Alcohol Reactions Flashcards
Which one is more acidic a primary or tertiary alcohol?
A primary alcohol because it has less steric hinderance.
If you react a primary alcohol with an oxidizing agent such as chromic acid, what will the product be?
A carboxylic acid, because this oxidizing agent is too strong and it oxidizes the OH straight to COOH.
What oxidizing agents are used to oxidize a secondary OH?
PCC, chromic acid, DMSO/Et3N, (COCl)2
What happens when you oxidize a primary alcohol vs. a secondary alcohol?
Primary –> aldehyde
Secondary –> ketone
What happens when you oxidize a tertiary alcohol?
No reaction
A tertiary alcohol is more likely to undergo a (SN1/SN2) reaction.
SN1
Possible oxidizing agents for:
Primary OH –> aldehyde
PCC, DMP, DMSO and COCl2 together
What reagents can we use to create this product?
HCl or SOCl2 & pyridine
What is the stereochemical outcome of this reaction?
inversion of configuration
In a reaction between SOCl2 and OH, what atom is the electrophile, what atom is the nucleophile?
The nucleophile is the O in OH, the electrophile is the S in SOCl2.
What is the most stable carboxylic acid derivative? Why?
An amide; the nitrogen in the amide acts as an electron donating group does donating electrons to the carbonyl group and making it less reactive.
What is the least stable/most reactive carboxylic acid derivative?
acid halide
Explain the general mechanism of a nucleophilic acyl substitution.
- Nucleophile attacks carbonyl group, pushing double bond up as electrons on O.
- Double bond between C and O reforms, causing ejection of LG.
What is the reagent PCC used for?
It is an oxidizing agent, which is used to oxidize a primary OH into an aldehyde.
In order to create an ester, what reactants do we need? What is the name of this mechanism?
An alcohol and a carboxylic acid under acidic conditions. (Cannot be performed under basic conditions.) The mechanism is Fischer esterification.
Why are alcohols converted into tosylates?
Tosylates make better leaving groups which can undergo SN2 reactions. This allows secondary OHs to only undergo SN2 w/o worrying about potential carbocation rearrangements.
What are the first steps of the mechanism between an alcohol and tosylate?
The O in the alcohol attacks the electrophilic S, forming a covalent bond between O and S.
What is the stereochemical outcome in converting an OH to OTs?
Retention of configuration
What is the purpose of the pinacol rearrangement?
It is used to convert a 1,2 diol into a ketone under acidic conditions.
Explain the mechanism of pinacol rearrangement.
- One OH group is protonated, become H2O
- H2O leaves, forming + carbocation
- Methyl or hydride shift occurs from the other C hydroxyl group
- charge moves onto the hydroxyl group + double bond forms to make a carbonyl
- Carbonyl is deprotonated forming a ketone
Which alcohol is more readily oxidized? Straight chain primary alcohol or phenol
Phenols undergo oxidation more readily than primary or secondary OHs
General EWGs to know
General EDGs to know
*Alkyl groups
EWGs (increase/decrease) acidity of carboxylic acids.
increase by removing electron density the conjugate base is more stabilized.
EDG (increase/decrease) the acidity of carboxylic acids. Why?
decrease because they add electron density, thus destabilizing the conjugate base.
