Isobutene tetramer

Recently we examined the possibility of selectively synthesizing the isobutene tetramer (IB4.) and trimer (IB3) by the reaction of two isobutene dimers (IBj) or isobutene dimer with isobutene (IB), respectively ... 

The second stage in the process is required because the MTBE formation is an equilibrium reaction. The temperature needed ( 100°C) to achieve a sufficiently high rate of conversion means a decrease in isobutene equilibrium conversion (XiB = 0.9 at 65°C, Xjb = -0.75 at 100°C). The main side reaction in the MTBE process is the dimerization of isobutene towards di-isobutene (two isomers). Side reactions with essentially no significance are the formation of f-butyl alcohol (due to the presence of water as feed impurity), the formation of dimethyl ether from methyl alcohol, and the oligomerization of isobutene towards tri- and tetramers. A (three stage) process is also in operation which tolerates butadiene. The butadiene/ methyl alcohol reaction is faster than that of the n-butenes but consider-... 

Fig. 7. MWD of oligomers obtained from diisobutene (IB2) with CF3SO3H or EtAlClj in CCI4 at 0 °C IB2]o = 10 vol %. IB4 and IBg indicate tetramers and hexamers of isobutene, respectively...

With vinyl monomers other than isobutene, attempts to prepare selectively trimers or tetramers from linear dimers have been unsuccessful thus far. The linear dimer of styrene (7) was expected to give an unsaturated tetramer 27, when dimerized by an 0x0 acid (Eq. (23)). However, the oligomerization of 1 with CF3SO3H or AcClO in benzene at 50 °C resulted in a mixture of oligomers with cyclic terminals, consisting... 

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