Question

Propose a mechanism from the reaction in the box

CH,CH,0 + NH CH:CH-OH + NH3 Use the diagram above for Questions 4-7. 4. Which reactant is the base? a) CH3CH20 b) NHÀ c.) CH,CHOH d.) NH3 5. Which product is the conjugate acid? a.) CH CH20 b.) NH4+ c.) CHCH2OH d.) NH3 6. Which reactant is the acid? a.) CH,CH20 b.) NHÀ c.) CH3CH2OH d.) NHS 7. Which product is the conjugate base? a.) CH,CH20 b) NH4* c.) CH,CH2OH d) NH3

Answer 1

Ans- The given reaction is an acid-base titration reaction. The substrate CH₃CH₂O^- behaves as the base and the oxygen atom bearing a negative charge will abstract proton from NH₄⁺ giving CH₃CH₂OH and NH₃ as the products. The mechanism is as follows:

H H3C + ΗΤΗ H H3C Conjugate Conjugate Base Base Acid acid + H2 IZ + HH Starting material again showing reversibility of reaction

The lone pair on NH₃ behave as the conjugate base and can abstract proton attached to oxygen in CH₃CH₂OH (conjugate acid) giving the starting material again, showing the reversibility of reaction.

The answers to the questions can be found from the above-shown reaction.

4 Ans: a. The base in the reaction is CH₃CH₂O^-

5 Ans: c. CH₃CH₂OH is conjugate acid.

6 Ans: b. NH₄⁺ is the acid.

7 Ans: d. NH₃ is a conjugate base.