Prep Of Eugenol Benzoate Fall 09
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Preparation of Eugenol Benzoate
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Transcript of Prep Of Eugenol Benzoate Fall 09
Preparation ofEugenol Benzoate
But first, a friendly reminder:
Wear them!It's the LAW
Preparation of Eugenol Benzoate
OH
CH2CH=CH2
OCH3
+
C
O
Cl
NaOH
O
CH2CH=CH2
OCH3
C
O
eugenol benzoyl chloride eugenol benzoate
Convert the eugenol present in clove oil to its benzoate ester:
This procedure will be the synthesis of a derivative of the eugenol.
C
O
Cl
O-
CH2CH=CH2
OCH3
Na+
+ OC
O
Cl
H3CO
CH2CH=CH2
OC
H3CO
CH2CH=CH2
O
+ NaCl
Reaction Mechanism
OH
CH2CH=CH2
OCH3
+1) 1 mL H2O
other compounds2) NaOH
O-
CH2CH=CH2
OCH3
Na+
Experimental Procedure
Step 1 – Acid/Base Reaction
- Add 1 mL of water to the centrifuge tube and then add 1M NaOH,
drop by drop, just until the oil dissolves.
The solution may be cloudy, but no oil droplets should be visible.
* If you do not have enough clove oil, get some from your TA.
(Water soluble)
+ Other Compounds
(Ether soluble)
- Transfer 0.2 mL* of your clove oil into a clean, dry centrifuge tube.
Step 2 - Extraction of Salt
O-
CH2CH=CH2
OCH3
Na+
+ othersether x 2
ether layer
aqueous layer
O-
CH2CH=CH2
OCH3
Na+
other compounds
Discard in ether waste bottle
KEEP IT!!!!
3 mL
Aqueous layer
(KEEP IT!)
Ether layerRemove it!
Experimental Procedure
• Add 4-5 drops of benzoyl chloride to the centrifuge tube IN THE HOOD.
• Stopper and shake mixture thoroughly.
• Remove stopper and warm mixture for 5 minutes in hot water bath.
Use water aspiration to remove noxious fumes during heating.
(Your TA will show you how to set up a pipet aspirator.)
• After cooling, add 2 mL of ETHER to the centrifuge tube and shake.
• Allow the layers to separate. Ether layer
Aqueous layer
Discard!!!! Use pipet to remove
KEEP IT!!
• Dry ether layer with a small amount of Na2SO4.
Experimental Procedure Step 3 – Extraction of Final Product
• Filter the ether layer through a cotton plugged
pipet into another test tube.
• Add 1 mL methanol then reduce the solution
volume to ~0.5 mL by using a hot water bath.
• Cool the remaining solution and scratch
glass to crystallize.
• Collect and dry the crystals.
• Determine the mp and % yield of eugenol
benzoate.Calculate % recovery of eugenol and determine mp and % yield of eugenol benzoate. Your recovery calculation will require you to obtain the density.
Submit your product in a sample vial as instructed by your TA.
Remember!!!
Experimental Procedure Step 4 – Recrystallization
Percent Yield
The yield is usually also given as a relative yield, which is the actual yield divided by the theoretical yield (the ideal or mathematically calculated yield). The relative yield is then converted to a percentage value, the percent yield:
( Actual Mass / Theoretical Mass ) X 100% = % Yield
The theoretical yield value always relates to one of the reactants. This is usually the limiting one, taking into account the molar relation of the reactants and the stoichiometry of the reaction.
The ideal percent yield of a chemical reaction would be 100%, a value that is rarely reached. (Wet product can make you think that you have a high yield.)
For this lab, you need to determine the mass of eugenol from its density:
Density = Mass / Volume >>> Mass = Density X Volume
