Experiment 23A – Synthesis of n-Butyl Bromide – Name _____________________
OH
NaBr, H2SO4
Br
1. Data Table: Fill in the appropriate spaces in the data table below. Under the Amount
column, use g for solids, mL for liquids. The abbreviation na stands for not applicable. A
mmol is 1/1000th of a mole.
Reagent
Amount
(g or mL)
mmol
bp (oC) observed
Sodium Bromide
na
1-Butanol
na
Sulfuric Acid (conc)
na
1-Bromobutane
2. Percent Yield (show calculations on a separate sheet and attach to this page)
Percent yield of distilled product
%
3. Mechanism. On a separate sheet (attach to this report), write a step-by-step
mechanism for the reaction of 1-butanol with sodium bromide and sulfuric acid.
4. Questions. On a separate sheet (attach to this report) provide answers to the
following questions.
A.) A by-product, dibutyl ether (C4H9OC4H9, FW 130.23, mp –98 oC, bp 142-143 oC) is
formed in the reaction. Propose a step by step mechanism for its formation. [hint:
see section 14.5 in Organic Chemistry, by Klein].
B.) Another by-product, 1-butene (C4H8, FW 56.11, mp –185 oC, bp –6.3 oC) is formed
in the reaction. Propose a step by step mechanism for its formation. [hint: E2, see
section 13.9 in Organic Chemistry, by Klein].
C.) NaHCO3, sodium bicarbonate is a weak base. Write an equation for the reaction of
sodium bicarbonate with aqueous sulfuric acid to produce carbon dioxide.
D.) Why are sodium bromide and sulfuric acid used in fairly large excess in this reaction.
[Hint: Sn2 rate = k [RX] [Nu-], where k = a rate constant, [RX] = concentration of
substrate, [Nu-] = concentration of nucleophile.] see p. 173 of the lab manual.