Question

2-bromopentane is heated with postassium ethoxide in ethano1 The major product obtained is .
A. Pentene-1
B. cis pentane-2
C. trans pentene-2
D. 2-ethoxypentane

Answer 1

Correct Answer - C
`CH_(3)-underset(Br)underset(|)(CH)-CH_(2)-CH_(2)-CH_(3)+KOH underset("Elimination in reaction")overset(C_(2)H_(5)OH)tounderset("2-pentene")(CH_(3)-CH)=CH-CH_(2)-CH_(3)`
When alkyl halide reacts with alc. KOH then it favours elimination reaction (Dehydrohalogenation). Since, trans pent-2-ene is more symmetrical tha cis isomer. Hence, it is main product.