Aspirin Can Be Synthesized by Reacting Acetic Anhydride

Experiment_614_Synthesis of Aspirin_1_1_2

1. Last updated

2. Save every bit PDF

Folio ID

305051

Student Proper noun		Laboratory Date: Appointment Report Submitted:	___________________________
Student ID		Experiment Number and Name	Experiment half dozen 1 4 : Synthesis of Aspirin

Experiment 6 one 4 : Synthesis of Aspirin

Section ane:  Purpose and Summary

• Bear a chemical reaction to produce aspirin.

• Separate the aspirin from the reaction by-products using vacuum filtration.

• Analyze the aspirin and guess its purity.

Acetylsalicylic acid, commonly known as aspirin, is the most widely used drug in the world today. Its analgesic, antipyretic, and anti-inflammatory backdrop arrive a powerful and effective drug to relive symptoms of pain, fever, and inflammation. Salicylic acid, whose name comes from Salix, the willow family of plants, was derived from willow bawl extracts. Hippocrates the ancient Greek physician, besides as Native Americans before Columbus' time, prepared willow bark teas as headache remedies and other tonics. In modern times, salicylic acrid is administered in the course of aspirin which is less irritating to the tum than salicylic acid.

To prepare aspirin, salicylic acid is reacted with an excess of acetic anhydride. A small amount of a strong acid is used equally a goad which speeds up the reaction. In this experiment, sulfuric acid will exist used as the catalyst. The excess acetic anhydride will be quenched (reacted) with the add-on of h2o. Overall, the reaction takes place between a carboxylic acid and an acid anhydride to form an ester.

Aspirin is not very soluble in water then the aspirin product volition precipitate when h2o is added. Some of the other compounds, acetic anhydride and acetic acrid, deliquesce in water, but salicylic acrid is just slightly soluble in cold water. Vacuum filtration will separate the crystalline aspirin away from everything else in the reaction mixture except for any salicylic acrid that did not react.

The aspirin should be analyzed for the presence of any contaminating salicylic acid. In the final role of today's lab, you will accept a small amount of your aspirin and test it with iron(3) chloride (FeCl₃). FeCl₃ reacts with phenols (alcohol groups attached to aromatic rings) to produce colored complexes. Notice that salicylic acid contains the phenol functional grouping but aspirin does not.  Therefore, the more salicylic acid that contaminates your aspirin, the darker the color will be with FeCl_iii.

Section 2:  Safety Precautions and Waste Disposal

Safety Precautions:

Use of eye protection is recommended for all experimental procedures.

Sulfuric acid (H₂And so₄) is highly corrosive. Avoid contact with your optics, skin, and clothing. In instance of contact, rinse with enough of water. Ask instructor to help with the cleaning of whatever spills.

Acetic anhydride is a lachrymator (its vapor irritates the eyes causing tears to flow).  Proceed it in the fume hood.

Waste Disposal:

The reaction mixtures used in this experiment may be safely disposed of in the sink, followed by copious amount of running h2o.

Solids, aspirin and salicylic acid, should be disposed of in the regular trash container.

Section 3: Procedure

Part i: Synthesis of Aspirin

Prepare a boiling-water bathroom by filling a 600-mL beaker with about 400 mL of tap water. Put the beaker on the hot plate.  Weigh out about 2.1 grams of salicylic acid on a slice of weighing paper. To do this, first tare a piece of weighing newspaper (This means to put a piece of newspaper on the rest and printing the zero or tare push button. Fig.1) Add together some salicylic acid a petty at a time onto the weighing newspaper until you take virtually 2.one gram of it on the paper.  It is OK to weigh a piffling extra mass (do non render excess salicylic acrid to its container as this might contaminate the unabridged amount if your spatula is not perfectly clean). Record the mass of the solid. Identify this solid into a 125-mL Erlenmeyer flask (other sizes may exist acceptable). In the fume hood, measure out out 4 mL of acetic anhydride in a small graduated cylinder and add it to the flask. From this point on, keep your flask under the hood, because it at present contains acetic anhydride (the vapors of acerb anhydride are very irritating).  Add nigh v drops of concentrated sulfuric acid. This will be the goad for the reaction.  Place the flask in the boiling water bath and clamp it in place. (Fig.two)  Heat the reaction for at to the lowest degree 15 minutes.  Put at least 60 mL of laboratory water into a 150mL beaker (or like size).  Then put this chalice in an water ice-h2o bathroom. Use this cold water in steps 9, 12, 13, and 14 below.  After the reaction has heated for at least 15 minutes, remove it from the boiling water bathroom.  In 1 or 2 mL portions, add nigh 10mL cold water to the reaction, swirl the reaction between each ane-2mL portions.  This water will react and destroy any remaining acetic anhydride. (Fig3.) Put the flask with the reaction into an ice water bathroom (Fig.4).  Crystals of aspirin should grade.  Chill for at least 10 minutes in order to obtain the maximum amount of crystalline product. Collect the aspirin crystals past vacuum filtration. To set up a vacuum filtration fix upwards: a)  Y'all will need a Buchner funnel, a clean 250-mL vacuum filter flask, a filter adaptor (often a one-pigsty stopper), a pre-cut filter paper and Beaker #2.WEIGH the dry out filter paper. b)  Place the filter newspaper on the Buchner funnel. The filter paper should fit snugly and cover all the pocket-size holes in the funnel. c)  Using the filter adaptor, place the Buchner funnel on top of a vacuum filter flask.  Yous might demand to use a clamp and a ring-stand to keep the setup intact and upright. d)  Connect a vacuum tubing hose to the vacuum filter flask and to the vacuum supply. e)  Wet the filter newspaper with a little laboratory water.  Turn the vacuum on and confirm that there are no leaks.(Fig.v) Add virtually 25 mL cold h2o to the reaction and mix well. Filter the crystals.  Use a few milliliters of cold water to transfer as much solid as possible. Disconnect the vacuum temporarily and add xv mL of cold water to the crystals in order to rinse them. Later the crystals have soaked in the common cold water for a few seconds, reconnect the vacuum to filter once more.  Leave the vacuum on for several minutes to air dry the crystals. With the vacuum on, stir the crystals carefully to aid dry them. Do this for about 15 minutes. Turn off the vacuum and weigh just the filter paper with the crystals. If you lot use a sentinel drinking glass to behave the filter paper and crystals to the balance, be sure to tare the weight of the scout glass (in other words, don't include the weight of the watch drinking glass with your filter paper and crystals.) Clean upwards: Exist sure to keep the aspirin for Parts ii & 3.  Throw away the filter paper in the trash. Dispose of the filtrate (the aqueous solution in the vacuum filtration flask) down the drain with plenty of water. In the fume hood, rinse with h2o all pipets and glassware in contact with acerb anhydride and pour the rinse water down the drain in the fume hood.

Mass of Salicylic Acid: ______________ grams Volume of Acetic Anhydride: ______________ mL Mass of filter newspaper: ______________ grams Mass of crystals and filter paper: ______________ grams

Function 2 : Analysis of Aspirin (How pure is information technology?)

Obtain 3 test tubes and about 1 mL of ethanol (CHthreeCH2OH) to all 3 examination tubes.  As well add 1-2 drops of i% FeCliii solution to each test tube.  Be sure all 3 test tubes have the same amounts of reagents.
Label the first exam tube "Aspirin" and add to this examination tube a few of your aspirin crystals that you fabricated today. Stir well.	Describe the Color:
Characterization the 2nd test tube "Salicylic Acid" and add a few crystals of Salicylic Acid to this 2nd test tube. Stir well. This is yourPositive Control. The positive control shows you what to look for when a test is positive: in today'south assay, the positive command shows you lot a dark color considering it contains unreacted salicylic acid.	Draw the Colour:
The third exam tube is yourNegative Command.  Do not add whatever crystals to this exam tube!  The negative control shows you what to look for when a test is negative: in today'southward analysis, the negative command shows you a color when no contaminating salicylic acid is nowadays.	Depict the Color:
Compare the colors among the 3 test tubes and depict their similarities and differences.	Describe the similarities and differences in color: (You tin utilise the empty space to the left besides).

Part iii : Analysis of Aspirin (How stable is information technology?)

Obtain a dry test tube and add about a pea-sized amount of your aspirin crystals (infringe some relatively pure crystals from a classmate if your aspirin was highly contaminated with salicylic acrid).  Tap the crystals to the lesser of the examination tube.  Utilise a test tube clamp to hold the test tube. Ignite a Bunsen burner. Pointing the open terminate of the test tube away from y'all, GENTLY oestrus the bottom of the test tube until the crystals melt. DON"T burn the aspirin.(Fig.five) Remove the test tube from the flame and carefully WAFT any odors from the open up cease of the test tube towards you.  Do you smell anything? (To waft the odors ways to "fan" the odors towards you, mixing in plenty of air to dilute the fumes.)  If you don't odour anything, try "pouring" the vapors out of the examination tube by holding the exam tube horizontally. Any odor detected may indicate that aspirin has decomposed with excessive heat. Aspirin may besides decompose slowly upon long-term storage in a humid surround. After the test tube cools, wash the exam tube in the sink with lather and water.

Describe the Odor:

Section 4: Calculations

Mass of salicylic acid (g)
Summate the number of moles of salicylic acid (mol)  (Molar mass =  138 yard/mol)
Volume of acetic anhydride (mL)
Calculate the number of grams of acetic anhydride (k) (Density = 1.08 chiliad/mL)
Summate the number of moles of acetic anhydride (mol)  (Molar mass =  102 g/mol)
Identify the Limiting Reagent (Proper name of compound)
Theoretical Yield of Aspirin (m) (Molar mass =  180 g/mol)
Mass of filter paper and aspirin (yard)
Mass of filter paper (g)
Summate the mass of aspirin (g)
Per centum Yield of Aspirin (%)

Post Lab Questions:

1.  Aspirin is slightly soluble in water: the solubility of aspirin in water is 0.33 grams per 100 mL h2o at room temperature.  In today's experiment, yous rinsed your aspirin with at least 50 mL of water.  If the water was at room temperature, how many grams of your aspirin would have dissolved by rinsing it today?

2.  Propose a reason why y'all were instructed to rinse the aspirin even though it is known that this will cause some of the aspirin to dissolve and be lost.

3.  Suppose that another educatee performed today's experiment, simply they forgot to air dry out the aspirin during vacuum filtration.  If they weigh the aspirin when it is even so damp, how will this affect the percent yield?

4.  Propose a scientific reason why we did not dry the aspirin in an oven today.

5.  A desiccant, or drying agent, is ofttimes added to a container with medications to prolong the shelf life.  Cotton is sometimes used as a desiccant which is often found inside a packet of aspirin. Moisture in the air (humidity) can cause aspirin to slowly decompose through a reaction called hydrolysis. The cotton wool absorbs moisture and delays hydrolysis.  Advise an like shooting fish in a barrel and quick fashion to determine if your aspirin at home has begun to hydrolyze.

6.  Suppose two groups of students performed today's experiment and obtained unlike results.  1 grouping obtained aspirin in 88% yield which turned dark in the FeCl_iii test. The other group obtained aspirin in 65% yield which produced no colour modify in the FeCl₃ examination. Explain which group was more than successful in lab.

strotherhawricer47.blogspot.com

Source: https://chem.libretexts.org/Courses/Los_Medanos_College/Chemistry_6_and_Chemistry_7_Combined_Laboratory_Manual/Experiment_614_Synthesis_of_Aspirin_1_1_2

Share this post