4-chlorobenzaldehyde

Definition

4-chlorobenzaldehyde is an organic compound with the chemical formula C6H5ClCHO. It is a colorless crystalline solid that is commonly used as a precursor in the synthesis of various pharmaceutical and agricultural compounds.

5 Must Know Facts For Your Next Test

1. 4-chlorobenzaldehyde exhibits a characteristic absorption band in the infrared (IR) spectrum due to the carbonyl (C=O) stretch of the aldehyde group.
2. The $^1$H nuclear magnetic resonance (NMR) spectrum of 4-chlorobenzaldehyde shows a distinct signal for the aldehyde proton (H-C=O) at around 10 ppm.
3. The $^{13}$C NMR spectrum of 4-chlorobenzaldehyde displays a characteristic signal for the carbonyl carbon (C=O) at around 190 ppm.
4. The presence of the chloro substituent on the benzene ring of 4-chlorobenzaldehyde affects the chemical shifts and coupling patterns observed in its NMR spectra.
5. Mass spectrometry analysis of 4-chlorobenzaldehyde can reveal the molecular ion peak and characteristic fragmentation patterns, providing information about the compound's structure.

Review Questions

• Explain how the presence of the chloro substituent on the benzene ring of 4-chlorobenzaldehyde affects its infrared (IR) spectrum.
  • The presence of the chloro substituent on the benzene ring of 4-chlorobenzaldehyde can influence the infrared (IR) spectrum of the compound. The chlorine atom's electronegativity and the resulting change in the electronic distribution within the molecule can affect the vibrational frequencies of the carbonyl (C=O) group, leading to a shift in the characteristic absorption band associated with the carbonyl stretch. This shift in the IR spectrum can provide valuable information about the structural features of 4-chlorobenzaldehyde and assist in its identification.
• Describe the key signals observed in the $^1$H and $^{13}$C nuclear magnetic resonance (NMR) spectra of 4-chlorobenzaldehyde and explain how they can be used to confirm the structure of the compound.
  • The $^1$H NMR spectrum of 4-chlorobenzaldehyde will display a distinct signal for the aldehyde proton (H-C=O) at around 10 ppm, which is characteristic of aromatic aldehydes. Additionally, the signals corresponding to the protons on the benzene ring will be affected by the presence of the chloro substituent, exhibiting altered chemical shifts and coupling patterns compared to the unsubstituted benzaldehyde. In the $^{13}$C NMR spectrum, the carbonyl carbon (C=O) will appear at around 190 ppm, and the carbon atoms in the benzene ring will show distinct signals due to the influence of the chloro substituent. The combination of these characteristic NMR signals can be used to confirm the structure of 4-chlorobenzaldehyde and distinguish it from other related compounds.
• Analyze how mass spectrometry can provide structural information about 4-chlorobenzaldehyde and discuss the significance of the molecular ion peak and characteristic fragmentation patterns in the interpretation of the mass spectrum.
  • Mass spectrometry analysis of 4-chlorobenzaldehyde can reveal valuable structural information about the compound. The molecular ion peak in the mass spectrum will correspond to the molecular formula of 4-chlorobenzaldehyde, $\mathrm{C_6H_5ClCHO}$, and provide evidence for the molecular weight of the compound. Additionally, the characteristic fragmentation patterns observed in the mass spectrum can be used to identify the presence of the chloro substituent on the benzene ring and confirm the aldehyde functional group. The fragmentation pathways and the resulting fragment ions can be analyzed to gain insights into the structural features of 4-chlorobenzaldehyde, which can be useful in its identification and differentiation from other similar compounds.

Related terms

Benzaldehyde: Benzaldehyde is the simplest aromatic aldehyde, with the formula C6H5CHO. It is a colorless liquid with a characteristic almond-like odor.

Halogenated Benzaldehydes: Halogenated benzaldehydes are a class of organic compounds where one or more hydrogen atoms on the benzene ring of benzaldehyde are replaced by halogen atoms, such as chlorine, bromine, or fluorine.

Aromatic Aldehydes: Aromatic aldehydes are a group of organic compounds containing an aldehyde functional group attached to an aromatic ring, such as benzene or its derivatives.