carbonlys (ketones + aldehydes key bits)

Question 1

describe conditions used to reduce carbonyls?

Answer 1

• NaBH4 dissolved in water and METHANOL !!!

Question 2

what is NaBH4 dissolved in?

Answer 2

methanol + water

Question 3

what is the name of the mechanism by which carbonyls are reduced?

Answer 3

• nucleophilic addition where H- from NaBH4 is a nucleophile as it has 2 lone pair electrons that are donated to C atom of C=O bond.

Question 4

how are hydroxynitriles formed

Answer 4

carbonlys react with HCN

Question 5

since HCN is toxic, how is it formed to make the hydroxynitrile

Answer 5

• Na/KCN dissolved in H2SO4 ( acidicified KCN)

Question 6

which is the nucleophile in nucleophilic addition to form hydroxynitriles?

Answer 6

C=N:-

Question 7

how do u test for aldehydes + ketones

Answer 7

• bradys solution where 2,4 DNP is dissolved in CONCENTRATED SULPHURIC ACID AND METHANOL.

Question 8

how do u identify the carbonyl compound after Brady’s solution

Answer 8

• recrystallise the orgage precipitate
• measyre melting point of orange crystals and cmpare with database to identify to identify the identity of the derivative

Question 9

how do u make Tollens reagent?

Answer 9

• add AgNO3 to a test tube with NaOH –> form a brown precipitate
• Add a few drops of DILUTE NH3 to dussolve the precip
• heat in HOT water bath bc aldehyde + ketones are flammable.

Question 10

what is oxidised + what is reduced in tollens reagent test b/w aldehydes + ketones

Answer 10

• aldehyde oxidised to carboxylic acid

- Ag3+ + e -> Ag(s) , so reduced bc gains an electron.