Download Esterification Worksheet

C3_ lesson 15
Tasker Milward Science
Rev. Sep 15
Esterification
Success Criteria:
• Describe the esterification of alcohols with carboxylic acids.
• Produce a sample of a pure Phenyl Benzoate ester using a range of advanced chemical
techniques.
• Explain the process of re-crystallisation.
Numeracy starter: Resolution of measuring Cylinder A= ________
B=_________
Which measuring cylinder would you use to measure 2cm3 of liquid? Why?
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TASK : Calculate the % error in each case. Show your workings:
% Error A = ______________ % Error B = ________________
Stretch and Challenge MAT: Why is there a temperature on the cylinder?
Name the compound 1 _________________, _________________, __________________
Name the compound 2_______________ , _______________, ________________, ______________
Explain which bonds are broken in this reaction.
C3_ lesson 15
Tasker Milward Science
Rev. Sep 15
2cm3 of Pentan-1-ol, 2cm3 of
glacial Ethanoic acid. Add a few
drops of concentrated Sulfuric
acid. HAZARDOUS
State and explain two methods to separate the ester from the reaction mixture.
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Answer the mini-plenary questions in your books.
C3_ lesson 15
Tasker Milward Science
Rev. Sep 15
HOMEWORK
•
Describe and explain the formation of Phenyl Benzoate from benzyl chloride and Phenol
including a detailed explanation of recrystallization.
Write a word equation for the synthesis of Octyl Ethanoate
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Synthesis of Ethyl Ethanoate
1180C
780C
540C
1000C Boiling points
Q1 What does reversible mean?
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H of the forward reaction is -20kJ.mol-1
Q2 How can we favour the forward reaction and make more Ester?
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Q3 Why do we warm the reaction mixture?
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Q4 Draw the two molecules you would need to react together to make Phenyl Benzoate
C3_ lesson 15
Tasker Milward Science
Rev. Sep 15
Method: Synthesis of Phenyl Benzoate
1/ Weigh 1.0g of Phenol into a small conical flask. HAZARD!
2/Add 18cm3 of 1M NaOH(aq) and bung the flask.
3/ HAZARD! In a fume cupboard add 2cm3 of Benzoyl Chloride in small quantities at a time.
4/ Fit a bung and shake vigorously with occasional cooling under the tap or in ice water. Release the
HCl gas formed into the fume cupboard every few minutes.
5/ After 15 minutes the solid Benzoate separates out: the solution should be alkaline at the end of
the reaction; if not alkaline, or if oily, add a solid pellet of sodium hydroxide and shake again.
6/ Buchner filtrate the Phenyl Benzoate and wash thoroughly with ice cold water. and re-crystallise
from ethanol (NO FLAMES!).
Q5 If a saturated solution of Phenyl
Benzoate in ethanol was cooled
from 55oC to 20oC what mass of the
ester would be precipitated?
Stretch and Challenge MAT
Q6 Why is it important not to cool
the re-crystallised product too
much?
Q7 What does super-saturated
mean?