1) Propose a structure for a molecule with a molecular formula C10H13No and the following 1H NMR data. Briefly explain your answer.

ppm                                              number of Hs                                         Multiplicity

1.05                                                  3                                                         triplet

1.75                                                  3                                                         singlet

3.70                                                  2                                                         quartet

7-7.6                                                 5                                                     complex mulitplet

2) Predict the number of signals that would appear in the 13C NMR spectrum of each of the molecules in Pre-Laboratory Assignment 3 (acetaminophen, acetic anhydride, p-aminophenol)

Answer:

1.

Molecular Formula : C7H16O ____ [ CnH2n+2O ] ----> Acyclic Saturated Compound ----> Alcohol _ or _ Ether

H-NMR Spectrum :
Singlet at ~ 1.38 ppm ; Area 1275 ; Disappear after Shaking with D2O ----> 1 Proton ; " acidic " proton - exchangable with D from D2O ; No Peak Splitting ( No Proton at Adjacent Carbon ) ----> Proton at -OH Group of Tertiary Alcohol

Quartet at ~ 1.42 ppm ; Area 7473 ----> 6 Identical Protons ; Located closer to Alcohol Group ; Peak Splitting by 3 Protons at Adjacent Carbon ----> [ Carbon with no H -- CH2 -- Methyl Group ] ----> 3 Identical -CH2- Groups

Triplet at ~ 0.9 ppm ; Area 11238 ----> 9 Identical Protons ; Located far away fromAlcohol Group Peak Splitting by 2 Protons at Adjacent Carbon ----> [ -- Carbon with 2 H -- CH3 ] ----> 3 Identical -CH3 Groups


Conclusions :

Tertiary Alcohol
[ One -OH Group ]

Three ( 3 ) Identical -CH2-CH3 Groups attached to Tertiary Carbon
[ Three -CH2- ( 6 Protons ) ; Three -CH3 ( 9 Protons ) ]

Structure ____ ( CH3CH2 )3C-OH

IUPAC Name ____ 3-Ethyl-3-pentanol

2.

For acetaminophen (C₈H₉NO₂)- In total there will be seven peaks. six for the carbons in the ring, and one for the methyl group in the ring.

For aminophenol there will be six signals.

and for acetic anhydride there will be again 3 signals.

PFA