Williamson Ether Synthesis: Determination of Rate
and Reaction Order
Teacher’s Guide
by: Ian Kihara (Pocatello High School)
Lesson Overview: Laboratory experiment: calculation of reaction rates and
order for the Williamson ether synthesis under varied conditions.
National Science Education Standards Addressed:
1. ?
Subject area(s): Synthetic and
Analytical Chemistry
Topic: Reaction rates and order
Materials:
 2-bromo-2-methylpropane, 2-chloro-2-methylpropane
 isopropanol
 deionized water
 phenolphthalein solution
 magnetic stir-bar(s) and stir-plate(s)
 125 mL Erlenmeyer flask(s)
 1-200 L micropipette
 stop-watch(es)
Suggested time: 50 minutes
1. 10 min pre-lab discussion
2. 30 min lab work
3. 10 min post-lab discussion
Audience: AP chemistry
Resources:
Attached hand-out
Learning Objectives:
Students will:
1. Calculate reaction rates using concentration and time.
2. Determine reaction order.
3. Determine solvent dependency for rate.
Background:
The Williamson ether synthesis is a very common and well known reaction in the field of
organic chemistry. There are two main reaction pathways including a first and a second order
mechanism, depending on the alkyl halide substrate. Students will have a chance to probe this
reaction to see which pathway the tertiary 2-bromo(chloro)-2-methylpropane undergoes.
Assessment Strategy:
1. Are students able to correctly calculate reaction rates?
2. Are students able to determine reaction order and explain the solvent dependency (or lack
thereof)?
Teaching Tips:
 Ensure that students wear protective clothing including goggles.
 Ensure students know how to use micropipette properly.
References:
Adapted from J. Manion, Modular Laboratory Program in Chemistry, J. Jeffers, editor, H. A. Neidig,
publisher, 2000, module 714.
This material was developed with support from the National Science Foundation’s Graduate Teaching Fellows in K-12 Education (GK-12) program
(DGE-0338184) and Idaho State University. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the
author(s) and do not necessarily reflect the views of the NSF.
Idaho State University’s GK-12 Project
http://www.isu.edu/%7Esanghann/Index.html
1
Williamson Ether Synthesis: Determination of Rate and
Reaction Order
OH
H
X
H 3C
C
C
CH3
CH3
X= Br, Cl
H3C
CH3
H3C
CH3
C
0.5 M NaOH
H2O, iPrOH
H3C
CH3
C
H
O
CH3
Goals:
 To learn basic organic synthesis techniques
 Determine reaction order and rate under various reaction conditions
 Compare different reaction substrates
References:
Adapted from J. Manion, Modular Laboratory Program in Chemistry, J. Jeffers, editor, H. A.
Neidig, publisher, 2000, module 714.
Experimental:
A.) Br vs. Cl
Objective:
Determine reactivity difference between halide substituents.
Materials:
 2-bromo-2-methylpropane, 2-chloro-2-methylpropane
 2-propanol, D.I. water
 phenolphthalein solution
 magnetic stir-bars and stir-plate
 125 mL Erlenmeyer flask
 stopwatch
Procedure:
To a clean Erlenmeyer flask equipped with a magnetic stir-bar add 50 mL 2-propanol
and 50 mL deionized water. To the flask add 5 drops of phenolphthalein solution and 200
L of 0.50 M NaOH. Add to the flask 50L of 2-bromo-2-methylpropane, immediately start
timing and place on the stir-plate. After the reaction time is taken, clean the flask and stirbar with deionized water and repeat the experiment with 2-chloro-2-methylpropane.
Idaho State University’s GK-12 Project
http://www.isu.edu/%7Esanghann/Index.html
2
Questions:
1. What were the respective reaction rates?
2. What might explain this difference?
B.) Reaction order (two groups)
Objective:
Determine reaction order with respect to each substrate.
Materials:
 2-bromo-2-methylpropane
 2-propanol, D.I. water
 phenolphthalein solution
 magnetic stir-bar and stir-plate
 125 mL Erlenmeyer flask
 stopwatch
Procedure:
To a clean Erlenmeyer flask equipped with a magnetic stir-bar add 2-propanol and
deionized water. To the flask add 5 drops of phenolphthalein solution and 0.50 M NaOH.
Add to the flask 2-bromo-2-methylpropane, immediately start timing and place on the stirplate. After the reaction time is taken, clean the flask and stir-bar with deionized water and
continue to the next experiment.
Group 1 (2-bromo-2-methylpropane):
Reaction 1
60 L
0.5 M NaOH 200 L
2-propanol
25 mL
D.I. water
75 mL
tBuBr
Reaction 2
30 L
200 L
25 mL
75 mL
Reaction 3
120 L
200 L
25 mL
75 mL
Questions:
1. What were the respective reaction rates?
2. What was the reaction order with respect to tBuBr?
C.) Solvent Dependency
Objective:
Determine rate dependence on solvent.
Materials:
 2-bromo-2-methylpropane
 2-propanol, D.I. water
 phenolphthalein solution
 magnetic stir-bar and stir-plate
Idaho State University’s GK-12 Project
http://www.isu.edu/%7Esanghann/Index.html
3


125 mL Erlenmeyer flask
stopwatch
Procedure:
To a clean Erlenmeyer flask equipped with a magnetic stir-bar add 2-propanol and
deionized water. To the flask add 5 drops of phenolphthalein solution and 0.50 M NaOH.
Add to the flask 2-bromo-2-methylpropane, immediately start timing and place on the stirplate. After the reaction time is taken, clean the flask and stir-bar with deionized water and
continue to the next experiment.
Reaction 1
50 L
0.5 M NaOH 200 L
2-propanol
30 mL
D.I. water
70 mL
tBuBr
Reaction 2
50 L
200 L
50 mL
50 mL
Reaction 3
50 L
200 L
70 mL
30 mL
Questions:
1. What were the respective reaction rates?
2. Did the reaction appear to be dependant on the solvent mixture?
3. What physical property could have contributed to this? Why?
This material was developed with support from the National Science Foundation’s Graduate Teaching Fellows in K-12 Education (GK-12) program
(DGE-0338184) and Idaho State University. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the
author(s) and do not necessarily reflect the views of the NSF.
Idaho State University’s GK-12 Project
http://www.isu.edu/%7Esanghann/Index.html
4