Distinction between pairs of compounds
n-Propyl iodide `(CH_(3)CH_(2)CH_(2)I)` and isopropyl iodide `(CH_(3)CHICH_(3))`

Explanation

Iodoform test helps to distinguish these. Isopropyl iodide on alkaline hydrolysis gives 2-propanol which when treate with `I_(2)//NaOH` or NaOI, gives yellow ppt. of iodoform. N-Propyl iodide gives n-propyl alcohol with NaOH(aq) which does not form iodoform with NaOI
`underset("Isopropyl iodide")((CH_(3))_(2)CHI)+NaOH(aq)rarrunderset("Isopropyl alcohol")((CH_(3))_(2)CHOH)+NaI`
`(CH_(3))_(2)CHOH+4NaOI`
`rarrundersetunderset(("yellow ppt."))("Iodoform")(CHI_(3)darr)+CH_(3)COONa+NaI+2NaOH+H_(2)O`
`underset("n-Propyl iodide")(CH_(3)CH_(2)CH_(2)I)+NaOH(aq)rarrunderset("n-Propyl alcohol")(CH_(3)CH_(2)CH_(2)OH)+NaI`
`CH_(3)CH_(2)CH_(2)OHoverset(NaOI)rarr"No Yellow ppt of "CHI_(3)`