Was this experiment green and were the solvents safe? Could other have alternatives been used (including less solvent)? Was this energy Intensive?
Was this experiment green and were the solvents safe? Could other have alternatives been used (including less solvent)? Was this energy Intensive?
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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Was this experiment green and were the solvents safe? Could other have alternatives been used (including less solvent)? Was this energy Intensive?

Transcribed Image Text:Ally
CHE 251L
Experiment 1: Isolation of Guaifenesin from a Tablet
Adapted from Semi-Microscale Williamson Ether Synthesis and Simultaneous Isolation
of an Expectorant from Cough Tablets, J. Chem Ed, 2003
There are classic reactions thatáre covered in the introductory organic chemistry
curriculum. The synthesis of an ether from an alhalide and an alkoxide is one such
reaction and is known as the Williamson ethersynthesis. We encountered this reaction
in Chapter 9 of the text, and it is introduced formally in Chapter 10 (Section 10-6). The
reaction proceeds via an S,2 mechanism. it is paramount that the alkyl halide be
sterically unhindered.
Ly Slow reaction î E
In striving to keep the course relevant to your interests, we are going to work with a
clinically relevant compound for the next two weeks, guaifenesin. Guaifenesin is an
expectorant, that is used to alleviate cold symptoms. The structure is shown below.
HO
но
OH
OH
(R)-(-)-guaifenesin
(S)-(+)-guaifenesin
Note that this compound has one stereogenic center, and two ether functional groups.
The first week of the experiment, we will isolate a racemic mixture of the compound
from a commercial tablet. You will characterize the tablet using its melting point, 1H
NMR and IR data. The idea is to familiarize yourselves with the pure compound before
attempting the synthesis. The second week, we will synthesize a racemic mixture using
a phenoxide and alkyl halide.
Procedure: Isolation of Guanefesin
A single Guai-Aid tablet (containing 600 mg (±) guaifenesin) is crushed to powder and
added to 5 mL ethyl acetate. The suspension is stirred at room temperature for 10 min
and any insoluble material removed by gravity filtration., Addition of 10 mL hexanes to
the filtrate in 2-mL portions causes white crystais to form on standing for a few min.
After cooling in an ice-bath the precipitate is collected by vacuum filtration and washed
with 5 mL cold hexanes. Obtain a melting point, 'H NMR spectrum, and IR spectrum of
the isolated compound.
Expert Solution
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Step 1
Guaifenesin is synthesized by Guaicol in an SN2 reaction with NaOH which provides conjugate base of Gauicol which is then dissolved in a solution of 3-chloro1,2-propanediol to form Guaifenesin and the reaction falls under the category of Williamson-ether synthesis.
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