Question

IUPAC name of the some alkenes are given below. Find out the correct stability order.
A. 2-Methylbut-2-ene
B. cis-But-2-ene
C. 2,3-Dimethylbut-2-ene
D. Prop-1-ene
Choose the correct answer from the options given below :

• A. C >A >B >D
• B. C >A >D >B
• C. B >D >A >C
• D. A > B > C > D

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The stability of alkenes is primarily determined by the degree of substitution at the double bond. According to Saytzeff's rule and hyperconjugation, more substituted alkenes are generally more stable. 
Step 2: Detailed Explanation: 
Stability increases with the number of $\alpha$-hydrogens (hyperconjugative structures). 
C. 2,3-Dimethylbut-2-ene: $(CH_3)_2C=C(CH_3)_2$. It is tetra-substituted and has 12 $\alpha$-H. (Most stable). 
A. 2-Methylbut-2-ene: $(CH_3)_2C=CHCH_3$. It is tri-substituted and has 9 $\alpha$-H. 
B. cis-But-2-ene: $CH_3CH=CHCH_3$. It is di-substituted and has 6 $\alpha$-H. 
D. Prop-1-ene: $CH_3CH=CH_2$. It is mono-substituted and has 3 $\alpha$-H. (Least stable). 
Order: C >A >B >D. 
Step 3: Final Answer: 
The stability order is C >A >B >D.