Question

5. Carcinogenic nitrosamines are produed from amines such as dimethylamine and nitrous acid according to the following mechanism: H + + HNO 2 → H 2 NO 2 + (fast, reversible) H 2 NO 2 + + (CH 3 ) 2 NH → (CH 3 ) 2 NHNO + + H 2 O (slow) (CH 3 ) 2 NHNO + → (CH 3 ) 2 NNO + H + (fast)

(a) What is the overall reaction?

(b) What is the molecularity of each step?

(c) Write the rate equation for the rate-determining step.

(d) What are the intermediates in this reaction? (If none, write “ none.”)

Answer 1

H + + HNO 2 → H 2 NO 2 + (fast, reversible)

H 2 NO 2 + + (CH 3 ) 2 NH → (CH 3 ) 2 NHNO + + H 2 O (slow)

(CH 3 ) 2 NHNO + → (CH 3 ) 2 NNO + H + (fast)

a. overall reaction HNO2 + (CH3)2NH -----------> (CH 3 )2 NNO + H2O

b. bimolecular , bimolecular, unimolecular

c. Slowest step is called rate-determining step.

(CH 3 ) 2 NH → (CH 3 ) 2 NHNO + + H 2 O (slow)

Rate = K[(CH 3 ) 2 NH]

d. H 2 NO 2 + , (CH 3 ) 2 NHNO + are intermediates

d.