CHEM 235 Lecture Notes - Lecture 3: Acetanilide, Watch Glass, Spatula

223 views2 pages

copperswan658

28 Sep 2017

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Never add boiling chip to a hot solution. Organic compounds that are solid at room temperature can be purified by. A boiling chip can only be used once. 2 - 50 ml erlenmeyer flasks with ground glass joints. 2 - watchglasses dropper filter paper hot plate. Mild irritant to skin, eyes, mucous membranes. Potential fire hazard. contamination with oxidants may cause ignition or explosion. Of the crude solid (benzoic acid, acetanilide) you will be recrystallizing. Size 7 , clamp the flask at 45 on the vertical poles. Need: suction trap, 125 ml filter flask, filter vac, buchner funnel, small filter paper, glass rod with rubber tip, spatula, watch glass, water solution. Use 3 pronged clamp to attach the suction flask onto the rod. Air dry the crystals for a few minutes with suction. Use solvent or the mother liquor to rinse.

Related Questions

Need isolated yield in moles, theoretical yield in moles and grams, and percent yield!

synthesis of Dulcin, 4-Ethoxyphenylurea

1. In a 50 mL round-bottomed flask, place 1.4 mL (1.4 g, 0.01 mole) of p-phenetidine, 2.4 g (0.04 mole) of urea, and 5 mL of distilled water.

2. To this mixture, add 1 mL of concentrated HCl and 5-6 drops of glacial acetic acid.

3. Fit the round-bottomed with a reflux condenser, add a boiling stone, swirl the material well and boil the mixture vigorously until the reaction is complete (30 min. maximum). At first, the dark colored solution remains clear, but in 15-20 minutes the product begins to separate rapidly. When the mixture sets to a semi-solid crystalline mass, stop the heating immediately.

4. After cooling the round-bottomed flask to room temperature, add 3-4 mL of cold water, stopper the flask tightly and shake it thoroughly to make a slurry of crystals.

5. Collect the product by vacuum filtration, wash it with cold water and dry the crystals by drawing air through them while they are still in the Hirsch funnel.

6. Recrystallize the crude product from boiling water (30 mL/g of product) using decolorizing charcoal to remove the brown color, as follows:

a. In a small beaker (100 mL) bring to a gentle boil the crude dulcin in the appropriate amount of water (donât forget the boiling chip).

b. Add a small amount of decolorizing charcoal over the boiling liquid and keep boiling for 1 minute.

c. If the liquid (not the dark, floating particulates) is colorless, filter the hot mixture through a pleated paper filter, placed in a stem less glass funnel, into another beaker. If the liquid is still pink, repeat step b.

7. Chill the filtrate in an ice bath before vacuum-filtering the purified crystals. Dry the product, weigh it, determine a melting point.

For step 5 the product was weighed and turned out to be .32 g then after finishing the lab with step 7 the final product weighed in at .07 g

Isolated Yield _____ moles _____ grams

Theoretical Yield _____ moles _____ grams

Percent Yield ______ %

Preparation of acetyl salicyclic acid (Aspirin) post-lab questions

1.)At the end of the reaction, you were asked to add ice-cold water to the reaction mixture. What do you think is the reason for this? Explain with chemical equations.

2.)How would the % yield of aspirin be changed if the final rinse of the solid product on the filter paper was done with warm water instead of ice-cold water?

3.)If you run a thin-layer chromatography for a mixture containing salicylic acid and aspirin using a 1:1 solvent mixture of ethyl acetate and hexane, which compound do you think would have more R_f value. Explain why? Bring in the structural features in your explanation.

summary Procedure of lab we did:

- Place approximately 0.300 g of salicylic acid in a tared empty 5 mL conical reaction vial. Record the actual weight of salicylic acid used. Using automatic pipet, add 0.8 mL of acetic anhydride (acetic anhydride vapors are very irritating-handle it carefully, in the hood). Add 2-3 drops of concentrated sulfuric acid using a dropper.

-Clamp the assembly so that the vial is partially submerged in the hot water. Turn on the magnetic stirrer. Once the water bath starts boiling, start timing the reaction. When the mixture has been allowed to react at 100 oC (the temperature of boiling water) for 15 minutes, you can consider the reaction to be complete. During the heating time, take about 20 mL of deionized water in a flask and chill it in an ice-water bath.

- After the reaction has gone on for 15 minutes, add very cautiously, drop by drop, 1 mL of deionized water to the reaction vial. At this point you should have a solution in your reaction vial. Remove the reaction vial form the hot water bath, add another 1-2 mL of DI water and let it stand at room temperature for few minutes. Then, detach the air condenser carefully and remove spin vane with forceps. Place the vial in a beaker and cool down to RT. During this time, the aspirin may begin crystallizing. If not, scratch the walls of the vial with a glass rod. Then, cool the vial in an ice-water bath.

- When the vial appears full of crystals, add about 3-4 mL of ice-cold DI water. Filter the aspirin using vacuum filtration (use Hirsch funnel). Leave the filtration setup in place for few minutes-this will draw air through the sample and will help dry aspirin.

Recrystallization of Aspirin:

- Transfer the rest of the crude aspirin to a 25 mL Erlenmeyer flask and do recrystallization using ethanol.

Purity of Aspirin:

- Using the melting point apparatus, determine the melting point of your crude aspirin and the recrystallized aspirin.

- To do FeCl3 test, get 4 test tubes. Place 1 mL of ethanol and 2 drops of 1% FeCl3 solution in each test tube. Add few crystals of salicylic acid to one test tube. Add few crystals of your crude aspirin product to the second test tube. In the thirst test tube, place a few crystals of your recrystallized aspirin. The fourth test tube will be your âblankâ. Shake each of the test tubes and record your observations.

CHEM 235 Lecture Notes - Lecture 3: Acetanilide, Watch Glass, Spatula

Document Summary

Get access

Related textbook solutions

Chemistry: Structure and Properties

Basic Chemistry

Principles of Chemistry Molecular Approach

Principles of Chemistry Molecular Approach

Chemistry: Structure and Properties

Chemistry: A Molecular Approach

Chemistry: A Molecular Approach

Principles of Chemistry: A Molecular Approach

Chemistry: The Central Science

Related Documents

CHEM 235 Lecture Notes - Lecture 2: Spatula, Benzocaine, Sodium Hydroxide

CHEM 235 Lecture Notes - Lecture 6: Sodium Bicarbonate, Litmus, Graduated Cylinder

CHEM 235 Lecture Notes - Lecture 11: Grignard Reaction, Phenylmagnesium Bromide, Separatory Funnel

Related Questions