I came across an exam question which asked the student to identify an ester from two apparently very similar structures and a proton NMR spectrum. This is my attempt to explain the spectra pictorially. I will bundle it with my other ‘NMR examples explained’ series.
(NB, I used spectra from a database. The original question shows an expansion of the multiplet peak due to methyl groups as a heptet, ie seven peaks, due to six protons, although this appears to be simulated. The methyl groups appear to be chemically equivalent to me so the multiplet should be a quartet, due to three protons, but I cannot tell from the database spectra. I have stuck with the exam board interpretation and mark scheme. The question is OCR A F324 Wednesday 27 January 2010 question 4)