Question

Name 9 H H нсь со ссн, Figure 1. Structural representation of ethyl acetate Table 1. 'H and 13C NMR Data for ethyl acetate Proton peaks (ppm) Carbon peaks (ppm) Proton Justification: Carbon Justification:

Provide the justification for the structure of ethyl acutate.

Answer 1

Table): Table Proton peaks (ppm) a 2.05(Q), 4.10(c), 1.26 (d) | carbon peaks (ppm) 21:13 (a), 171:19 (6),60-43(c),14-32 (d) In Proton Justification is protons at carbon à has no other protons, adjacent carbon. Therefore, a singlet NMR peak I will apear for this. Also, the a adJacent carbon is a carbonyl carbon, which increases the ppm value to ~ 2.00 (here -2.05). Peak at 2.05 ppm is singlets represento protons at carbon a. i) At carbon or the protons are adjacent to electronegative "ol-atom; comes at higher porn value in proton NMR (4.00 to 4.50). Also, it will be a quartett NMR peak alla since it has 3-H-atoms in the adjacent carbon. Therefore, (4.07 ~ 4.18) ppm = protons at carbon c. ii) Protons at carbon &d should appear as a triplet NMR peak M a s two hydrogens are there in the adjacent se carbon. Also, it has no election with drawing group (or atom) attacked, so it will have lowest ppm value. Then, (1.22 130) ppm. = protons at carbon de Carbon Justification: Carbon "à: 1 electron-withdrawing group attached, appears at higher region than normal -CH₂ & carbons (ie. 10-15 ppm). 21.13. ppm . [range 20-30 ppm carbon b: 11 tetra-substituted ; carbonge carbon doubly a bonded to appears highest at BC-NMR 17119 ppm. (any & carbon generally appear in the range 180-220 ppm)