3mmm not always.
Is there any relation between basisity and nucleophilicity?
Can we compare them?
-
UP 0 DOWN 0 0 8
8 Answers
3which is a better nucleophile and which is a better base
1)pyrrole or 2)pyridine.
1Base-pyradine
Nucleophile-...........??????????? pyridine?
1generally nucleophilicity and basicity increase and decrease orders are same but its not always so as the definitions of nucleophilicity and basicity are not at all similar....
nucleophilicity is decided on the basis of relative rates of reactions by how rapidly an electron pair donor reacts with an atom bearing the leaving group...
larger the size of anion more is the polarisibility and hence more is its nucleophilicity.....
and higher the charge density more is the basic strength...
eg
nucleophile strength-
CN- > OH-
but basic strength
CN- < OH-
11Yeah , sorry me wrong.[2]
Similarily is the case with ethoxide ion (I), isopropanide ion (II), and tertiary butoxide ion (III),
order of nucleophilicity is I > II > III
basic strength III > II > I
39I used to have sillier doubts than these and still do sometimes, so no need to worry.
Basicity is the proton-abstracting ability of a substance. It is measured by base dissociation constant Kb.
Nucleophilicity is the ability of a substance to attack an electron deficient center. It is measured by the rate constant K.
Substances which rather abstract protons are bases and which rather attack electrophilic centers are nucleophiles.
Substrates on which negative charge is delocalised make good leaving groups/nucleophiles. Those which have localised charges make strong bases.