Alcohol Flashcards
How many ways are there to prepare alcohol from alkenes?
•Acid-catalyzed hydration, •oxymercuration-demercuration, •hydroboration-oxidation.
What are the reagents of acid-catalyzed hydration?
H2O or H2SO4 dilute.
Is there formation of intermediate in acid-catalyzed hydration?
There is formation of carbocation.
So check for the rearrangement.
What are the steps of acid-catalyzed hydration of alkene?
1.) Addition of H+ from dilute H2SO4 after removing the double bond.
2.) Formation of carbocation intermediate.
3.) Addition of OH- from water
What are the reagents of oxymercuration-demercuration?
Hg(OAc)2
H2O
NaBH4
What are the basic steps of oxymercuration in alkene?
On the reagent side:
In Hg(OAc)2 forms into Hg+OAc and Ac-
Now:
1.) This Hg+OAc ion reacts to alkene and forms partial bond by breaking double bond and satisfies it’s+ve charge by becoming neutral after this.
2.) H2O attaches to the carbon with less Hydrogen and breaks partial bond of one side. Hence Hg forms a complete bond with carbon having more Hydrogen.
3.) Oxygen here attains +ve charge making it unstable, throws one of it’s H.
4.) We obtain a product of Anti-Addition of OH(on carbon with less hydrogen) and HgOAc (on Carbon with more Hydrogen).
What kind of addition is found in the product after oxymercuration is completed?
Anti
What happens in the process of demercuration step-by-step?
On the reagent side:
NaBH4 breaks into Na+, BH3 and H+ ions
1.) This H+ attacks in the anti addition product of oxy-mercuration
2.) Forms alcohol, Hg+ and OAc- ion
Is rearrangement possible in oxymercuration-demercuration steps?
No
Simply, what has happened in the process of oxymercuration-demercuration?
ANTI-addition of water by MARKOVNIKOV rule
What are the sources of…
1.)OH
2.)H
OH___H2O
H_____NaBH4
What are the Reagents of Hydroboration Oxidation?
•Tetrahydrofuran(THF),
•Hydrogen peroxide(H2O2)
•B2H6, and
•OH- ion.
