Hydrogenation of 1,5-Cyclooctadiene COD

The isomerization of 1,5-COD to 1,3- or 1,4-COD as reported for hydrogenation on Ir [1] can be excluded for the Ni catalyst used A test in N2 (to suppress hydrogenation) gave no evidence of 1,3- or 1,4-COD formation [52]. The yield of trans-COE is lower than the yield of ds-COE by a factor of more than 20, and the rates of the subsequent hydrogenation of the intermediates dx- and trans-COE to COA were found to be equal [52]. Therefore, both COE isomers are subsequently treated as one pseudo-component COE. 

This strong influence of the IL layer on selectivity cannot be explained by the influence of the IL on the effective concentrations of COD and COE compared to the uncoated catalyst For two first-order reactions occurring in series in a porous catalyst (here hydrogenation of COD to COE and to COA), the maximum yield of the intermediate COE in the absence of any mass transfer resistances (//po e = V 

For a given particle size of 30-50 pm, the influence of pore diffusion on selectivity can be excluded, as proved by additional experiments discussed in Section 14.4.2.4. On the basis of our current knowledge, the only plausible explanation is that the IL changes the chemical properties of the Ni catalyst and acts as a cocatalyst, for example, by the hindrance of the (re) adsorption of COE (or hydrogen) on the active Ni sites. 

Besides [BMIM][OcS04], other ILs were also tested for the SCILL concept and the model reaction of COD hydrogenation (Table 14.2). Three of them are liquids at the reaction temperature of 50 °C ([BMIMjlMeSO ], [BMIM BF ], and [TBA][C1]) 

8 mol m (0.1 wt% in /i-dodecane), p 2) = 50 bar). (Reproduced from [53] with kind permission ofWiley-VCH Verlag GmbH. Co. KGaA). 

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The partial hydrogenation of multiple bonds includes chemical reactions of industrial interest for example, the partial hydrogenation of benzene to cyclohexene used to synthesize several compounds, from which the main is nylon production, the partial hydrogenation of 1,5-cyclooctadiene (COD) to cyclooctene (COE), which is an important industrial intermediate product for manufacturing special polymers such as poly-octenamers via ring-opening metathesis polymerization, which is used as a modifier in mbbers and thermoplastics (Sato, Aoki, Noyori, 1998 Rylander, 1985 Schmidt Schomacker, 2007). 

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