Introduction
We are going to have to do this one in two stages. We don’t know enough (yet) to give a full treatment of the problem, but it’s too important to not make a start!
Acid catalysis is widely used to increase the rates of...
Chapter
Acid Catalysis in Organic Reactions Part 1
Chapter
Acid Catalysis in Organic Reactions Part 2
Answer 1
Here is the equilibrium again.
[image]
We know that...
Chapter
Acid Catalysis in Organic Reactions Part 2
Introduction
We started looking at this problem in Basics 22. Now we have looked at the thermodynamics of reactions involving charged species (Basics 35), we can consider the implications of acid catalysis with a strong acid and with a weak acid....
This...
Chapter
Afterword
So, you’ve got to the end. Hopefully you have enjoyed reading this book. More importantly, I hope you have understood all of the explanations and learned quite a lot of organic chemistry.
Did you ‘just’ read this book?
If you did, then that’s okay. The...
Chapter
Allylic Substitution
Introduction
An adjacent double bond can influence the outcome of a substitution reaction in several ways. The purpose of this chapter, as always, is to explore fundamental principles. Therefore, we will establish, and then build on, what we know.
Chapter
Always Draw Structures with Realistic Geometry
In the previous chapter, I mentioned the importance of forming good habits. I want to formalize this by including short chapters focused only on this one theme. Here is the first one!
Chapter
Assigning Stereochemistry
The Point of The Exercise
During various chemical transformations, the stereochemistry of a given stereogenic centre may change. If it does, you need to know about it. The labels are very useful for keeping track.
Let’s not have any illusions about this. If you give...
Chapter
Assignment of Stereochemistry—The Cahn–Ingold–Prelog Rules
It takes a little time to get used to assigning stereogenic centres. After a while, you will be able to do it without thinking. As with so many other aspects of organic chemistry, the route to competence is practice. Don’t learn this once, think it...
Chapter
Bond Dissociation Energy
In order to better understand bond dissociation energy, and the energetics of bond breaking, we need to look at three reactions, all of which simply involve the breaking of a C–H bond.
Make sure you follow the curly arrows in each case, and you understand...
Chapter
Bond Lengths and Strengths
Much of the focus of this book is building patterns and habits. I have tried to keep the factual information to a minimum, but of course it is still there.
Here is the problem. A chemical bond is between 1.0 and 1.6 Å in length....
Chapter
Bond Polarization and Electronegativity
The Purpose of The Exercise
You need to be thinking about the distribution of charge in organic structures. You need to be able to do this no matter how complex the structure. In order to do this, you will need to ‘see’ functional groups even...
Chapter
Bonding and Antibonding Orbitals
Electrons reside in orbitals. In stable molecules, these tend to be bonding orbitals— there is a high probability of finding electron density between the nuclei involved in the bond.
Whenever we form a bonding orbital by overlap of electrons from two atoms, we always form...
Chapter
Bonding Beyond Hybridization
When we think of electrons and orbitals, we use quantum mechanics. It is impossible to accurately solve the Schrödinger equation for anything other than the simplest systems. For real organic molecules, you cannot do it at all. Therefore, everything you will ever be told about...
Chapter
Bonding in Organic Compounds
We need to cover the basics of bonding and molecular orbitals here, to give you the tools you need to describe bonds and their reactivity.
We are going to discuss the overlap of orbitals to form σ (sigma) and π (pi) bonds. Before we do...
Chapter
Bonds Can Rotate
This chapter highlights molecular models that can be twisted and turned. This provides insight into what might happen in a real molecule. It considers how some compounds prefer to react in specific orientations and how the ease of adopting a particular orientation often determines the reactivity of the compound. It also discusses conformational isomers or conformers which regard a special type of stereoisomer related simply by rotation around single bonds. The chapter reviews the applications of conformational isomerism in substitution reactions and the energy difference between conformers fundamental to E2 elimination reactions. It outlines the fundamental principles of conformational analysis in cyclohexanes to substitution and elimination reactions.
Chapter
Breaking Bonds—Linking Curly Arrows and Molecular Orbitals
Now we have examined the nature of bonding in organic compounds, we need to revisit the curly arrows from Basics 8, and present them in a more formal way, considering what type of bond is being formed or broken in each case. We...
Chapter
Building Skills
This chapter presents a series of worked problems within organic chemistry that vary in scope and complexity and require the basic application of knowledge to predict the outcomes of reaction. It includes activities that require the drawing of correct curly arrows showing either a substitution or an elimination reaction. It also presents a question on whether it is possible for all nine C–H bonds in the t-butyl carbocation to simultaneously overlap with the vacant p orbital. The chapter reviews the thermodynamics of reactions involving charged species and considers the implications of acid catalysis with a strong acid and a weak acid. It compares two processes that established that the activation energy from the protonated alcohol is significantly lower.
Chapter
Calculating Enthalpy of Reaction from Bond Dissociation Energies
Introduction
If we know how strong each chemical bond in a molecule is, we can calculate the enthalpy change for a reaction.
Here is a table of average bond dissociation energies, all in kJ mol−1. These are representative values for the...
Chapter
Calculating Enthalpy of Reaction from Bond Dissociation Energy
The Purpose of The Exercise
In my experience, it is pretty rare for an organic chemist to carry out one of these calculations. However, they will look at a reaction and intuitively know whether it is likely to be endothermic or exothermic...
They can...
Chapter
Carbanions 2—Stability and pK a
We are still at the stage of building patterns and habits, so I want to focus primarily on relating carbanions to other systems that you know, and build on the theme of drawing and understanding resonance forms.
We are going to discuss the stability of...
