Question

19. You are given a sample with the molecular formula CsHio0. From chemical tests you know it is a ketone. What are the possible molecular structures? How could you distinguish between them by proton NMR?

Answer 1

DATE The possible molecular structures of are 41-2-pentanone 3 Now, for studying NMR sianal, let us lo bel the ydr ogen atoms or convenience 0 一at ype-of-protons-EMs-protons ) will-give singlet at 2 2.3 PPm oton CH2 is adiacentto banyl. Tt will give a tiplet at 2:1- 213 Pppm tupe proton (-cH will give a sextet ot 14 ppm d type protoo will give triplet ot.

DATE 3-pentanane Let us label bydrogen atoms Now this阜is a summetrical molealle-Go, only two t升pes rotons are present d type proton ill give a tiplet pea e proton will ive a quartet near 2.2-2-4 ppm 3 Let us label bydrogen otoms HAC-CHーどーCH

are present. Here 3-tupe-oP -proton e of pro-ton will give doublet ear o9-1.2 PPm b type of proton wil give a septet multiplet at 21-2-3 Ppm proton ill aive a Sina 0t 21-2 Ppm 10 2-pentanone we g NMR Signal P NMR signa Tn 3-metbul-2-butanone we get 3 tupe oP N MR Sianal this, wecan一一distinguish between the tbree molecularStructures of CHo