Question #c209b

1 Answer
Oct 15, 2017

A nucleophile is a chemical species that donates an electron pair to an electrophile to form a chemical bond in relation to a reaction. All molecules or ions with a free pair of electrons or at least one pi bond can act as nucleophiles. A good nucleophile has the ability to pluck a proton from the strongest of molecules and sometimes add to molecules replacing weaker nucleophiles or more stable ones.

Nucleophilicity and basicity are very similar. One difference is that nucleophile strength is measured by how fast it reacts, whereas acid-base strength is measured by equilibrium (pKa).

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An alkoxide molecule has more steric hindrance and less distinct polarization, making it less attracted to the positive carbon center.
So #"OCH3"^-# is a weaker nucleophile than the hydroxide ion in a protic solvent though #"OCH3"^-# is a stronger base.

#"C"_2"H"_5"O"# is more bulky than (more steric hindrance)#"OCH3"^-# so reasonably it is less nucleophilic

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