carbonyl compounds

how does liAlH4/ NaBH4 work

B and Al is less EN than H, thus producing H- as a nucleophile

Why LiAlH4 stronger reducing agent than NaBH4

Boron is more EN than Al (Al<B<H) Thus theres a higher difference in EN between Al-H than B-H, thus LiAlH4 produces a stronger nucleophile than NaBH4. H- produced by LiAlH4 is more electron rich than that of NaBH4. Thus Al-H more polar than B-H

Why LiAlH4 can’t reduce alkenes

LiAlH4 produces H-. C=C is e rich pi electron cloud repels incoming H- ion, therefore it can’t reduce

what are the 3 reducing agents

LiAlH4 in dry ether, NaBH4 in methanol, and H2 in Ni catalyst , increased T and P

What can the 3 reducing agents reduce and not reduce

LiAlH4 in dry ether =everyth but alkene

H2 with Ni catalyst = aldehyde, ketone, nitrile, alkene

NaBH4 in methanol= aldehyde and ketone only

What are the reactions carbonyl compounds undergo

Condensation, Oxidation, Reduction, Nucleophilic Addition

what does reduction of aldehyde and ketone form

aldehyde: primary alcohol

ketone: secondary alcohol

what does oxidation of aldehyde form

carboxylic acid

Why are ketones less reactive than aldehydes in nucleophilic addition

1.) Electronic effect - addition of alkyl group (EDG) reduces the partial positive charge on the carbonyl C

2.)steric hinderance - bulky alkyl group results in increased steric hinderance hunders nucleophile attack

Why trace NaCN/NaOH with HCN for nucleophilic addition of carbonyl compounds

NaCN: increase conc. of CN- as ionisation of HCN ⇌ H+ CN- conc of CN- low

NaOH: shfits POE to the right to increase conc of CN-

d.t for 2,4 dnph tollens and fehling and I2

2,4 dnph orange ppt is formed for all carbonyl compunds

tollens: silver mirror for all alldehyde

Fehlings: brick red ppt formed for aliphatic aldehyde

I2 aq : ketone yellow ppt