Imines Flashcards
Reactions you need to know
Draw the mechanism for the formation of an imine from a ketone/carbonyl species
Check notes
Why is pH 6 required for the synthesis of an imine
The protonation of the Oh group required acid, however, the acidic conditions cannot be too strong otherwise the nucleophile will be protonated
How many products form when ammonia/primary amine forms an imine
- There is a mixture of E/Z isomers. The ratio depends on sterics and other conditions
Draw the mechanism for the hydrolysis of an imine an outline the conditions
Check notes. pH 6 again
What is a ‘stable imine’
An imine with an electronegative atom bonded to the nitrogen. There is more delocalisation of electron density between the atom X and the pi system of the C=N bond. This makes the carbon less electrophilic, and therefore, it will not be hydrolysed
Name of a stable imine species
Oximes (OH)
Uses of semi-carbazones
Used to differentiate between carbonyl species with the same/very similar boiling points
Oxonium ions and iminium ions, 1 similarity and 1 difference
They are both electrophilic however, oxonium ions tend to react again to form acetals whereas iminium ions readily deprotonate to form imines
Secondary amines do not form imines when reacting with carbonyl species. What do they form and what is the main difference in the product
They form enamines through the loss of the alpha proton. This product is a single isomer as supposed to a mixture of E/Z (there is only 1 alpha proton anti to the iminium ion)
Mechanism for the formation of an enamine using a secondary amine
Check notes
Strecker synthesis outline
Formation of an amino acid using an ammonia salt and NaCN
Draw the mechanism for the Strecker synthesis
Check notes
Why does the Strecker Synthesis work, in that all reagents can be added at once
The iminium ion is more electrophilic than the aldehyde and hence, the CN- ion can only attack the iminium species not the aldehyde
What does reductive amination form
Amines from carbonyls
Give the reagents and conditions for reductive amination
NH4Cl, pH 6 and BH3CN
