Propylene reductive carbonylation

Another commercial process, for 1-butanol production by reductive carbonylation of propylene with water, catalysed by Fe(CO)5, was developed by the Reppe group (eq. 1.4). 

Reductive carbonylation of alkenes occurs with Fe(CO)5. The water-gas-shift reaction catalysed by Fe(CO)5 generates H2 from water and CO as shown in eq. (7.1). CO is a reducing agent of water. 1 -Butanol had been produced once commercially by the reaction of propylene with CO in water catalysed by Fe(CO)5. The process was called Reppe butanol process. 

Well-defined arene complexes of Group 4 metals in various oxidation states have been isolated. The air- and moisture-sensitive complexes Ti(r -arene)2 (56) have a sandwich structure similar to that of the related chromium compounds [176-178]. They have been used for deoxygenation of propylene oxide and coupling reaction of organic carbonyl compounds [179]. The first synthesis of 56 was cocondensation of metal vapor with arene matrix [176]. Two more convenient methods are reduction of TiCl4 with K[BEt3H] in arene solvent [180] and reaction of TiCl4(THF)2 with arene anions followed by treatment with iodine [170,176]. The latter method involves the formation of an anionic titanate complex, [Ti(ri -arene)2] (57), which can also be formed from KH and 56 [181]. 

The Pd-catalyzed carbonylation proceeds through an oxidative addition-reductive elimination cycle in which the Pd oxidation state cycles between -I- 2 and 0. Thus, there is a tendency for Pd metal to drop out of the catalytic regime. Supported Pd catalysts would conceivably lock the metal in a fixed environment and minimize such losses. In fact, Pd/C and Pd/zeolites with HI or C3H7I as promoters have been employed to carbonylate ethylene and higher olefins in acetic acid. High conversions and yields are obtained at 10 MPa at a 2 3 ratio of CO propylene and a 1 1 ratio of H20 propylene at 100°C. 

In another vein, secondary amines prepared by the reductive amination of appropriate carbonyl compounds with methyl 12,14-dinitrodehydroabietate (Fig. 4.22) gave promising results when used as stabilizers against thermal, photochemical and oxidative degradation of low-density polyethylene and ethylene-propylene elastomers [114—116]. This active role is not surprising given the well-known fact that aromatic amines are excellent free radical traps. 

The direct evidence of this reaction mechanism is the observation of carbonyl stretching signature at -1,650 cm" in FTIR spectrum. The decomposition products from lithium salt were also found through the XPS surface analysis, such as alkoxides or oxides, a competition reaction between solvents and salts. However, the formation of alkyl carbonate seems to be predominant when EC is the component of electrolyte because of the more reactive nature of EC toward cathodic reductions [28]. The formation of lithium alkyl carbonate was also confirmed in an independent work, where the reduction products of EC in a supporting electrolyte were hydrolyzed by DjO and then subject to NMR analysis, which identified ethylene glycol as the major products formed, as indicated by the singlet at H spectrum [29]. Therefore, Aurbach and co-workers concluded the reduction products of EC and PC, lithium ethylene dicarbonate (LEDC) and lithium propylene dicarbonate (LPDC), respectively ... 

Carbonylation of Olefins. A catalyst, containing 5% Pd on active carbon exhibits high activity and selectivity in propylene carbonylation (14) (Table 2). The catalyst is prepared by soaking active carbon by H2PdCl4 solution further, H2PdCl4 is converted into Pd(OH)2 by precipitation with sodium carbonate, with subsequent reduction of Pd(II) to Pd(0) by molecular hydrogen at room temperature. The carbonylation reaction is carried out under static conditions in... 

To circumvent die problem of carbonyl reduction during the 16 11 convmion, 16 was converted to its ethylene ketal 16a (Scheme 3). Mild acid hydrolysis of 17a achieved hydrolysis of the enamine, but not of ibt ketal, and, in fact, hydrolysis of the product 11a required such forcing conditions that aromatization became a conqieting reaction, producing the hydroquinone derivative 18. In contrast, both the enamine and ketal functionalities of the propylene ketal 17b were smoothly hydrolyzed with mild acid to provide the target ketone 11. 

---