The purpose of this lab experiment is to study a simple esterification reaction, producing acetylsalicylic acid (aspirin), thus becoming familiar with synthetic chemistry tools and techniques.
Organic molecules can be classified based on the functional groups that they possess. One of these classes is esters, which are produced from an acid and an alcohol as shown in the following figure.
Figure 1: Reaction of a carboxylic acid and an alcohol to form and ester.2
Based on the above reaction, a wide variety of esters can be formed since there are so many acids and alcohols that could be combined. Typically, the resultant is an equilibrium mixture containing the ester, the water, the acid and the alcohol.
In this lab …show more content…
3. Place the Erlenmeyer flask into the hot water bath and gently swirl. The solution will liquefy and crystals of acetylsalicylic acid will start to form. Remove the flask from heat once crystal formation begins and take note of the smell.
4. Allow the flask to cool down to room temperature on the lab bench before placing it into the ice-water bath.
5. Break up the crystals with a glass stir rod and slowly add 20 mL of pre-cooled distilled water to destroy an unreacted acetic anhydride. Cool the flask for several minutes to get as many crystals as possible.
6. Use vacuum filtration to collect the ASA crystals. Wash the crystals using about 10 mL of ice cold water three times. In order to allow the cold water to destroy impurities in the crystals, momentarily disconnect the tubes to reduce suction rate before allowing the water to be filtered out.
7. Transfer the crystals to a pre-weighed watch glass, break them up and spread them out, then place them into the oven for approximately 10 minutes.
8. Record the mass of the watch glass and the crude product, wait 5 minutes and then weigh the sample again.
Part II Recrystallization5
1. Weigh approximately 1 g of crude ASA into a 150 mL beaker. Put about 30-35 mL of distilled water into a 50 mL beaker and bring it to a boil. Use tongs to hold the beaker and pour approximately 10 mL of the boiling water into the beaker containing crude ASA.
2. Place the beaker with the crystals onto the hot plate and only keep it hot enough so
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27. Heat the water to 40°C with an alcohol lamp by setting up the apparatus as shown in figure 3 below:
The product was placed in a Craig tube and several drops of hot (100°C) solvent (50% water, 50% methanol, by volume) was added and heated until all of the crystals dissolved. The Craig tube was plugged and set in an Erlenmeyer flask to cool. Crystallization was induced once the mixture was at room temperature by scratching the inner wall of the tube. It was then placed into an ice bath for ten minutes until crystallization was complete. The tube was then
Salicylic acid was esterfied using acetic acid and sulfuric acid acting as a catalyst to produce acetylsalicylic acid and acetic acid. The phenol group that will attack the carbonyl carbon of the acetic anhydride is the –OH group that is directly attached to the benzene since it is more basic than the –OH group attached to the carbonyl group. This method of forming acetylsalicylic acid is an esterification reaction. Since this esterification reaction is not spontaneous, sulfuric acid was used as a catalyst to initiate the reaction. Sulfuric acid serves as the acid catalyst since its conjugate base is a strong deprotonating group that is necessary in order for this reaction to be reversible. The need for the strong conjugate base is the reason why other strong acids such as HCl is not used since its conjugate base Cl- is very weak compared to HSO3-. After the reaction was complete some unreacted acetic anhydride and salicylic acid was still be present in
Measure 500ml of tap water in the 500cm3 beaker, then measure 5g of sodium hydrogen carbonate using the 50cm3 beaker and weight scale and place in the beaker of water, using the glass rod to dissolve it into the mixture.
To tube 2 and tube 3 a boiling chip is added. The two tubes are boiled to remove any residual ether. Next, the tubes are cooled to room temperature and placed into an ice bath to allow for crystallization. The solution is then removed from the solid in each tube and discarded. To tube 2 and 3 ~0.5 ml of H2O is added for recrystallization, the tubes
Place 100 ml of distilled water in a 250-ml (or 400-ml) beaker. Add 1.26g of oxalic acid dihydrate (H2C2O4.2H2O) and 1 ml of concentrated ammonia. Stir the mixture until the solid has dissolved completely.
XIII. Carefully remove the copper metal from the filter paper onto the watch glass. (with a spatula) Place a 400 ml beaker on a hot plate contained with water. Carefully place the watch glass before the water boils to dry the copper metal. (Use the tongs to handle the hot watch glass)
1) Separate the solid from the liquid in the beaker by decanting the liquid. Ask your instructor to demonstrate the correct procedure.
Esters are carbonyl compounds with groups that can be replaced by a nucleophile. Esters perform hydrolysis reactions, where it reacts with water for form a carboxylic acid and an alcohol. Esters can also perform alcoholysis reaction, where it reacts with an alcohol to form a new ester and alcohol. This is also known as transesterification reaction since one ester creates another. The experiment conducted was an example of a transesterification reaction; mixing acetic acid and isoamyl alcohol to synthesize isoamyl acetate and water.
As the crystals are drying, obtain the weight of the watch glass to the nearest 0.0001 grams. The alum crystals that are on the filter paper are transferred to the watch glass in order to receive the mass of the
A 10 mL round-bottom flask was weighed both before and after approximately 1.5 mL of the given alcohol, 4-methyl-2-pentanol, was added. 3 mL of glacial acetic acid, one boiling chip, and 2-3 drops of concentrated sulfuric acid were added to the flask in that order. The reflux apparatus was assembled, the
In this experiment, a Fischer Esterification reaction was performed with two unknown compounds. The unknown compounds, Acid 2 and Alcohol D, were identified by using the knowledge of the reaction that took place, and the identity of the product that was synthesized. The identification of the product resulted from analysis of IR and NMR spectra.