Organic Compounds Containing Halogens Question 156
Question: 2-bromopentane is heated with potassium ethoxide in ethanol. The major product obtained is
[CBSE PMT 1998]
Options:
A) Pentene-1
B) cis pentene-2
C) trans pentene-2
D) 2-ethoxypentane
Show Answer
Answer:
Correct Answer: C
Solution:
$ CH_3-\underset{Br}{\mathop{\underset{|}{\mathop{CH}}}}-CH_2-CH_2-CH_3+KOH $
$ \underset{\begin{smallmatrix} Elimination \\ reaction \end{smallmatrix}}{\mathop{\xrightarrow{C_2H_5OH}}}\underset{\text{2-Pentene}}{\mathop{CH_3-CH=CH-CH_2-CH_3}} $ When alkyl halide reacts with alc. KOH then it favours elimination reaction (Dehydrohalogenation). Since, Trans pentene-2 is more symmetrical than cis isomers. Hence, it is main product.
BETA
