Assignments:

1. Check whether the following statements are true or false

A)  Bimolecular nucleophilic substitution reaction reaction SN₂ is steriospecific and proceeds with inversion of configuration – T
B)  SN₂ reactions proceeds more rapidly in solvents like water and alcohol than in aprotic solvents like DMF or DMSO –T
C)  Rates of SN₁ reactions are affected by the concentration and nature of the nucleophile – F
D)  Rates of SN₁ reactions decreases with better leaving group– F
E)  The substitution of electron donating groups to a nucleophile produces a better nucleophile –T
F)  The weaker the basicity of a group, the greater its leaving ability –T

2. Which of the following halides will react most rapidly in a SN₂ reaction?

A)  CH₃F
B)  CH₃Cl
C)  CH₃Br
D)  CH₃I

The carbon-iodine bond is the weakest bond due to mismatched orbital levels and the iodide ion is the most stable of the halide ions due to polarizability.

3. Which of the following would not be a reasonable nucleophile in an SN₂ reaction?

A)  NH₃
B)  NC^-
C)  H₂O
D)  HO^-

Although water has 2 pairs of non-bonded electrons, it has a high electronegativity and these pairs are tightly held and thus not readily shared

4. Consider the SN₁ solvolysis of the following 1°-alkyl chlorides in aqueous ethanol.

            a)  CH₃CH₂CH₂Cl   b)  CH₂ = CHCH₂Cl  c)  CH₃OCH₂Cl  d)  CF₃CF₂CH₂Cl
              What is the order of decreasing reactivity?

A)  d > c > b > a
B)  c > b > a > d
C)  c > a > d > a
D)  a > d > b > c

5.  Which of the following reagents would you expect to react with bromocyclopentane by an SN₂ mechanism?

A)  C₂H₅OH
B)  C₂H₅O^(-) K⁽⁺⁾
C)  NaCN
D)  (CH₃)₃N

Answers:

2. (D)     3. (C)     4. (B)