Analysis

Medium

A chemist analyses a naturally occurring aromatic compound, X.

The percentage composition by mass of X is:

$C,68.85%;H,4.92%;O,26.23%\text{C}, 68.85\%; \quad \text{H}, 4.92\%; \quad \text{O}, 26.23\%$

Mass spectrum of compound X with relative intensity on the y-axis from 0 to 100% and m/z on the x-axis from 0 to 150.

Determine the molecular formula of X. Show your working.

[4]

Qualitative tests are carried out on compound X. The results are shown below.

Test	Acidity	$Na2CO3(aq)\text{Na}_2\text{CO}_3\text{(aq)}$	2,4-DNP	Tollens' reagent
Observation	$pH=5\text{pH} = 5$	No observable change	Orange precipitate	Silver mirror

Determine the functional groups in X. Explain your reasoning.

[3]

The carbon-13 NMR spectrum of compound X is shown below.

Carbon-13 NMR spectrum of compound X, with chemical shift in ppm on the x-axis ranging from 0 to 220 ppm.

Using the NMR spectrum and the results from parts (a) and (b), determine the structure of the compound. Explain your reasoning.

[3]

Analysis Questions