Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
8 Cards in this Set
- Front
- Back
The most general rxn of aldehydes and ketones is the
|
nucleophilic addition rxn
|
|
What happens during a nucleophilic addition rxn of Aldehydes /ketones?
|
- A nucleophile, :Nu-, approaches from a angle of 45 degrees to the plane of the carbonyl group and adds to the electrophilic C=O carbon atom.
- At the same time, rehybridization of the carbonyl carbon from sp2 to sp3 occurs, an electron pair from the carbon-oxygen double bond moves toward the electronegative oxygen atom, and a tetrahedral alkoxide ion intermediate is produced |
|
The nucleophile of Aldehydes /ketones rxn can be either.....
|
negatively charged (:Nu-) or neutral(:Nu)
|
|
If the nucleophile of Aldehydes /ketones rxn is neutral, the nucleophile usually carries ?
|
a hydrogen atom that can subsequently be eliminated
|
|
What are some negatively charged nucleophiles of Aldehydes /ketones rxns
|
HO- (hydroxide ion)
H- (Hyride ion) R3C- (carbanion) RO- (an alkoxide ion) n=-C- (cyanide ion *3 lines) |
|
What are some neutral nucleophiles of Aldehydes /ketones rxns
|
HOH (water)
ROH (an alcohol) H3N (ammonia) RNH2 (an amine) |
|
Nucleophile additions to aldehydes and ketones have two general variations
|
- the tetrahedral intermediate is pronated by water or acid to give an alcohol
- The carbonyl oxygen atom is eliminated as HO- or H2O to give a product with a C=Nu double bond |
|
With Aldehydes /ketones rxns, we are concerned both with the reversibility of a given reaction and with the acid or base catalysis of that rxn
Facts about Nucleophilic addition rxn and catalysis |
- Some Nucleophilic addition rxn take place reversibly and some do not
- Some occur w/o catalysis, but many others require acid or base to proceed |