Question

All of the following qualities of a carbonyl carbon make it a good electrophile EXCEPT: A. its stereochemistry B. its partial positive charge C. its planar shape D. its lone pair of electrons

Short answer

D. its lone pair of electrons

Step-by-step solution

- Understand the Nature of an Electrophile

An electrophile is a chemical species that attracts electrons due to its positive charge or partial positive charge. It seeks to accept an electron pair.

- Identify Characteristics of Carbonyl Carbon

A carbonyl carbon is part of a carbon-oxygen double bond (C=O). It has a partial positive charge because oxygen is more electronegative and pulls electron density away from the carbon.

- Analyze Each Option

Consider how each option influences the carbonyl carbon's ability to be an electrophile: A. Stereochemistry does not directly impact its electron-attracting ability.B. The partial positive charge makes it a good electrophile since it attracts electrons.C. Its planar shape allows better overlap in reactions, aiding in its electrophilic nature.D. It does not have a lone pair of electrons; the oxygen does.

- Determine the Incorrect Quality

Based on the analysis, option D (its lone pair of electrons) is incorrect because the carbonyl carbon itself does not have a lone pair of electrons; the oxygen atom in the carbonyl group does.

Key concepts

partial positive charge

A molecule has a partial positive charge when electrons are pulled away from one of its atoms due to the presence of a more electronegative atom. In the case of a carbonyl group, the oxygen atom is more electronegative than the carbon atom. As a result, oxygen attracts more electron density towards itself, leaving the carbon with a partial positive charge.

This partial positive charge makes the carbonyl carbon an excellent electrophile. Electrophiles are species that seek electrons, and a positively charged center is highly attractive to electron-rich species (nucleophiles). Because the carbonyl carbon is electron-deficient, it readily accepts electrons from nucleophiles.

carbonyl carbon

The carbonyl group (C=O) consists of a carbon atom double-bonded to an oxygen atom. The carbon in this group is known as the carbonyl carbon. This carbonyl carbon is a significant player in many organic reactions due to several key properties:

• It has a partial positive charge, making it an attractive site for nucleophiles.
• Its planar shape allows for optimal overlap during chemical reactions, facilitating efficient nucleophilic attack.
• It is involved in a variety of functional groups like aldehydes, ketones, carboxylic acids, and esters.

Because of these properties, the carbonyl carbon frequently acts as an electrophile, seeking to attract and bond with nucleophiles in chemical reactions.

stereochemistry

Stereochemistry refers to the three-dimensional orientation of atoms within a molecule. While it is crucial in determining the behavior and reactivity of many molecules, the stereochemistry of a carbonyl carbon does not directly influence its capacity to act as an electrophile. Instead, factors like the partial positive charge and the planar shape of the carbonyl group are more significant in this context.

Even though the stereochemistry doesn’t affect the electrophilicity of the carbonyl carbon directly, it can play a role in the overall mechanism and outcome of a reaction. For instance, different isomers might react differently with the same nucleophile due to spatial orientation, but this is a secondary effect compared to the immediate factors related to electrophilicity.

electronegativity

Electronegativity is the tendency of an atom to attract electrons towards itself. In a carbonyl group (C=O), the oxygen atom is highly electronegative, meaning it pulls electron density away from the carbon atom.

This shift in electron density causes the carbonyl carbon to develop a partial positive charge, making it an electrophile. Electronegativity directly impacts the carbonyl carbon's reactivity; the more electronegative the oxygen atom, the more electron-deficient the carbon atom becomes.

Understanding electronegativity helps explain why the carbonyl carbon is an effective site for nucleophilic attacks. The high electronegativity of oxygen makes the carbonyl carbon eager to accept electrons, thus enhancing its electrophilicity.