Synthesis of Isoamylene via Olefin Disproportionation

Abstract

rates of all the isomerization reactions; the cis-and transisomers are simply indicated as lumped in Equation 4. The important result here is that the secondary isomerization step (Equation 4) is not immeasurably fast compared with the primary dealkylation step (Equation 3), but rather the rates are commensurable under the conditions of ester dealkylation over an acidic catalyst. The rate constants measured by the slopes of the lines in Figure 3 pertain to ky in Reaction 3, since all the butenes are lumped in the computation of conversion.If the simplified schematic indicated by Equations 3 and 4 is correct, we may expect in general that different activation energies would characterize the two reactionsfor example, Hightower et al. (1967) on the isomerization kinetics of 1-butene over fluorided alumina. If this occurs, the extent of secondary isomerization would be different at the two temperatures, for a given conversion. Our data bear out this expectation, although the effect is not great. At a conversion of about SOU, for example, the butenes produced at 178.5°C contained about 26' --butene; for the same conversion at 189°C they contained about 33'7 1-butene. A similar, small difference was

Synthesis of Cyclohexene, Cyclohexadiene, and Benzene via Disproportionation of Butadiene over Tungsten Oxide-Silica Catalyst

“…A continuous-flow system similar to those described previously (Heckelsberg, et al, 1969;Banks and Regier, 1971) was used for the diene disproportionation tests. The fixed-bed reactor was constructed from a 15-in.…”

Catalytic Metathesis of Alkenes

“…Dolgoplosk [147] carried out a systematic study of reactions occurring between typical compounds of active metathesis catalyst systems. For instance, he observed that in a mixture of WC1 6 and CD3Li the gas phase after 2 h reaction contained CD 4 , CD 3 -CD 3 and C 2 D 4 • In a number of cases he observed that the amount of CD 4 exceeded considerably the value that should be expected from equations (48) and (49). This led him to the conclusion that also carbyne and carbide species are formed.…”

“…An example is the synthesis of isopentene, a precursor of (poly)isoprene and a high-octane fuel component, via the metathesis of a mixture of isobutene and 2-butene (or propene) [6]:…”

“…For instance, for the metathesis of unsaturated esters WC1 6 -SnR4 (R = alkyl), WOC1 4 -SnMe 4 and WOC1 4 -CP2 TiMe2 are the most active and selective catalysts, hardly any other homogeneous system has been found to possess comparable catalytic properties [32]. It is interesting that catalysts consisting of the combination WC1 6 -SnMe 4 and WOCl 4 -SnMe 4 exhibit about the same activity for the metathesis of methy oleate, which suggests that the ester converts WC1 6 to WOCI 4 , the precursor of the active intermediate [98]. Other combinations, such as WC1 6 and organoaluminum compounds, which are highly active for the metathesis of simple alkenes, are mostly inactive for functionalized alkenes.…”

“…It is interesting that catalysts consisting of the combination WC1 6 -SnMe 4 and WOCl 4 -SnMe 4 exhibit about the same activity for the metathesis of methy oleate, which suggests that the ester converts WC1 6 to WOCI 4 , the precursor of the active intermediate [98]. Other combinations, such as WC1 6 and organoaluminum compounds, which are highly active for the metathesis of simple alkenes, are mostly inactive for functionalized alkenes. When effective they are less selective due to their Lewis acidity, resulting in double-bond isomerization and subsequent (undesired) metathesis reactions.…”