What is the action of following reagents on Bromoethane?(i) KNO2(ii) ‘Mg’ metal(iii) Silver acetate(b) Draw structure - DDT insecticide.

Answer:

(a) (i) KNO₂: KNO₂ is ionic; the nitrite ion attacks through oxygen, giving ethyl nitrite:

C₂H₅Br + KNO₂ \(\xrightarrow{\text{alc.},\ \Delta}\) C₂H₅–O–N=O + KBr

(ii) Mg metal (in dry ether): ethylmagnesium bromide, a Grignard reagent, is formed:

C₂H₅Br + Mg \(\xrightarrow{\text{dry ether}}\) C₂H₅MgBr

(iii) Silver acetate: ethyl acetate (an ester) is formed:

C₂H₅Br + CH₃COOAg \(\xrightarrow{\Delta}\) CH₃COOC₂H₅ + AgBr↓

(b) DDT (p,p′-dichlorodiphenyltrichloroethane), formula (ClC₆H₄)₂CH–CCl₃:

[Structure described: a central carbon bearing one H atom and a –CCl₃ group, and attached to two benzene rings; each benzene ring carries a Cl atom at the para (4-) position relative to the central carbon.]

Cl–C₆H₄–CH(CCl₃)–C₆H₄–Cl