Carbonyls 6B

What are Carbonyls

Molecules that contain the C=O

What are the two types of bond in a C=O

P orbitals overlap sideaways

Pi bonds form above and below the sigma bond

Bond angle and shape of carbonyls

120°

Trigonal planar

Are carbonyls soluble

They are reasonably soluble as there is a lone pair on oxygen atom that can form hydrogen bonds

How are aldehydes and keystones reduced back into alcohols

Using NaBH4

Sodium tetrahydrioborate (III)

How is sodium borohydride represented in these reactions

[H]

Example of reduction of carbonyls

What is the mechanism for reduction of carbonyls

Nucleophillic addition

Two reagents used to test for carbonyls

what do both of them test for

2,4 DNPH (Brady’s reagent) and Tollens Reagent

Brady’s reagent is used to test for Aldehydes or Ketones

Tollens is used to identify an aldehyde so can be able to distinguish if something is a ketone

Positive and negative observation of Brady’s reagent

Positive = orange solution goes to orange precipitate

Negative = solution remains an orange solution

Reagent and conditions for Tollens reagent

Ammoniacal silver nitrate

Positive and negative test observation for Tollens reagent

Positive = silver mirror forms

Negative = no reaction/ solution remains colourless

What Type of reaction is Tollens

What type of reaction is Brady’s

Oxidation

Condensation (produces water)

How do you test for a carboxylic acid and what is positive result

How do you test for primary and secondary alcohols and what is positive result

How do you test for an alkene and what is positive result

How do you test for a phenol and what is the positive result

Sodium carbonate and effervescence

Acidified potassium dichromate and orange solution turns green

Add bromine water and it will decolourise it

Add bromine water and it forms a white precipitate

3 ways to test an aldehyde

Acidified potassium dichromate, Tollens, Brady’s

How can else can you test for aldehydes and ketones

Fehlings solution

Warm with iodine and sodium hydroxide solution

What is the result for aldehyde and ketones for fehlings solution

What is the result for warm iodine and sodium hydroxide solution

Aldehyde = red/orange ppt

Ketone = no change and stays blue

Aldehyde = no change

ketone = Yellow precipitate with antiseptic smell

what is the test for haloalkanes

test with silver nitrate

silver chloride = white

silver bromide = cream

silver iodide = yellow

What are nitriles

Functional group with a carbon atom triple bonded to nitrogen atom

How do you name nitriles

Full name and nitrile eg: butanenitrile

What happens in nucleophillic addition of nitriles

Reagents

Aldehyde / ketone turns back to (hydroxynitrile) - OH group on nitrile = hydroxynitrile

Reagents are HCN or NaCN with H2SO4

What happens in nucleophillic substitution

Reagents

Haloalkane turns into nitrile

Reagent = NaCN in ethanol

What happens in reduction of nitriles

Reagents

Nitrile goes to amine

Reagents= H2 and Nickel catalyst and 150°

What happens in hydrolysis of nitriles

Reagents

Nitrile is turned into a carboxylic acid

Hcl(aq) with heat