Nylon-6,6 was the first completely synthetic fiber, initially prepared in the mid-1930s at DuPont. It is a copolymer whose subunits are alternating molecules of 1,6-hexanediamine and hexanedioic (adipic) acid, linked by amide functions. 

(a) Write a structural representation of Nylon-6,6. 

(b) Hexanedinitrile (adiponitrile) may be used as a common precursor to both 1,6-hexanediamine and hexanedioic acid. Show the reactions necessary to convert the dinitrile into both the diamine and the diacid. 

(c) Formulate a mechanism for the conversion into the diacid under the reaction conditions that you chose in (b).