The three isomers constituting n-butenes are l-butene, cis-2-butene, and
trans-2-butene. This gas mixture is usually obtained from the olefinic C4
fraction of catalytic cracking and steam cracking processes after separation
of isobutene (Chapter 2). The mixture of isomers may be used directly for
reactions that are common for the three isomers and produce the same intermediates
and hence the same products. Alternatively, the mixture may be
separated into two streams, one constituted of l-butene and the other of cisand
trans-2-butene mixture. Each stream produces specific chemicals.
Approximately 70% of l-butene is used as a comonomer with ethylene to
produce linear low-density polyethylene (LLDPE). Another use of l-butene
is for the synthesis of butylene oxide. The rest is used with the 2-butenes to
produce other chemicals. n-Butene could also be isomerized to isobutene.