Organic Chemistry -- Ch. 10 Review (McMurray)

What are the three steps for radical reactions and which mechanisms go with each?

Initiation - homolytic bond cleavage,

Propagation - addition to a pi bond, hydrogen abstraction, halogen abstraction, elimination

Termination - coupling

Radical Addition of HBr (HBr/ ROOR) to an alkane

Initiation: homolytic cleavage of ROOR with heat to make two radicals

hydrogen abstraction of HBr to make and ROH and radical Br

Propagation: addition of Br radical to an alkene to make alkyl halide radical

hydrogen abstraction of H from HBr to make an alkyl halide and a Br radical

Termination: coupling of Br radicals to make Br2

Radical Polymerization

initiation: homolytic cleavage of ROOR, addition of RO radical to alkene

Propagation: addition to make polymer

Termination: coupling

Alcohol + PBr3

Alcohol + SOCl2

formation of alkyl halide by Sn2 (draw mechanisms for both)

Alcohol + tosyl chloride in the presence of pyridine

tosylate + pyridine*HCl

Stereochemistry of Tosylates being converted into Ethers

Tos + alcohol via Sn2 to make an ether, inversion of stereocenter

Sn2 of alcohol via alkyl halide, 2 inversions (retention)

Radical Halogenation

initiation: homolytic cleavage

propagation: hydrogen abstraction, halogen abstraction

termination: coupling

Allylic Bromination

using NBS/ light; allylic radical is resonance stabilized, Br may be installed at either radical position giving a mixture of products

Grignard Reagent

R-Mg + X → R-MgX, where R is primary, secondary, or tertiary alkyl, aryl, and vinylic

• react with carbonyl compounds to make alcohol, can act as nucleophilic carbon anions

Gilman Reagents

made through reaction of an alkyllithium with a copper salt

R-Li + CuX → (ether) → R-Cu-R + LiX

Ketones from Acid Halides

acid chloride -(gilman / ether)→ ketone + R’Cu with a acyl diorganocopper intermediate