functional groups in organic chemistry · functional groups in organic hemistry, teacher’s guide...

Functional Groups in Organic Chemistry, Teacher’s Guide 1

Green Chemistry Module Level: High School Regents

Functional groups in Organic Chemistry

Laboratory Experiment Created By: Dr. Martin Walker, State University of New York at Potsdam

Module Contributors: Dr. Mark Noll and Jana Panders, State University of New York at Brockport

Kate Winnebeck, NYS Pollution Prevention Institute Mary E. Courtney, Palmyra, NY

Funding provided by the New York State

Department of Environmental Conservation

2012


Functional Groups in Organic Chemistry In this lab experiment, students will be performing a series of tests to determine the identity of their assigned unknown. This experiment can be tailored to the readiness level of the students in the class. For example, the teacher may decide to remove the flow chart and leave the students with only the procedure in order to figure out their unknown. The teacher may also choose to have students guess to which class a molecule belongs based on the name of the molecule, not the structure. The instructor might wish to design a scenario of some kind (ala CSI crime scene) to introduce the unknown substances, and assign the students the role of crime scene investigators. Two versions of the lab are provided. Basic Level Instruction: Suitable for a Regents chemistry class, the lab sequences students through a series of simple chemical tests, leading to identification of an unknown. A flowchart and checkbox data collection table simplifies the task. Advanced Level Instruction: For an advanced class (AP), the lab may be useful as an introduction to an organic synthesis, purification and analysis lab, particularly for students who may not have taken Regents Chemistry prior to AP Chemistry. The laboratory activities are identical to the basic level, but there is far less written guidance. Students follow the flow chart, create their own data collection scheme and make a conclusion based on the test results. Students may be assigned more than one unknown in order to broaden their experiences and hone their identification skills. The laboratory write-up for the advanced level laboratory is a stand-alone report generated by the student.


Functional Groups in Organic Chemistry: Teacher’s Guide Intended Audience: High School Regents Chemistry Students This experiment is aimed at students in high school learning about chemical changes and reaction types. The experiment would also be suitable for an introductory college laboratory. Recommended Student Background: Students should read the introduction and have some familiarity with Table R of the Regents Chemistry Reference Tables. Activity Timeline: This experiment should be completed in 40 minutes. Safety Issues: Wear approved safety goggles and suitable clothing when working with or near all chemicals in this experiment. As they leave the laboratory, students should wash hands well. Some of the compounds can stain your skin or the lab bench, so take care to avoid spillage. Most of the compounds are classed as irritants, so avoid direct contact with the skin; if exposure occurs, wash well with water. Spills can be cleaned up by washing with a large amount of water. Keys to Success: Students must be detail-oriented and carefully label their test tubes so they know which step of the sequence they are on. Carefully following the testing sequence while paying attention to which reagents they are using should assure reliable results. Use of the flowchart may help many students to stay on track. Completing the data checklist as the experiments proceed will be very helpful in making a good conclusion. Students should be careful to note that positive tests for aldehydes and amines then instruct them to skip the alcohol test. If they do not follow this instruction, they will obtain false positive results on the alcohol test and likely misidentify their unknown. Advanced Preparation: The instructor will need to prepare the unknowns and test solutions ahead of time in order for this lab to be completed in one lab period. Two sets of preparation instructions are included below, one set for amounts of test reagents and unknowns for larger classes, with instructions following for teachers with fewer students or lab sections. Note that part of the Green Chemistry principles include only preparing as much solutions as needed in order to minimize waste. The unknowns are prepared as 5% solutions in water. With salicylic acid, students should be given a small amount (0.05 g) of the solid for the test with sodium bicarbonate; for the remaining tests, a 5% solution of sodium salicylate in water is suitable. For vanillin, a 5% solution in 50% ethanol should be used (being an aldehyde, the alcohol test will not be performed). Unknowns can be supplied to students in 10 ml graduated cylinders or test tubes clearly marked. Test reagents could be provided to students in clearly labeled dropper bottles so that each lab station has a complete set of test reagents. This could help to minimize cross contamination between reagents and reduce the number of disposable pipettes being used. Test reagents All reagents are stable for at least several months. The potassium permanganate solution should be kept out of the light.


Sodium bicarbonate solution Either 1.0 M or saturated NaHCO3 solution is suitable. Prepare a 1.0 M solution by dissolving 84 g sodium bicarbonate in one liter of distilled water. Benedict's solution can be purchased, or prepared as follows 5.19 g Sodium citrate 3.0 g Sodium carbonate 5.19 g Copper sulfate In a 125 mL Erlenmeyer flask, labeled “Solution A”, dissolve the sodium citrate and sodium carbonate (masses above) in 24 mL of distilled water. Use heat if necessary to totally dissolve solid. In another 125 mL Erlenmeyer flask, labeled “Solution B”, dissolve the copper sulfate (mass above) in 60 mL of distilled water. Just before the lab period, combine solutions A and B to complete the preparation of Benedict’s solution; care should be taken, as some fizzing may occur. The combined solution can be used for several weeks without a problem. Acidified iron(III) sulfate solution Prepare a 0.1 M acidic solution, by dissolving 4.0 g anhydrous iron(III) sulfate (or 4.9 g of the pentahydrate), in 100 mL of 0.5 M sulfuric acid. Ninhydrin solution for testing for amines Prepare solution by dissolving 0.10 g ninhydrin in 100 mL ethanol. Acidified potassium permanganate solution for testing for primary/secondary alcohols Make a 0.1 M KMnO4 (in 0.5 M H2SO4) by dissolving 1.58 g potassium permanganate in100 mL of 0.5 M sulfuric acid. SMALL VOLUME INSTRUCTIONS If you have only a small number of students or you will have no need to re-use test solutions for multiple class periods, you may want to prepare smaller volumes of these solutions. Below are edited test solution preparation instructions for those that seek smaller amounts of each solution (Note that the Benedict’s Solution preparation has not been changed). Test reagents All reagents are stable for at least several months. The potassium permanganate solution should be kept out of the light. Sodium bicarbonate solution Either 1.0 M or saturated NaHCO3 solution is suitable. Prepare a 1.0 M solution by dissolving 0.050 g sodium bicarbonate in 50mL of distilled water. Benedict's solution can be purchased, or prepared as follows 5.19 g Sodium citrate 3.0 g Sodium carbonate 5.19 g Copper sulfate In a 125 mL Erlenmeyer labeled “Solution A”, dissolve the sodium citrate and sodium carbonate in 24 mL of distilled water. Use heat if necessary to get the remaining solid dissolved. In an additional 125 mL Erlenmeyer labeled “Solution B”, dissolve the copper sulfate in 60 mL of distilled water. Before the lab period, combine


solutions A and B to complete the preparation of Benedict’s solution; care should be taken, as some fizzing may occur. The combined solution can be used for several weeks without a problem. Acidified iron(III) sulfate solution Prepare a 0.1 M acidic iron (III) sulfate solution by dissolving 2.0 g anhydrous iron(III) sulfate (or 2.45 g of the pentahydrate) in 50 mL of 0.5 M sulfuric acid. Ninhydrin solution for testing for amines Prepare solution by dissolving 0.05 g ninhydrin in 50 mL ethanol. Acidified potassium permanganate solution for testing for primary/secondary alcohols Make a 0.1 M KMnO4 solution (in 0.5 M H2SO4) by dissolving 0.80 g potassium permanganate in 50 mL of 0.5 M sulfuric acid. Materials Check List:

Sodium bicarbonate, saturated solution (ca. 8.4% or 1.0 M) Benedict's solution (made from copper(II) sulfate, sodium citrate and sodium carbonate) Iron(III) sulfate or Iron (III)pentahydrate (0.1% in 0.1 M H2SO4) Potassium permanganate (0.1% solution in 0.1 M H2SO4) Ninhydrin in ethanol (0.1% solution) Glassware: 5 test tubes Test tube rack Disposable pipettes A hot water bath (set up by instructor)


Unknowns:

Unknown Found in Functional Group Buy from Quantity Price

Acetic Acid Distilled Vinegar Carboxylic Acid Grocery store 16oz $1.00

Acetone Certain nail polish removers

Ketone Fisher Scientific 500mL $9.15

Vanillin Ether, phenol, aldehyde

Acros Organics 2g $20.70

Glucose ReliOn® Glucose tablets

Alcohol, aldehyde WalMart 50 tablets $5.00

Salicylic Acid Carboxylic acid, phenol

Fisher Scientific 100g $7.25

2-Propanol Isopropyl Alcohol Alcohol Grocery store 16oz $1.00

Tartaric Acid Cream of Tartar Carboxylic acid, alcohol

Grocery store 1.5oz $3.49

Glycine Amine, carboxylic acid

Acros Organics 100g $19.50

CC

OH

O

H

HH

CC

C

O

H

HH

H

H

H

CC

C

OH

H

HH

H

H

H

H

C C

O H

N

H

H

OH

H CC

OH

O

O

H

CC

OH

OO

H

H

H

CH2

CHCH

CHCH

2

CO

H

OH

OH

OH

OH

C

CC

C

CC C

H

O

O

H

O

H

H

H

HC

CC

C

CC C

O

H

O

H

H

H

O

CH3

H

Acetic acid,a carboxylic acidfound in vinegar

Acetone,a ketone used in nail polish remover

Propan-2-ol or isopropyl alcohol,an alcohol usedfor rubbing alcohol

Glycine, an amineand carboxylic acid, is the simplestamino acid.

Tartaric acid is a carboxylic acid. It is a by-product of winemaking.

Glucose is both an alcoholand an aldehyde. It is acommon sugar.

Salicylic acid is both a phenol and a carboxylic acid. It occurs in willow bark, and was used as a herbal cure for headaches.

Vanillin is an ether, a phenol and an aldehyde.It is a major componentof vanilla essence.

Measurements: The students will make qualitative observations during this laboratory (color, precipitate formed, fizzing, etc).

Recycling and disposal: All contents of all test tubes except for the one instance noted below can be washed away down the drain in a stream of running water, without further treatment. All organics used in this laboratory exercise are non-toxic and naturally occurring. The quantities of materials such as acetone and potassium permanganate are small enough that they will not cause a problem in the environment.


The one cleanup problem involves the positive tests using potassium permanganate, where manganese(IV) oxide may be formed and adhere to the test tubes. These tubes can be washed with 3 M sulfuric acid, and this can be neutralized with 1 M sodium acetate solution before washing down the drain. It is recommended to have a teacher complete this portion of the disposal process in order to assure it is done safely and accurately. Green Chemistry: Making materials sustainably Chemical manufacturing is as old as civilization and the discoveries of bronze and iron came to define the eras that ensued. In modern times, we take for granted a plentiful supply of metals, plastics, dyestuffs and medicines. We have come to depend on the chemical industry to provide us with all the materials we need for our "materialist" society. But the supply of these materials is not infinite. As the human population grows, and demands an ever higher standard of living, the consumption of the Earth's materials is in danger of getting out of control. It is therefore essential that chemists become responsible stewards of the raw materials that remain. We need to develop methods for chemical processing that are both chemically and environmentally efficient, and which move us towards a sustainable society. We need new materials that can provide what we need without destroying the Earth. Green chemistry is designed to help us meet these needs. It aims not just to treat waste, but to avoid producing waste in the first place. Products and processes should be "benign by design," but they must also be practicable. In this lab manual, we will explore how we can this can be achieved in practice – how we can use chemistry to help solve our environmental problems. We will never be able to build a sustainable society if we don't understand the basic science of where our materials come from, and how they are produced. The goal of this manual is to provide that science, presented within the context of green chemistry. The Twelve Principles of Green Chemistry The basic principles of green chemistry were first laid out by two US chemists, Paul Anastas and John Warner, in their 1998 book, "Green Chemistry: Theory and Practice:" 1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up. 2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no

toxicity. 3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or

no toxicity to humans and the environment. 4. Use renewable feedstocks: Use raw materials and feedstocks that are renewable rather than depleting.

Renewable feedstocks are often made from agricultural products or are the wastes of other processes; depleting feedstocks are made from fossil fuels (petroleum, natural gas, or coal) or are mined.

5. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.

6. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.

7. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms.

8. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals.


9. Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible.

10. Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.

11. Analyze in real time to prevent pollution: Include in-process real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.

12. Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.

It must be recognized that these represent a target, and we will not be able to satisfy every principle immediately with every process and product. Nevertheless, if we design our chemistry with these principles in mind, we will make great strides towards achieving sustainability.

Why should you teach about functional groups in organic chemistry? Organic compounds comprise thousands of everyday substances we use, benefit from and sometimes are harmed by. Having a basic understanding of organic compounds, how they are similar to and different from each other, and how they can be formed helps us to understand how many everyday substances function. Everything from hydrocarbon fuels to plastics to pharmaceuticals are organic compounds. Using observations in a laboratory, students can practice and reinforce identification of chemical reactions. Observing similarities in reactions between different unknowns helps students be able to classify substances based on chemical reactivity. Correlation of the experiment with Green Chemistry Green Chemistry Principles: 1. Prevent waste Curriculum alignment Alignment to the NYS Regents Chemistry Curriculum: VII.3 Organic acids, alcohols, esters, aldehydes, ketones, ethers, halides, amines, amides, and amino acids are categories of organic molecules that differ in their structures. Functional groups impart distinctive physical and chemical properties to organic compounds. (3.1hh) This experiment correlates directly with the following sections of the New York State Core Curriculum: Standard 4: The Physical Setting.

Key Idea 3: Matter is made up of particles whose properties determine the observable characteristics of matter and its reactivity.

Performance Indicator 3.1 Explain the properties of materials in terms of the arrangement and properties of the atoms that compose them.

Major Understandings 3.1hh Organic acids, alcohols, esters, aldehydes, ketones, ethers, halides, amines, amides, and amino acids are categories of organic compounds that differ in their structures. Functional groups impart distinctive physical and chemical properties to organic compounds.


Background and Fundamentals for Basic Level Instruction: Introduction: Carbon is a unique element in the periodic table, since it is able to form stable bonds to itself and other non-metals. This means carbon can form an almost infinite number of chemical compounds. The different bonds carbon forms and the different elements carbon can bond to are what make various functional groups – connected groups of atoms with characteristic properties and reactivity. For example, the hydroxyl group (O-H, found in alcohols) undergoes specific reactions that distinguish it from other functional groups.

Natural chemical pathways, such as those found in the human body, often use functional groups to direct biochemical processes. Chemists also use functional groups when designing routes for producing pharmaceuticals. In such ways, syntheses can be developed that allow complex molecules to be built up selectively, forming simple drugs (which may contain a dozen carbons) and up to DNA (which contains many millions of carbon atoms).

Some of the most common functional groups can be seen in Table R of the Regents Chemistry Reference Tables (page 7):


Note that aldehydes and ketones each contain one oxygen atom, whereas organic acids (also known as carboxylic acids) and esters contain two. These functional groups appear in all manner of organic compounds, as can be seen from Figure 1:

Figure 1. Some common organic compounds and the classes to which they belong.

In this experiment, students will use characteristic reactions of the functional groups present in some organic compounds in order to identify them. They will be given an unknown substance, and carry out a series of functional group tests. Based on the results, students should be able to deduce which functional groups are present, and thereby identify the unknown. Guidance Notes: Test results Typical results are shown for all tests and all compounds. If students perform the tests correctly, some of these tests will be omitted as redundant.

Benedict’s Fe2(SO4)3

+ NaHCO3

Ninhydrin Acidified KMnO4 NaHCO3

Acetone No rxn No rxn No rxn Turned magenta and remained the same color.

No rxn

Acetic Acid

No rxn No rxn No rxn Turned purple and remained purple

Fizzing


Vanillin Turned green and then dark amber

Turned

Purple

No rxn Turned yellow initially and decolorized

No rxn

Ethanol No rxn No rxn No rxn Turned brown and decolorized mostly and

left brown ppt after heating

No rxn

Tartaric Acid

No rxn Turned yellow

No rxn Decolorized upon addition Fizzing

Salicylic Acid

Formation of a lower green layer, apparent

fizzing

Turned purple

No rxn Decolorized and left a grey ppt upon heating

Fizzing

2-Propanol No rxn No rxn No rxn Turned red-amber and a brown ppt formed upon

heating

No rxn

Glycine Turned royal blue No rxn Turned purple after ~ 25 s

Turned brown and brown ppt formed upon heating

Fizzing

Citric Acid No rxn No rxn No rxn Decolorized upon heating Fizzing

Glucose Turned yellow and then red ppt settled in a blue solution

No rxn No rxn Decolorized upon heating No rxn

Pictures of normal test results

Acetone

Vanillin

Tartaric acid

Ethanol

2-Propanol (Isopropyl alcohol)

Salicylic acid

Glycine

Citric acid

Glucose


Pictures during tests 1. Benedict’s solution This is traditionally used to detect reducing sugars. All monosaccharides and almost all disaccharides (except sucrose) will reduce copper(II) under Benedict conditions to produce a precipitate of copper(I) oxide on heating. An orange-red precipitate indicates the presence of an (aldehyde). With vanillin, the result is a very dark, amber color is observed:

Glucose gives more "standard" results: 5% Glucose solution

5% Glucose solution with Benedict’s solution Before heating After 20 s heating After 1 min heating After settling

5% Glycine solution with Benedict’s solution – a negative test, though interestingly the amino group darkens the blue color (upper tube in picture)


2. Test for amines using ninhydrin

3. Test for primary and secondary alcohols. Before heating After heating

Cleanup and disposal All contents of all test tubes (except positive potassium permanganate tests) can be washed away down the drain in a stream of running water, without further treatment. All organics used in this laboratory exercise are non-toxic and naturally occurring. The quantities of materials such as acetone and potassium permanganate are small enough that dilution prevents environmental problems. The one disposal issue involves the positive tests using potassium permanganate, where manganese(IV) oxide may be formed and adhere to the test tubes. These tubes can be washed with 3 M sulfuric acid, and this can be neutralized with 1 M sodium acetate solution before washing down the drain. It is recommended that the teacher completes this task for safety reasons.


Answers Pre-lab Questions: Using Table R of the Regents Chemistry Reference Tables to guide you, identify what class each of these compounds belongs to. Write your answer in the space below each compound.

NH2

CC

CC

CNH

2

HH

H H

HH

H H

HH

CH3

CHCH

2

CH2 O

CCH

3

CH3 O

CC

CC

O

H H H

H

H

H

H

HCH3

Br

Cadaverine - a foul-smellingcompound formed during putrefaction of animal tissue

Isoamyl acetate - a major componentof banana oil

Butanone or MEK - used as anindustrial solvent

Bromomethane - formerly usedas a pesticide

Halide Aldehyde Amine Carboxylic acid

Questions: 1. You were given an unknown compound X, and you know it is one of the example compounds shown in

Figure 1 in the lab introduction. A solution of X gave the following test results:

The solution of X fizzed when sodium bicarbonate was added. → Organic Acid

When treated with Benedict's solution, the solution remained clear and blue. → No aldehyde

When treated with acidified iron(III) sulfate, the solution turned deep blue. → Phenol

When treated with ninhydrin, the solution remained colorless. → No amine

The solution of X remained purple when acidified potassium permanganate was added.→ No alcohol What is the identity of X? Answer: Coumaric Acid

2. You work for the Colorado state crime lab, and you are investigating a possible murder. There is evidence that find that someone was poisoned; however, the area also has a large population of Colorado River Toads, which secrete a toxin called bufotenin (structure shown below). So could it just be toad poison?

In what functional group categories does bufotenin belong? Phenol and amine

If you were to test a sample of bufotenin using the same five tests you used in lab, what results would you find?

C

C

C C

NH

C

CC

C

OH

CH2

CH2

N

H

H

H

H

CH3

CH3

Bufotenin

List your predicted test results as either POSITIVE or NEGATIVE.

Organic Acid test Negative

Aldehyde test Negative

Phenol test Positive

Amine test Positive

Alcohol test Negative


Extension Activities: Use the Internet to find the chemical name and structure of each of the following common organic substances. List the chemical name, draw the structure and from the name and chemical structure, tell which Table R Class of Compound(s) it belongs to.

Common Name IUPAC Chemical Name Chemical Structure Class(es) of

Compounds (from Table R)

1. Motrin 2-[4-(2-methylpropyl) phenyl]propanoic acid

Organic acid

2. Plexiglas poly(methyl 2- methylpropenoate)

Ester

3. Albuterol

(asthma medicine inhaler)

(RS)-4-[2-(tert-butylamino)- hydroxyethyl]-2- (hydroxymethyl)phenol

Alcohol, amine

4. Vitamin C 2-Oxo-L-threo-hexono- 1,4-lactone-2,3-enediol

Alcohol

http://upload.wikimedia.org/wikipedia/commons/e/e7/L-Ascorbic_acid.svg


Background and Fundamentals for Advanced Level Instruction: The background and fundamentals of the lab are the same as in the basic level: the lab illustrates the concepts of identification of organic functional group classification of compounds based on qualitative experimental results. This lab may be useful as a brief introduction to organic functional groups if students have not completed Regents Chemistry previously, and could be used as an introductory organic lab before conducting an Organic Synthesis, Purification and Analysis lab as recommended in the AP Chemistry course description. Guidance Notes: Students must be detail-oriented and carefully label their test tubes so they know which step of the sequence they are on. Carefully following the testing sequence while paying attention to which reagents they are using should assure reliable results. Use of the flowchart may help many students to stay on track. Completing the data checklist as the experiments proceed will be very helpful in making a good conclusion. Students should be careful to note that positive tests for aldehydes and amines then instruct them to skip the alcohol test. If they do not follow this instruction, they will obtain false positive results on the alcohol test and likely misidentify their unknown.


Answers: Pre-Lab: Write the structural formula for each of the following compounds, and identify the organic functional groups that are found in the molecule. 1. Chloroethane

halide 2. 2-Pentanone

ketone 3. Methyl tert-butyl ether

ether 4. Pentanoic acid

organic acid or carboxylic acid 5. 4-bromo, 5-methyl 2-hexanone

halide, ketone

http://upload.wikimedia.org/wikipedia/commons/7/7d/Chloroethane-full.png

http://img.guidechem.com/pic/image/500733-06-2.gif




The solution of X fizzed when sodium bicarbonate was added. → Organic Acid

When treated with Benedict's solution, the solution remained clear and blue. → No aldehyde

When treated with acidified iron(III) sulfate, the solution turned deep blue. → Phenol

When treated with ninhydrin, the solution remained colorless. → No amine

The solution of X remained purple when acidified potassium permanganate was added. → No alcohol What is the identity of X? Answer: Coumaric Acid

2. You work for the Colorado state crime lab, and you are investigating a possible murder. There is evidence that find that someone was poisoned; however, the area also has a large population of Colorado River Toads, which secrete a toxin called bufotenin (structure shown below). So could it just be toad poison?

In what functional group categories does bufotenin belong? Phenol and amine


C

C

C C

NH

C

CC

C

OH

CH2

CH2

N

H

H

H

H

CH3

CH3

Bufotenin


Organic Acid test Negative

Aldehyde test Negative

Phenol test Positive

Amine test Positive

Alcohol test Negative

Extension Activities: Use the Internet to find the chemical name and structure of each of the following common organic substances. List the chemical name, draw the structure and from the name and chemical structure, tell which Class of Compound(s) it belongs to.

Common Name IUPAC Chemical Name Chemical Structure Class(es) of

Compounds

1. Motrin 2-[4-(2-methylpropyl) phenyl]propanoic acid

Organic acid


2. Plexiglas poly(methyl 2- methylpropenoate)

Ester

5. Albuterol

(asthma medicine inhaler)

(RS)-4-[2-(tert-butylamino)- hydroxyethyl]-2- (hydroxymethyl)phenol

Alcohol, amine

6. Vitamin C 2-Oxo-L-threo-hexono- 1,4-lactone-2,3-enediol

Alcohol

http://upload.wikimedia.org/wikipedia/commons/e/e7/L-Ascorbic_acid.svg

Functional Groups in Organic Chemistry, Basic Student Packet 1

Functional Groups in Organic Chemistry Laboratory Experiment # ______ Name ____________________________________ Date _______________________________ Partner ___________________________________ Introduction: Carbon is a unique element in the periodic table, since it is able to form stable bonds to itself and other non-metals; this allows it to form an almost infinite number of chemical compounds. The different bonds carbon forms, to itself as well as to elements like nitrogen or oxygen, lead to the concept of the functional group – a connected group of atoms with characteristic properties and reactivity. For example, the hydroxyl group (O-H, found in alcohols) has specific reactions that distinguish it from other functional groups. Natural systems such as the human body often use functional groups to direct biochemical processes. Chemists also use functional groups when designing routes for producing pharmaceuticals. In such ways, syntheses can be developed that allow complex molecules to be built up selectively, from drugs, which may contain a dozen carbons, right up to DNA, which contains many millions of carbon atoms. Some of the most common functional groups can be seen in Table R of the Regents Chemistry Reference Tables. Note that aldehydes and ketones contain one oxygen atom, whereas organic acids (also known as carboxylic acids) and esters contain two. These functional groups appear in all manner of organic compounds. In this experiment, you will use characteristic reactions of the functional groups present in some organic compounds in order to identify them. You will be given an unknown substance, and carry out a series of functional group tests. Based on the results, you will deduce which functional groups are present, and thereby identify your unknown.


Figure 1. Some common organic compounds and the classes to which they belong

What is Green Chemistry? The goal of green chemistry is to design chemicals and processes that reduce or eliminate negative environmental impacts. This includes products and processes that use or generate less hazardous substances, reduced waste products, less or non-toxic components, and using substances more efficiently. Green chemistry is a highly effective approach to pollution prevention because it applies innovative scientific solutions to real-world environmental situations. Green chemistry provides a number of benefits, including:

reduced waste, eliminating costly end-of-the-pipe treatments safer products reduced use of energy and resources improved competitiveness of chemical manufacturers and their customers.

There are twelve principles that green chemistry relies on that were first laid out by two US chemists, Paul Anastas and John Warner, in their 1998 book, "Green Chemistry: Theory and Practice”: 1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up. 2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no



Renewable feedstocks are often made from agricultural products or are the wastes of other processes;


depleting feedstocks are made from fossil fuels (petroleum, natural gas, or coal) or are mined. 5. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used

in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.








Why is this experiment green? This experiment is green due to the very small scale of the chemicals used, both unknowns and reagents. It is not necessary to use large volumes of chemicals to qualitatively observe reactions. Green chemistry in the laboratory setting involves using the smallest volumes of chemicals needed to obtain the desired results. In this case, each lab group uses only 5 ml of unknown and just drops of reagents to conduct multiple tests. Safety

Wear approved safety goggles and suitable clothing when working with or near all chemicals in this

experiment. As they leave the laboratory, students should wash hands well.

Some of the compounds can stain your skin or the lab bench, so take care to avoid spillage.

Most of the compounds are classed as irritants, so avoid direct contact with the skin; if exposure occurs,

wash well with water. Spills can be cleaned up by washing with a large amount of water.

Materials and Equipment Sodium bicarbonate, saturated solution (ca. 8.4% or 1.0 M) Benedict's solution (made from copper(II) sulfate, sodium citrate and sodium carbonate) Iron(III) sulfate or Iron (III)pentahydrate (0.1% in 0.1 M H2SO4) Potassium permanganate (0.1% solution in 0.1 M H2SO4) Ninhydrin in ethanol (0.1% solution)

Glassware: 5 test tubes Test tube rack Disposable pipettes A hot water bath Experiment Pre-lab:


Using Table R of the Regents Chemistry Reference Tables to guide you, identify what class each of these compounds belongs to. Write your answer in the space below each compound.

NH2

CC

CC

CNH

2

HH

H H

HH

H H

HH

CH3

CHCH

2

CH2 O

CCH

3

CH3 O

CC

CC

O

H H H

H

H

H

H

HCH3

Br

Cadaverine - a foul-smellingcompound formed during putrefaction of animal tissue

Isoamyl acetate - a major componentof banana oil

Butanone or MEK - used as anindustrial solvent

Bromomethane - formerly usedas a pesticide

Procedure: Note: It is important to carry out the tests in the order given below. You may refer to the Logic Diagram flowchart to help guide the testing.

1. Label five test tubes with your initials, the number of unknown being tested, and the test to be performed (one test in each of five test tubes). Use the following abbreviations: OA for organic acid, ALD for aldehyde, PH for phenol, AM for amine, and ALC for alcohol. Fill each test tube with approximately 1 mL of the unknown sample.

2. Test for Organic Acids (also known as carboxylic acids) Add 3-5 drops of the saturated sodium bicarbonate solution to your test tube that has your unknown and is

labeled “OA”.

A. If you observe fizzing or bubbling, you have a carboxylic acid. B. If it doesn't fizz, you do not have a carboxylic acid, or it is an amino acid such as glycine.

Record the results using the checkbox in the Data section.

3. Test for Aldehydes (Benedict's test) Add about 1 mL of Benedict’s solution to the test tube with your unknown that is labeled “ALD” and shake

thoroughly by holding the test tube at the top and flicking the bottom with the fingers of your other hand.

Heat the solution for about one minute at 95°C in a water bath.

A. If you see the formation of an orange-red precipitate, you have an aldehyde. Omit the test for alcohols (#6). B. If the solution remains blue, and you don't see an orange-red precipitate, you don't have an aldehyde.


4. Test for Phenols Add 2-3 drops of the acidified iron(III) sulfate solution to your test tube labeled “PH”.


A. If you see an intense purple or blue color, you have a phenol. B. If you see no obvious change to purple or blue color, you do not have a phenol.


5. Test for Amines Add 2-3 drops of ninhydrin solution to your test tube labeled “AM”.

A. If you see an intense purple color, you have an amine. Omit the test for alcohols (#6).

B. If you see no obvious change, you do not have an amine.


6. Test for Primary and Secondary Alcohols. If you have an aldehyde or amine, omit this test, because it will give a "false positive."

Add 1 drop of the acidified potassium permanganate to your test tube labeled “ALC”, then warm the

mixture in a hot water bath for 1-2 minutes.

A. If the purple color is removed (you may see a brown precipitate, or a colorless mixture), then

you have an alcohol.

B. If the purple color remains, then you do not have a primary or secondary alcohol.


Once you have completed these tests, you should be able to identify the unknown. Recycling and disposal: Positive result potassium permanganate test tubes should be returned to the instructor for treatment and

disposal. All other solutions from the student tests can be washed away down the sink with a large volume of

water. The testing solutions – sodium bicarbonate solution, Benedict's solution, acidified iron(III) sulfate,

ethanolic ninhydrin and acidified potassium permanganate – should be returned to the instructor for storage

and re-use.


Add NaHCO3

Fizzes => carboxylic acid (unless amino acid)

No fizzing => Not acarboxylic acid

(except amino acids)acetic acid, tartaric acid, salicylic acid

glycineglucose

2-propanolvanillinacetone

Orange red ppt => aldehyde

Benedict's test

Stays blue, no ppt=> not an aldehyde

glycine2-propanol

acetone

glucosevanillin

Phenol testPhenol test

Purple/blue=> phenol Purple/blue

=> phenol

No change=> not phenol No change

=> not phenolvanillin glucose

Amine test

Should give no changeIf intense purple, you

made a mistake earlier!

Amine test

Intense purple=> amine

No major change=> not an amine

Glycine2-propanolacetone

Alcohol test

No change=> NOT a primary or

sec. alcohol

End of tests

Purple coloris discharged=> primary orsec. alcohol

2-propanol

acetone

End of tests

End of tests

Phenol test

Purple/blue=> phenol

No change=> not phenol

salicylic acid tartaric or acetic acid

Remainingtests confirm

Benedict's test- no change?

Amine test- no change?

Alcohol test

No change=> NOT a primary or

sec. alcohol

Purple coloris discharged=> primary orsec. alcohol

End of tests

End of testsTartaric acid

Acetic acid

LOGIC DIAGRAM FORFUNCTIONAL GROUPEXPERIMENT


Data: Each unknown will give a characteristic set of test results, different from every other unknown, as can be seen from the logic diagram above. Keep track of your results below, by checking in the appropriate boxes.

Test for . . . Positive Negative

Organic acids (also known as carboxylic

acids)

positive = fizzing or bubbling

acetic acid, tartaric

acid, salicylic acid

glycine, glucose, 2-

propanol, acetone,

vanillin

Aldehydes

positive = orange-red solid forms glucose, vanillin

glycine, acetone, 2-

propanol, acetic acid,

tartaric acid, salicylic

acid

Phenols

positive = blue or purple color salicylic acid, vanillin

glycine, glucose,

acetone, 2-propanol,

acetic acid, tartaric acid

Amines

positive = purple color glycine

glucose, acetone, 2-

propanol, acetic acid,

tartaric acid, salicylic

acid

Primary and Secondary Alcohols

positive = purple solution turns colorless or

forms a brown solid

2-propanol, glucose,

tartaric acid

acetone, acetic acid,

salicylic acid

Note: Vanillin and glycine will also give a "positive" alcohol test because of the aldehyde or the amino group.

Conclusions: Review the test results, and deduce the identity of your unknown.

My unknown is therefore ___________________________




The solution of X fizzed when sodium bicarbonate was added.

When treated with Benedict's solution, the solution remained clear and blue.

When treated with acidified iron(III) sulfate, the solution turned deep blue.

When treated with ninhydrin, the solution remained colorless.

The solution of X remained purple when acidified potassium permanganate was added.

What is the identity of X?

2. You work for the Colorado state crime lab, and you are investigating a possible murder. There is evidence

that find that someone was poisoned; however, the area also has a large population of Colorado River Toads, which secrete a toxin called bufotenin (structure shown below). So could it just be toad poison?

In what functional group categories does bufotenin belong?


C

C

C C

NH

C

CC

C

OH

CH2

CH2

N

H

H

H

H

CH3

CH3

Bufotenin


Organic Acid test _________

Aldehyde test _________

Phenol test _________

Amine test ________

Alcohol test _________


Extension Activities: Use the Internet to find the chemical name and structure of each of the following common organic substances. List the chemical name, draw the structure and from the chemical structure, tell which Table R Class of Compound(s) it belongs to. Common Name IUPAC Chemical Name Chemical Structure Class(es) of Compounds

(from Table R)

1. Motrin

2. Plexiglas

3. Albuterol (asthma

medicine inhaler)

4. Vitamin C

Functional Groups in Organic Chemistry, Advanced Student Packet 11

Functional Groups in Organic Chemistry Laboratory Experiment # ______ Name ____________________________________ Date _______________________________ Partner ___________________________________ Carbon is a unique element in the periodic table, since it is able to form stable bonds to itself and other non-metals; this allows it to form an almost infinite number of chemical compounds. The different bonds carbon forms, to itself as well as to elements like nitrogen or oxygen, lead to the concept of the functional group – a connected group of atoms with characteristic properties and reactivity. For example, the hydroxyl group (O-H, found in alcohols) has specific reactions that distinguish it from other functional groups. Natural systems such as the human body often use functional groups to direct biochemical processes. Chemists also use functional groups when designing routes for producing pharmaceuticals. In such ways, syntheses can be developed that allow complex molecules to be built up selectively, from drugs, which may contain a dozen carbons, right up to DNA, which contains many millions of carbon atoms. Some of the most common functional groups can be seen in Table R of the Regents Chemistry Reference Tables. Note that aldehydes and ketones contain one oxygen atom, whereas organic acids (also known as carboxylic acids) and esters contain two. These functional groups appear in all manner of organic compounds. In this experiment, you will use characteristic reactions of the functional groups present in some organic compounds in order to identify them. You will be given an unknown substance, and carry out a series of functional group tests. Based on the results, you will deduce which functional groups are present, and thereby identify your unknown.


Figure 1. Some common organic compounds and the classes to which they belong

What is Green Chemistry? The goal of green chemistry is to design chemicals and processes that reduce or eliminate negative environmental impacts. This includes products and processes that use or generate less hazardous substances, reduced waste products, less or non-toxic components, and using substances more efficiently. Green chemistry is a highly effective approach to pollution prevention because it applies innovative scientific solutions to real-world environmental situations. Green chemistry provides a number of benefits, including:

reduced waste, eliminating costly end-of-the-pipe treatments safer products reduced use of energy and resources improved competitiveness of chemical manufacturers and their customers.

There are twelve principles that green chemistry relies on that were first laid out by two US chemists, Paul Anastas and John Warner, in their 1998 book, "Green Chemistry: Theory and Practice”: 1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up. 2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no



Renewable feedstocks are often made from agricultural products or are the wastes of other processes; depleting feedstocks are made from fossil fuels (petroleum, natural gas, or coal) or are mined.

5. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used


in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.








Why is this experiment green? This experiment is green due to the very small scale of the chemicals used, both unknowns and reagents. It is not necessary to use large volumes of chemicals to qualitatively observe reactions. Green chemistry in the laboratory setting involves using the smallest volumes of chemicals needed to obtain the desired results. In this case, each lab group uses only 5 ml of unknown and just drops of reagents to conduct multiple tests. Safety

Wear approved safety goggles and suitable clothing when working with or near all chemicals in this experiment. As they leave the laboratory, students should wash hands well.

Some of the compounds can stain your skin or the lab bench, so take care to avoid spillage.

Most of the compounds are classed as irritants, so avoid direct contact with the skin; if exposure occurs, wash well with water. Spills can be cleaned up by washing with a large amount of water.

Materials and Equipment Sodium bicarbonate, saturated solution (ca. 8.4% or 1.0 M) Benedict's solution (made from copper(II) sulfate, sodium citrate and sodium carbonate) Iron(III) sulfate or Iron (III)pentahydrate (0.1% in 0.1 M H2SO4) Potassium permanganate (0.1% solution in 0.1 M H2SO4) Ninhydrin in ethanol (0.1% solution)

Glassware: 5 test tubes, test tube rack, disposable pipettes, a hot water bath Experiment Pre-lab: Write the structural formula for each of the following compounds, and identify the organic functional groups that are found in the molecule. 1. Chloroethane

2. 2-Pentanone

3. Methyl tert-butyl ether

4. Pentanoic acid

5. 4-bromo, 5-methyl 2-hexanone


Procedure: Complete the following procedure for each unknown you are assigned. 1. Label five test tubes with your initials, the number of unknown being tested, and the test to be performed

(one test in each of five test tubes). Use the following abbreviations: OA for organic acid, ALD for aldehyde, PH for phenol, AM for amine, and ALC for alcohol. Fill each test tube with approximately 1 mL of the unknown sample.

2. Test for Organic Acids (also known as carboxylic acids) Add 3-5 drops of the saturated sodium bicarbonate solution to the test tube of unknown labeled “OA”.

A. Fizzing or bubbling indicates a carboxylic acid. B. Absence of fizz indicates it is not a carboxylic acid, or it is an amino acid such as glycine.

3. Test for Aldehydes (Benedict's test) Add about 1 mL of Benedict’s solution to the test tube of unknown labeled “ALD” and shake thoroughly by

holding the test tube at the top and flicking the bottom with the fingers of your other hand. Heat the

solution for about one minute at 95°C in a water bath.

A. Formation of an orange-red precipitate indicates an aldehyde. Omit the test for alcohols (#6). B. The solution remaining blue with no orange-red precipitate indicates it is not an aldehyde.

4. Test for Phenols Add 2-3 drops of the acidified iron(III) sulfate solution to your test tube labeled “PH”.

A. An intense purple or blue color indicates a phenol. B. If there is no obvious change to purple or blue color, it is not a phenol.

5. Test for Amines Add 2-3 drops of ninhydrin solution to the unknown test tube labeled “AM”.

A. An intense purple color indicates an amine. Omit the test for alcohols (#6).

B. If there is no obvious change, the sample is not an amine.


6. Test for Primary and Secondary Alcohols. Add 1 drop of the acidified potassium permanganate to the unknown test tube labeled “ALC”, then warm

the mixture in a hot water bath for 1-2 minutes.

A. Discharge of the purple color (you may see a brown precipitate, or a colorless mixture),

indicates an alcohol.

B. If the purple color remains, the sample is not a primary or secondary alcohol.

Recycling and disposal: Positive result potassium permanganate test tubes should be returned to the instructor for treatment and

disposal. All other solutions from the student tests can be washed away down the sink with a large volume of

water. The testing solutions – sodium bicarbonate solution, Benedict's solution, acidified iron(III) sulfate,

ethanolic ninhydrin and acidified potassium permanganate – should be returned to the instructor for storage

and re-use.

Conclusions: Use the following data table to determine the identity of your unknown samples.

Test for . . . Positive Negative

Organic acids (also known as

carboxylic acids)

acetic acid, tartaric acid,

salicylic acid

glycine, glucose, 2-propanol, acetone,

vanillin

Aldehydes glucose, vanillin glycine, acetone, 2-propanol, acetic acid,

tartaric acid, salicylic acid

Phenols salicylic acid, vanillin glycine, glucose, acetone, 2-propanol,

acetic acid, tartaric acid

Amines glycine glucose, acetone, 2-propanol, acetic acid,

tartaric acid, salicylic acid

Primary and Secondary

Alcohols

2-propanol, glucose, tartaric

acid acetone, acetic acid, salicylic acid

Report: The lab report should consist of an introduction, answers to pre-lab questions, brief description of procedures, a flow chart depicting the sequence of tests and all possible outcomes, a data table showing your specific results for each unknown and a conclusion. Be sure to include answers to the Questions and the Extension activities.




The solution of X fizzed when sodium bicarbonate was added.

When treated with Benedict's solution, the solution remained clear and blue.

When treated with acidified iron(III) sulfate, the solution turned deep blue.

When treated with ninhydrin, the solution remained colorless.

The solution of X remained purple when acidified potassium permanganate was added.

What is the identity of X?

2. You work for the Colorado state crime lab, and you are investigating a possible murder. There is evidence

that find that someone was poisoned; however, the area also has a large population of Colorado River Toads, which secrete a toxin called bufotenin (structure shown below). So could it just be toad poison?

In what functional group categories does bufotenin belong?


C

C

C C

NH

C

CC

C

OH

CH2

CH2

N

H

H

H

H

CH3

CH3

Bufotenin


Organic Acid test ________________

Aldehyde test ________________

Phenol test ________________

Amine test ________________

Alcohol test ________________


Extension Activities: Use the Internet to find the chemical name and structure of each of the following common organic substances. List the chemical name, draw the structure and from the chemical structure, tell which Class of Compound(s) it belongs to.

Common Name IUPAC Chemical Name Chemical Structure Class(es) of Compounds

1. Motrin

2. Plexiglas

3. Albuterol (asthma

medicine inhaler)

4. Vitamin C

functional groups in organic chemistry · functional groups in organic hemistry, teacher’s guide...

Documents