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Two students are given a homework assignment that involves analysing a set of spectra and identifying an unknown compound - VCE - SSCE Chemistry - Question 7 - 2021 - Paper 1
Question 7
Two students are given a homework assignment that involves analysing a set of spectra and identifying an unknown compound. The unknown compound is one of the molecul... show full transcript
Worked Solution & Example Answer:Two students are given a homework assignment that involves analysing a set of spectra and identifying an unknown compound - VCE - SSCE Chemistry - Question 7 - 2021 - Paper 1
Step 1
Eliminate options based on functional groups
Answer
Start by analysing the functional groups present in each compound based on their structure.
- Compound P: Has no -OH group, eliminated due to lack of IR absorbance at 3500 cm⁻¹.
- Compound Q: Contains a carboxylic acid group, but shows no broad -OH absorption.
- Compound R: Contains -OH but lacks clear evidence of carboxylic acid.
- Compound S: Has no -OH group, eliminated for the same reason as Compound P.
- Compound T: Contains a -OH group but needs further analysis against NMR data.
Step 2
Analyze the 13C NMR spectrum
Answer
Examine the peaks in the 13C NMR spectrum. The significant features include:
- Any clear strong peaks can indicate the presence of certain functional groups.
- Lack of a peak in the region for a carboxylic acid would support the elimination of options like Compound Q.
- Consider the shift values associated with each peak to decipher the molecular environment around each carbon.
Step 3