1. Hydrohalogenation
The reagent for this reaction is HX, where X is either Cl, Br or I.
Product: Turn double bond into single and add X (halogen) to the MOST substituted carbon from the double bond (Markovnikov rule). Warning: Rearrangements are possible!
The reaction is also called addition of hydrogen halides to alkenes.
2. Acid Catalyzed Hydration Of Alkenes
The reagent is H2O with any catalytic acid such as H2SO4. Examples are: H2O/H2SO4, H3O+
Product:Turn double bond into single and add OH to the MOST substituted carbon from the double bond (Markovnikov rule). Warning: Rearrangements are possible!
3. Hydroalkoxylation
This reaction is an addition of alcohol with an acid catalyst to an alkene. It is similar to the acid catalyzed hydration described above except that instead of OH, OR group will be added.
The reagent is ROH with a catalytic acid.
Product: Turn double bond into single and add OR to the MOST substituted carbon from the double bond carbons.
4. Halogenation
The reagent is Br2 or Cl2 with a solvent such as (CH2Cl2).
Product: Turn double bond into single and add two bromines (or chlorines) one on each carbon from the double bond. Stereochemistry: ANTI ( one is on a wedge and another is on a dash).
The reaction is also called addition of halogens to alkenes.
5. Halogenation Of Alkenes In the Presence Of Water/ Formation of Halohydrins
The reagent is Br2 or Cl2 with H2O.
Product: Turn double bond into single and add OH to the most substituted carbon from the double bond and Br (or Cl) to the less substituted carbon from the double bond. Stereochemistry: TRANS
6. Oxymercuration
The reagent is 1.Hg(OAc)2, H2O 2.NaBH4
Product: Turn double bond into single and add OH to the most substituted carbon from the double bond. The other carbon gets the hydrogen. No Rearrangements!
This reaction is very useful. Both acid catalyzed alkene hydration and oxymercuration give the same product, but the difference is that oxymercuration can not have any rearrangements. Therefore, for synthesis, it might be a better choice for the reagent.
7. Alkoxymercuration
The reagent is 1.Hg(OAc)2, ROH 2.NaBH4
Product: Turn double bond into single and add OR to the most substituted carbon from the double bond. The other carbon gets the hydrogen. No Rearrangements!
8. Hydroboration
The reagent is 1.BH3, THF 2. H2O2, NaOH or 1.B2H6,diglyme 2.H2O2, NaOH
Product: Turn double bond into single and add OH to the LEAST substituted carbon from the double bond (Anti Markovnikov Rule) and hydrogen on the most substituted carbon from the double bond. OH and H add syn (same side, both are dash or wedge)
Hydroboration is a very useful reaction because it is rare for reactions to go the anti Markovnikov way.
If we notice OH on the less substituted carbon in the product in a synthesis problem, hydroboration most likely led to that product.
9. Syn Hydroxylation
The reagent is 1.OsO4 2.H2O2 OR 1.KMnO4 2. H2O, OH- (cold, dilute)
Product: Turn double bond into single and add two OHs, one on each carbon from the double bond. Stereochemistry: syn (same side, both wedge or both dash).
10. Catalytic Hydrogenation Of Alkenes
The reagent is H2 with a metal catalyst such as Pt, Pd, or Ni
Product: Turn double bond into single by adding 2 hydrogens ,one on each carbon from the double bond. Hydrogen add syn (both wedge or both dash)
11. Ozonolysis With Reductive Workup
The reagent is 1.O3 2. (CH3)2S (also called DMS) OR Zn, H2O
Product: Break the double bond in two and add two oxygens, one on each end of the double bond broken.
12. Ozonolysis With Oxidative Workup
The reagent is 1.O3 2.H2O2
Product: Break the double bond in two and add two oxygens, one on each end of the double bond broken. If you made an aldehyde (C=O connected to H), you have to change H into OH to make carboxylic acid.
This product can be also achievedwith KMnO4 (warm, concentrated)
13. Epoxidation
The reagent is RCO3H (peroxyacid). Popular reagents include CF3CO3H and mCPBA
Product: Turn double bond into a single bond and attach the two carbons that had a double bond to an oxygen, making an epoxide. The epoxide can on a wedge (both carbons attached to the oxygen on a wedge) or dashed.
14. Radical Addition Of HBr
The reagent is HBr, ROOR (peroxide)
Product: Turn double bond into a single bond and attach Br to the LEAST substituted carbon from the double bond carbons (Anti Markovnikov).
The reaction is also called Free-Radical Addition of HBr
15.The Simmons-Smith Reaction
The reagent is CH2I2 with Zn,CuCl
Product: Turn double bond into single bond and attach the two carbons from the double bond to another carbon making a cyclopropane (triangle).
Are you looking for an online organic chemistry tutor? Click HERE
We also have: General chemistry tutor online
Download Alkene Reactions Cheat Sheet