BTEC Applied Science Unit 4 Assignment B - Synthesis
of Aspirin
Acetic Anhydride - ANSWER BP: 139.8C
Benefits of Aspirin - ANSWER Fever reducer, pain reducer, anti inflammatory
What is an esterification reaction? - ANSWER Adding an R group (COCH3 in this
case) to a molecule
What is the basic reaction scheme for the synthesis of aspirin - ANSWER Salicylic
acid + Acetic Anhydride with H3PO4 as catalyst, Alcohol in salicylic on ring gets
replaced with OCH(=O)(-CH3), acetic acid as byproduct.
Acetic Acid - ANSWER
What acid catalyst is used in the synthesis of aspirin - ANSWER H3PO4 (Phosphoric
Acid)
Why do we add an excess of acetic anhydride - ANSWER This is an equilibrium
reaction, we need to push it toward completion. Also, it acts as the solvent
Stoichiometric Ratio of acetic anhydride to salicylic acid - ANSWER 1:1, but we use
excess, which is optimized at 3:1
Which solvent is best for recrystallization and why? - ANSWER Water, because the
product dissolves at high temperatures but not at room temperature
What do we use to test for leftover salicylic acid? - ANSWER Iron Trichloride, if
phenols remain test will turn dark purple
Why do you do this reaction in an Erlenmeyer Flask rather than a beaker? -
ANSWER The sloping sides of an Erlenmeyer flask makes it so that evaporation
occurs at a significantly reduced rate. Erlenmeyer flasks have a smaller opening hole
surface area than normal glassware.
What are the characteristics of a good recrystallization solvent? - ANSWER Good
recrystallization solvent dissolve solids at hot temperatures and makes the solid
insoluble in cold or room temperature.
What is thermometer lag? How will this affect your melting points? How can you
avoid thermometer lag? What is another part with determining your melting point too
quickly? - ANSWER Thermometer lag occurs when the solution heats up too rapidly.
The extreme change makes the thermometer have to play catchup. Hence, the
melting point appears to be lower than it really is. They way to avoid this is to heat
of Aspirin
Acetic Anhydride - ANSWER BP: 139.8C
Benefits of Aspirin - ANSWER Fever reducer, pain reducer, anti inflammatory
What is an esterification reaction? - ANSWER Adding an R group (COCH3 in this
case) to a molecule
What is the basic reaction scheme for the synthesis of aspirin - ANSWER Salicylic
acid + Acetic Anhydride with H3PO4 as catalyst, Alcohol in salicylic on ring gets
replaced with OCH(=O)(-CH3), acetic acid as byproduct.
Acetic Acid - ANSWER
What acid catalyst is used in the synthesis of aspirin - ANSWER H3PO4 (Phosphoric
Acid)
Why do we add an excess of acetic anhydride - ANSWER This is an equilibrium
reaction, we need to push it toward completion. Also, it acts as the solvent
Stoichiometric Ratio of acetic anhydride to salicylic acid - ANSWER 1:1, but we use
excess, which is optimized at 3:1
Which solvent is best for recrystallization and why? - ANSWER Water, because the
product dissolves at high temperatures but not at room temperature
What do we use to test for leftover salicylic acid? - ANSWER Iron Trichloride, if
phenols remain test will turn dark purple
Why do you do this reaction in an Erlenmeyer Flask rather than a beaker? -
ANSWER The sloping sides of an Erlenmeyer flask makes it so that evaporation
occurs at a significantly reduced rate. Erlenmeyer flasks have a smaller opening hole
surface area than normal glassware.
What are the characteristics of a good recrystallization solvent? - ANSWER Good
recrystallization solvent dissolve solids at hot temperatures and makes the solid
insoluble in cold or room temperature.
What is thermometer lag? How will this affect your melting points? How can you
avoid thermometer lag? What is another part with determining your melting point too
quickly? - ANSWER Thermometer lag occurs when the solution heats up too rapidly.
The extreme change makes the thermometer have to play catchup. Hence, the
melting point appears to be lower than it really is. They way to avoid this is to heat
