Reactions of Carbonyl Compounds Flashcards
what are the reactions of carbonyl compounds?
- oxidation of aldehydes to form carboxylic acids
- nucleophilic addition reactions
what is the suitable oxidising agent to oxidise aldehydes?
- acidified dichromate (H+/CR2O7^2-)
- which is made by mixing potassium dichromate and sulfuric acid
what is the colour change for potassium dichromate?
orange to green
how should the oxidation be carried out?
carried out at reflux
what are the differences between alkene and carbonyls?
- alkenes have a double bond between 2 carbon atoms whereas carbonyls have a double bond between carbon and oxygen atoms
- alkenes have no difference in electronegativity whereas carbonyls have a difference in electronegativity
- the alkenes do not have a polarised bond and carbonyls do have a polarised bond
- alkenes react with electrophiles whereas carbonyls react with nucleophiles
what is the structure of a C=O bond?
- p orbitals overlap
- difference in electronegativity between carbon and oxygen
- creates a dipole in the C=O bond
what is an aldehyde?
- carbon on carbonyl group is attached to one carbon atom
- suffix = ‘-al’
what is a ketone?
- carbon on carbonyl group is attached to two other hydrogen atoms
- suffix = ‘-one’
what is the suitable reducing agent when reducing aldehydes and ketones?
- NaBH4
- sodium borohydride
what does NaBH4 generate?
- it readily generates hydride ions (H-)
- hydride ions are negatively charged ions with a lone pair of electrons
what are aldehydes reduced to form?
- primary alcohols
what are ketones reduced to form?
- secondary alcohols
what does the mechanism of nucleophilic addition need?
protonation
- using H2O when forming alcohols
- using H+ ion when forming hydroxynitriles
what is used to form hydroxynitriles from carbonyl groups?
- NaCN or KCN followed by the addition of dilute HCl
- -C triple bond N
- H+ used in protonation
what are the two uses of nitriles?
1) formations of carboxylic acids
2) reduction
