Systems and processes for the production of a high purity isobutylene stream, a high purity isooctene stream or for the co-production of a high purity isobutylene and a high purity isooctene. The systems and processes advantageously process mixed C4 hydrocarbon streams via etherification, back cracking, isomerization, and/or dimerization, along with various separation systems, to produce the desired high purity streams.