Identify each of the following compounds from its molecular formula and its IR and 1H NMR spectra: d. C11H14O2 <IMAGE>
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Analyze the molecular formula (C11H14O2): Calculate the degree of unsaturation using the formula: \( ext{Degree of Unsaturation} = rac{2C + 2 - H + N - X}{2} \), where C = number of carbons, H = number of hydrogens, N = number of nitrogens, and X = number of halogens. This will help determine the presence of rings or double bonds in the structure.
Examine the IR spectrum: Look for key functional group absorptions. For example, a strong absorption around 1700 cm⁻¹ indicates a carbonyl group (C=O), while a broad absorption around 3200-3600 cm⁻¹ suggests an -OH group. Identify any other significant peaks that could indicate functional groups like ethers, esters, or aromatic rings.
Interpret the 1H NMR spectrum: Analyze the chemical shifts, splitting patterns, and integration values. For example, chemical shifts around 6-8 ppm suggest aromatic protons, while shifts around 2-4 ppm could indicate protons near electronegative atoms or in an alpha position to a carbonyl group. Use the integration values to determine the number of protons contributing to each signal.
Combine the information: Use the molecular formula, degree of unsaturation, IR data, and 1H NMR data to piece together the structure. For example, if the IR spectrum shows a carbonyl group and the NMR spectrum indicates aromatic protons, consider the possibility of an aromatic ester or ketone.
Propose the structure: Based on the combined data, propose a structure that matches the molecular formula, degree of unsaturation, and spectral data. Verify that the structure accounts for all observed peaks in the IR and NMR spectra and satisfies the molecular formula.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Molecular Formula Interpretation
The molecular formula provides essential information about the number and types of atoms in a compound. For C11H14O2, it indicates the presence of 11 carbon atoms, 14 hydrogen atoms, and 2 oxygen atoms. Understanding how to interpret this formula is crucial for deducing the compound's structure and potential functional groups.
IR spectroscopy is a technique used to identify functional groups in a molecule based on the absorption of infrared light. Different bonds absorb characteristic wavelengths, allowing chemists to infer the presence of specific functional groups, such as alcohols, carbonyls, or esters, which can be crucial for identifying the compound represented by the molecular formula.
Proton Nuclear Magnetic Resonance (1H NMR) Spectroscopy
1H NMR spectroscopy provides information about the hydrogen atoms in a molecule, revealing their environment and connectivity. The chemical shifts, splitting patterns, and integration of peaks in the NMR spectrum help determine the number of hydrogen atoms in different environments, aiding in the elucidation of the compound's structure and confirming its identity.