Question

Which of the following order(s) is/are correct?

• A. Dipole moment:
  
  
• B. Stability of free radical:
  
• C. Basic strength: $C{H}_3{O}^{\ominus }>\stackrel{\ominus }{O}H>R{S}^{\ominus }$
  
• D. Basic and nucleophilic strength: $I^{\ominus }>B{r}^{\ominus }>C{l}^{\ominus }>F^{\ominus }$

Answer 1

Answer: (A), (B)

Stability of free radical:


The smaller the angle, the larger the dipole moment, so $\mu$ of I > II > III.

b. (I) is $3^o$ Allylic with conjugation.
(II) is $3^o$ Allylic.
(III) $3^o$ free radical. Hence, the order is I > II > III.

c. Acidity: $RSH>C{H}_{3}OH>H_{2}O$
Basic strenth: $R{S}^{\ominus }<C{H}_3{O}^{\ominus }<\stackrel{\ominus }{O}H$

d. Acidity: $HI>HBr>HCl>HF$
Basicity: $I^{\ominus }<B{r}^{\ominus }<C{l}^{\ominus }<F^{\ominus }$
Nucleophilicity: $I^{\ominus }>B{r}^{\ominus }>C{l}^{\ominus }>F^{\ominus }$
When nucleophilic centres are different and belong to the same group of periodic table, nucleophilicity is antiparallel to basicity.