Lab Notes 5

Question 1

What is the purpose of this experiment?

Answer 1

qualitative tests for identifying aldehydes (Tollen’s test and Schiff’s test) and methyl ketones (Iodoform Test)

Question 2

If a good nucleophile is present in a carbonyl group, what occurs?

Answer 2

Nu(-) attacks C, double bond e- transfers to O

O- attacks E+ and makes single bond

Question 3

If a weak nucleophile is present in a carbonyl group, what occurs?

Answer 3

O attacks E+ and double bond e- transfers to O

Nuc- attacks C+

Question 4

aldehyde react faster than ketones bc

Answer 4

less steric hindrence

Question 5

what is the Tollen’s test?

Answer 5

presence of aldehyde (H gets oxidized by Ag(NH2)2 and OH-)

siler mirror or black ppt

Question 6

What is the Schiff’s test?

Answer 6

Schiff reagent = bulky nuc that prefers to bind to aldehyde

makes magenta/purple colour

Question 7

what is the iodoform test?

Answer 7

1. proton removal from a C (carbanion)
2. carbanion attacks I2 making H’s on same C acidic and makes 3 I’s attached to C (or Br or Cl)
3. add base
4. makes yellow ppt

presence of methyl ketone

Question 8

can’t add acetone before iodoform test?

Answer 8

acetone reacts with reagents (NaOH and iodine) bc it has a methyl ketone