Ester synthesis experiments are representative experiments commonly performed in organic chemistry laboratories.
Esters are synthesized by reacting carboxylic acids with alcohols, and the odor of the product, yield, separation operations, and characteristics of the equilibrium reaction are discussed.
Many low-molecular-weight esters have fruit-like odors, and in experiments, changes in odor may be used as a clue indicating formation of the target product.
In an ester synthesis report, it is not sufficient simply to write that “a sweet odor was detected” or “the yield was ○%.”
It is necessary to discuss why the odor changed, why the yield becomes lower than the theoretical value, and the effects of the equilibrium reaction, formation and removal of water, acid catalyst, extraction, washing, and drying in relation to one another.
This article clearly explains how to interpret the results of ester synthesis experiments, how to think about odor, yield, and equilibrium reactions, sources of error, points for improvement, and discussion examples that can be used in reports.
Note:
This article is a reference intended to assist with discussions of results obtained in chemistry experiments at universities and similar institutions.
For the actual synthesis procedures, acid catalyst, heating, extraction, washing, drying, distillation, waste-liquid disposal, and safety precautions, always follow the instructions in your university’s laboratory manual and those given by your instructor or TA.
- What Is an Ester Synthesis Experiment?
- Main Items to Include in the Results
- How to Discuss the Odor of an Ester
- Discussion When the Odor Is Weak
- Esterification as an Equilibrium Reaction
- How to Shift the Equilibrium Toward Ester Formation
- Effect of Water on Yield
- Role of the Acid Catalyst
- Calculation and Discussion of Yield
- Causes of Low Yield
- Discussion When the Yield Is Too High
- Discussion of Extraction Operations
- Discussion of Washing Operations
- Discussion of Drying Operations
- Discussion of Purification by Distillation
- Discussion Using an IR Spectrum
- Effects of Reaction Time and Temperature
- Discussion When Unreacted Starting Materials Remain
- Discussion of Side Reactions
- Discussion of Ester Hydrolysis
- Relationship Between Odor and Purity
- When the Result Can Be Considered Good
- Example Discussion When the Experiment Did Not Go Well
- How to Write Points for Improvement
- Difference Between a Superficial Discussion and a Good Discussion
- Examples of Expressions That Can Be Used in Reports
- Points to Check When Discussing Ester Synthesis
- Summary
What Is an Ester Synthesis Experiment?
An ester synthesis experiment is an experiment in which a carboxylic acid and an alcohol are reacted to obtain an ester.
Typically, it is studied as a reaction in which a carboxylic acid and an alcohol are heated in the presence of an acid catalyst to produce an ester and water.
This reaction is sometimes called Fischer esterification.
Esters may show physical properties and odors different from those of carboxylic acids and alcohols.
Therefore, in experiments, whether the target product was formed is judged based on changes in odor before and after the reaction, phase separation of the product, yield, boiling point, IR spectrum, and similar results.
Carboxylic acid + Alcohol ⇄ Ester + Water
Example Discussion:
In this experiment, the carboxylic acid and alcohol are considered to have reacted in the presence of an acid catalyst to produce an ester.
If a sweet odor different from that of the starting materials was observed after the reaction, this provides a clue indicating that an odor characteristic of the ester was produced.
However, because formation of the target product cannot be concluded from odor alone, it is necessary to make a judgment together with results such as yield, boiling point, and IR spectrum.
Main Items to Include in the Results
In the results of ester synthesis, organize not only the mass and yield of the product but also odor, phase separation, the condition after extraction, mass after drying, boiling point, spectra, and similar observations.
Odor is an important observation, but because it is also subjective information, it should be discussed together with other measurement results.
Main Items to Include in the Results
- Type and amount of carboxylic acid used
- Type and amount of alcohol used
- Limiting reagent
- Whether an acid catalyst was used
- Appearance during heating and after the reaction
- Change in odor before and after the reaction
- Condition of the layers after extraction and washing
- Mass or volume of the product
- Theoretical yield
- Yield
- Physical properties such as boiling point and refractive index
- Analytical results such as IR spectra
Example of How to Write the Results:
After the reaction, a sweet odor different from the acidic odor before the reaction was confirmed.
After extracting, washing, and drying the product, a liquid considered to be the target compound was obtained.
The mass of the obtained product was ○○ g, and the yield calculated from the theoretical yield was ○○%.
These results suggest that the ester was formed, but because the yield did not reach 100%, the effects of the equilibrium reaction and losses during separation operations must be considered.
How to Discuss the Odor of an Ester
Many low-molecular-weight esters have sweet, fruit-like odors.
In ester synthesis experiments, changes in odor after the reaction may be treated as one clue indicating formation of the target product.
For example, while the starting carboxylic acid may have an irritating or sour odor, the produced ester may show a fruit-like odor.
However, perception of odor differs among individuals, and odors from starting materials, solvents, and impurities may also be mixed together.
Therefore, the target product should not be identified from odor alone, but should be discussed together with results such as yield, physical properties, and spectra.
Example Discussion:
Because a sweet odor was observed after the reaction, an ester may have been formed.
Esters may show odors different from those of the starting carboxylic acid and alcohol, and the change in odor provides a clue that the functional group changed.
However, odor is a subjective observation and is also affected by impurities and unreacted starting materials, so confirmation of the product requires a judgment together with other analytical results.
Discussion When the Odor Is Weak
If the expected odor is weak, possible causes include a small amount of ester being formed, odors from unreacted carboxylic acid or alcohol being mixed in, insufficient separation of the product, or loss through volatilization.
The strength of the odor also differs depending on the type of ester.
Example Discussion:
One possible reason the characteristic ester odor was weak is that the reaction did not proceed sufficiently and only a small amount of ester was formed.
In addition, if unreacted carboxylic acid or alcohol remained, their odors may have mixed with the ester odor and made it difficult to recognize.
Furthermore, if extraction or drying was insufficient, impurities may have remained in the product and affected the evaluation of the odor.
Esterification as an Equilibrium Reaction
The reaction used to synthesize an ester from a carboxylic acid and an alcohol is generally reversible.
In other words, the reverse reaction in which an ester and water return to a carboxylic acid and an alcohol can also occur.
Therefore, the reaction does not proceed completely in only the forward direction, and after progressing to some extent, it approaches an equilibrium state.
Because of this property, it is difficult to obtain 100% of the theoretical yield in ester synthesis.
When considering causes of low yield, it is necessary to take into account not only operational errors but also the fact that the reaction is an equilibrium reaction.
Example Discussion:
Esterification is a reversible equilibrium reaction, so the reaction does not proceed completely toward ester formation.
The reverse reaction, in which the produced ester and water return to the carboxylic acid and alcohol, may also occur.
Therefore, some starting materials remained after the reaction, and the yield is considered not to have reached 100% of the theoretical yield.
How to Shift the Equilibrium Toward Ester Formation
In an equilibrium reaction, changing the conditions can change the direction in which the reaction proceeds more readily.
In ester synthesis, the equilibrium can be shifted toward ester formation by using an excess of alcohol, removing water, or separating the produced ester.
However, in actual student experiments, the conditions specified in the laboratory manual are followed.
In a report, “why excess alcohol is used” and “why the effect of water is a problem” can be explained from the perspective of equilibrium.
| Condition | Effect on Equilibrium | Perspective for Discussion |
|---|---|---|
| Use excess alcohol | More readily shifts toward ester formation | Increase the concentration of a reactant to shift the equilibrium |
| Remove the produced water | More readily shifts toward ester formation | Suppress the reverse reaction |
| Separate the produced ester | More readily shifts toward ester formation | Reduce the amount of product in the reaction system |
Example Discussion:
When an excess of alcohol is used, the concentration of the alcohol, which is a reactant, becomes higher, so the equilibrium shifts more readily toward ester formation.
In addition, if the produced water can be removed, the reverse reaction, hydrolysis, becomes less likely to occur and the ester yield can be increased.
Therefore, in ester synthesis, how the equilibrium is shifted toward the product side is important.
Effect of Water on Yield
In esterification, water is produced as a product.
If a large amount of water is present in the reaction system, the ester is hydrolyzed and the reverse reaction returning it to the carboxylic acid and alcohol occurs more readily.
Therefore, the presence of water may lead to a decrease in ester yield.
In addition, if reagents or apparatus already contain moisture before the reaction, it may also affect reaction progress and product separation.
In a report, moisture contamination or insufficient removal of water can be discussed as sources of error.
Example Discussion:
One possible cause of the reduced yield is the effect of moisture in the reaction system.
Water is produced during esterification, but if a large amount of water is present, the reverse reaction, ester hydrolysis, occurs more readily.
Therefore, the equilibrium may not have shifted sufficiently toward ester formation, resulting in a smaller amount of target product.
Role of the Acid Catalyst
An acid catalyst may be used in esterification.
The acid catalyst makes the carbonyl group of the carboxylic acid more reactive and allows the reaction with the alcohol to proceed more readily.
Because it is a catalyst, it is theoretically not consumed over the overall reaction.
If the amount of acid catalyst is insufficient, the reaction rate becomes slower and a sufficient amount of ester may not be formed within the reaction time.
On the other hand, if the acidic conditions are too strong or the heating conditions are inappropriate, side reactions, decomposition, or difficulty in workup may occur.
Example Discussion:
The acid catalyst has the role of facilitating the reaction between the carboxylic acid and alcohol.
The acid catalyst activates the carbonyl group and makes it easier for the alcohol to react, thereby promoting ester formation.
If the amount of acid catalyst or reaction time was insufficient, the reaction rate may have been slow and unreacted starting materials may have remained when the reaction was ended.
Calculation and Discussion of Yield
In ester synthesis, the theoretical yield is calculated from the limiting reagent and compared with the amount of ester actually obtained to calculate the yield.
Yield is an important value indicating how far the reaction progressed and how much product could be recovered.
Yield (%) = Actual yield ÷ Theoretical yield × 100
However, because ester synthesis is an equilibrium reaction and losses occur during operations such as extraction, washing, drying, and distillation, it is generally difficult for the yield to reach 100%.
In a report, the limitations of the reaction itself and losses during operations should be considered separately.
Example Discussion:
The yield of the obtained ester was lower than the theoretical value.
Possible causes include the esterification reaction not proceeding completely because it is an equilibrium reaction and part of the ester being lost during extraction and washing.
Therefore, the decrease in yield is considered to originate not only from the reaction conditions but also from the separation and purification operations.
Causes of Low Yield
Causes of low yield in ester synthesis are easier to organize by dividing them into cases where the reaction did not proceed sufficiently and cases where the product was lost during separation and purification.
| Stage | Cause | Effect on Yield |
|---|---|---|
| Reaction | The reaction does not proceed completely because of equilibrium | Amount of target product formed is limited |
| Reaction | Hydrolysis caused by water | Amount of ester decreases |
| Reaction | Insufficient reaction time or temperature | Unreacted starting materials remain |
| Extraction | Ester remains in the aqueous layer | Recovered amount decreases |
| Washing | Product dissolves in the washing solution | Yield decreases |
| Drying / Distillation | Loss through volatilization or transfer | Actual yield becomes smaller |
Example Discussion:
One possible cause of the low yield is that esterification is an equilibrium reaction and the starting materials were not completely converted into products.
In addition, the produced ester may have some volatility or slight solubility in water, so part of it may have been lost during extraction, washing, or transfer.
Therefore, both the reaction equilibrium and losses during operations are considered to have contributed to the reduction in yield.
Discussion When the Yield Is Too High
If the yield exceeds 100% or is unnaturally high, components other than the target ester may be included in the measured mass.
If unreacted alcohol or carboxylic acid, residual water, solvent, acid catalyst, inorganic salts, or similar substances are mixed in, the actual yield is overestimated.
Particularly with liquid products, water, solvent, and starting materials may remain because of insufficient drying or separation, making the yield appear high.
Example Discussion:
One possible reason the yield was estimated to be high is that unreacted alcohol, residual water, or solvent was mixed into the product.
In this case, the measured mass includes components other than the target ester, so the actual yield becomes overestimated.
Therefore, even when the yield is high, the product is not necessarily highly pure, and it is necessary to check whether drying and purification were sufficient.
Discussion of Extraction Operations
After ester synthesis, the reaction mixture may contain the target ester, unreacted acid and alcohol, acid catalyst, water, and similar substances.
Therefore, the target ester is separated by extraction and washing.
If the ester moves into the organic layer and acids and water-soluble impurities move into the aqueous layer, the purity of the product can be increased.
If extraction is insufficient, part of the ester remains in the aqueous layer, or impurities may remain in the organic layer.
As a result, yield and purity are affected.
Example Discussion:
The extraction operation was intended to move the target ester mainly into the organic layer and remove acids and water-soluble impurities into the aqueous layer.
However, if the ester dissolved slightly in the aqueous layer, the amount of product recovered would decrease.
In addition, if the layers were mistaken or separation was insufficient, this could cause a reduction in yield or contamination by impurities.
Discussion of Washing Operations
The organic layer after ester synthesis may contain unreacted carboxylic acid or acid catalyst.
To remove these, the organic layer may be washed with water, a basic aqueous solution, or similar solutions.
Removing acidic components by washing may improve the odor and purity of the product.
However, excessive washing may cause the ester to dissolve in the washing solution or may increase the effect of hydrolysis.
Therefore, both insufficient washing and excessive washing can be discussed.
Example Discussion:
Washing is considered to have removed water-soluble components such as unreacted carboxylic acid and acid catalyst.
This may have reduced acidic impurities in the product and improved the purity of the ester.
On the other hand, if part of the ester dissolved in the washing solution or if hydrolysis proceeded during washing, this may have led to a reduction in yield.
Discussion of Drying Operations
Water may remain in the organic layer after extraction and washing.
Removing water with a drying agent makes it easier to obtain a higher-purity ester.
If drying is insufficient, water remains in the product, causing the mass to be overestimated and possibly promoting hydrolysis.
On the other hand, if the drying agent is not completely removed and contaminates the product, the mass and purity are also affected.
For liquid esters, insufficient drying readily leads to overestimation of the yield.
Example Discussion:
If drying of the product was insufficient, water may have remained and caused the measured mass to be larger than the actual mass of the target ester.
As a result, the yield would be overestimated.
In addition, because residual water may also promote ester hydrolysis, drying is an important operation that affects both yield and purity.
Discussion of Purification by Distillation
If the ester is a liquid, it may be purified by distillation.
Distillation separates the target ester from unreacted alcohol, solvent, and impurities by using differences in boiling points.
If the boiling point of the collected fraction is close to the literature value, the target ester may have been obtained as the main component.
However, if the distillation rate is too fast, components with similar boiling points are mixed, or product remains in the apparatus, purity and yield are affected.
Example Discussion:
If the boiling point of the fraction obtained by distillation was close to the literature value for the target ester, the target compound is considered to have been recovered as the main component.
On the other hand, if the boiling-point range was broad, unreacted alcohol, solvent, or similar components may have been mixed in.
In addition, if liquid remained inside the distillation apparatus, part of the ester that had actually been formed could not be recovered, which may have reduced the yield.
Discussion Using an IR Spectrum
In ester synthesis, changes in functional groups can be confirmed by IR spectroscopy.
Esters show absorptions derived from carbonyl groups and C-O bonds, providing clues for product confirmation.
In addition, if the broad O-H absorption characteristic of the starting carboxylic acid becomes weaker, the amount of starting material may have decreased.
An IR spectrum provides more objective evidence for product confirmation than odor.
However, the structure should not be completely determined from IR alone, but should be judged together with yield, boiling point, NMR, and similar results.
Example Discussion:
If an absorption corresponding to the carbonyl group of an ester was observed in the IR spectrum, this supports the possibility that the target ester was formed.
In addition, if the broad O-H absorption derived from the starting carboxylic acid became weaker, the carboxylic acid is considered to have been consumed by the reaction.
However, because unreacted starting materials or by-products may also be present, the spectral results must be evaluated together with other physical-property data.
Effects of Reaction Time and Temperature
Esterification is affected by reaction time and temperature.
If the reaction time is too short or the temperature is too low, the reaction may not proceed sufficiently and unreacted starting materials may remain.
On the other hand, excessive heating may cause loss of volatile components or side reactions.
Example Discussion:
One possible cause of the low yield is that the reaction time was insufficient and the reaction may have been stopped before reaching equilibrium.
In addition, if the temperature was low, the reaction rate would be slow and a sufficient amount of ester would not be formed within a fixed time.
Conversely, if heating was too strong, volatile starting materials or products may have been lost, leading to a reduction in yield.
Discussion When Unreacted Starting Materials Remain
Carboxylic acid or alcohol may remain after ester synthesis.
Possible causes include the fact that the reaction is an equilibrium reaction, insufficient reaction time or temperature, insufficient action of the acid catalyst, and the effect of water.
If unreacted carboxylic acid remains, it may affect acidic odor, acidic reactions, O-H absorption in the IR spectrum, and similar results.
Example Discussion:
If unreacted carboxylic acid remained in the product, incomplete progress of the reaction may be a cause.
Because esterification is an equilibrium reaction, a certain amount of starting material may remain even at the end of the reaction.
In addition, under conditions containing a large amount of water, the reverse reaction proceeds more readily, so carboxylic acid and alcohol are considered more likely to remain.
Discussion of Side Reactions
Side reactions other than the target reaction may occur during ester synthesis.
For example, dehydration of alcohols, hydrolysis of esters, and decomposition of starting materials or products may occur under strongly acidic or heated conditions.
When side reactions occur, the yield of the target ester decreases and the odor and physical properties of the product are also affected.
Example Discussion:
If the yield was low and the odor or boiling point of the product differed from expectations, side reactions may have occurred.
Under strongly acidic conditions or excessive heating, reactions other than the target esterification may proceed and starting materials may be consumed to form substances other than the target product.
As a result, the amount of target ester formed decreases and the yield is considered to have been reduced.
Discussion of Ester Hydrolysis
In the presence of water, esters may be hydrolyzed and return to carboxylic acids and alcohols.
Considering that ester synthesis is an equilibrium reaction, the reverse reaction must also be taken into account under conditions where the product comes into contact with water.
If washing or drying is insufficient, some of the produced ester may be hydrolyzed.
Example Discussion:
If acidic components remained in the product, not only contamination by unreacted carboxylic acid but also partial hydrolysis of the produced ester may be considered.
Esters may react in the presence of water and return to carboxylic acids and alcohols.
Therefore, if water remained because of insufficient drying after washing, it may have affected the purity and yield of the product.
Relationship Between Odor and Purity
Even if the odor of an ester is confirmed, the product is not necessarily pure.
Even a small amount of ester may have a strong odor, and it may be difficult to judge purity from odor alone even when unreacted starting materials or impurities are mixed in.
Conversely, even if the target ester is formed, the odor may be difficult to recognize if the odor of the starting material or acid is strong.
Example Discussion:
Confirmation of the characteristic ester odor provides one piece of evidence for formation of the target product.
However, odor may be detectable even from a small amount of product and does not directly indicate the purity or yield of the product.
Therefore, odor should be treated as supplementary information and judged together with the IR spectrum, boiling point, yield, and similar results.
When the Result Can Be Considered Good
A good result in ester synthesis is indicated when an odor characteristic of the ester and different from that of the starting materials is confirmed after the reaction, the yield is reasonable, and the product after washing and drying is considered to contain little starting material or moisture.
If an IR spectrum or boiling-point measurement was performed, obtaining results corresponding to the target ester is also important.
Example Discussion:
After the reaction, a sweet odor different from that of the starting materials was confirmed, and absorptions characteristic of an ester were also observed in the IR spectrum of the product.
In addition, the yield was within a reasonable range when losses caused by the equilibrium reaction and separation operations were taken into account.
From these results, the target ester is considered to have been synthesized generally successfully.
Example Discussion When the Experiment Did Not Go Well
If ester synthesis does not go well, possible causes are considered from results such as a weak ester odor, remaining acidic odor, low yield, excessively high yield, insufficient phase separation, or starting-material absorptions remaining in the IR spectrum.
Organizing the effects of the equilibrium reaction, water, reaction time, extraction, washing, and drying separately makes the discussion easier to write.
Example Discussion:
In this experiment, the characteristic ester odor was weak and the yield was also low.
Possible causes include the esterification reaction not proceeding completely because it is an equilibrium reaction and hydrolysis, the reverse reaction, occurring because of water.
In addition, if part of the ester was lost during extraction or washing, the recovered amount would decrease.
Therefore, both the reaction conditions and the workup operations may have affected the results.
How to Write Points for Improvement
In a discussion of ester synthesis, including points for improvement in addition to sources of error makes the report easier to organize.
Improvements are easier to write when divided into methods for promoting the reaction, improvements in separation and purification, and improvements in measurement and confirmation.
Improvements for Promoting the Reaction
- Allow sufficient reaction time
- Maintain appropriate temperature conditions
- Use the acid catalyst appropriately
- Avoid moisture contamination as much as possible
- Use one of the starting materials in excess when necessary
- Consider conditions that shift the equilibrium toward ester formation
Improvements to Separation and Purification
- Confirm phase separation sufficiently
- Confirm which layer contains the target ester
- Use an appropriate amount and number of washing operations
- Remove water sufficiently with a drying agent
- Do not leave drying agent or water in the product
- When distilling, confirm the boiling-point range
Improvements to Confirmation Methods
- Do not identify the product from odor alone
- Confirm the ester bond using an IR spectrum
- Compare physical properties such as boiling point and refractive index
- If TLC or NMR is used, check for residual starting materials
- Evaluate yield and purity separately
Example of How to Write Points for Improvement:
To improve the yield, it is necessary to appropriately control the reaction time and temperature and establish conditions that shift the equilibrium toward ester formation.
In addition, because water promotes hydrolysis and shifts the equilibrium back toward the starting-material side, it is important to reduce moisture in the reaction system and product as much as possible.
During separation operations, avoiding mistakes in identifying the layers and appropriately performing washing and drying can reduce product loss and contamination by impurities.
Difference Between a Superficial Discussion and a Good Discussion
In discussing ester synthesis, simply writing that “it smelled good” or “the yield was low” results in a superficial discussion.
A persuasive discussion can be produced by relating odor, equilibrium reaction, water, acid catalyst, extraction, washing, and drying.
| Superficial Discussion | Good Discussion |
|---|---|
| There was a sweet odor. | Because a sweet odor different from that of the starting materials was confirmed after the reaction, an ester may have been formed. However, odor is a subjective observation and may be detected even from a small amount of product, so it must be judged together with the IR spectrum and physical-property values. |
| The yield was low. | Possible causes of reduced yield include the fact that esterification is an equilibrium reaction and does not proceed completely, hydrolysis caused by water, and losses during extraction, washing, and transfer. |
| The odor of acid remained. | If an acidic odor remained, unreacted carboxylic acid may have remained in the product. Possible causes include incomplete reaction, residual starting material caused by equilibrium, or insufficient washing that failed to remove acidic components sufficiently. |
Examples of Expressions That Can Be Used in Reports
The following expressions can be used when writing the results and discussion of an ester synthesis experiment.
Adjust the necessary parts according to your own experimental results.
- A sweet odor different from that of the starting materials was confirmed after the reaction, suggesting that an ester may have been formed.
- Because odor is a subjective observation, confirmation of the product requires comparison with IR spectra and physical-property values.
- Because esterification is a reversible equilibrium reaction, the reaction does not necessarily proceed completely toward the product side.
- If water is present, the reverse reaction, hydrolysis, may proceed and lead to a reduction in yield.
- The acid catalyst activates the carbonyl group and facilitates reaction with the alcohol.
- Possible causes of reduced yield include incomplete reaction caused by equilibrium, losses during extraction and washing, and losses through volatilization.
- If the yield is too high, unreacted starting materials, residual water, solvent, or similar substances may be mixed into the product.
- Washing is considered to have removed unreacted acid and acid catalyst and improved the purity of the product.
- If drying is insufficient, residual water increases the measured mass and causes the yield to be overestimated.
- The formation of the target ester must be judged comprehensively from yield, odor, IR spectrum, boiling point, and similar results.
Points to Check When Discussing Ester Synthesis
Checking the following points before writing the report makes the discussion easier to write.
- Have you recorded the difference in odor before and after the reaction?
- Have you avoided identifying the target product from odor alone?
- Have you explained that esterification is an equilibrium reaction?
- Have you considered the effects of water formation and hydrolysis?
- Have you explained the role of the acid catalyst?
- Is the yield calculation correct?
- Have you considered the causes of reduced yield separately for the reaction and workup stages?
- If the yield is too high, have you considered contamination by impurities?
- Have you discussed the effects of extraction, washing, and drying?
- Have you related the discussion to confirmation results such as IR spectra and boiling point?
- Have you considered residual unreacted carboxylic acid or alcohol?
- Do the points for improvement correspond to the sources of error?
Summary
In an ester synthesis experiment, a carboxylic acid and an alcohol are reacted to obtain an ester.
The produced ester may show a fruit-like or sweet odor different from that of the starting materials, and the change in odor provides one clue indicating formation of the target product.
However, odor is a subjective observation and is also affected by impurities and unreacted starting materials, so it must be judged together with other results.
Because esterification is an equilibrium reaction, the reaction does not proceed completely and the yield tends not to reach 100%.
If water is present, the reverse reaction, hydrolysis, becomes more likely to proceed and may lead to a reduction in yield.
In addition, losses of product and contamination by impurities may occur during workup operations such as extraction, washing, drying, and distillation.
In a report, do not simply write that “there was an odor” or “the yield was low,” but explain the relationship among odor, yield, equilibrium reaction, the effect of water, acid catalyst, extraction, washing, and drying.
Separately evaluating yield and purity and discussing them together with objective results such as IR spectra and boiling point makes it possible to produce a persuasive ester synthesis report.
