A process comprising: forming a mixed C 4 metathesis feed stream by: obtaining a mixed C 4 stream containing 5-50 wt. % or 10-30 wt. % 1-butene, 5-50 wt. % or 10-30 wt. % 2-butene, 5-70 wt. % or 10-60 wt. % isobutylene and 0-25 wt. % butane based on 100 wt. % of 1-butene, 2-butene, isobutylene and butane, removing at least a portion of the 2-butene from the mixed C 4 stream thereby producing an isobutylene-containing stream and a 2-butene-containing stream, isomerizing the removed portion of the 2-butene in the 2-butene-containing stream in an isomerization reactor to obtain additional 1-butene, and combining the additional 1-butene with the isobutylene-containing stream to form the mixed C 4 metathesis feed stream; reacting the mixed C 4 metathesis feed stream in the presence of a first metathesis catalyst to produce an intermediate product stream comprising 2-methyl-2-pentene and at least one of ethylene and propylene, fractionating the intermediate product stream to form a 2-methyl-2-pentene stream and at least one of an ethylene stream and a propylene stream, subjecting the separated 2-methyl-2-pentene stream to pyrolysis to produce a reaction product stream comprising isoprene, and separating the isoprene to form an isoprene product stream using fractionation. forming a mixed C 4 metathesis feed stream by: obtaining a mixed C 4 stream containing 5-50 wt. % or 10-30 wt. % 1-butene, 5-50 wt. % or 10-30 wt. % 2-butene, 5-70 wt. % or 10-60 wt. % isobutylene and 0-25 wt. % butane based on 100 wt. % of 1-butene, 2-butene, isobutylene and butane, removing at least a portion of the 2-butene from the mixed C 4 stream thereby producing an isobutylene-containing stream and a 2-butene-containing stream, isomerizing the removed portion of the 2-butene in the 2-butene-containing stream in an isomerization reactor to obtain additional 1-butene, and combining the additional 1-butene with the isobutylene-containing stream to form the mixed C 4 metathesis feed stream; obtaining a mixed C 4 stream containing 5-50 wt. % or 10-30 wt. % 1-butene, 5-50 wt. % or 10-30 wt. % 2-butene, 5-70 wt. % or 10-60 wt. % isobutylene and 0-25 wt. % butane based on 100 wt. % of 1-butene, 2-butene, isobutylene and butane, removing at least a portion of the 2-butene from the mixed C 4 stream thereby producing an isobutylene-containing stream and a 2-butene-containing stream, isomerizing the removed portion of the 2-butene in the 2-butene-containing stream in an isomerization reactor to obtain additional 1-butene, and combining the additional 1-butene with the isobutylene-containing stream to form the mixed C 4 metathesis feed stream; reacting the mixed C 4 metathesis feed stream in the presence of a first metathesis catalyst to produce an intermediate product stream comprising 2-methyl-2-pentene and at least one of ethylene and propylene, fractionating the intermediate product stream to form a 2-methyl-2-pentene stream and at least one of an ethylene stream and a propylene stream, subjecting the separated 2-methyl-2-pentene stream to pyrolysis to produce a reaction product stream comprising isoprene, and separating the isoprene to form an isoprene product stream using fractionation.