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The molecular formula of an unknown compound, X, is C4H8O2: The infrared \(^{13}C\) NMR and \(^{1}H\) NMR spectra of this compound are shown below - VCE - SSCE Chemistry - Question 2 - 2010 - Paper 1
Question 2
The molecular formula of an unknown compound, X, is C4H8O2: The infrared \(^{13}C\) NMR and \(^{1}H\) NMR spectra of this compound are shown below. **infrared spec... show full transcript
Worked Solution & Example Answer:The molecular formula of an unknown compound, X, is C4H8O2: The infrared \(^{13}C\) NMR and \(^{1}H\) NMR spectra of this compound are shown below - VCE - SSCE Chemistry - Question 2 - 2010 - Paper 1
Step 1
Analyze the Infrared Spectrum
Answer
In the infrared spectrum, identify key absorption peaks and their corresponding functional groups. Commonly, a broad peak around 3000-3600 cm⁻¹ may indicate an alcohol or carboxylic acid. A peak around 1710 cm⁻¹ suggests a carbonyl group (C=O). Identify these functional groups to guide the interpretation of the NMR data.
Step 2
Interpret the 13C NMR Data
Answer
The (^{13}C) NMR spectrum gives insights into the carbon environment in the molecule. Look for shifts that indicate the presence of methyl (0-15 ppm), methylene (20-50 ppm), and carbonyl (150-220 ppm) environments. Count the number of distinct carbon signals to infer the structural components.
Step 3
Interpret the 1H NMR Data
Answer
The (^{1}H) NMR spectrum reveals the hydrogen environment. Look for integration values that show how many protons are present for each signal. Analyze the splitting patterns to determine the number of neighboring protons (n + 1 rule), which helps in deducing the structure. Peaks for functional groups related to the previous analysis should correlate with the (^{13}C) and IR findings.