nitrogen Flashcards
Number (1o, 2o and 3o etc) of hydrocarbons substituents bonded to the nitrogen affect?
the aqueous solubility of the compound
The number and size of substituents affect?
steric hindrance at the lone pair
EDG and EWG affect
availability of the nitrogen’s lone pair
At equilibrium the weaker acid?
generated
Keq»0
indicates a favourable reaction
keq≤0
indicates the opposite of favourable reaction
when is a compound less basic( more acidic)?
when its nitrogen’s lone pair electrons are delocalised by interaction with the
aromatic ring π electron system and are less available to bond with H+
why are less basic ( more acidic ) compounds stabilised?
due to their resonance structures that can be drawn.
EWD and EDG affect basicity by
decreasing or increasing the basicity of the neighbouring base
steric hindrance to the lone pair of nitrogen reduces basicity by?
preventing protonation
Pyrrolidine and piperidine have the typical pka value of secondary amines. why does N-methylpiperidine, a tertiary amine have a slightly lower pKa value( is slightly more acidic) than the former two mentioned?
due to steric hindrance at the nitrogen atom of the latter mentioned.
what does EWG do? give an example
EWG decrease basicity of the neighbouring base by reducing the availability of nitrogen’s lone pair hence reducing its basicity.
EXAMPLE:
Morpholine: the presence of the electron withdrawing oxygen reduces the electron density on the nitrogen and its basicity.
what happens in piperizine?
the positive charge on the monoprotonated conjugate acid repels a second proton.
why is guanidine a strong base?
due to resonance delocalisation of the positive charge present on its conjugate acid (the guanidinium cation) - note that the structure of guanidine is flat and all its nitrogen atoms are sp2 hybridised.
why can guanidine derivatives mimic inorganic metal cations?
Due to its high pKa
