CHEM 1LD EXPERIMENT 3 & 4: ASPIRIN
SYNTHESIS AND ANALYSIS QUESTIONS
WITH CORRECT ANSWERS
\.Experiment 3 Key Ideas - ANSWERS-- Salycilic acid - Pka is low
- Esterification Reaction- Removal of trhe carboxylic acid functional group to an
ester to form ASA
- TLC-
-Mobile Phase- Eluent
- mobile phase moves up the plate based on capillary action
- the compounds that interact more strongly with the polar silica will not move up
the plate as much
- Compounds that react less with the plate will move up more
- non polar moves up higher
-changing the solvent can affect how the compunds move up the plate
- Stationary Phase- silica plate
\.Objective - ANSWERS-Understand the synthesis of ASA from salicylic acid
(esterification) in aspirin. Phosphoric acid is a catalyst for this reaction that is
completed once all solid disappears. Thin layer chromatography (TLC) is a
technique that separates compounds based on competing intermolecular
interactions of the polar silica plate and less polar solvent. Determine the purity
and concentration of the aspirin product with 3 techniques: melting point,
reaction with FeCl3, and absorbance spectrum
, \.Why must TLC analysis be performed on all the known components of the
chemical reaction before conducting the synthesis? - ANSWERS-TLC analysis must
be performed on all known components of the chemical reaction before
conduction synthesis because to be able to recognize the products of the
chemicals once the analysis has been completed.
\.Describe the polarity of this solution. Why is this mixture a more effective
mobile phase compared to pure ethyl acetate or pure ethanol? - ANSWERS-The
mobile phase is more effective compared to pure ethyl acetate or pure ethanol
since ethanol is more polar compared to ethyl acetate, therefore the mixture is
stronger.
\.What feature in the molecular structures of both SA and ASA, Figure 1 and 2 of
the manual introduction, allows both compounds to be visualized under UV light?
- ANSWERS-The feature in the molecular structures of both SA and ASA that
allows both compounds to be visualized under UV light is the benzene ring that is
connected to the carboxylic acid.
\.Why can the Rf values NOT be calculated in this situation? (SCREENSHOT IN DATA
AND CALCULATIONS) - ANSWERS-Rf values cannot be calculated in this situation
because when the filter paper and the TLC plate touch each other in the chamber
the solution gets pulled toward the filter paper, therefore, the Rf values would be
incorrect.
\.Why is it essential for the vial to be completely dry in this instance? - ANSWERS-
It is essential for the vial to be completely dry when adding Acetic Anhydride
because water will react with it
SYNTHESIS AND ANALYSIS QUESTIONS
WITH CORRECT ANSWERS
\.Experiment 3 Key Ideas - ANSWERS-- Salycilic acid - Pka is low
- Esterification Reaction- Removal of trhe carboxylic acid functional group to an
ester to form ASA
- TLC-
-Mobile Phase- Eluent
- mobile phase moves up the plate based on capillary action
- the compounds that interact more strongly with the polar silica will not move up
the plate as much
- Compounds that react less with the plate will move up more
- non polar moves up higher
-changing the solvent can affect how the compunds move up the plate
- Stationary Phase- silica plate
\.Objective - ANSWERS-Understand the synthesis of ASA from salicylic acid
(esterification) in aspirin. Phosphoric acid is a catalyst for this reaction that is
completed once all solid disappears. Thin layer chromatography (TLC) is a
technique that separates compounds based on competing intermolecular
interactions of the polar silica plate and less polar solvent. Determine the purity
and concentration of the aspirin product with 3 techniques: melting point,
reaction with FeCl3, and absorbance spectrum
, \.Why must TLC analysis be performed on all the known components of the
chemical reaction before conducting the synthesis? - ANSWERS-TLC analysis must
be performed on all known components of the chemical reaction before
conduction synthesis because to be able to recognize the products of the
chemicals once the analysis has been completed.
\.Describe the polarity of this solution. Why is this mixture a more effective
mobile phase compared to pure ethyl acetate or pure ethanol? - ANSWERS-The
mobile phase is more effective compared to pure ethyl acetate or pure ethanol
since ethanol is more polar compared to ethyl acetate, therefore the mixture is
stronger.
\.What feature in the molecular structures of both SA and ASA, Figure 1 and 2 of
the manual introduction, allows both compounds to be visualized under UV light?
- ANSWERS-The feature in the molecular structures of both SA and ASA that
allows both compounds to be visualized under UV light is the benzene ring that is
connected to the carboxylic acid.
\.Why can the Rf values NOT be calculated in this situation? (SCREENSHOT IN DATA
AND CALCULATIONS) - ANSWERS-Rf values cannot be calculated in this situation
because when the filter paper and the TLC plate touch each other in the chamber
the solution gets pulled toward the filter paper, therefore, the Rf values would be
incorrect.
\.Why is it essential for the vial to be completely dry in this instance? - ANSWERS-
It is essential for the vial to be completely dry when adding Acetic Anhydride
because water will react with it
