Formaldehyde

Definition

Formaldehyde is a simple aldehyde compound with the chemical formula CH2O. It is a colorless, flammable gas with a pungent odor that is widely used in various industrial and commercial applications. Formaldehyde is a key term that is important in the context of several organic chemistry topics, including functional groups, oxidation of alkenes, naming aldehydes and ketones, nucleophilic addition of water, and spectroscopy of aldehydes and ketones.

5 Must Know Facts For Your Next Test

1. Formaldehyde is the simplest aldehyde, with a single carbon atom and a hydrogen atom attached to the carbonyl group.
2. Formaldehyde is a common product of the oxidation of alkenes, where the carbon-carbon double bond is cleaved to form two carbonyl compounds.
3. In the IUPAC naming system, formaldehyde is named as methanal, where the suffix '-al' indicates an aldehyde functional group.
4. Formaldehyde undergoes nucleophilic addition of water (hydration) to form the geminal diol, methanediol (CH2(OH)2).
5. Formaldehyde has a characteristic absorption band in the infrared (IR) spectrum around 1730 cm^(-1), corresponding to the carbonyl (C=O) stretch.

Review Questions

• Explain how the aldehyde functional group in formaldehyde is classified as per the IUPAC system.
  • According to the IUPAC naming system, the aldehyde functional group in formaldehyde is classified as a methanal group. The prefix 'meth-' indicates a single carbon atom, and the suffix '-al' denotes the aldehyde functional group, where the carbonyl carbon is bonded to a hydrogen atom and another carbon-containing group (in this case, the other hydrogen atom).
• Describe the role of formaldehyde in the oxidation of alkenes and the formation of carbonyl compounds.
  • During the oxidation of alkenes, the carbon-carbon double bond is cleaved, resulting in the formation of two carbonyl compounds. Formaldehyde is a common product of this oxidation process, where one of the carbonyl compounds formed is the simplest aldehyde, with a single carbon atom and a hydrogen atom attached to the carbonyl group. This reaction is an important step in the conversion of alkenes to carbonyl compounds, which are key intermediates in various organic synthesis reactions.
• Analyze the spectroscopic properties of formaldehyde and explain how it can be identified using infrared (IR) spectroscopy.
  • Formaldehyde exhibits a characteristic absorption band in the infrared (IR) spectrum around 1730 cm^(-1), corresponding to the carbonyl (C=O) stretch. This distinctive absorption peak can be used to identify the presence of the formaldehyde molecule in a sample, as the carbonyl group's vibrational frequency is a unique fingerprint for this compound. By analyzing the IR spectrum of an unknown sample and comparing it to the known IR spectrum of formaldehyde, organic chemists can confidently identify the presence and confirm the identity of this important aldehyde compound.

Related terms

Aldehyde:

A functional group consisting of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydrogen atom and another carbon-containing group.

Oxidation:

A chemical reaction that involves the loss of electrons or an increase in oxidation state of a molecule, atom, or ion.

Nucleophilic Addition:

A type of reaction where a nucleophile (an electron-rich species) attacks an electrophilic carbon, resulting in the addition of the nucleophile to the molecule.