Carbonyl Compounds 6.1.2 Flashcards
What are Carbonyls Compounds?
Organic compunds which contain at least one C=O bond.
What are names of tests for Aldehydes and Ketones?
Tollens’ Reagent
Brady’s Reagent (2,4 - DNPH, aka 2,4-DiNitroPhenylHydrazine)
What is the proccess for testing with Tollens’ Reagent?
When mixed and warmed with an aldehyde, the silver in [Ag(NH3)2]+ is reduced and forms a silver mirror on the walls of the test tube.
How does the Tollens’ test work?
The aldehyde is oxidised to its corresponding carboxylic acid.
eg: RCHO (aq) + [Ag(NH3)2]+ (aq) + H2O (l) → RCOOH (aq) + Ag (s) + 2NH4+ (aq)
What is the proccess for testing with Brady’s Reagent?
When Brady’s reagent is added to a Ketone or Aldehyde, it will form a bright orange precipitate.
How is Brady’s Reagent used in the identification of Aldehydes and Ketones?
The Orange precipitate can be seperated using vacuum filteration, then purified using recrystallisation. This compounds melting point can then be found, this allows for it to be compared to the melting point of known substances.
What is Recrystallisation and how does it work?
The Sample is dissolved into a solvent then warmed, increasing the solubility. It is then cooled which causes the sample to grow crystals, these can then be seperated.
What is the product when an Aldehyde is Reduced through Nucleophilic Addition?
A Primary Alcohol and OH-
What is used as a Reducing Agent for Aldehydes?
NABH4
Sodium Tetrahydridoborate
What is the product when a Ketone is Reduced through Nucleophilic Addition?
A Seconadry Alcohol and OH-
What is the proccess for Nuclephilic Addition of an Aldehyde and Ketones?
The Carbon Oxygen π bond transfers its electrons to the O atom.
The H- ion supplied by NaBH4 transfers its lone pair to the Carbon (to which the O is bonded).
The O- transfers a lone pair to the H with in a H2O, bonding with the H.
Leaving an alcohol (from the OH bonding) and a OH- (remains of the water).
What are the Conditions and Reagents to turn a Carbonyl to a Nitrile?
Conditions:
In dilute acid (eg H2SO4)
Reagents:
CN- ions (usualy from HCN)
What is the name for the Mechanism for turning a Carbonyl to a Nitrile?
Nucleophilic Addition
What is the proccess for turning a Carbonyl to a Nitrile?
The Carbon Oxygen π bonds electrons transfer to the O atom. Causing the O to have a lone pair.
The lone pair of the CN- transfers to the C atom.
The lone pair of the O- attracts and bonds with a H froma Water molecule, and the bonding pair between the H-O in water transfers to the O.
Resulting in a Nitrile and and a OH-.
Why is the Carbonyl to Nitrile reaction special?
It adds another carbon to the chain.
