Which example indicates that a chemical change has occurred? *
1 answer:
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Answer:
Here's what I get
Explanation:
You may have done a Williamson synthesis of guaifenesin by reacting guaiacol with 3-chloropropane-1,2-diol.
A. Mechanism
Step 1
NaOH converts guaiacol into a phenoxide ion.
Step 2
The phenoxide acts as the nucleophile in an SN2 reaction to displace the Cl from the alkyl halide.
B. Improve the yield
You probably carried out the reaction in ethanol solution — a polar protic solvent.
You might try doing the reaction in a polar aprotic solvent— perhaps DMSO.
A polar aprotic solvent does not hydrogen bond to nucleophiles, so they become stronger.
C. Another method of ether synthesis —dehydration of alcohols
Sulfuric acid catalyzes the conversion of primary alcohols to ethers.
This is also a nucleophilic displacement reaction.
Protonation of the OH converts it into a better leaving group.
Attack by a second molecule of alcohol forms the protonated ether.
A molecule of water then removes the proton.
