Organic Reactions

Making Music With Mechanisms

Making Music With Mechanisms

April 4, 2014

My friend Harry has an annoying habit. When we’re hanging out, every once in awhile, he’ll put on a serious face and say he has something very important to tell me. Then, when he has my attention, he breaks out that annoying Bryan Adams song that begins with “Pleeease forgive me…”. He thinks this is hilarious. While it *is* [...]

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Guest Post On SN1/SN2/E1/E2 (3): Step 1 – The Nucleophile

November 12, 2013

Following from Adam’s last guest post on the SN1/SN2/E1/E2 (“The Leaving Group“) here is part 3 of the series!  – James Step One: What is the nature of the nucleophile? by @azmanam Last time, we talked about the quick check on the nature of the leaving group. Today, we’ll discuss how the nature of the [...]

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Initiation, Propagation, Termination

September 6, 2013

Waaay back when we started to go through free radical substitution reactions, you might recall that we looked a reaction like this one:   Now that we know a little more about what free radicals are and their key properties, the question for today is, “how does this reaction work?“. We’re going to go through the [...]

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Alkynes Via Elimination Reactions

Alkynes Via Elimination Reactions

June 11, 2013

We’ve gone through elimination reactions before – treatment of alkyl halides with base gives alkenes.  Some time ago we discussed elimination reactions here. Elimination reactions follow the general pattern below, where two adjacent bonds to carbon are broken – usually C-H and C-X, where X is a leaving group – and in place we form [...]

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Organic Reaction Flashcards Version 2.0 Is Here!

Organic Reaction Flashcards Version 2.0 Is Here!

May 10, 2013

Do you ever study by making flashcards of reactions? You might recall that a few months ago Rich Apodaca (of Metamolecular) and myself released the first version of The Organic Reactions Flashcard App for iPhone, a mobile app for learning organic chemistry reactions. That initial version of Flashcards was pretty basic – 25 reactions and [...]

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Summary: Alkene Reaction Pathways

April 25, 2013

In this post we’ll do a final review of alkene addition reactions and sum up the three major pathways (and two minor classes of reactions worth paying attention to). Reaction Pathway #1 – The Carbocation Pathway In the Carbocation Pathway, the alkene acts as a nucleophile and attacks an electrophile, resulting in the formation of [...]

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Alkene Addition Pattern #3: The “Concerted” Pathway

April 2, 2013

In contrast to alkene addition reactions in the Carbocation Pathway and the 3-Membered Ring Pathway, we saw in the last two posts that hydroboration of alkenes is anomalous. The regioselectivity of the reaction is “anti-Markovnikov” and the stereochemistry of the addition is “syn“: We also saw that the “syn” stereochemistry is due to the concerted [...]

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Bromination of Alkenes: The Mechanism

Bromination of Alkenes: The Mechanism

March 15, 2013

In the last post of this series we showed how the mechanism for bromination of alkenes can’t possibly go through a carbocation intermediate. Why not? We have at least 3 good reasons: The two atoms that form new bonds to carbon add to opposite faces of the alkene (“anti” stereoselectivity) The reaction is stereospecific – (Z)-2-butene [...]

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Bromination of Alkenes – How Does It Work?

March 6, 2013

In a previous post we went through the key reactions of the carbocation pathway. It’s a family of reactions which proceed through 1) attack of an alkene upon an acid, forming a free carbocation, and 2) attack of a nucleophile upon the carbocation. Although we saw that several key reactions of alkenes were consistent with [...]

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Addition Pattern #1: The “Carbocation Pathway”

Addition Pattern #1: The “Carbocation Pathway”

February 22, 2013

MOC: What were some of your biggest roadblocks in learning organic chemistry? OCI: Not learning the patterns. I think I wasn’t told that there were patterns. -from this post A Key Pattern For Alkene Addition Reactions The last several posts have primarily dealt with one reaction: the addition of HCl to alkenes. As we’ve seen, [...]

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