CHEM120L Lecture Notes - Acetic Anhydride, Vacuum Flask, Purified Water

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blueduck407

14 Apr 2014

School

University of Waterloo

Department

Chemistry

Course

CHEM120L

Professor

Carey Bissonnette

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Document Summary

Experiment procedure summary 1: synthesis of acetaminophen: sign out from storeroom, 1 50 ml round bottom flask, 500 ml vacuum flask, buchner funnel, powder funnel, pick up from the side bench, 1 metal rod, utility clamp, filter paper. Using a hot-plate, set up a water bath using a 250ml of deionized water in a 400 ml beaker. The reaction mixture will be heated in a water bath at 65-75 degrees, monitor the temperature. Find a setting on hot-plate to maintain the water bath. Weigh 3. 0 g (top loading balance) of p-aminophenol into a clean, dry 50 ml beaker. Record the actual mass used on your data sheet. Using a powder funnel, add the p-aminophenol to the 50ml round bottom flask. Measure 10ml of water using the 25ml graduated cylinder. When the water bath has reached the desired temperature range, attach a utility clamp to the neck of the round bottom flask, and clamp it in place in the water bath.

Related Questions

Provide the mechanism for the haloform reaction in part B of this experiment

Also explain how the added acetone in step 4 destroys any unreacted hypochloride.

Miniscale nitration of methyl benzoate was performed in the lab:

Procedure below:

1. Prepare and ice bath in a 100mL beaker on a magnetic stir plate.

2. To a clean, dry 25 mL Erlenmeyer flask, add 1.0 mL of methyl benzoate via pipet.

3. Calculate the mass of methyl benzoate.

4. To the methyl benzoate, add 2.25 mL of concentrated (18M) sulfuric acid and a spin bar.

5. Carefully clamp the flask so that it is immersed in the ice bath and begin stirring.

6. Prepare the nitrating solution by adding 0.75mL of concentrated (18M) sulfuric acid and 0.75mL of concentrated (16M) nitric acid to a clean, dry vial.

7. Cool the mixture in a second ice bath.

8. With a Pasteur pipet, slowly add the cooled sulfuric acid-nitric acid solution to the stirred solution of methyl benzoate. *Addition should take approximately 15 minutes. Adding the nitrating agent more rapidly will increase the amount of by-products and decrease the yield

9. After all of the nitrating agent has been added, carefully remove the ice bath.

10. Continue stirring until the reaction has come to room temperature.

11. Then let the reaction flask stand undisturbed for 15 minutes.

12. Place 10 g of ice in a 100mL beaker.

13. With a Pasteur pipet, carefully transfer the reaction mixture to the beaker.

14. Rinse the flask with 5mL of cold water.

15. When the ice has melted, vacuum filter the crude crystals using a Buchner funnel.

16. Wash the crystals with 2 5mL portions of cold water and finally with 2 1.5mL of cold methanol.

17. The crude product can be recrystallized from methanol.

18. Record the mass of the dry product and calculate the yield.

QUESTION: What is the major product formed in this reaction? Justify your reasoning..

PROCEDURE TO DO Â· Weigh benzocaine isolated from last day and record the mass in the raw data from last day Determine experimental melting point of benzocaine sample and record the melting point in Dispose of benzocaine sample in appropriate dump bottle. Caution: All concentrated acids, particularly conc. sulfuric acid, will burn the skin. Handle them carefully (wear gloves) and wash up immediately if you spill any on your hands. NOTE: Wash the graduated cylinder used to obtain the acid (with cold water) to remove all traces of sulfuric acid Weigh a 4.0 g sample of salicylic acid and place it in a 50 mL round bottom flask (along with some boiling stones). Make sure that there is no solid material trapped in the neck of the round bottom flask. In a dry 50 mL Erlenmeyer flask, place 10 mL of methanol and (while cooling the flask in an ice- water bath) slowly add 4 mL of concentrated (18 moL) sulfuric acid while swirling. This solution wil become very hot, therefore the addition must be done slowly. Pour the methanoW/acid mixture into the round bottom flask which contains the salicylic acid. Attach a reflux condenser and reflux the mixture for 30 minutes using a heating mantle and variac (set at-80% to start then reduce to 40-50%). The reflux must be monitored to ensure that the reflux line does not become too high. If the reflux line is too high, the product may escape from the condenser.During this reflux, the product will be visible as a small layer on top of the methanol/acid mixture. After the reflux is finished, shut off the variac and remove the heating mantle to allow the reaction mixture to cool to room temperature for a few minutes and then place an ice-water bath around the flask to cool for 4-5 minutes. Pour the chilled reaction mixture into a 125 mL Erlenmeyer flask which contains 10 mL of cold water and then rinse out the round bottom flask with a second 10 mL portion of water and add this to the Erlenmeyer flask also. Pour the resulting mixture into a separatory funnel (do not allow the boiling stones into the separatory funnel). Rinse the reaction flask (50 mL RBF) with 20 mL of ethyl acetate and pour this into the separatory funnel (do not allow the boiling stones into the separatory funnel). Rinse the Erlenmeyer flask with 20 mL of ethyl acetate and add this to the separatory funnel also. Shake the funnel with venting and after the layers have separated, drain the lower layer (methanol & sulfuric acid). The lower layer contains concentrated sulfuric acid and can be disposed of as follows. Pour the lower layer into a large volume of water in a beaker, stir to mix and then dispose of it down the drain in the fume hood followed by a copious amount of water

CHEM120L Lecture Notes - Acetic Anhydride, Vacuum Flask, Purified Water

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