LAB 5 - CARBOXYLIC ACIDS AND DERIVATIVES
- Page ID
- 506282
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)CARBOXYLIC ACIDS, ESTERS, AND AMIDES
The purpose of this experiment is to:
- Name and draw structures for carboxylic acids, esters, and amides
- Explore the physical properties and reactions of carboxylic acids, esters, and amides
INTRODUCTION
Carboxylic acids are organic compounds in which -OH is bonded to a carbonyl group. In the derivatives of carboxylic acids, the -OH group bonded to the carbonyl carbon is replaced by another group. Two common derivatives are esters and amides. In esters, the carbonyl group is bonded to an alkoxy group, -OR (where R is an alkyl group), while amides contain a nitrogen atom bonded to a carbonyl group.
Like alcohols and thiols, carboxylic acids behave as weak acids. They also react with alcohols to produce esters. Both esters and amides can be hydrolyzed in sodium hydroxide to yield carboxylic acid salts. In this experiment, you will investigate these reactions and analyze the products using various methods.
1) Always wear goggles while working with chemicals in this lab.
2) Wear gloves while working on this experiment.
3) Always handle all chemicals under a working fume hood.
4) Dispose of all waste in the appropriate waste container, which should always be kept under a fume hood.
5) Thoroughly clean all glassware and your work area at the end of the experiment.
6) Before leaving the lab, wash your hands.
CHEMICALS AND EQUIPMENT NEEDED
CHEMICALS |
CHEMICALS |
CHEMICALS |
EQUIPMENT |
EQUIPMENT |
|---|---|---|---|---|
|
Acetic acid |
Methyl salicylate |
1-pentanol |
Hot plate |
Red litmus paper |
|
Citric acid |
Salicylic acid |
Methanol |
600 mL beaker |
Test tube rack |
|
Benzoic acid |
10% NaOH |
Ethanol |
Thermometer |
pH paper |
|
Acetamide |
10% HCl |
1-propanol |
Stirring rod |
Spatula |
|
Benzamide |
Propanoic acid |
1-butanol |
Non-halogenated waste container |
5 small or medium-sized test tubes |
|
Water |
Sodium bicarbonate |
1-octanol |
Halogenated organic waste container |
- |
EXPERIMENTAL PROCEDURE
Part A: Structure, Solubility, and pH of Carboxylic Acids and Amides
1) Draw the structures for the following compounds: acetic acid, citric acid, benzoic acid, acetamide, and benzamide. Identify the primary functional group in each compound.
2) Gather five small to medium-sized test tubes, and add the following reagents in each test tube:
Test tube 1: 2 mL of water and 1 mL of acetic acid
Test tube 2: 2 mL of water and a small amount of citric acid (enough to cover a spatula tip)
Test tube 3: 2 mL of water and a small amount of benzoic acid (enough to cover a spatula tip)
Test tube 4: 2 mL of water and a small amount of acetamide (enough to cover a spatula tip)
Test tube 5: 2 mL of water and a small amount of benzamide (enough to cover a spatula tip)
3) Use a stirring rod to mix each solution, ensuring that the rod is clean between each test tube. Record whether the substances dissolve in water.
4) Test the pH of each solution using pH paper. To do this, dip a stirring rod into the solution and touch its tip to pH paper. Ensure that you rinse and dry the stirring rod between each solution, using only a minimal amount of pH paper.
5) Save test tubes 1 to 3 for part B. Pour the contents of test tubes 4 and 5 into the non-halogenated waste container. Clean and dry the test tubes, and save them for future use.
Part B: Reactions of Carboxylic Acids with Sodium Bicarbonate
1) Place test tubes 1-3 from part A in a test tube rack.
2) Measure the room temperature with a thermometer. Keep the thermometer in the air until the temperature stabilizes.
3) To test tube 1, add a small scoop of sodium bicarbonate, and record your observations.
4) After about 10 to 15 seconds, measure the temperature of the solution in test tube 1. Wait for the thermometer reading to stabilize before recording the temperature.
5) Repeat steps 2-4 with test tubes 2 and 3.
6) Pour the contents of each test tube into the non-halogenated waste container. Clean and dry the test tubes, then save them for future use.
Part C: Formation of Esters
For this section of the experiment, you will create three esters. Select combinations of carboxylic acids and alcohols from the list below:
Carboxylic Acids |
Alcohols |
|---|---|
|
Acetic acid |
Methanol |
|
Salicylic acid |
Ethanol |
|
Propanoic acid |
1-propanol |
|
1-butanol |
|
|
1-pentanol |
|
|
1-octanol |
1) Obtain three small or medium test tubes. Add 3 mL of alcohol, 2 mL of carboxylic acid, and 10 drops of concentrated sulfuric acid to each test tube while ensuring they are properly labeled.
2) Place the test tubes in a boiling water bath (a 600 mL beaker three-quarters filled with water on a hot plate) for 15 minutes. Do not start the timer until the water has come to a boil.
3) Carefully take out the test tubes from the hot water bath and detect the odor of each solution by gently wafting the vapors toward you.
4) Formulate an equation for the creation of each ester and include a name for each ester.
5) Pour the contents of each test tube into the non-halogenated waste container. Clean and dry the test tubes, then save them for future use.
Part D. Ester Hydrolysis
1) Carefully detect the odor of methyl salicylate.
2) Add 3 mL of water, five drops of methyl salicylate, and 1 mL of 10% NaOH to a medium-sized test tube. Note your initial observations.
3) Put the test tube in a boiling water bath for 30 minutes. Wait to start the timer until the water reaches a boil.
4) Remove the test tube from the water bath with care, and note your observations, including any changes in odor.
5) Compose an equation for the reaction that occurred.
6) Add drops of 10% HCl to the test tube contents until a solid forms.
7) Formulate an equation to clarify the observations noted in step 6.
8) Transfer the contents of the test tube into the halogenated organic waste container.
Part E. Amide Hydrolysis
1) Combine 2 mL of water, a small amount of acetamide (enough to cover the tip of the spatula), and 2 mL of 10% NaOH in a medium-sized test tube.
2) Place the test tube in a boiling water bath for 5 minutes. Do not start the timer until the water reaches a boil.
3) While the test tube is placed in the water bath, hold a piece of red litmus paper over its opening. Note any change in the litmus paper's color and any odors detected.
4) Write an equation to explain the observations noted in step 3.
5) Pour the contents of the test tube into the non-halogenated waste container.
PRE-LAB QUESTIONS
Name: ____________________________________
1) Provide a reasonable name for the following organic compounds.
2) Draw structures for each compound.
Part A: 2,2-dimethyl butanoic acid
Part B: Butyl ethanoate
Part C: pentanamide
Part D: sodium propanoate
Part E: cyclopentyl hexanoate
3) Predict the products of the following reactions.
DATA AND OBSERVATIONS
Name _________________________Lab Partner(s) ______________________________
Part A. Structure, Solubility, and pH of Carboxylic Acids and Amides
Compound |
Structure |
Soluble or Insoluble in Water? |
pH |
|---|---|---|---|
|
Acetic Acid |
|||
|
Citric Acid |
|||
|
Benzoic Acid |
|||
|
Acetamide |
|||
|
Benzamide |
Part B: Reactions of Carboxylic Acids with Sodium Bicarbonate
Test Tube |
Initial Temperature (air) |
Observations upon the Addition of Sodium Bicarbonate |
Final Temperature (Temperature of Solution) |
|---|---|---|---|
|
1. (Acetic Acid) |
|||
|
2. (Citric Acid) |
|||
|
3. (Benzoic Acid) |
Part C: Formation of Esters
Name of Alcohol |
Name of Carboxylic Acid |
Reaction |
Name of Ester |
Odor |
|---|---|---|---|---|
Part D. Ester Hydrolysis
1) Odor of methyl salicylate:
2) Initial observations (before heating):
3) Final observations (after heating):
4) Final odor:
5) Equation for the hydrolysis of methyl salicylate:
6) Observations upon addition of HCl:
7) Equation to describe the formation of a solid upon the addition of HCl:
Part E. Amide Hydrolysis
1) Observations of reaction (change in litmus paper, odor, etc.):
2) Equation to describe the hydrolysis of acetamide:
POST-LAB QUESTIONS
1) For part A, account for any differences in the solubility of citric acid and benzoic acid in water.
2) For part B, is the reaction between carboxylic acids and sodium bicarbonate exothermic or endothermic? Explain.
3) Name the following esters. Conduct a literature search to determine the odor (if any) associated with each ester.
4) Soaps, which we will explore in future experiments, are formed from the reaction of a triglyceride with aqueous sodium hydroxide. Based on the results from part D of this experiment, predict the product(s) of the following response.
5) For part E, what is responsible for the odor produced during the saponification of acetamide?
Please click here to access the Pre-Lab, Data Tables, and Post-Lab in Word or PDF format. Complete them and upload the lab report according to your instructor's instructions.