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The molecular formula of an unknown compound, X, is C₈H₁₀O₂ - VCE - SSCE Chemistry - Question 2 - 2010 - Paper 1
Question 2
The molecular formula of an unknown compound, X, is C₈H₁₀O₂. The infrared ¹³C NMR and ¹H NMR spectra of this compound are shown below. ### Infrared Spectrum transm... show full transcript
Worked Solution & Example Answer:The molecular formula of an unknown compound, X, is C₈H₁₀O₂ - VCE - SSCE Chemistry - Question 2 - 2010 - Paper 1
Step 1
Identify the Absorption Peaks in the Infrared Spectrum
Answer
Examine the infrared spectrum for significant absorption peaks. Look for key functional group regions, such as:
- A strong peak around 1700 cm⁻¹ suggests the presence of a carbonyl group (C=O).
- Peaks in the region of 3200–3600 cm⁻¹ may indicate the presence of O-H groups in alcohols or phenols.
Step 2
Analyze the ¹³C NMR Spectrum
Answer
In the ¹³C NMR spectrum, observe the number of distinct peaks:
- Each unique carbon environment corresponds to a peak. A total of 8 peaks matches the molecular formula C₈H₁₀O₂, indicating multiple unique carbon environments.
- Look for chemical shifts that indicate the presence of functional groups like alkyl chains or aromatic rings.
Step 3
Examine the ¹H NMR Spectrum
Answer
The ¹H NMR spectrum will provide information about the hydrogen environments:
- Count the number of distinct sets of peaks to determine the number of unique hydrogen environments that correspond to the empirical formula.
- Analyze the chemical shifts to draw conclusions about the molecular structure and potential functional groups.