Prelab 6 williamson ether synthesis PDF

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Experiment 6: Williamson Ether Synthesis

Announcements - Please do not lose the spin vanes! Make sure to clean up the lab before you leave. - Only take the amount of chemicals you need for the reaction. - All week B lab reports are due the week after Thanksgiving, 2 weeks after you did the lab. - No make-up labs the week after Thanksgiving. - If you miss lab 5 or 6, please contact me as soon as possible to reschedule if possible.

Announcements - This is the last prelab lecture. Evaluations will be done at the end of class: bu.campuslabs.com/courseeval. Please bring your cell phone to your last lab section to do TF evaluations. - All locks will be cut off the lockers in the lab once lab 6 is complete. Please remove your locks! - Prelab: Purpose, reaction scheme, mechanism, procedure - Experiment 6: Lab report. You will need IR, TLC, GC/MS and NMR data. Due one week after you do the lab. - You need both the reaction scheme and mechanism for your prelab. They are 2 separate things. Reaction scheme: A+BC Mechanism: Arrows and intermediates

Williamson Ether Synthesis

Organic Process Research & Development 2005, 9, 206−211.

UV Absorbers for Skin Protection

Synthesis of Nerolin

Nerolin Used in perfume to smell of orange blossoms

Why do you add KOH to your reaction? A. To deprotonate the OH group on 2-naphthol and make it a better nucleophile. B. To make iodoethane a better electrophile C. To solubilize iodoethane D. To protonate the oxygen on 2-naphthol

Microwave -Microwave allows us to heat the reaction mixture above its boiling point, making the reaction go faster. No product or very little product would be formed in the same time period if you just refluxed the reaction mixture.

Plastic wrench Microwave tube Includes: stir bar, Teflon plug, cap and tube microwave Return your microwave vial to your TF including stirbar and teflon plug when you are finished. Do not throw these away! They are very expensive ($200).

Reaction Set-Up - Add 2-naphthol, KOH in ethanol and ethyl iodide to a microwave vial. Make sure to have a stir bar in the tube. Put teflon stopper and cap on. Tighten with wrench. - Put a colored piece of tape with your name on it on top of the cap. Do not cover the vent hole with the tape - Your TF will microwave the reaction for 10 minutes at 130 °C. - Make sure to let the tube cool before you open it.

Extraction

- At the end of the reaction you will have a mixture of starting material and product. First the salts from the reaction are removed by adding water and diethyl ether.

Extraction

- By extracting the diethyl ether layer with 2M NaOH we can deprotonate the OH on the starting material and extract it into the water layer. - Wash the organic layer with saturated sodium chloride solution.

Why do you extract with 2 M NaOH? A. It deprotonates the starting material B. It makes the starting material more soluble in the water layer. C. It brings the product into the organic layer. D. It gets rid of inorganic salts

Product Isolation

Separate the organic layer and dry over sodium sulfate

Filter and blow off the solvent while gently heating to yield a white solid. The product has a low melting point. It may melt if you heat it too high so it may be a liquid, but will solidify upon cooling

TLC

2-naphthol

after extraction

immediately after microwaving

Analysis - TLC, IR, 1H NMR and GC/MS. Make sure to draw out your TLC plate in your lab notebook and calculate the RFs for your starting material and product. - In your discussion of your lab report you should describe how you know the product was obtained and pure by TLC, IR, 1H NMR, GC/MS. - What would be the difference between your starting material and product in all the methods mentioned above? - Assign peaks in both IR and NMR. IR: C-H stretches and C-O stretches. NMR: Assign aromatic peaks (you don’t have to assign them individually) and the peaks on the ethyl group. - GC/MS sample preparation: Dissolve one drop of your NMR sample in 1.5 mL of hexane and add to a GC/MS vial. - Answer postlab questions.

NMR

Which lab was your favorite this semester?

A. B. C. D. E.

Lab 1: Trimyristin from Nutmeg Lab 2: Acetaminophen/TLC Lab 3: Citronellal Cyclization Lab 4: Radical Bromination Lab 5: Methyl stearate

bu.campuslabs.com/courseeval...