Ch. 20: Carbonyl chemistry, organometallics, oxidation/reduction Flashcards
What is the most common type of protecting group?
TBDMS (tert-butyldimethylsilyl ether)
What is the most common type of de-protecting reagent?
tetrabutylammonium fluoride
What determines the type of reaction that carbonyl molecule will undergo?
The presence or absence of a leaving group
What type of reaction do aldehydes and ketones undergo?
Nucleophilic addition
What type of reaction do carbonyl compounds undergo if they contain a leaving group?
Nucleophilic substitution
What are the two steps of nucleophilic addition?
1-Nucleophilic attack
2-Protonation of the negatively charged oxygen
Why are out the aldehydes more reactive than ketones?
Aldehydes are less sterically hindered, and also because they have less R-groups to donate electron density to the partial positive carbon (less stable means more reactive)
What are the two steps of nucleophilic substitution?
1-Nucleophilic attack on the electrophilic carbonyl
2-The extra lone pair of electrons on the oxygen reforms a pi bond with the carbonyl carbon causing the leaving group to leave
What does catalytic hydrogenation of an aldehyde or ketone produce?
Primary or secondary alcohols
If you have a compound which contains a C=C bond and a C=O bond, how can you selectively reduce the C=C bond?
Use only one equivalent of H2 and catalyst. These reagents react faster with C=C bonds than C=O bonds.
Do C=C bonds react with LiAlH4 or NaBH4?
NO, the C=C bond is inert to these reagents
What does the LiAlH4 reduction of an amide produce?
Amine
Why is NaBH4 useful?
Because it selectively reduces aldehydes and ketones in the presence of most other functional groups, including Carboxylic acids.
What is the biggest difference in reducing a Carboxylic acid, ketone, or aldehyde compared to an amide?
The carbonyl oxygen in an amide will be completely removed, whereas the carbonyl oxygen in the others will become an OH group
What does hydrolysis of imines and enamines form?
Aldehydes and ketones
