June 17, 2024, 10:31:52 PM
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Topic: Williamson Ether Experiment (Nerolin) Possible Side Reactions?  (Read 1008 times)

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Offline AngeloNahga

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Context: College class expt

- A week before, we synthesized our own ethyl iodide by reacting ethanol with red phosphorus and iodine.
- The class was also given the option to use already prepared ethyl bromide.
- The main expt was to synthesize Nerolin using beta-naphthol, KOH, and ethyl iodide in methanol. We did melting point determination and IR spectroscopy to verify the product.

Main Problem: The synthesized products were divided into two.
- Products who used stock ethyl bromide had a melting point of 36 °C, close to the literature value for nerolin.
- However, those who used the synthesized ethyl iodide had a melting point of around 65 °C, some not even melting at higher temps. The IR spectra of all products seem to represent nerolin.

Theories:
- The distillation processes were done rashly. Excess iodine, potassium and other reagents could still be present in ethyl iodide. Although, the crude ethyl iodide liquids were clear in color due to washings, and what effect does it make?
- [main one] 2-methoxynaphthalene has a melting point around 70 °C. The methanol solvent could have reacted with the naphtholate. Though, why did it only favor the products which used ethyl iodide?
- 2-iodonaphthalene is formed since it also has a melting point of 55°C-ish. Although, this shouldn’t occur due to steric hindrance.

Attached is a sort-of-detailed flowchart used for the experiment to provide further context.

Offline rolnor

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Re: Williamson Ether Experiment (Nerolin) Possible Side Reactions?
« Reply #1 on: April 20, 2023, 03:59:22 AM »
It seems you somehow got methyl iodide. If you distill more carefully and establish bp. this can be avoided.

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