Chemical Bonds

Elimination Reactions (2): Zaitsev’s Rule

August 31, 2012

So far, we’ve only looked at some very simple elimination reactions. In this post we’ll look at some examples where we start to see some of the extra “wrinkles” that can be present in elimination reactions. For example, if you treat the alcohol below with a strong acid (like sulfuric acid, H2SO4) and heat, you [...]

Tagged as: alkene stability, alkenes, alkyl halides, alpha carbon, beta carbon, elimination, substitution

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Walkthrough of Substitution Reactions (1) – Introduction

May 31, 2012

Today starts a new series of posts on walking through one of the key classes of reaction in organic chemistry: substitution reactions. The goal of this series is to teach you:  How to recognize substitution reactions when they are presented to you What the key components of a substitution reaction are (substrate, nucleophile, and leaving [...]

Tagged as: acids, bases, electrophile, introduction, nucleophile, sn1, SN2, substitution, walkthrough

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Acid Base Reactions Are Fast

May 21, 2012

Common dilemma in organic chemistry as you move through the latter parts of Org 1 and then into Org 2: When more than one reaction is possible, how do you know which one will happen? In a steel cage match between an acid base reaction and other types of reactions, which wins? Here’s a good [...]

Tagged as: acidity, basicity, conjugate acid, conjugate base, nucleophile, nucleophilicity, pka, trick questions

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Walkthrough of Acid Base Reactions (1)

April 11, 2012

Now that we’ve described how to figure out where the electrons are in a molecule,  the factors that stabilize negative charge and positive charge, and gone into the curved arrow formalism for reactions, we’re ready to start going into more detail on some of the key reactions in organic chemistry. Let’s start with acid base [...]

Tagged as: acidity, acids, anion, bases, basicity, cation, charge, conjugate base, negative charge, positive charge, stability

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The Second Most Important Question to Ask When Learning A New Reaction

November 9, 2011

So once you can recognize the key bonds that are forming and breaking in a chemical reaction, the second most important question to ask yourself when learning a new reaction is “how do the electrons move?” I have a friendly disagreement with a lot of instructors on this point, since it’s common to claim that [...]

Tagged as: accounting, arrow pushing, curved arrows, electron densities, electron flow, electronegativity, opposite charges attract

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Introduction to Oxidative Cleavage Reactions

November 1, 2011

The four posts on acid-base, substitution, addition, and elimination covered the 4 main reactions in organic chemistry I. In this second series of posts we go beyond these to introduce a few of the less common (but still important) reactions you learn in organic chemistry 1. We’ve talked about rearrangements and free-radical substitution: we finish up here with lots of  cleavage (oxidative cleavage). [...]

Tagged as: C-C bond breaking, cleavage, naIO4, o3, oxidation, oxidative cleavage, oxidizing agents, ozone, ozonolysis, pb(oac)4

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Introduction to Elimination Reactions

October 10, 2011

As  part 4 of the most important reactions you learn in org 1, (acid-base, substitution, and addition) here’s an introduction to the elimination reaction. This series requires that you understand how to read line diagrams (click for video introduction) as well as to understand what wedge-dash notation means (for showing molecules in 3D). But otherwise [...]

Tagged as: acid, alkenes, base, e1, e2, elimination, zaitsev

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Introduction to Addition Reactions

October 3, 2011

Following up on the 4 most important reactions you learn in Org 1, and the posts on acid-base and substitution reactions, here’s the third in the series: addition reactions. You’ll have to know line diagrams to get this – see the video here – and to truly grok the point of the last two images, [...]

Tagged as: addition, important reactions, markovnikoff, patterns, regioselectivity, stereoisomers

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Introduction to Nucleophilic Substitution Reactions

September 26, 2011

Following up on the 4 most important patters of reactions in Org 1, and introduction to acid-base reactions, here’s the second major pattern. It’s called nucleophilic substitution. I won’t go into nucleophiles and electrophiles in this post. The point is actually not to understand what’s going on here! Don’t understand the reactions below. Just focus [...]

Tagged as: electrophiles, leaving groups, nucleophiles, nucleophilic substitution, sn1, SN2, substitution

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Introduction to Acid-Base Reactions

September 19, 2011

Following up on the 4 major classes of reactions you encounter in Org 1, let’s look at the first of those four: acid base reactions. The focus here is not initially to understand why things happen the way they do – that comes later. The initial focus is to be able to recognize what is happening. Just [...]

Tagged as: acids, bases, conjugate acids, conjugate bases, equilibrium, formal charge, stability

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