Alkyl Halides

1-Bromobutane

Primary alkyl halide used to synthesize 1-iodobutane.

Reaction mechanism for 1-bromobutane + NaI in acetone

SN2 substitution.

Why is acetone used in the Finkelstein reaction

It is a polar aprotic solvent that enhances nucleophilicity of iodide.

Why does the Finkelstein reaction proceed to completion despite an unfavorable equilibrium

NaBr precipitates out of solution, driving the equilibrium toward products.

What precipitates during the reaction of NaI and 1-bromobutane

Sodium bromide (NaBr).

What is removed by filtration after reflux

Precipitated sodium bromide.

Why wash the reaction mixture with water

To remove residual sodium iodide and acetone.

Which layer contains 1-iodobutane during workup

The lower organic layer.

Why wash with sodium bisulfite (NaHSO3)

To remove iodine by reducing I2 to I−.

What is the purpose of sodium sulfate (Na2SO4)

To dry the organic layer by removing water.

What purification method is used for 1-iodobutane

Distillation.

Boiling point correction formula

Observed BP = Literature BP − 0.05(AP − 760).

NaI in acetone test

Test for SN2 reactivity.

Positive NaI/acetone test

Formation of a white precipitate.

AgNO3 in ethanol test

Test for SN1 reactivity.

Why does AgNO3 promote SN1 reactions

Ag+ assists leaving group departure and carbocation formation.

Positive AgNO3/ethanol test

Formation of an AgX precipitate.

Leaving group ability order

I− > Br− > Cl− >> F−.

SN2 substrate reactivity order

Methyl > 1° > 2° >> 3°.

SN1 substrate reactivity order

3° > 2° > 1° > methyl.

Why do vinyl and aryl halides resist substitution

The C–X bond is attached to an sp2 carbon.