Question

how to the product differ when ethyl Bromide reacts separately with KCN and its AGCN?? name the products .

Answer 1

KCN is predominantly ionic and therefore both C and N are available for the donation of electron but the reaction occurs through carbon as C-C bonds are stronger than the C-N bond therefore attack occurs the carbon atom of the cyanide group forming alkyl cyanide as the main product.
CH3CH2Br + KCN -> CH3CH2CN + KBr
on the other hand AgCN is predominantly covalent in nature and N is free to donate electron pair forming isocyanides as the main product.
CH3CH2Br + AgCN -> CH3CH2NC + AgBr