Ethylene carbonylations

Ethylene Carbonylation. The classical rhodium catalyzed carbonylation of ethylene to propionic acid (Eqn. 1) used ethyl iodide or HI as a co-catalyst (6). In the presence of excess ethylene and CO the process could proceed further to propionic anhydride (Eqn. 2). While additional products, such as ethyl propionate (EtC02Et), diethyl ketone (DEK), and ethanol were possible (See Eqns. 3-5), the only byproduct obtained when using a rhodium-alkyl iodide catalyst was small amounts (ca. 1-1.5%) of ethyl propionate. (See Eqns. 3-5.)... 

It appeared that, we needed to limit or omit the ethyl iodide if we were going to operate the ethylene carbonylation in ionic liquids. Unfortunately, the previous literature indicated that EtI or HI (which are interconvertible) represented a critical catalyst component. Therefore, it was surprising when we found that, in iodide based ionic liquids, the Rh catalyzed carbonylation of ethylene to propionic acid was still operable at acceptable rates in the absence of ethyl iodide, as shown in Table 37.2. Further, we not only achieved acceptable rates when omitting the ethyl iodide, we also achieved the desired reduction in the levels of ethyl propionate. More importantly, when the reaction products were analyzed, there was no detectable ethyl iodide formed in situ. However, we should note that we now observed traces of ethanol which were normally undetectable in the earlier Ed containing experiments. 

Methanol Carbonylation without Mel. While resolving the selectivity issue in ethylene carbonylation was exciting, the observations indicating that the reaction was likely proceeding via a nncleophihc reaction between Rh and the ionic liqnid and did not require EtI provided an even more exciting opportnnity. If a nncleophihc mechanism is operahve, it is likely that we conld extend the technology to the much more commercially important carbonylahon of methanol. 

The rhodium catalyzed carbonylation of ethylene and methanol can be conducted in the absence of added alkyl halide if the reactions are conducted in iodide based ionic liquids or molten salts. In the case of ethylene carbonylation, the imidazolium iodides appeared to perform best and operating in the absence of ethyl iodide gave improved selectivities relative to processes using ethyl iodide and ionic hquids. In the case of... 

Organic constituents that may be found in ppb levels in WP/F smoke include methane, ethylene, carbonyl sulfide, acetylene, 1,4-dicyanobenzene, 1,3-dicyanobenzene, 1,2-dicyanobenzene, acetonitrile, and acrylonitrile (Tolle et al. 1988). Since white phosphorus contains boron, silicon, calcium, aluminum, iron, and arsenic in excess of 10 ppm as impurities (Berkowitz et al. 1981), WP/F smoke also contains these elements and possibly their oxidation products. The physical properties of a few major compounds that may be important for determining the fate of WP/F smoke in the environment are given in Table 3-3. 

Stannyl anions with a highly coordinated tin center are also known. A hydridostannyl anion in the shape of a trigonal bipyramid in which two iodine atoms occupy the apical positions was obtained by oxidative addition of lithium iodide to the corresponding tin hydride (equation 58) . It was characterized by Sn NMR. Since apical iodines are more nucleophilic than the hydrogen, in its reactivity with a-ethylenic carbonyl compounds, attack by iodine precedes reduction by hydrogen, achieving regioselective 1,4 reductions. 

Iridium complexes containing triphenylphosphine, e.g., HIr(CO)2(PPh3)2, in propionic acid catalyze ethylene carbonylation to propionic anhydride . Reaction occurs at a reasonable rate at 195°C and 5 Pa of CO/ethylene pressure. The corresponding Rh complexes are ineffective. The reaction is inoperative with higher olefins, even propylene. 

Isomerisation of a-acetylenic alcohols into a,P-ethylenic carbonyl derivatives in vapor phase... 

The rearrangement of a-acetylenic alcohols into a-p ethylenic carbonyl derivates has been extensively studied. Different catalysts have been proposed acid catalysts such as sulfuric, hydrochloric or acetic acids which give rise to unselective rearrangements [1,2] and more recently, oxo derivatives of vanadium, molybdenum or tungsten in liquid phase [3]. 

Propionic acid represents the basic product of ethylene carbonylation in the presence of Pd/C catalyst and HI, HBr, and C2H5I promoters (14). Simultaneously, small quantities of ethyl ester of propionic acid and diethyl ketone are formed. A 15-fold increase of Pd content supported on carbon (from 0.1 to 1.5%) results in a 2-fold decrease in the reaction time (Table 4). A further increase of Pd content from 1.5 to 10% does not influence the rate of the reaction. Pd/C catalysts exhibit high stability. The activity and selectivity of a 10% Pd/C catalyst does not change after 10 successive cycles of carbonylation. 

Table 4. Influence of Pd Content in Pd/C Catalyst on Ethylene Carbonylation ...

On the other hand, new processes are being researched, such as i) the named Alpha process via ethylene carbonylation to methyl propionate, very similar to the aforementioned BASF route ii) the one-step method of propyne catal3dic carbonylation and iii) direct oxidation of isobutane to methacrolein or methacrylic acid. The use of isobutyraldehyde and isobutyric acid as feedstocks has also been explored. Among all these methods, the one employing the alkane in a one-step reaction to form methacrylic acid is the most simple and interesting process from both... 

Conjugate addition of cis- or /ra 5-l-alkenyl-lithium cuprates (R—CH= CH—jgCuLi to a/5-unsaturated carbonyl compounds also occurs with high retention of double-bond geometry, affording isomerically pure cis- or trawj-yd-ethylenic carbonyl compounds (Scheme 20). ... 

Bis(dimethylphenylphosphine)(ethylene)(carbonyl)dichlororuthenium is the first example of a six-co-ordinate complex containing ethylene as a ligand which has been studied by X-ray crystallography (18). The ethylenic double bond is closely parallel to the Ru—P bonds the Ru—C(ethylene) distance is 2.214(4) A and C=C is 1.376(10) A. The analysis indicates that the ethylene is possibly non-planar with the hydrogen atoms bent away from the metal. 

Polyketones can be sulfonated by reaction with chlorosulfonic acid the products are chemically reactive and are useful as strongly acidic esterification catalysts and ion-exchange resins. The sulfonation of ethylene-carbonyl copolymer was achieved by treatment of the substrate with chlorosulfonic acid in dichloroethane at 0 C. " ... 

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