(Solved): Compound A has the molecular formula C14H25Br and was obtained by reaction of sodium acetylid ...

Compound $\mathrm{A}$ has the molecular formula ${\mathrm{C}}_{14}{\mathrm{H}}_{25}\mathrm{Br}$ and was obtained by reaction of sodium acetylide with 1,12-dibromododecane. On treatment of compound $\mathrm{A}$ with sodium amide, it was converted to compound $\mathrm{B}\left({\mathrm{C}}_{14}{\mathrm{H}}_{24}\right)$. Ozonolysis of compound $\mathrm{B}$ gave the diacid ${\mathrm{HO}}_2\mathrm{C}{\left({\mathrm{CH}}_2\right)}_{12}{\mathrm{CO}}_2\mathrm{H}$. Catalytic hydrogenation of compound $B$ over Lindlar palladium gave compound $\mathrm{C}\left({\mathrm{C}}_{14}{\mathrm{H}}_{26}\right)$, and hydrogenation over platinum gave compound $\mathrm{D}\left({\mathrm{C}}_{14}{\mathrm{H}}_{28}\right)$. C yielded $\mathrm{O}=\mathrm{CH}{\left({\mathrm{CH}}_2\right)}_{12}\mathrm{CH}=\mathrm{O}$ on ozonolysis. Assign structures to compounds $\mathrm{A}$ through $\mathrm{D}$ so as to be consistent with the observed transformations. When 1,2-dibromodecane was treated with potassium hydroxide in aqueous ethanol, it yielded a mixture of three isomeric compounds of molecular formula ${\mathrm{C}}_{10}{\mathrm{H}}_{19}\mathrm{Br}$. Each of these compounds was converted to 1 -decyne on reaction with sodium amide in dimethyl sulfoxide. Identify these three compounds.