Analyse the spectrum and identify two bonds other than C–H that are present and one that is absent in this compound. Refer to Table 17 of the Data booklet to complete the table.

Bonds present:

Bond absent:

The mass spectrum of the same compound contains strong peaks of \({({M_{\text{r}}} - 15)^ + }\) and \({({M_{\text{r}}} - 17)^ + }\) ions. The first signal corresponds to the loss of a methyl group, \({\text{C}}{{\text{H}}_{\text{3}}}\), from the molecule. Deduce which fragment is lost to produce the second peak.

Using the information above, deduce the identity of the organic compound.

Predict the number of peaks in the \(^{\text{1}}{\text{H}}\,{\text{NMR}}\) spectrum of this compound.

Bonds present: [2 max]

Bonds absent: [1 max]

Accept other bonds/groups (C􀀀\(\equiv\)C/ alkyne, etc.) even if they do not present in any of the three molecules.

No credit if atoms other than C, H or O are involved.

Award marks for functional group/bond names and ignore wavenumbers.

OH/hydroxyl/alcohol;

Accept ⁺OH.

propan-1-ol/CH₃CH₂CH₂OH;

Accept “alcohol”.

4;

Accept ECF from (c) – if propanoic acid/propanal = 3 peaks.

In (a), the spectrum was well interpreted and few had little difficulty in gaining three marks. The three possible compounds were given in the stem so candidates did not score the last mark if the “absent” bond included an atom not present. One G2 respondent commented that asking students to locate bonds in the fingerprint region is questionable; as it turned out, the candidates had no difficulty with this.

Most were then able to progress through the rest of the question without difficulty although several gave compounds in (c) that were not in the stem of the question.

In (d) the answer given was generally consistent with the answer given in (c).