ESTER LAB “The smelliest lab of the year”
Honors level 2014
Introduction:
The purpose of this lab is to determine the ester created by reacting an organic acid and an alcohol, and to
write the correct reaction showing the formation of the ester made.
http://www.chemguide.co.uk/organicprops/alcohols/esterification.html This link helps to explain the
entire “esterification” process.
When an organic acid (
) and an alcohol (R-OH) are mixed together and heated in the presence of an
acid catalyst (such as H2SO4), the two will react to form an ester (plus H2O). This process is called
esterification.
Each ester has its own unique odor, and with a discriminating nose, one can use this fact to help identify
them.
http://www.chemguide.co.uk/physical/catalysis/esterify.html great link shows how the esters are made.
Example of the reaction:
Esterification reaction are both slow and reversable. The equation between an organic acid (-COOH)
and an alcohol (-OH) where R and R’ can be the same or different is written below.
The organic acid drops the OH at the end and the alcohol drops the H. The H and OH bond to make
water and the remaining two structures bond to make the ester.
Concepts: Work in these terms into your introduction.
Esterification reaction, esters, organic acids, alcohols, acid catalyst, olfaction, olfactory epithelium,
solubility, protein binding (lock and key model) you work on these terms last year when you worked on “The
Smells Lab”.
(Bibliography: 3 or more sources MLA format). Keep track of your research!
Hypothesis: If (Independent variable) then (dependant variable)and (maybe) because _________________.
Assume that your ester is n-pentyl hexanoate (this is just an example and is not one of the possibilities).
 The first part of the name, n-pentyl, refers to the alcohol needed to make the ester, in this case n-pentyl
alcohol (1-pentanol).
 The second part of the name, hexanoate, refers to the carboxylic acid needed, in this case, hexanoic
acid (drop -ate and add -ic acid).
 Next, use structural formulas to write out the balanced equation for the preparation of the ester. In this
example,
Procedure:
GOGGLES MUST BE WORN AT ALL TIMES!
In this lab you will be reacting various organic acids (acetic acid, salicylic acid, butryic acid*) with various
alcohols (methyl, ethyl, isopropyl, n-butyl, isopentyl, octyl alcohols)
You will make five different esters with odors that should be familiar to you.
* butryic acid (smells like vomit work in fume hood)
 Get 3 erlenmeyer flasks, labeled: “1”, “2”, & “3”
 Erlenmeyer flask #1: Add 10 drops of ethanoic acid (acetic acid),
10 drops of isopropanol (isoprpyl alcohol), and 2 drops of H2SO4.
 Erlenmeyer flask #2: Add 1 scoop of 2-Hydroxybenzoic acid
(salicylic acid), 15 drops of methanol, and 2 drops of H2SO4.
 Erlenmeyer flask #3: Add 10 drops of acetic acid, 10 drops of
ethanol, and 2 drops of H2SO4.
 Mix the content of each erlenmeyer flask by the knocking
method.
 Clamp the erlenmeyer flask and lower into the warm water bath
for approximately 1 minute.
 Remove (carefully!) the erlenmeyer flask from the hot water and
note the smell of each ester by wafting the vapors towards your
nose.
 Repeat the procedure for Erlenmeyer flask 2&3
 A forth reaction can be done and the choice is your as to what
ester you would like to make.
To name of your ester you must first determine what alcohol and what carboxylic acid will be needed to
prepare that ester. To do this you must know how esters are named. Read the references using an on-line
source.
Data/Data Analysis Table:
Odor
Reactants
Organic Acid
+ water
Example
Pentanoic acid
+
+ (n-butyl alcohol )
1-butanol
+
Test Tube
#1:
Alcohol

Products (name of ester)
 IUPAC name of ester
 butyl pentanoate

+ water
+
______________ acid + __________alcohol 
Diagram the structural formulas for all the reactants and products
+ water
Test Tube
#2
Test Tube
#3
_______________ acid + __________ alcohol 
+ water
Diagram the structural formulas for all the reactants and products
_______________ acid + __________ alcohol 
+ water
Diagram the structural formulas for all the reactants and products
Conclusion:
Aside from the normal requirements given in your lab report writing standards relate 2 of the major themes
of chemistry and real-world applications to the results of your experiment.
Questions: Answer these questions after you have completed the requirements for the lab.
1. Why do you think you were instructed to use an electric hot plate to heat the water instead of a Bunsen
burner?
2. Why do you think you were instructed to waft the odors instead of sniffing them directly?
3. What role did the H2SO4 play? How does it affect the esterification reaction?
4. Why did you use warm water instead of boiling hot water?
5. Explain a) How we are able to smell certain smells in the first place (what goes on in the nose and the
brain).
Name:
Systematic/IUPAC name
Ethanoic acid
Structural Formula
Common name
or acetic acid
or
2-Hydroxybenzoic acid
Butanoic acid
Systematic/IUPAC name
or salicylic acid
Butryic acid
or Common name
Methanol
or Methyl alcohol
Systematic/IUPAC name
Common name
Ethanol
or
Systematic/IUPAC name
Isopropanol
Systematic/IUPAC name
n-butanol
or
Systematic/IUPAC name
Ethyl alcohol
Common name
or Isopropyl alcohol
Common name
or
n-butyl alcohol
Common name
Isopentyl alcohol (amyl alcohol)
Isopentanol
or Isopentyl alcohol
Systematic/IUPAC name
Common name
n-octanol
or
Systematic/IUPAC name
Ester
odor
n-octyl alcohol
Common name
Alcohol
Acid
Ester Name
Water
?
Banana
Orange
Wintergreen
Raspberry
Pineapple **
Isopentyl alcohol
Octyl alcohol
Methyl alcohol
Isobutyl alcohol
Ethyl alcohol
Pear
Rum
Apple **
n-Propyl alcohol
Isobutyl alcohol
Methyl alcohol
Pear-like
Benzyl alcohol
Perfume
Isopropyl alcohol
** Work in the fume hood
Acetic acid
Acetic acid
Salicylic acid
Formic acid
Butyric acid
(smells like vomit)
Acetic acid
Propionic acid
Butyric acid
(smells like vomit)
Acetic acid
Acetic acid
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water