Aldehydes and ketones

Question 1

how are aldehydes produced

Answer 1

partial oxidation of primary alcohols

Question 2

describe the three tests for aldehydes?

Answer 2

tollens reagent- add NaOH and ammonia.Aldehyde produces silver mirror precipitate. No reaction for ketones
fehlings solution- heated up. Ammonia produces red precipitate of copper oxide. No reaction for ketones
potassium dichromate solution - turns aldehydes green to orange. No reaction for ketones

Question 3

how are all ketones and aldehydes reduced to primary and secondary alcohol?

Answer 3

NaBh4 where :H- acts as a nucleophile
in a nucleophillic addidtion reaction
the :H- attacks the C+ in the C=O
the reaction requires a H+ so it occurs in aqueous conditions

Question 4

describe the process of nucleophillic addition?

Answer 4

nucleophile e.g(:CN)
attacks positive charge on C+ in C=O carbonyl
C=O double bond is broken
lone pairs move from nucleophile to C+
lone pairs in :O move from O to aqueous substance e.g H
this produces OH

Question 5

how are hydroxynitriles formed?

Answer 5

:CN- nucleophile can attack ketones/aldehydes to form hydroxynitriles in a nucleophillic addition reaction

Question 6

why is the :H- in NaBH4 an unlikely nucleophile?

Answer 6

the negatively charged :H- could potentially deflect against the high electron density around the C=C bond