Chapter 4 Flashcards
Cyanohydrin SM, reagent and product
Ketone, aldehyde, NaCN, H2O, HO, CN
Organometalic reactions SM, reagent, product
Ketone, aldehyde, R-MgBr, Et2O, H+ or R-Li, Et2O, H+ work up , R and OH
Mechanism for the reducing actions
Al-H attacks the carbonyl carbons
Reducing reactions SM, reagent, product
Ketone, aldehyde, NaBH4, MEOH or LiAlH4, EtO2+ H+ work up, OH
Esters(double additions) reagent and product
R-MgBr, Et2O, H+ work up leads to secondary alcohol with RR whereas LiAlH4, Et2O, H+ work up leads to primary alcohol with HH (hidden)
Formation of hemiacetal reagent and product
NaOR, ROH and the product includes OH and OR
Formation of acetal reagent and product
MeOH, H+ cat. Product includes MeO, MeO
Mechanism for acetal formation
- Protonation at carbonyl carbon 2. MeOH attacks the carbonyl 3. H+ transfer to OH to make it into H2O. 4. OME comes down while H2O leaves 5. MEOH attacks the carbonyl carbon again making the intermediate 6. H gets deprotonated
Conjugated system reagent that leads to both 1, 2 and 1, 4 addition products
R-MgBr, EtO2, H+
1, 2 addition only reagents
NaBH4, CeCl3, EtOH or R-Li, Et2O, H+ work up
1, 4 addition only reagents
Na+, SR-, ETOH or R2CuLi, Et2o, H+ work up
Why carbonyls are electrophilic at carbon while the alkenes are not electrophilic(nucleophilic)
When you draw the resonance, carbonyl carbons are 2pC as the carbocation(delocalizing the charges since oxygen gets - charge and carbon gets the positive charge) while alkenes are changing the position of the carbocation
In terms of FMO theory, explain why carbonyl carbons are better electrophile than alkenes
LUMO is involved (lowest unfilled molecular orbitals)-oxygen from the carbonyl carbon is more electronegative so it occupies lower LUMO than alkene
OH and NR in terms of nucleophile and electrophile
NR is the better nucleophile as it is less EN than oxygen and is willing to donate more electrons. OH is a better electrophile than NR as it draws more oxygen than nitrogen given it is more EN
[Carbonyl reactivity] Why does F3C and CF3 as part of carbonyl carbon have significant amount of Keq value that leads to hydrate?
The fact that Keq value is significantly larger than 1 indicates that hydrate is more favored and this means that the F3C and CF3 are very reactive (excellent electrophile) The reason being due to inductive effective, F(more EN) draws electrons to itself making the carbonyl carbon very electron deficient. This causes the low electron density around the carbonyl carbon as well making it very easy for the nucleophile to attack
Anytime you have a EWG(significantly more EN atoms next to carbon) what do you do?
Think of it as very unstable as it creates the low electron density environment for the carbonyl carbon
[Carbonyl reactivity] Alkanes as the group?
Alkanes are EDG meaning it actually donates the electrons to carbonyl carbon which actually is very satisfied and stable. Given this, it does not function well as the electrophile and in the presence of nucleophile, the reaction does not happen very fast
[Carbonyl reactivity] benzene ring next to the carbonyl carbon?
Benzene can offer extra resonance structure to the carbonyl group and is very stable. In fact, this does not function as the electrophile anymore so it does not react with nucleophile
