NMR question

leoishush

15

Im stuck on an NMR question where did I go wrong

(edited 8 months ago)

Original post by leoishush

Im stuck on an NMR question where did I go wrong

C₇H₁₂O₃

All carbon environments different (7 peaks in the ¹³C NMR)

The integration ratio tells you 2:2:2:3:3 which makes up all of the H atoms

Peak at 4.10 is due to CH₂ split by a neighbouring CH₃ - The shift suggests that the CH₂ is adjacent to an oxygen (electronegative) of a ester group

CH₃CH₂-O-C=0

The triplet at 1.26 is the first CH₃

The two triplets at 2.60 and 2.56 appear to be -CH₂CH₂- attached to a carbonyl group

CH₃CH₂-O-CO-CH₂CH₂

So we are still missing C₂H₃O

The singlet at 2.19 is due to CH₃, which leaves another carbonyl group, causing the shift to 2.19

CH₃CH₂-O-CO-CH₂-CH₂-CO-CH₃

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Colourful Solutions IB Chemistry Testing and Notes

Reply 2

leoishush

OP

15

Original post by charco

C₇H₁₂O₃

All carbon environments different (7 peaks in the ¹³C NMR)

The integration ratio tells you 2:2:2:3:3 which makes up all of the H atoms

Peak at 4.10 is due to CH₂ split by a neighbouring CH₃ - The shift suggests that the CH₂ is adjacent to an oxygen (electronegative) of a ester group

CH₃CH₂-O-C=0

The triplet at 1.26 is the first CH₃

The two triplets at 2.60 and 2.56 appear to be -CH₂CH₂- attached to a carbonyl group

CH₃CH₂-O-CO-CH₂CH₂

So we are still missing C₂H₃O

The singlet at 2.19 is due to CH₃, which leaves another carbonyl group, causing the shift to 2.19

CH₃CH₂-O-CO-CH₂-CH₂-CO-CH₃

-----------------------------------------------------------------------------------------------
Signature
Colourful Solutions IB Chemistry Testing and Notes

didn't i get some of this right tho? why did i only get 1 mark