Tetrahedral Alkoxide Intermediate

Definition

The tetrahedral alkoxide intermediate is a key species that arises during the nucleophilic addition of hydrogen cyanide (HCN) to a carbonyl compound, leading to the formation of a cyanohydrin. This intermediate is characterized by a central carbon atom with four attached substituents, adopting a tetrahedral geometry.

5 Must Know Facts For Your Next Test

1. The tetrahedral alkoxide intermediate is a crucial step in the mechanism of the nucleophilic addition of HCN to a carbonyl compound, leading to cyanohydrin formation.
2. The central carbon atom of the tetrahedral alkoxide intermediate is sp3 hybridized, with four substituents arranged in a tetrahedral geometry to minimize steric strain.
3. The tetrahedral alkoxide intermediate is formed when the nucleophilic cyanide ion (CN-) attacks the electrophilic carbonyl carbon, creating a new carbon-carbon bond and a negatively charged oxygen atom.
4. The negative charge on the oxygen atom of the tetrahedral alkoxide intermediate is stabilized through resonance with the adjacent carbonyl group.
5. The tetrahedral alkoxide intermediate is a high-energy, short-lived species that quickly rearranges to form the final cyanohydrin product.

Review Questions

• Describe the role of the tetrahedral alkoxide intermediate in the nucleophilic addition of HCN to a carbonyl compound.
  • The tetrahedral alkoxide intermediate is a key step in the mechanism of the nucleophilic addition of HCN to a carbonyl compound. It is formed when the nucleophilic cyanide ion attacks the electrophilic carbonyl carbon, creating a new carbon-carbon bond and a negatively charged oxygen atom. The central carbon atom of the intermediate adopts a tetrahedral geometry, and the negative charge on the oxygen is stabilized through resonance with the adjacent carbonyl group. This high-energy, short-lived intermediate then rearranges to form the final cyanohydrin product.
• Explain the significance of the tetrahedral geometry of the alkoxide intermediate and how it relates to the overall mechanism.
  • The tetrahedral geometry of the alkoxide intermediate is crucial in the nucleophilic addition of HCN to a carbonyl compound. The central carbon atom is sp3 hybridized, with four substituents arranged in a tetrahedral configuration to minimize steric strain. This tetrahedral geometry is a hallmark of the alkoxide intermediate and is a key structural feature that distinguishes it from the planar carbonyl starting material. The tetrahedral arrangement of the substituents around the central carbon atom facilitates the subsequent rearrangement to form the final cyanohydrin product, which also adopts a tetrahedral configuration around the carbon bearing the hydroxy and cyano groups.
• Analyze the role of the tetrahedral alkoxide intermediate in the overall mechanism of cyanohydrin formation and discuss how it relates to the stereochemistry of the final product.
  • The tetrahedral alkoxide intermediate is a critical step in the mechanism of cyanohydrin formation through the nucleophilic addition of HCN to a carbonyl compound. The formation of this intermediate, with its characteristic tetrahedral geometry around the central carbon atom, is a key determinant of the stereochemistry of the final cyanohydrin product. The tetrahedral arrangement of the substituents, including the newly formed carbon-carbon bond and the negatively charged oxygen, sets the stage for the subsequent rearrangement to the final product. The stereochemistry of the cyanohydrin is directly influenced by the orientation of the substituents in the tetrahedral alkoxide intermediate, as the rearrangement typically occurs with retention of configuration. Understanding the role and characteristics of the tetrahedral alkoxide intermediate is essential in predicting and explaining the stereochemical outcome of the overall cyanohydrin formation reaction.

Related terms

Nucleophilic Addition: A type of organic reaction where a nucleophile (electron-rich species) attacks an electrophilic carbon, often a carbonyl carbon, to form a new covalent bond.

Carbonyl Compound: An organic compound containing a carbonyl group (C=O), such as aldehydes and ketones, which are susceptible to nucleophilic addition reactions.

Cyanohydrin: A compound formed by the addition of hydrogen cyanide (HCN) to a carbonyl compound, resulting in a hydroxy group and a cyano group attached to the same carbon atom.