(7) a) Describe the coupling pattern (i.e. doublet, triplet, doublet of doublets
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(7) a) Describe the coupling pattern (i.e. doublet, triplet, doublet of doublets etc) for the peak at 5.31, and calculate the coupling constant (J) value(s) (see p29, 31). Note - the 1H NMR spectrum was obtained on a 300 MHz spectrometer. Chem 112B Lab Manual Winter 2016 Page | 17
b) Describe the coupling pattern (i.e. doublet, triplet, doublet of doublets etc) for the peak at 4.29, and calculate the coupling constant (J) value(s).
c) Describe the coupling pattern (i.e. doublet, triplet, doublet of doublets etc) for the peak at 3.60, and calculate the coupling constant (J) value(s).
d) Describe the coupling pattern (i.e. doublet, triplet, doublet of doublets etc) for the peak at 3.25, and calculate the coupling constant (J) value(s)
e)Using the coupling constants you calculated above, identify which protons 1 - 4 couple to each other (i.e. does 1 couple with 2, etc)
A close up of the numbers too difficult to view
Solvent: CDCI, Spectrometer: 300 MHz OD / NN My ult 5.35 5.30 5.25 63533.3 3.2 7.0 6.5 6.0 4.5 4.0 3.0 2.5 ppm 2.0 CHEM112B 'H NMR of Bromoindanol ProductExplanation / Answer
a) at 5.31 ppm
Doublet =peak difference
J=* =(5.310-5.286)ppm *(300 MHz)=7.2 Hz
b) at 4.29 ppm
Doublet of doublets
=peak difference between peak 1 and 2 and 1 and 3
1,2=4.294-4.270=0.024
1,3=4.294-4.246=0.048
J1,2=1,2* =(0.024)ppm *(300 MHz)=7.2Hz
J1,3==1,3* =(0.048)ppm *(300 MHz)=14.4 Hz
c) at 3.60 ppm
doublet of doublets
=peak difference between peak 1 and 2 and 1 and 3
1,2=3.608-3.584=0.024
1,3=3.608-3.554=0.054
J1,2=1,2* =(0.024)ppm *(300 MHz)=7.2Hz
J1,3==1,3* =(0.054)ppm *(300 MHz)=16.2 Hz
d) at 3.25 ppm
doublet of doublets
=peak difference between peak 1 and 2 and 1 and 3
1,2=3.253-3.229=0.024
1,3=3.253-3.199=0.054
J1,2=1,2* =(0.024)ppm *(300 MHz)=7.2Hz
J1,3==1,3* =(0.054)ppm *(300 MHz)=16.2 Hz
e)4 lines exists when CH protons couples with two similar protons in the vicinity
Ja,b when Ha couples with Hb(doublet)
Jb,c when two Hb doublet couples with Hc (doublet of doublet)
proton at 1 (-CH) couples with protons at 2 only.
proton at 2 (-CH) couples with protons at 1 and 3(both CH)
proton at 3 (-CH) couples with protons at 3 and 4(both CH)
proton at 4 (-CH) couples with protons at 3 and one other proton in the vicinity(both CH)
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