Compound B has the composition 62.1% carbon, 10.3% hydrogen and 27.6% oxygen. Its mass and 1H NMR spectra are shown below.

a.

b.

a. Calculate the empirical formula of B.

b. From the mass spectrum, find the molecular mass of B and hence its molecular formula.

c. i. Draw displayed formulae for the possible isomers of B which contain a carbonyl group.

ii. Use the 1H NMR spectrum of B to decide which isomer is B.

iii. Explain your reasoning.

d. Explain what caused the peak at δ = 1.1 ppm and why it is split into a triplet in the 1H NMR spectrum of B.

e. Predict the number of signal lines present on the carbon-13 NMR spectrum of:

i. Compound B, stating the origin of each line

ii. The isomer of compound B identified in your answer to c part i, stating the origin of each line.

Transcribed Image Text:

100 80 60 40 20 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Mass-to-charge ratio (m/e) Relative abundance