Organic Reactions

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 [...]

Tagged as: app, flashcards, iphone, reagents, study tips

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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 [...]

Tagged as: alkenes, bromination, carbocation, hydroboration, markovnikoff, markovnikov, patterns, stereochemistry

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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 [...]

Tagged as: addition, ch2i2, cyclopropanation, dichlorocarbene, dihydroxylation, epoxidation, hydroboration, hydrogenation, mCPBA, osmylation, oso4, simmons smith, zn-cu

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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 [...]

Tagged as: alkenes, anti, bromination, bromonium, chlorination, halogenation, halonium, markovnikov, mechanisms, syn

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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 [...]

Tagged as: alkenes, anti, bromination, bromohydrin, carbocation, markovnikoff, markovnikov, stereochemistry

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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, [...]

Tagged as: alkene, carbocation, hbr, hcl, hi, hydration, hydrohalogenation, markovnikoff, markovnikov, regioselectivity, stereoselectivity

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Now Available: The Organic Reactions Flashcard App for iPhone

Now Available: The Organic Reactions Flashcard App for iPhone

February 14, 2013

Today, in partnership with Rich Apodaca of Metamolecular, I’m happy to announce the release of a new app for the Apple iOs: Organic Reaction Flashcards for iPhone.   It should come as no surprise that one of the greatest difficulties students have in learning organic chemistry is in keeping track of all the reactions. That’s [...]

Tagged as: app, flashcards, metamolecular, oxymercuration

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Markovnikov’s Rule (2) – Why It Works

February 11, 2013

Understanding Why Markovnikov’s Rule Works Let’s assemble all the facts we know about the reactions of alkenes with an acid like HCl so far. Regiochemistry: as we saw in the last post, reactions of alkenes with acids like HCl follow Markovnikov’s rule: the major product formed is that where the hydrogen adds to the carbon [...]

Tagged as: addition reactions, alkenes, hcl, markovnikoff, markovnikov, rearrangements, regiochemistry, stereochemistry

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Addition Reactions: Regioselectivity

January 28, 2013

In the previous post on addition, we talked about the key pattern of addition reactions [break C-C π, form two new bonds to adjacent carbons] and how this is the exact opposite pattern of elimination reactions we went through earlier. Going forward, we’re going to use a lot of structure shortcuts. So it’s helpful to be [...]

Tagged as: addition, anti, bromination, regioselectivity, stereochemistry, syn

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Addition Reactions: Elimination’s Opposite

Addition Reactions: Elimination’s Opposite

January 22, 2013

In previous series, we’ve discussed acid-base reactions, nucleophilic substitution reactions, and elimination reactions. These represent three of the four most important reaction types in a typical Org 1 course. What each of these reactions have had in common so far is that each of them begin with a Lewis base (which we call a “base” [...]

Tagged as: addition, alkenes, elimination, hbr, markovnikov

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