OChem Exam 4

Alkene Halogenation

Br₂ & CH₂Cl₂ that forms a bromonium ion intermediate than trans enantiomers through anti-addition

Alkene Halohydrin Formation

Br₂ & H₂O that forms a bromonium ion intermediate with excess water creating the non-symmetrical bromohydrin product through anti-addition

also can use NBS with water and DMSO and no UV light

Alkene Acid-Catalyzed Hydration

H₂SO₄/H₂O & THF working best for 3^o alcohols so the OH attacks the more substituted carbocation with the H on the other side of the double bond

Alkene Oxy-Mercuriation Hydration

Hg(OAc)₂ that forms a mercurinium mechanism in neutral conditions where the OH attacks the more substituted carbocation

Alkene Hydroboration

BH₃ & THF where the B attacks the least substituted carbocation on the same side where the H will attack through a region specific, non-Markovnikov, SYN-addition

Alkene Carbene Addition

CH₂ carbenes are added through a Simmons-Smith Reaction to form cyclopropanes in a one step, concentrated, stereospecific, SYN-addition mechanism with two enantiomers

Alkene Catalytic Hydrogenation

H₂ in the presence of a platinum of palladium catalyst in a stereospecific, SYN-addition mechanism

Alkene Epoxidation

peroxide and MCPBA helps convert into an epoxide in one step

Alkene Oxidative Cleavage

O₃ cleaves the double bond to give two carbonyl compounds with Hs

KMnO₄ cleaves the double bond to give ketones/carboxylic acids with OHs

Alkene Cis-1,2-Diol Formation

OsO₄ forms an epoxide transition state that is cleaved by NaHSO₃ to form the diol in a SYN-addition and can recycle the leftovers for another reaction

Alkene Cis-1,2-Diol Cleavage

HIO₄ & water form an epoxide transition state that is cleaved by an oxidizing reagent but only with trans conformations

Stereochemistry of Achiral Alkenes

α = 0 and continues to be 0 when it transforms into a Racemic Conformer

Stereochemistry of Chiral Alkenes

α ≠ 0 and continues to not be 0 when it transforms into two Unequal Diastereomers

Terminal Alkyne

R - C -= C - H

Internal Alkyne

R - C -= C - R’

Alkyne Addition of Hydrogen Halide

Alkyne Addition of Halogen

Alkyne Oxy-Mercuriation Hydration

Alkyne Hydroboration

Alkyne Hydrogenation

Alkyne Oxidation

Acidity Comparison

alkyne > alkene > alkane

pKa = 25 > pKa = 44 > pKa = 60

Stability Comparison

acetylide > vinylic > alkyl