Alkene Reaction Mechanisms in Organic Chemistry

organic chemistry alkene reaction mechanism tutorial videosAlkene reactions are the core foundation to learning reaction mechanisms in organic chemistry. These are likely the first set of reaction mechanisms covered in your Orgo 1 course. But the concepts and foundations learned in these reactions will carry through to the rest of your organic chemistry 1 and 2 courses.

Below is my alkene reaction mechanism tutorial video series taking you through each reaction 1 at a time, focusing on the WHY and HOW for every step in every mechanism starting with an understanding of pi bond reactivity, role of nucleophile/electrophile and even covering hydride shifts and ring expansions.

Alkene Reaction Study Guide Cheat Sheet

Alkene Reaction Study Guide Cheat Sheet

Included in this series:

  1. Naming Alkenes
  2. Introduction to nucleophile, electrophile and pi bond reactivity
  3. Hydrohalogenation
  4. Halogenation
  5. Halohydrin formation
  6. Acid Catalyzed Hydration
  7. Hydride Shift and Methyl Shift
  8. Ring Expansion via Hydride AND Methyl Shift
  9. Oxymercuration-Demercuration
  10. Alkoxymercuration-Demercuration
  11. Hydroboration Oxidation
  12. Alkene Epoxidation
  13. Ozonolysis of Alkenes
  14. Markovnikov v. Anti-Markovnikov
  15. Alkene Reaction Overview 

Don’t forget to download the Cheat Sheet + try the Alkenes Quiz after going through the series!

Video 1 – Naming Alkenes

Naming Alkenes Video Tutorial by Leah4sci OrgoFirst, before we start looking at all of the various alkene reactions and mechanisms, do you remember how to name alkenes?

This video shows you how to name alkene molecules– from the simple to the more complex– using my puzzle piece approach to IUPAC naming of organic compounds.

It also includes a quick introduction to pi bonds and the hydrogen deficiency alkenes.

Video 2 – Introduction to Nucleophile/Electronphile and Pi Bond Reactivity

Introduction to nucleophile electrophile and pi bond reactivity in alkene reaction mechanismsDon’t dismiss the intro video as ‘unimportant’ this may very well be the most important video in this series.

In this video you’ll get a proper view at the pi bond orientation and how this relates to alkene reactivity.

You’ll also learn the true meaning of Nucleophile and Electrophile, including how to recognize them and why they react as they do.

And finally, this video takes you through a sample alkene reaction mechanism focusing on they WHY and HOW to ensure you understand the movement of electrons every step of the way.

Video 3 – Hydrohalogenation Reaction Mechanism

Hydrohalogenation of alkenes reaction mechanism tutorial videoThe hydrohalogenation reaction is one in which the pi bond breaks adding a halogen to the more substituted carbon in keeping with Markovnikov’s rule.

This video takes you through the reaction and step by step mechanism for both a symmetrical starting alkene, and and asymmetrical starting alkene.

This mechanism typically involves hydrobromination and hydrochlorination in an inert solvent.

Carbocation rearrangements may be observed.

Video 4 – Halogenation of Alkenes Reaction Mechanism

Alkene Halogenation Reaction Mechanism Tutorial VideoThe alkene halogenation reaction is one in which the alkene pi bond breaks adding TWO halogen atoms to neighboring carbons. This occurs via a cyclic bromonium or chloronium intermediate.

This video helps you understand the step by step reaction mechanism, from the halogen reactivity, bridge formation, and overall anti addition.

Do not confuse this with the alkene hydrohalogenation which only ads a single halogen along with a hydrogen atom.

This video demonstrates the mechanism for a symmetrical and asymmetrical starting molecule.

Video 5 – Halohydrin Formation

Halohydrin formation alkene reaction mechanism tutorial videoThe halohydrin formation is an alkene reaction in which a halogen and an alcohol add to the broken pi bond.

This reaction starts out just like the halogenation reaction, but since it takes place in a reactive solvent, you get a solvent molecule partaking in the reaction mechanism.

This video provides with a step by step breakdown of the mechanism and helps you understand WHY this reaction undergoes anti addition and still follows Markovnikov’s rule.

Backpack Trick for Organic Chemistry Reactions by Leah4sciLearn The Backpack Trick

When students merely memorize, any change to a reaction may lead to panic. The backpack trick will help you figure out how to swap out atoms and groups to apply what you know to a new version of the reaction, specifically for oxygen containing reactions from acid catalyzed hydration and more.


Video 6 – Acid Catalyzed Hydration Alcohol Formation 

Acid catalyzed hydration alcohol formation alkene reaction mechanismAcid catalyzed hydration is the reaction in which an alcohol is added to a pi bond following Markovnikov’s rule.

This tutorial video gives you a step by step logical breakdown of every step in the reaction mechanism to ensure you understand WHY each atom attacks as it does.

This reaction covers the role of solvent and catalyst in hydration reactions, and well as regioselectivity in accordance with Markovnikov’s rule. Practice problems included.

Also check out the article Acid Catalyzed Hydration of Alkenes Reaction and Mechanism for another step by step explanation.  

Video 7 – Hydride Shift and Methyl Shift in Alkene Reactions

hydride shift methyl shift tutorial video

This video helps you understand the logic behind the carbocation rearrangement, along with specific patterns to look for when deciding between a hydride shift or methyl shift.


Video 8 – Ring Expansion Example with Hydride and Methyl ShiftRing Expansion via Hydride Shift and Methyl Shift Video Tutorial

This video helps you understand the logic behind the carbocation rearrangement, along with specific patterns to look for when deciding between a hydride shift or methyl shift.


Video 9 –
Oxymercuration & Demercuration

oxymercuration demercuration alkene reaction mechanism tutorial videoThis video takes you through the step by step reaction mechanism for oxymercuration and helps you understand WHY there is no carbocation rearrangement.


Video 10-
Alkoxymercuration & Demercuration

Alkoxymercuration Demercuration Reduction Alkene Reaction Mechanism Leah4sciAlkoxymercuration-Demercuration Reduction is the alcohol version of the oxymercuration reaction.

Just like its counterpart above, this reaction is regioselective in following Markovnikov’s rule and will not exhibit a carbocation rearrangement.

The product of this reaction is an ether as detailed in this tutorial video.

Video 11 – Hydroboration

hydroboration oxidation alkene reaction mechanism tutorial video

The video below helps you understand the reactivity of Boron as well as the hydroboration and oxidation steps of the reaction mechanism.



Video 12 – Alkene Epoxidation

Alkene Epoxidation organic chemistry tutorial video to convert alkene to epoxideUnderstand peroxy acid (mCPBA and peroxyacetic acid). See a shortcut to quickly find the products, and finally the concerted cyclic mechanism to form the epoxide and carboxylic acid.


Video 13 – Ozonolysis of Alkenes

Ozonolysis of Alkenes ReactionThe ozonolysis reaction of alkenes is one which breaks (or “lyses) both the sigma and pi bond of an alkene by reaction with a molecule of ozone. This video covers both the reductive and oxidative workups of the reaction.

It also provides a shortcut for quickly finding the products of an ozonolysis reaction, as well as the detailed step-by-step ozonolysis mechanism.

Video 14 – Markovnikov v. Anti-Markovnikov
Markovnikov vs Anti-Markovnikov in Alkene Addition Reactions by Leah4sci

In so many of these alkene reactions, you might be asking yourself which addition product ACTUALLY forms? Or maybe, which one forms most often?

Asymmetrical alkenes can form two different addition products: one major and one minor. This video walks you through Markovnikov’s rule, including memorization shortcuts, to ensure you understand how to identify Markovnikov and anti-Markovnikov addition products.

Video 15 – Alkene Reaction Overview 

Alkyne Reactions Products and Shortcuts by Leah4sciTime to review everything you’ve learned! This video reviews all 18 reactions covered on my alkene reaction cheat sheet and study guide. It also provides a quick overview of the regioselectivity and stereoselectivity of products.


Ready to test your skills? Click HERE for my FREE Alkene Reactions Practice Quiz

Need a quick review of alkene reactions? 

Download my free Alkene reactions study guide cheat sheet!

alkene reaction study guide cheat sheet

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