Hydroformylation 1,3-butadiene

The interest in 1,3-butadiene hydroformylation is the atom-efficient green route for producing /1, y-unsaturated aldehyde and 1,6-hexanedial (adipaldehyde), which is a valuable precursor for producing a-caprolactam and adipic acid/hexamethylene-1, 6-diamine (HMDA) as key monomers in nylon-6 and nylon-6,6 manufacture. 

The first systematic B3LYP DPT investigation into the complete catalytic cycle of 1,3-butadiene hydroformylation using HCo(CO)3 as active catalyst was reported by Huo et al. [78]. It was found that the coordinatimi mode of 1,3-butadiene to HCo (CO)3 is similar to that of propene [55]. The most stable structure has the C=C bond perpendicular to the H-Co bond (10), and butadiene moiety can rotate freely with the rotation barrier of 23.8 kJ/mol in free energy, while the structures with the C=C bond parallel to the H-Co bond facilitate the subsequent insertion reaction leading to Markoviukov alkyl complex (11a) or anti-Markovnikov alkyl complex (11b), as shown in Scheme 14 (the relative free energies are based on HCo(CO)3, butadiene, CO, and H2, scaled at 403 K and 200 atm.). 

Direct hydroxycarbonylation can be advantageous with respect to the more traditional approach of butadiene hydroformylation to yield 1,6-hexanedial (adipal-dehyde), via intermediate pentenal, catalyzed by a metal organophosphorus ligand complex catalyst [32i]. In this latter process, the dialdehyde can either be transformed into e-caprolactone [32j] or oxidized to AA. 

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... 

The chemo- and regioselectivities of hydroformylation reactions of open chain, conjugated dienes using the usual catalyst are, in most cases, rather low [36]. The rhodium/ mesitylene co-condensate (catalyst A), in the presence of bis(diphenylphosphino)ethane, DPPE, catalyses the hydroformylation of 1,3-butadiene, isoprene, and E,Z)-, 3-pentadiene to the corresponding p,y-unsaturated monoaldehydes, with unusually high chemo- and regioselectivities (Scheme 17). 

The results obtained are reported in Table 5. Under the hydroformylation conditions, 1,3-butadiene is converted... 

A method to reduce degradation/deactivation of a phosphite modified rhodium hydroformylation catalyst in the separation system involves feeding a diene such as butadiene to the vaporizer to convert the phosphite-modified rhodium catalyst to a more stable form. [34] In the reactor, the diene is hydrogenated and catalyst activity is restored. 

Hydroformylation comprises the state-of-the-art of bulk chemical production via aqueous-biphasic processes. At present five plants produce worldwide some 800,000 tpy of oxo products [1], Another bulk process - the hydrodimerization of butadiene and water, a variant of telomerization - is mn by Kururay with a capacity of 5000 tpy (Equation 5.2 [3 lb,36]). 

A wide variety of new approaches to the problem of product separation in homogeneous catalysis has been discussed in the preceding chapters. Few of the new approaches has so far been commercialised, with the exceptions of a the use of aqueous biphasic systems for propene hydroformylation (Chapter 5) and the use of a phosphonium based ionic liquid for the Lewis acid catalysed isomerisation of butadiene monoxide to dihydrofuran (see Equation 9.1). This process has been operated by Eastman for the last 8 years without any loss or replenishment of ionic liquid [1], It has the advantage that the product is sufficiently volatile to be distilled from the reactor at the reaction temperature so the process can be run continuously with built in product catalyst separation. Production of lower volatility products by such a process would be more problematic. A side reaction leads to the conversion of butadiene oxide to high molecular weight oligomers. The ionic liquid has been designed to facilitate their separation from the catalyst (see Section 9.7)... 

Butadiene, the simplest conjugated diene, appears to be a promising substrate for the hydroformylation reaction, because the expected product (hexanedial) could be easily converted to useful products. Oxidation would produce adipic acid, hydrogenation hexanediol, and reductive amination hexamethylenediamine. However, this objective has been difficult to realize. 

Cobalt hydroformylation of butadiene produced low yields (24%) of an equimolar mixture of n- and isovaleraldehyde (40). It has been established that the cobalt hydrocarbonyl adds to form a stable 7r-allyl complex (93, 94). 

A two-stage process for the hydroformylation of butadiene to give good yields of a desired product—1,6-hexanediol—has been described (100). The first stage employed [(C6H5)3P]2Rh(CO)Br and excess triphen-ylphosphine as catalyst and reaction conditions of I20°C and 200 atm of 1/1 H2/CO in methanol as solvent. The principal product was 3-penten-l-al dimethyl acetal. This was treated with 1,3-propanediol to form a cyclic acetal, then hydroformylated with Co2(CO)8 and dodecyl-9-phospha-9-bicyclononane at 170°C and 80-110 atm of 2/1 H2/CO. The product of... 

For this reaction, the early investigations of Reppe pointed out the need for catalyst precursors to operate at high pressure [2], It is necessary to work at 150-300 bar of CO in order to stabilize the two catalytic species [Co(H)(CO)4] or [Ni(H)(X)(CO)2] that adopt a mechanism analogous to the cobalt-catalyzed hydroformylation [44,45]. Many industrial applications have been reported [28,46,47] for the synthesis of plasticizers and detergents. Similarly, the two-step methoxycarbonylation of 1,3-butadiene has been explored by BASF and other companies to produce dimethyl 1,6-hexanedioate (adipate) directly from the C4 cut [28,48]. The first step operates at 130 °C and... 

The new recycling concept was apphed to several C - C bond-forming reactions, for example, to the telomerization of butadiene with ethylene glycol or carbon dioxide, to the isomerizing hydroformylation of frans-4-octene and to the hydroamino-methylation of 1-octene with morpholine. 

Hydroformylation of Other Lower Olefins and Dienes - Lower olefins such as 1-butene or 1,3-butadiene are hydroformylated with acceptable rates using Rh/tppts catalysts according to the RCH/RP process. Hoechst AG Werk Ruhrchemie has developed an attractive new process350 for the hydroformylation of raffinate II, a mixture of 1-butene, cis- and /rbutane derived from the C4 stream of naphtha crackers (after removal of 1,3-butadiene... 

On the industrial level, aqueous two-phase systems are used more often than nonaqueous two-phase systems. The Kuraray Co. operates a pilot plant for the hydrodimerization of 1,3-butadiene in a two-phase system with a Pd/tppms catalyst (140). The reaction is carried out in sulfolane-water, from which the products, the octadienols, separate. The final products can be octanol or nonanediol made by subsequent isomerization and hydroformylation. The capacity of the Kuraray process is about 5000 tons/year. 

Since conjugated dienes form stable rc-allyl complexes with [Co(CO)4]2, they undergo hydroformylation very slowly to give saturated monoaldehydes in low yields.8 Mixtures of mono- and dialdehydes are usually formed in rhodium-catalyzed hydroformylations.71 72 Saturated monoaldehydes were isolated, however, when 1,3-butadiene and 1,3-pentadiene were hydroformylated in the presence of rhodium dioxide.70... 

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