Chapter 8 - Key mechanisms Flashcards
What type of addition occurs in the Hydrohalogenation reaction with HBr?
Markovnikov addition
In Markovnikov addition, the hydrogen atom from HBr adds to the less substituted carbon, while the bromine adds to the more substituted carbon.
What is the first step in the Hydrohalogenation mechanism?
Protonation of the alkene
The π-bond attacks H+, forming a carbocation at the more substituted carbon.
What is formed after the nucleophilic attack in Hydrohalogenation?
The product CH3−CHBr−CH3
Bromide ion (Br−) attacks the carbocation to form the final product.
What is the reaction for Acid-Catalyzed Hydration?
CH3−CH=CH2 + H2O → H2SO4 CH3−CHOH−CH3
This reaction involves the addition of water in the presence of sulfuric acid.
What is the result of the deprotonation step in Acid-Catalyzed Hydration?
Formation of an alcohol
Another water molecule removes the extra proton from the oxonium ion.
What is the key intermediate formed during Oxymercuration-Demercuration?
Mercurinium ion
The π-bond attacks Hg(OAc)+, forming a cyclic intermediate.
What replaces the mercury group in the Oxymercuration-Demercuration reaction?
Sodium borohydride (NaBH4)
NaBH4 replaces the mercury with a hydrogen atom.
What type of addition occurs in Hydroboration-Oxidation?
Anti-Markovnikov addition, syn addition
Boron attaches to the less substituted carbon, while hydrogen attaches to the more substituted carbon.
What is the function of peroxide in Hydroboration-Oxidation?
Replace boron with a hydroxyl group
Peroxide and hydroxide are used to oxidize the boron compound.
What is the reaction outcome for Halogenation with Br2 in CCl4?
CH3−CH=CH2 + Br2 → CH3−CHBr−CH2Br
This reaction results in the formation of dibrominated products through anti addition.
What intermediate is formed during the Halogenation process?
Bromonium ion
The π-bond attacks one bromine atom, resulting in a three-membered ring.
What is the result of the Syn Dihydroxylation reaction?
Formation of a 1,2-diol
Osmium tetroxide reacts with the alkene to form a cyclic osmate ester, which is then cleaved.
What is produced from the oxidative cleavage using O3/DMS?
CH3−CHO (acetaldehyde) + HCHO (formaldehyde)
Ozone forms a molozonide that rearranges to an ozonide, which is then reduced to aldehydes.
Fill in the blank: The first step in Hydroboration is _______.
Hydroboration
Borane (BH3) adds across the double bond.
True or False: In syn dihydroxylation, the addition of hydroxyl groups occurs on opposite sides of the double bond.
False
Syn dihydroxylation refers to the addition of hydroxyl groups on the same side of the double bond.
