Fischer Speier Esteriterification

Kemian opetuksen keskeiset alueet II, spring 2012

Christian Franklin and Joonas Hippeläinen

11 April 2012

Lesson plan for teaching the Fischer–Speieresterification using the historical approach

Contents1 Time requirements 2

2 Teaching purpose 2

3 Epistemological issues 2

4 Lessons 3

4.1 Lesson 1 3

4.1.1 Part 1: Theory and history (35 minutes) 3

4.1.2 Part 2: Designing the practical experiments (30–40 minutes) 9

4.2 Lesson 2 9

4.2.1 Part 1: Quick review of the first lesson (5 minutes) 9

4.2.2 Part 2: Explaining the practical part, special focus on safety (5 minutes) 9

4.2.3 Part 3: Practical experiments (55 minutes) 10

4.2.4 Part 4: Review (10 minutes) 11

5 References 12

6 Links 13

A Appendices 14

A.1 Appendix 1: Experiment instructions 14

A.2 Appendix 2: Product information given to students to design their synthesis 31

1

1 Time requirements

This plan is for two 75-minute lessons. The first lesson will probably not take a total of 75

minutes. Instead, 5 to 10 minutes at the beginning can be used to check the homework from

the previous lesson. The timing of the practical could be varied according to need by excluding

some of the design phases and experiments.

2 Teaching purpose

• To teach an important reaction of organic chemistry synthesis within a historical context.

• To show how science is a cumulative group endeavour.

• To review the esterification mechanism, and provide the students with an opportunity to

try out several esterifications.

3 Epistemological issues

• Scientific knowledge development as a process.

• Science within a community of researchers.

• Scientific approach in organic synthesis.

2

4 Lessons

4.1 Lesson 1

4.1.1 Part 1: Theory and history (35 minutes)

Introduction

• Ask students to discuss what they know about esters. List the points. This helps the

students link the lesson to their previous knowledge.

• Ask students to describe how they think science develops to make their preconceptions

clear.

• History section: organic synthesis as a developmental process. Show Prezi (section 6)

which sketches development. Point out the links and influences. Then go through indi-

vidual scientists and their work.

• Fischer’s life story to link history to esterification (using Prezi).

• Theory about esters: properties and esterification + mechanism (using Prezi).

Organic chemistry and synthesis history

The term ‘organic chemistry’ was first used by Berzelius in 1806. In its early days organic

chemistry was concerned with the isolation and purification of organic products, notably that

of ethanol distilled in Europe as early as the 12th century. Berzelius mentored Friedrich Wöhler

(Wikipedia, 2001a), who through an act of serendipity in 1828 synthesised urea while attempt-

ing to prepare ammonium cyanate from silver cyanate and ammonium chloride. Famously,

this is often given as the experiment that heralded the death of vitalism in chemistry, even

though Wöhler himself made no such claim. In any case, the cat was now out of the box and it

was apparent that organic compounds could be synthesised, from inorganic sources if need be.

(Hudson, 1992, pp. 104–105)

In 1860 Berthelot first used the word ‘synthesis’ and wrote a book on synthetic organic chem-

istry, which collected the means by which many compounds could be generated from their

elements. The field of organic synthesis grew, and in 1877 the Friedel–Crafts reaction was dis-

covered whereby, in the presence of an aluminium chlorine catalyst, acyl or alkyl groups could

be added onto a benzene ring. (Hudson, 1992, p. 143)

Wöhler worked with Justus von Liebig, who was also involved in studying organic chemistry

(Wikipedia, 2001a) and developed the law of the minimum, an idea similar in principle to that

of limiting reagents. He also discovered nitrogen’s role as a fertiliser. The vapour condensation

device he popularised for his research is still known as a Liebig condenser (Wikipedia, 2001b).

3

In turn von Liebig had a major influence via his lectures on two other organic chemists, Emil

Erlenmeyer and August Kekulé. Erlenmeyer worked with alcohols and ketones as well as the

hydrolysis of ether to alcohol (Wikipedia, 2004a). Kekulé found out that tetravalent carbons

could link together. His most famous work was on the structure of benzene. In 1865 Kekulé

published a paper suggesting that the structure contained a six-membered ring of carbon atoms

with alternating single and double bonds (Wikipedia, 2002a). Robert Bunsen, the developer of

the Bunsen burner, was also influenced by von Liebig (Wikipedia, 2001c) and shared a doctoral

student with Kekulé called Baeyer who was involved in the synthesis of plant dyes. Baeyer in

turn had an assistant and doctoral student called Emil Fischer (Wikipedia, 2004b).

Emil Fischer was influential in organic synthesis during this period. In addition to working

on purines and proteins, he synthesised glucose from glycerol in 1890, producing a synthe-

sis that involved isomerism. Fischer also worked on synthesis reactions to extend the carbon

chains of sugars (Hudson, 1992, p. 153) as well as the synthesis of caffeine (Wikipedia, 2004c).

Hermann Emil Fischer (1852–1919)

Fischer was always academically gifted, although his destiny was not always apparent to his

parents who tried to get him to join the family timber firm, calling him stupid when he failed

in the business. Fischer initially studied physics at the University of Bonn and was awarded his

doctorate from the University of Strasbourg, in time becoming a professor of chemistry. For his

work in organic chemistry Emil Fischer was awarded the Nobel Prize in chemistry. (Hudson,

1992, p. 153) Fischer was active during World War I and organised chemical production for the

Germans. Sadly he lost two of his sons in the war and was struck by depression, and unfortu-

nately he also contracted cancer, possibly from the toxic effects of chemicals used during his

work. He ended up committing suicide. (McMurry, 2007, p. 795)

Emil Fischer and Arthur Speier first wrote about a new type of esterification reaction in 1895.

This was later named after them as the Fischer–Speier esterification. Their first esterifications

were carried out with methanol and ethanol in the presence of sulphuric acid or hydrochloric

acid. (Fischer and Speier, 1895) Fischer also developed a method for modelling carbohydrate

stereochemistry, which represented multiple chirality centers by projecting them onto a flat

surface. This process allowed for clearer identification of sugars, and carbohydrates modelled

in this fashion are called Fischer projections. (McMurry, 2007, pp. 975–978) Some Fischer

projections can be seen in Figure 4.1.

4

Figure 4.1: Fischer projections of D-glucose. A is the conventional Fischer projection, B is a

‘line structure’ variation without hydrogens and carbons, and C is the ‘zigzag’ style. (UC Davis

University of California)

Organic synthesis is concerned with the construction of organic compounds via organic reac-

tions. Robert Burns Woodward is regarded as the father of modern organic synthesis. He re-

ceived the 1965 Nobel Prize for Chemistry for a number of total syntheses. His 1954 synthesis

of strychnine (Figure 4.2), for example, had 29 steps in it. (Wikipedia, 2003b)

Figure 4.2: Woodward’s 1954 synthesis of strychnine. (Synarchive)

5

Woodward was an excellent student and went to Massachusetts Institute of Technology (MIT)

when he was sixteen years old. He did his PhD when he was twenty and spent the rest of his

academic life at Harvard, where he realised the power of spectroscopy. He solved many differ-

ent structures using UV-absorption spectra. These included alpha and beta unsaturated ketones

as well as the structures of penicillin and strychnine. He also completed syntheses of quinine,

cholesterol, chlorophyll and vitamin B12, and developed many new reactions and techniques

that are still used today. Impressively, his synthesis of vitamin B12 (C63H90CoN14O14P) was

carried out in partnership by teams in Harvard and Zürich, needing 100 chemists and taking 11

years. (Hudson, 1992. p. 156)

The design aspect is an important part of organic synthesis. When designing a synthesis, one

has to consider issues such as the price of the chemicals, toxicity of the chemicals and pro-

cesses, amount of waste, time, equipment and yield. Later on strychnine was synthesised in

only 11 steps. The modern way to do synthesis design is through retrosynthetic analysis, for

which Elias James Corey won the Nobel Prize in Chemistry in 1990. The idea of retrosynthetic

analysis is to start the planning going backwards from the product to the reagents. (Wikipedia,

2005)

Esters: properties, esterification, mechanism

Esters are chemical compounds that are usually organic and most commonly formed by con-

densing an acid with an alcohol. The functional group of an ester is R-COO-R. Esters are

found everywhere. Most naturally occurring fats and oils are butyric acid esters of glycerol. Es-

ters with a low molecular weight are commonly used as fragrances and found in fruits, essential

oils and pheromones. (Wikipedia, 2001d) Aspirin, or acetylsalicylic acid, is an example of a

generally known ester. It was first made in 1853. Aspirin is not the most typical ester, however,

since it is made starting from an acid and an acid anhydride. Another commonly used ester is

ethyl acetate, which is found in glues, nail polish removers and cigarettes.

Figure 4.3: Aspirin synthesis. (California State University, Stanislaus)

6

The Fischer–Speier esterification is an organic reaction. It is carried out by refluxing an alco-

hol and a carboxylic acid in the presence of an acid catalyst. The alcohol used in this reaction

can be primary or secondary, as usually tertiary alcohols are prone to elimination and phenols

are too unreactive. Typical reaction times vary from 1 to 10 hours at temperatures of 60–110◦C. (Wikipedia, 2004d) Some of the commonly used acid catalysts are sulphuric acid and hy-

drochloric acid (McMurry, 2007, p. 796).

A nucleophile is a species that donates an electron pair to an electrophile to form a chemical

bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles.

(Wikipedia, 2002b) An electrophile (literally ‘electron-lover’, which can be used as a way

to memorise which way these work) is a reagent attracted to electrons that participates in a

chemical reaction by accepting an electron pair in order to bond to a nucleophile. (Wikipedia,

2004e)

The reaction is a nucleophilic acyl substitution, which is based on the electrophilicity of the

carbonyl carbon and the nucleophilicity of the alcohol. Direct acylations of alcohols with car-

boxylic acids are preferred over acylations with anhydrides and acid chlorides, which have poor

atom economy and are moisture sensitive respectively. (Wikipedia, 2004d)

In general carboxylic acids will not undergo the nucleophilic addition found in the first part of

the reaction due to low reactivity. In the presence of a strong acid, however, the reactivity is

increased. The reaction mechanism (Figure 4.4) begins when the acid catalyst protonates the

carbonyl group’s oxygen, which increases the electrophility of the carbonyl carbon. There are

three resonance structures at this point. (McMurry, 2007, pp. 795–796) The resonance struc-

tures are a way of describing delocalised electrons, which are not associated with a single atom

or one covalent bond (Wikipedia, 2003a). The middle one is the closest to ‘real life’ because the

positive charge is on the carbon atom. The carbonyl carbon is then attacked by the nucleophilic

oxygen atom of the alcohol. Next, another proton transfers from the oxonium ion to the alcohol,

giving an activated complex. The hydroxyl of the activated complex is then protonated, which

leads to a second oxonium ion. This oxonium ion is then eliminated as water and, lastly, after a

deprotonation, the acid catalyst is regenerated and the ester product is ready. (McMurry, 2007,

pp. 795–796)

7

Figure 4.4: Reaction mechanism of the Fischer–Speier esterification.

8

4.1.2 Part 2: Designing the practical experiments (30–40 minutes)

First, students should be divided into groups of three and told they will be designing the ester

synthesis in groups.

• Give the groups the chemical formula of the first ester product: methyl salicylate.

• They need to work out what reagents are required to produce the ester.

• They need to draw the structures of the product (first one is already drawn) and the

reagents that are required and name them.

• Once they think they have the answer ready, they should show it to you to confirm

whether it is correct or not. If it is not, give them additional instructions about what

went wrong. They should then try to correct it.

• Once they have the correct answer, give them the next ester product information sheet

(Appendix A.2) for them to design that one too. All groups can make as many designs as

they have time for, ideally all seven.

4.2 Lesson 2

4.2.1 Part 1: Quick review of the first lesson (5 minutes)

History, theory, designing the experiments.

4.2.2 Part 2: Explaining the practical part, special focus on safety (5 minutes)

• Explain how the experiments work and what the students need to do.

• Clarify safety issues: Lab coats, goggles and rubber gloves are to be used at all times.

Everything must be done in the fume hoods, except when the students try to establish

the ester fragrances at the end. Extreme caution is needed when handling concentrated

sulphuric acid, and some of the other chemicals are dangerous too. Some (butyric acid,

acetic acid) will also smell very bad and must never be handled outside of a fume hood.

Additionally, point out that methanol is also dangerous and must not be inhaled.

• Give the general instructions (first two pages of Appendix A.1) and tell the students that

they should read through them.

• Tell the students to put on their safety gear.

9

4.2.3 Part 3: Practical experiments (55 minutes)

• Divide the students into their previous groups of three.

• Give the groups the first synthesis instructions (pages 3 and 4 of Appendix A.1)

• Tell the groups to put around 4 cm water in a beaker and heat it until it boils.

• During the first three-minute heating period, encourage them to study the reaction mech-

anism, which is found on the back of the instructions.

• Once the heating is completed and distilled water added, tell the students to try and

identify the fragrance of the ester. The first one is oil of wintergreen, which will be

difficult to specifically identify.

• After all the groups have finished the first esterification, give them brief practical infor-

mation about oil of wintergreen.

Oil of wintergreen is naturally produced by many species of plants. Some of the plants which

produce it are called wintergreens (Figure 4.5), hence the common name. Methyl salicylate

may also be used by plants as a pheromone to warn other plants of pathogens as in the case

of the tobacco mosaic virus. It is also used as a mint flavour in some kinds of chewing gum

and candy as an alternative to the more common peppermint and spearmint oils as well as a

flavouring in root beer. (Wikipedia, 2004f)

Figure 4.5: Wintergreen plants (Gaultheria procumbens). (Wikipedia, 2004f)

It is probably worth mentioning to the students that the rest of the fragrances are easier to

recognise.

10

• After the groups have done their first experiment, give the instructions (found in Ap-

pendix A.1) for one of the other esters they designed and tell them to synthesise it.

• During the heating periods, instruct them to practise the reaction mechanism by filling

out incomplete reaction mechanisms found on the back of the instruction sheet.

• Once they have heated the mixture for 3 minutes and added water, they will have the

product ready.

• All the ester products apart from the first one have distinct identifiable fragrances, which

the students should be able to identify by smelling them, and their goal is to do so.

• Groups should do as many esterifications as they can within the time reserved for the

experimental part.

• At the end students should dispose of the waste safely and clean the lab equipment they

used. Some of the esters formed in the experiments are waxy and difficult to clean. It is

a good idea to use plastic test tubes and throw them away afterwards. If plastic test tubes

are used, take extra care when heating them in the water bath. If these test tubes come

into contact with the floor of the beaker they might melt. This problem can be solved by

balancing the test tubes in the water bath using, for example, wooden test tube holders.

• In the end each group should have synthesised 2–7 products. If some groups have not

had time to do all of them, those groups can try to identify the fragrances of the products

other groups have made. This way all the groups would get to sample a fragrance of all

the different products that were made during the lesson and can express their opinions.

• Lead a discussion to see what fragrances they came up with and discuss the correct an-

swers. Relate this back to the product names, structures and starting chemicals (Appendix

A.1: Table A.1).

4.2.4 Part 4: Review (10 minutes)

• Discuss the students’ previous knowledge and have them think about what they have

learned. Refer to the list about esters that the students made at the start of the first lesson.

Students can review their knowledge and think about their learning gains.

• Go through the mechanism again. Finish by asking the students about the esterification

reaction in the context of Fischer and the scientific community. This could be parallelled

with their own experience in the lab working as a team. After the students have reflected

upon their experiences, they should fill in the questionnaire.

11

5 References

Athabasca University. Fischer Esterification: An ester from a carboxylic acid and an alcohol.http://science.pc.athabascau.ca/chem360.nsf/f8ba9a4e31825f6f87256b6700619e85/

$FILE/360Exp10-02.doc, accessed 13.2.2012.

California State University, Stanislaus. The Synthesis and Characterization of Aspirin.

http://science.csustan.edu/stone/2090/The%20Synthesis%20and%

20Characterization%20of%20Aspirin.htm, accessed 13.2.2012.

Hudson, J. The history of chemistry, 1st edition, Macmillan, England, 1992, pp. 104, 105, 143,

153, and 156.

Johnson, K. Synthesis of Fragrant Esters. http://faculty.eicc.edu/kjohnson/labbook/

physicalscience/esters.pdf, accessed 13.2.2012.

McMurry, J.E. Organic Chemistry. 7th ed. Brooks Cole, 2007, pp. 795–796, 807 and 975–978.

Self determination theory. Intrinsic Motivation Inventory (IMI).

http://www.selfdeterminationtheory.org/questionnaires/10-questionnaires/

50, accessed 9.4.2012.

Synarchive. Synthesis of Strychnine by Robert B. Woodward in 1954. http://www.

synarchive.com/syn/10, accessed 4.3.2012.

UC Davis University of California. Fischer and Haworth projections.

http://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_

a_Biological_Emphasis/Chapter__3%3A_Conformations_and_Stereochemistry/

Section_3.8%3A_Fischer_and_Haworth_projections, accessed 13.2.2012.

Wikipedia. Adolf von Baeyer, 2004b. http://en.wikipedia.org/wiki/Adolf_von_

Baeyer, modified 22.2.2012, accessed 11.3.2012.

Wikipedia. Electrophile, 2004e. http://en.wikipedia.org/wiki/Electrophile, modified

31.1.2012, accessed 4.3.2012.

Wikipedia. Emil Erlenmeyer, 2004a. http://en.wikipedia.org/wiki/Emil_Erlenmeyer,

modified 17.12.2011, accessed 11.3.2012.

Wikipedia. Ester, 2001d. http://en.wikipedia.org/wiki/Ester, modified 2.3.2012, ac-

cessed 4.3.2012.

12

http://science.pc.athabascau.ca/chem360.nsf/f8ba9a4e31825f6f87256b6700619e85/$FILE/360Exp10-02.doc

http://science.pc.athabascau.ca/chem360.nsf/f8ba9a4e31825f6f87256b6700619e85/$FILE/360Exp10-02.doc

http://science.csustan.edu/stone/2090/The%20Synthesis%20and%20Characterization%20of%20Aspirin.htm

http://science.csustan.edu/stone/2090/The%20Synthesis%20and%20Characterization%20of%20Aspirin.htm

http://faculty.eicc.edu/kjohnson/labbook/physicalscience/esters.pdf

http://faculty.eicc.edu/kjohnson/labbook/physicalscience/esters.pdf

http://www.selfdeterminationtheory.org/questionnaires/10-questionnaires/50

http://www.selfdeterminationtheory.org/questionnaires/10-questionnaires/50

http://www.synarchive.com/syn/10

http://www.synarchive.com/syn/10

http://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_a_Biological_Emphasis/ Chapter__3%3A_Conformations_and_Stereochemistry/Section_3.8%3A_Fischer_and_Haworth_projections



http://en.wikipedia.org/wiki/Adolf_von_Baeyer

http://en.wikipedia.org/wiki/Adolf_von_Baeyer

http://en.wikipedia.org/wiki/Electrophile

http://en.wikipedia.org/wiki/Emil_Erlenmeyer

http://en.wikipedia.org/wiki/Ester

Wikipedia, Fischer–Speier esterification, 2004d. http://en.wikipedia.org/wiki/

Fischer%E2%80%93Speier_esterification, modified 22.1.2012, accessed 13.2.2012.

Wikipedia. August Kekulé, 2002a. http://en.wikipedia.org/wiki/Friedrich_August_

Kekul%C3%A9_von_Stradonitz, modified 14.3.2012, accessed 18.3.2012.

Wikipedia. Friedrich Wöhler, 2001a. http://en.wikipedia.org/wiki/Friedrich_W%C3%

B6hler, modified 10.3.2012, accessed 11.3.2012.

Wikipedia. Emil Fischer, 2004c. http://en.wikipedia.org/wiki/Hermann_Emil_

Fischer, modified 8.3.2012, accessed 18.3.2012.

Wikipedia. Justus von Liebig, 2001b. http://en.wikipedia.org/wiki/Justus_von_

Liebig, modified 13.3.2012, accessed 18.3.2012.

Wikipedia. Methyl Salicylate, 2004f. http://en.wikipedia.org/wiki/Methyl_

salicylate, modified 3.3.2012, accessed 4.3.2012.

Wikipedia. Nucleophile, 2002b. http://en.wikipedia.org/wiki/Nucleophile, modified

23.1.2012, accessed 4.3.2012.

Wikipedia. Organic synthesis, 2005. http://en.wikipedia.org/wiki/Organic_

synthesis, modified 6.2.2012, accessed 4.3.2012.

Wikipedia. Resonance (chemistry), 2003a. http://en.wikipedia.org/wiki/Resonance_

%28chemistry%29, modified 30.12.2011, accessed 4.3.2012.

Wikipedia. Robert Bunsen, 2001c. http://en.wikipedia.org/wiki/Robert_Bunsen, mod-

ified 8.3.2012, accessed 11.3.2012.

Wikipedia. Robert Burns Woodward, 2003b. http://en.wikipedia.org/wiki/Robert_

Burns_Woodward, modified 9.2.3012, accessed 4.3.2012.

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6 Links

Link 1: Prezi

http://prezi.com/-t4lo4-4-aqt/copy-of-org-synth/

13

http://en.wikipedia.org/wiki/Fischer%E2%80%93Speier_esterification

http://en.wikipedia.org/wiki/Fischer%E2%80%93Speier_esterification

http://en.wikipedia.org/wiki/Friedrich_August_Kekul%C3%A9_von_Stradonitz

http://en.wikipedia.org/wiki/Friedrich_August_Kekul%C3%A9_von_Stradonitz

http://en.wikipedia.org/wiki/Friedrich_W%C3%B6hler

http://en.wikipedia.org/wiki/Friedrich_W%C3%B6hler

http://en.wikipedia.org/wiki/Hermann_Emil_Fischer

http://en.wikipedia.org/wiki/Hermann_Emil_Fischer

http://en.wikipedia.org/wiki/Justus_von_Liebig

http://en.wikipedia.org/wiki/Justus_von_Liebig

http://en.wikipedia.org/wiki/Methyl_salicylate

http://en.wikipedia.org/wiki/Methyl_salicylate

http://en.wikipedia.org/wiki/Nucleophile

http://en.wikipedia.org/wiki/Organic_synthesis

http://en.wikipedia.org/wiki/Organic_synthesis

http://en.wikipedia.org/wiki/Resonance_%28chemistry%29

http://en.wikipedia.org/wiki/Resonance_%28chemistry%29

http://en.wikipedia.org/wiki/Robert_Bunsen

http://en.wikipedia.org/wiki/Robert_Burns_Woodward

http://en.wikipedia.org/wiki/Robert_Burns_Woodward

http://prezi.com/-t4lo4-4-aqt/copy-of-org-synth/

A Appendices

A.1 Appendix 1: Experiment instructions

Synthesis of fragrant esters

using the Fischer–Speier esterification:

An ester from a carboxylic acid and an alcohol

with the help of an acid catalyst

Introduction

An ester is an organic compound that is formed when a carboxylic acid reacts with an alcohol

yielding water as a byproduct. The purpose of this experiment is to provide a practical example

of the synthesis of an ester using the acid catalysed using the Fischer–Speier esterification

method.

We are not going to use the exact method of the Fischer–Speier esterification as it would require

refluxing and purification and we do not have enough time for those. Instead, we will do a

simplified version.

Esters formed from carboxylic acids and alcohols often have fruity scents or flavours. These

synthetic esters produced in the laboratory are very similar to - or even the same as - the

molecules that give fruits their characteristic flavours. In this experiment you will first pro-

duce the esters and then try to identify their fragrances.

Safety

You will be using concentrated sulfuric acid (H2SO4) as a catalyst. Sulfuric acid is very dan-

gerous and can cause severe chemical burns when in contact with all human tissues.

• Make sure you take extreme care when working with sulfuric acid. Some other dangerous

chemicals will also be used.

• You must wear lab coats, safety goggles and rubber gloves at all times.

• You must carry out the experiments in the fume hoods.

14

Experimental method

We will be using water baths for heating the experimental mixture.

• Set up the water bath by measuring about 4 cm of hot water into a beaker and heating it

until it boils. Add water later if there is not enough.

• Your group should do as many different syntheses as you can within the time reserved

for the experiment.

Every synthesis will begin with the design. You were given some information about the product

and you worked out the name of the ester and the chemicals that were needed to form the prod-

uct during your previous session. Now you can use your designs and make the products. You

will be given the instructions for the experiments one at a time, starting with methyl salicylate.

15

1. Methyl salicylate

SAFETY ALERT: Remember to use concentrated sulfuric acid with extreme care. Make sure

it does not come into contact with your skin as it will vigorously attack tissue. If you get any

on your skin, immediately wash it off with plenty of cool water and tell the teacher.

1. Place 0.2 grams of salicylic acid into a clean, dry test tube.

2. Add 6 drops of methanol and agitate the tube until the contents are well mixed.

3. Then add 1 drop of concentrated sulfuric acid.

4. Agitate the tube contents and place the tube in a beaker of boiling water for 3 minutes.

5. After heating is complete, remove the tube from the bath and add 15 drops of distilled water

to the tube contents.

6. Cautiously note the fragrance of the products in the test tube by wafting the scent to your

nose. Do this until you can detect a fragrance. Write it down.

16

Study the reaction mechanism. Ignore the resonance structures on the left and right.

17

2. Propyl acetate

SAFETY ALERT: Remember to use concentrated sulfuric acid and glacial acetic acid with

extreme care. Make sure they do not come into contact with your skin as they will vigorously

attack tissue. If you get any on your skin, immediately wash it off with plenty of cool water and

tell the teacher.

1. Prepare propyl acetate by putting 6 drops of propanol in a clean, dry test tube.

2. Add 2 drops of glacial acetic acid.

3. Add 1 drop of concentrated sulfuric acid, agitate the tube to mix the contents, and place the

test tube in boiling water bath for 3 minutes.

4. When heating is completed, remove the test tube from the bath, and add 20 drops of distilled

water to the test tube contents. Agitate to mix.



18

Complete the reaction mechanism. Ignore the resonance structures on the left and right.

19

3. Isopentyl acetate




tell the teacher.

1. Prepare isopentyl acetate by putting 6 drops of isopentyl alcohol in a clean, dry test tube.








20


21

4. Octyl acetate




tell the teacher.

1. Prepare octyl acetate by putting 6 drops of octanol in a clean, dry test tube.








22


23

5. Benzyl acetate




tell the teacher.

1. Prepare benzyl acetate by putting 6 drops of benzyl alcohol in a clean, dry test tube.








24


25

6. Butyl butyrate



on your skin, immediately wash it off with plenty of cool water and tell the teacher. Because

butyric acid has a strong unpleasant odor, special attention must be paid when using it. DO

NOT handle it outside of a fume hood at all.

1. Prepare butyl butyrate by putting 6 drops of butanol in a clean, dry test tube.

2. Add 2 drops of butyric acid.



4. When heating is completed, remove the test tube from the bath, and add 20 drops of water to

the test tube contents. Agitate to mix.



26


27

7. Ethyl butyrate



on your skin, immediately wash it off with plenty of cool water and tell the teacher. Because

butyric acid has a strong unpleasant odor, special attention must be paid when using it. DO

NOT handle it outside of a fume hood at all.

1. Prepare ethyl butyrate by putting 6 drops of ethanol in a clean, dry test tube.

2. Add 2 drops of butyric acid.



4. When heating is completed, remove the test tube from the bath, and add 20 drops of water to

the test tube contents. Agitate to mix.



28


29

Table A.1: Reagents, products and fragrancies. (Johnson; Athabasca University)number alcohol carboxylic acid ester (product) fragrance

1 methanol salicylic acid methyl salicylate wintergreen

2 propanol acetic acid propyl acetate pear

3 isopentyl alcohol acetic acid isopentyl acetate banana

4 octanol acetic acid octyl acetate orange

5 benzyl alcohol acetic acid benzyl acetate peach

6 butanol butyric acid butyl butyrate pineapple

7 ethanol butyric acid ethyl butyrate strawberry

Concentrated sulphuric acid and distilled water are also needed.

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A.2 Appendix 2: Product information given to students to design their synthesis

1. Molecular formula: C8H8O3

Structure:


Both reagents are directly alkane-based structures. The alcohol has more carbons than the acid.

The acid is not methanoic acid.


The alcohol begins with ‘iso’. The acid has an icy feeling to it.


Both reagents are directly alkane-based structures. The alcohol has two more carbons than the

longest chain name that students learn in basic education.


The alcohol has an aromatic ring but it is not a phenol. The acid is not methanoic acid.


Both reagents are directly alkane-based structures. You cannot go wrong with a 4.


Both reagents are directly alkane-based structures. The acid, the alcohol, the answer to

everything (well at least the number of carbons). OR Both reagents are directly alkane-based

structures. The acid has more carbons than the alcohol. The alcohol is not methanol.

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Fischer Speier Esteriterification

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Transcript of Fischer Speier Esteriterification