Organic Chemistry - Alkene Reactions

Hydrohalogenation

Addition of a H and a halide. H goes to the C with more H.

Halogenation

Addition of 2 halides, usually Cl and Br, to give 1,2-dihalides. If in a ring, the halogens are always trans to each other.

Halohydrin

Addition of OH and a halide to give a 1,2-halo alcohol. The reagent is the halide (Br or Cl) and H2O. OH goes to the more subsidized C.

Bromohydrin

Br is a difficult reagent to use in this reaction, so N-bromosuccinimide is used instead. The Br and OH will be trans to each other. Water is also used as a reagent. OH goes to the more subsidized C.

Hydration by Acid and H2O

Addition of H2O (H-OH) to give an alcohol. Acid catalysts are used in a high temperature (H3PO4).

Hydration by Oxymercuration

Addition of H2O (H-OH) to give an alcohol. Reactants are mercuric acetate in THF, followed by sodium borohydride. Results in an anti-addition of H and OH. OH goes to the more subsidized C.

Hydration by Hydroboration

Addition of H2O (H-OH) to give an alcohol. Reactant is borane (BH3), which will give you an organoborane. OH goes to the less subsidized C and will give you syn stereochemistry.

Hydrogenation

Addition of H-H across C double bond. Reagents are Pt or Pd as powders. H’s add to the same side (syn), but don’t end up on the same side of bulky groups if bulky groups are present.

Epoxidation

Addition of O to form a cyclic ether with an O atom. Meta-chloroperoxybenzoic acid (mCPBA) is used as an oxidizing agent. Resulting in an epoxide.

Hydroxylation

Converts to a syn-diol. Reactants are osmium tetraoxide, then sodium bisulfite. Two OH products that are cis-1,2 diol. You can use an epoxide to form a trans-1,2 diol.

Ozonolysis

Addition of ozone (O3) followed by zinc and water. C becomes a carbonyl group, always yields at least two products.

Permanganate Oxidation

Also cleaves alkenes. Reacted with potassium permanganate (KMnO4). Can produce carboxylic acids and carbon dioxide. Only works if there are vinyl H, if not it words like ozonolysis. 1 vinyl H = carboxylic acid, 2 vinyl H = carbon dioxide. Oxidizes again if aldehydes are formed to produce carboxylic acid.

1,2 Diol Cleavage

1,2 diol reacts with periodic acid (HIO4) and cleaves the diol into two carbonyl compounds. Opens a ring into a chain.