NMR

BenchtopONMR forO O+ HO+OH
EducationalExperiments
HOO
H2SO42XO

H2SO4Nu

X Nu

O+ HO+ −OH
Williamson
Ether Synthesis Reaction
Nu−XHO
2X

Nu

X NuY

YNu−

YX−OY

YOBr +- NO

OO

Y++This- N experiment+ is designed to teach- theN practical aspects and principles of the Williamson ether
O
NOO
synthesisreaction,case via an SN2 reaction:
N+ inH thisO
2O

NH+N+N+Refluxing, isolationof organic compounds,
purification by solvent evaporation.
ONO+O

H2NTotal
Br experiment time: 2 hours

ONH

The Williamson ether synthesis reaction involves the reaction+ of an alkoxide ion with a primary alkyl halide via an SN1 or SN2Nreaction forming an ether group, and is of the generalOequation:
O+
An example is the reaction is between p-cresol and 1-iodobutane
to form p-butoxytoluene.
+OHOH+

CH3

H3C+

CH3

H3CBrOO

BrO

Pulsar™, a 60MHz benchtop NMR spectrometer can be OR
usedBrto measure the spectra of the starting materials and reaction
product HOconfirmingthat the reaction hasBr completed and no starting materials remain. High quality spectra can be collected
Br
Brwithin O2 minutes.
The spectra of the starting materials p-cresol and 1-iodobutane, along with the final product p-butoxytoluene

are shown in Figure 1 (see over page).

ORBr

HO

It is clear from thesespectra that p-cresol is not present in the spectrum of the product. However, the peak at about 3.2ppm
Brand the overlap of the peaks in the region 1.2-2.0ppm suggests there is still some 1-iodobutane present in the spectrum ofp-butoxytoluene. The p-butoxytoluene has tetramethylsilane (TMS) added as a chemical shift reference material showing a peak at0ppm chemical shift.
The student can sign the peaks in the spectrum and generate peak integrals in order to verify the identity of the reaction product.

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XOH

O+
N+
N

Y

O+
NO
O+

Br+
N

H2NO

O+++
NO
NH++
N

O+
N

H2NBrOO

NH+
N+

O

O+
N
O

H2NOH
O

++

+OH CH3NH

H3CBr

Br

HO+O+

allowing hands-on NMR for students.

+A simple to use software interface andBrBrO+
Br

CH3 Brthe undergraduate chemistry laboratoryOOOH

spectrometer that can easily be sited inO

ONPulsar is a cryogen-free benchtop NMR

CH3CH3H3C

CH3++CH3OH
HOH3C ORBr

CH3OR
H3C

CH3BrO

CH3O

H3COO

HOstandard sampling using 5mm NMR tubes
enables a high throughput of samples ina busy laboratory.

BrCH3BrBrBrORBrOR

Figure 1. From top to bottom: p-cresol,
1-iodobutane and p-butoxytoluene spectra

BrHOBr

BrBr
ORBr

Contact us now for more information!
magres@oxinst.com!

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for more information visit www.oxford-instruments.com/pulsar
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relating to the products or services concerned. Oxford Instruments’ policy is one of continued improvement. The company reserves theright to alter, without notice the specification, design or conditions of supply of any product or service. Oxford Instruments acknowledges
all trademarks and registrations. © Oxford Instruments plc, 2018. All rights reserved. Part no: Pulsar/Expt5/03-18

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