in the presence of excess PPhs leads to relatively rapid catalyst deactivation to unidentified species. The addition of just over 1 equivalent of dppb, for example, leads to a stable, active hydroformylation catalyst. Use of dppb either by itself, or in quantities higher than 2 equivalents, leads to catalyst deactivation and/or poor activities and selectivities. ARCO Chemical Co. licensed the Kuraray technology to build the first conunercial plant (1990) for the hydroformylation of allyl alcohol to produce 1,4-butanediol (Scheme 11). 

The same catalyst precursor, generated from [(EDTA)RuCI] which is also water soluble, was used for the hydroformylation of allylic alcohol under the same reaction conditions (//). At 50 bar and 130°C, in water as solvent, 4-hydroxybutanal was produced [Eq. (5)], together with about 2% of formaldehyde. However, the reaction proceeded further to give butane-1,4-diol by hydrogenation and y-butyrolactone as well as dihydrofuran by cyclization [Eq. (6)]. The same catalytic cycle as that proposed in Scheme 3 can be considered. A kinetic investigation revealed a first-order dependence on the ruthenium complex concentration and on the allyl alcohol... 

The kinetics of the new commercial process of hydroformylation of allyl alcohol was studied by Chaudhari in the temperature range from 60 to 80 °C [114]. The rate of reaction is first order in catalyst concentration and 1.5th order in hydrogen partial pressure. The dependence on p CO) does not differ from that observed in the hydroformylation of nonfunctionalized olefins. The reaction is retarded at higher substrate concentrations (> 1.25 mol/L). This substrate inhibition is not fully understood on the molecular level. The apparent activation energy for the oxo reaction of allyl alcohol was found to be 94 kJ/mol. 

The kinetics of the above-mentioned biphasic hydroformylation of allyl alcohol (see eq. (6)) were described by the rate eq. (12) [20]... 

Hydroformylation of allyl alcohol HRh(CO)(PPh3)3 G-L-L/organic phase catalysis [10]... 

ORTHO-DIPHENYLPHOSPHANYLBENZOYL-(o-DPPB) DIRECTED DIASTEREOSELECTIVE HYDROFORMYLATION OF ALLYLIC ALCOHOLS... 

The second step is the hydroformylation of allyl alcohol to 4-hydroxybutyr-aldehyde. This reaction is discussed further in section II.B of Chapter 7. The chemical reaction is illustrated in Eq. (24) ... 

Chemistry. The hydroformylation of allyl alcohol is illustrated in Eq. (58). The catalyst is a rhodium complex modified with triphenylphos-phine of the same type used for production of n-butyraldehyde from propylene in the oxo process. The reaction takes place in a toluene solution at approximately 2-3 atm pressure (15-30 psig) and 60°C (140 F). The conversion to 4-hydroxybutyraldehyde is 98% based on allyl alcohol with a selectivity of 79.1%. 

Related Rh systems have also been used for the hydroformylation of allyl alcohol. The competing isomerization to propionaldehyde was dependent on the presence of aluminium in silica supports and also on the Rh concentration. This could be suppressed by using supports with a very low A1 content and phosphine-rich Rh complexes. Operating at 88-108 °C and 0.1-0.4 MPa, propionaldehyde and 4-hydroxybutyraldehyde were the only products observed. This SLPC system was more active for the hydroformylation of allyl alcohol than for propene by a factor of 10-30. Similar trends have been observed earlier for homogeneous systems. ... 

This concept has been extended to the hydroformylation of allyl alcohol in an aqueous phase and of the [Rh(H)(CO)(PPh3)3] complex in toluene in the presence of small amounts of TPPTS, which increases notably the rate of the reaction [62]. 

Propylene-Based Process Hydroformylation of Allyl Alcohol... 

An alternative route to generate 1,4-butanediol is via the hydroformylation of allyl alcohol. This method was commercialized by LyondellBasell Industries and Dairen Chemical Corporation. Allyl alcohol is produced to isomerize propylene oxide derived from propylene over a lithium phosphate catalyst. Hydroformylation is performed to form 4-hydroxybutyraldehyde (Eq. (10.6)) followed by hydrogenation using Raney Ni catalyst to form 1,4-butanediol (Eq. (10.7)). The patent of Dairen Chemical showed 93% allyl alcohol conversion and 67% 1,4-butanediol selectivity and 31% 2-methyl-propanediol selectivity [7aj. 

The high rate of hydroformylation of allyl alcohol in Table 10 could also involve some stabilization of intermediate alkyl complexes by 17 electron donation from the oxygen. 

Allylic alcohols are versatile substrates for hydroformylation. Hydroformylation of allyl alcohol typically favors the linear regioisomer, and this reaction formed the basis of a route to manufacture 1,4-butanediol [15]. Landis recently reported the use of a chiral diazaphospholane for the asymmetric hydroformylation of aUyl silyl ethers [16]. The TBDMS aUyl ether, formed from reaction of allyl alcohol with TBDMSCl, was hydroformylated in 96%ee and 2 1 branched/linear to give the Roche aldehyde (12) which is a widely used chiral building block. High molar substrate/catalyst ratios (10,000 1) and low syngas pressures (15 psi) make this reaction potentially attractive for commercial development. 

Pittman CU, Honnick WD (1980) Rhodium-catalyzed hydroformylation of allyl alcohol. A potential route to 1,4-butanediol. J Org Chem 45 2132-2139... 

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