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Substitution versus Elimination
using a weak Nu also acting as weak base
• Primary alkyl halides don’t react with weak Nu/Bases.
• Secondary and tertiary alkyl halides form major substitution products
with respect to elimination when reacting with weak
bases/nucleophiles.
REMEMBER from alkyne lecture
❖ When primary alkyl halide is used, the major product is SN2
to give the extended alkyne.
❖ If a secondary or tertiary alkyl halide is used then
elimination (E2) of the alkyl halide to alkene will be the
major product instead of higher alkyne formation,
because NaNH2 is a strong base .
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