Carbonyl compounds Flashcards
Structural formula of propanone
CH3COCH3
structural formula of propanal
CH3CH2CHO
aldehyde + ketone functional group
C=O (carbonyl)
what type of boiling point to aldehydes and ketones have
lower boiling point than equivalent alcohols
explain why aldehydes and ketones have a low boiling point
- don’t have polar OH bond so can’t form hydrogen bonds with other aldehyde/ketone molecules
- lower boiling point than equivalent alcohols which do form hydrogen bonds (strongest intermolecular force)
name the forces within aldehydes and ketones
- london forces
- permanent dipole- permanent dipole
describe solubility of aldehydes and ketones
- soluble in water
- lone pair of electrons on O of C=O
- form hydrogen bonds with H atoms on water molecules
when are aldehydes and ketones not soluble
- longer chained ketones + aldehydes cannot H bond with water
- hydrocarbon chains disrupt H bonding between water molecules
- london forces between aldehyde + ketone molecules (+) hydrogen bonding between water molecules stronger than hydrogen bonding between water + aldehyde/ketone
- compound won’t dissolve
which compound can be oxidised further
aldehydes
describe test for aldehyde with Fehlings/benedicts solution
- Fehlings: Copper(II) ions dissolved in sodium hydroxide
-Benedicts: Copper(II) ions dissolved in sodium carbonate
-positive result- Blue- Brick red precipitate
Fehlings/Benedicts reduction equation
Cu2+ (aq) + e- –> Cu+ (s)
Describe tollens reagent
colourless solution of silver nitrate dissolved in aqueous ammonia
describe test with Tollens reagent
- heated in a test tube (water bath) with sample
- ‘silver mirror’ forms
tollens reagent reduction equation
Ag(NH3)2(aq)+ + e- –> Ag(s) + 2NH3(aq)
what is acidified potassium dichromate
oxidising agent