Question

What do you predict will be the order of reactivity of the following alkenes: 1-butene, (E)-2-butene, (Z)-2-butene, or 2-methylpropene? Please list them from most reactive to least reactive.

a) (E)-2-butene, 2-methylpropene, 1-butene, (Z)-2-butene
b) (E)-2-butene, 1-butene, (Z)-2-butene, 2-methylpropene
c) 2-methylpropene, 1-butene, (E)-2-butene, (Z)-2-butene
d) 2-methylpropene, (Z)-2-butene, 1-butene, (E)-2-butene

Answer 1

The most reactive alkene among those given is 2-methylpropene, followed by (Z)-2-butene, 1-butene, and lastly (E)-2-butene, due to factors like substitution and steric accessibility.

Step-by-step explanation:

The order of reactivity of the alkenes given: 1-butene, (E)-2-butene, (Z)-2-butene, and 2-methylpropene (isobutene), can be predicted based on their structures and the stability of their intermediates during reactions such as addition reactions.

The reactivity of alkenes in addition reactions generally follows this trend: the more substituted the double bond, the more stable the intermediate carbocation will be, leading to higher reactivity. When comparing (E)- and (Z)-2-butene, the (Z)-isomer is usually more reactive due to steric and electronic factors that make the double bond more accessible to reagents. The presence of alkyl groups also increases reactivity by providing electron donation through hyperconjugation.

Therefore, the order of reactivity from most to least reactive is likely 2-methylpropene, (Z)-2-butene, 1-butene, and finally (E)-2-butene. So, the correct answer is option (d).