Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 16: Problem 45

Provide an argument not involving molecular orbitals to explain why a carbon- oxygen double bond protonates on \(\mathrm{O}\), not \(\mathrm{C}\).

Short Answer

Expert verified
The oxygen atom protonates because it is more electronegative, making it electron-rich and more attractive to protons.

Step by step solution

01

Understanding the Functional Groups

The carbon-oxygen double bond consists of a carbon atom double-bonded to an oxygen atom. This is also known as a carbonyl group.
02

Electronegativity Consideration

Oxygen is more electronegative than carbon, which means it has a greater tendency to attract electrons. This results in a partial negative charge on the oxygen and a partial positive charge on the carbon.
03

Charge Distribution in the Carbonyl Group

Due to the difference in electronegativity, the electron density is skewed towards the oxygen atom. This leaves the carbon atom electron-deficient and the oxygen atom electron-rich.
04

Proton Affinity

A proton (H⁺) is attracted to regions of high electron density. Since the oxygen atom carries a partial negative charge and is electron-rich, it is more likely to attract and bind with a proton.
05

Conclusion

Therefore, the carbon-oxygen double bond protonates on oxygen (O), not carbon (C), because the oxygen atom has a higher electron density and a partial negative charge, making it more favorable for protonation.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Functional Groups in Organic Chemistry
In organic chemistry, molecules have specific arrangements of atoms known as functional groups. These groups determine the chemical reactivity and properties of molecules. The carbonyl group is one such functional group. It contains a carbon atom double-bonded to an oxygen atom. This group is usually involved in many types of chemical reactions. By recognizing functional groups, chemists can predict how a molecule will react in different situations.

For example, a molecule with a carbonyl group will often undergo reactions where the double-bonded oxygen plays a key role. The nature of the interactions within these groups helps explain their behavior in chemical processes.
Electronegativity
Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. In the periodic table, oxygen is more electronegative than carbon, which means it pulls electrons toward itself more effectively. This property affects how atoms in a molecule share electrons.

In a carbon-oxygen double bond, the oxygen atom attracts the shared electrons more strongly, creating a partial negative charge on the oxygen and a partial positive charge on the carbon. This uneven distribution of electrons is crucial in understanding why certain atoms are more attractive to protons.
Carbonyl Group
The carbonyl group, characterized by a carbon double-bonded to an oxygen, is a very reactive functional group. This group is present in many organic compounds, including ketones and aldehydes. The structure of the carbonyl group means that the oxygen atom has a significant pull on the shared electrons.

This electron attraction leads to a situation where the oxygen atom is electron-rich while the carbon atom is electron-deficient. Understanding the behavior of carbonyl groups helps in predicting reaction mechanisms, such as the protonation process discussed in this problem.
Charge Distribution in Molecules
Charge distribution in molecules is all about where the electrons are most likely to be found. Because oxygen is more electronegative than carbon, the electrons in a carbonyl group hover closer to the oxygen atom. This distribution makes the oxygen partially negative and the carbon partially positive.

This difference in charge plays a key role in chemical reactions. For example, a proton (H⁺) will be naturally attracted to the negatively charged oxygen atom rather than the positively charged carbon. Understanding this concept is like knowing why magnets attract - opposite charges pull towards each other.
Proton Affinity
Proton affinity refers to how strongly a molecule or atom attracts protons (H⁺). In the case of the carbonyl group, the oxygen atom is more likely to attract a proton because it is electron-rich and carries a partial negative charge.

When a proton encounters a carbonyl group, it will be drawn to the oxygen atom due to its higher electron density. This is why protonation occurs at the oxygen rather than the carbon atom. Proton affinity is an essential concept for predicting reaction sites in a molecule, helping chemists design better reactions and synthesize compounds effectively.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

There are many reagents that have been developed to oxidize alcohols to ketones or aldehydes. The chromium reagents work very well, but other procedures are preferred. Why do you suppose that other reagents are favored? What are the hazards of using \(\mathrm{Cr}(\mathrm{VI})\) ?

Treatment of 2-thiabicyclo[2.2.1]heptane (1) with 1 equivalent of hydrogen peroxide affords a mixture of diastereomers 2 and 3 of molecular formula \(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{OS}\). Both diastereomers 2 and 3 yield the same product \(4\left(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O}_{2} \mathrm{~S}\right)\) upon treatment with peracetic acid. Compound 4 is also produced when 1 reacts with 2 equivalents of peracetic acid. Propose structures for compounds \(\mathbf{2}, \mathbf{3}\), and 4. Hint: Start by drawing a good Lewis structure for the starting material \(1 .\)

Draw structures for the following compounds: (a) \(p\)-nitrobenzaldehyde (b) \((S)-4\)-methylhexanal (c) \((E)-2\)-butenal (d) \(c i s-2-\) bromocyclopropanecarboxaldehyde

cis- 1,2 -Cyclopentanediol is much more reactive toward periodic acid than the trans isomer. Explain why.

Draw structures for the following compounds: (a) 3,5 -di-tert-butyl-4-hydroxybenzaldehyde (b) \((S)-5\)-bromo-2-cyclopentenone (c) \(2,4^{\prime}\)-dichloro-4-nitrobenzophenone (d) 6-methyl-2-pyridinecarboxaldehyde (e) (E)-4-phenyl-3-buten-2-one (f) aminoacetaldehyde dimethyl acetal
See all solutions

Recommended explanations on Chemistry Textbooks

Kinetics

Read Explanation

Chemical Analysis

Read Explanation

Making Measurements

Read Explanation

Inorganic Chemistry

Read Explanation

Physical Chemistry

Read Explanation

Chemical Reactions

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free