synthesis of isopentyl (amyl) acetate ester (banana oil)
DESCRIPTION
Synthesis of Isopentyl (Amyl) Acetate Ester (Banana Oil). Resources Pavia: p. 84 – 91; 686 – 688; 693 – 697 Lab Website: http://classweb.gmu.edu/chemlab Schornick: http://classweb.gmu.edu/ jschorni/chem318. - PowerPoint PPT PresentationTRANSCRIPT
Synthesis of Isopentyl (Amyl) Acetate Ester (Banana Oil)
04/21/23 1
Resources
Pavia: p. 84 – 91; 686 – 688; 693 – 697
Lab Website: http://classweb.gmu.edu/chemlab
Schornick: http://classweb.gmu.edu/ jschorni/chem318
Synthesis of Isopentyl (Amyl) Acetate Ester (Banana Oil)
Overview Synthesis – Acid (H2SO4) catalyzed Fischer Esterification
reaction of a Carboxylic Acid (Acetic Acid) with the Hydroxyl group of an Alcohol (Isopentyl [Amyl] Alcohol)
This is a Condensation reaction where the molecules become joined through the intermolecular elimination of water
Refluxing - Reagents will be Refluxed for about 60 minutes.
Liquid/Liquid Extraction - The product will be washed several times with Water, Sodium Bicarbonate, Sodium Chloride
Dry Sample
Refractive Index (with temperature correction)
Infrared Spectrum04/21/23 2
Synthesis of Isopentyl (Amyl) Acetate Ester (Banana Oil)
04/21/23 3
The Laboratory Report: Synthesis Experiment
Mass, Moles, Molar Ratio, Limiting Reagent, Theoretical Yield
Procedures Title – Concise: Simple Distillation, Dry Sample,
IR Spectrum, etc. Materials & Equipment (2 Columns in list
(bullet) form)Note: include all reagents & principal
equipment used, including details of distillation setup
Description:Use list (bullet) formConcise, but complete descriptionUse your own words – Don’t copy book!!
Synthesis of Isopentyl (Amyl) Acetate Ester (Banana Oil)
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The Laboratory Report: (Con’t) Results – Neat, logically designed template to
present results Summary – experimental results, including
Theoretical Yield results, in paragraph form Analysis & Conclusions
Limiting reagent Discuss reaction mechanism in the context of
your experimental results Verification of product
Synthesis of Isopentyl (Amyl) Acetate Ester (Banana Oil)
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Synthesis of Isopentyl (Amyl) Acetate Ester (Banana Oil)
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Reagents ProductAcetic Acid Isopentyl (amyl) Acetate
Mol Wgt - 60.05 g/mole Mol Wgt - 130.19 g/moleDensity - 1.049 g/mL Density - 0.876Boiling Point - 117.9oC Boiling Pnt - 142oC% Acid - 100% Ref. Index - 1.4040
Isopentyl (amyl) AlcoholMol Wgt - 88.15 g/mole Density - 0.809 g/mLBoiling Point - 130.0oC
Sulfuric AcidMol Wgt - 98.08 g/moleDensity - 1.84 g/mL% Acid - 96.5 %Molarity - 36 moles/Liter
Synthesis of Isopentyl (Amyl) Acetate Ester (Banana Oil)
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Heating Under Reflux
The reaction mixture is heated in a “reflux apparatus” consisting of a 25 or 50 mL round bottom flask attached to a vertical water-cooled condenser set in a heating mantle. Liquid/Liquid Extraction
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
04/21/23 8
Elements of the Experiment
Equilibrium
Reaction equilibrium does not favor formation of the ester
Therefore, an excess of one of the reagents (Acetic Acid – Cheap!!!) is used to force the equilibrium to product side, i.e., to the right
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
04/21/23 9
Elements of the Experiment (Con’t)
Liquid/Liquid Extraction
The reaction mixture is mixed with Distilled Water and placed in a separatory funnel where the phases separate into two layers – Aqueous (higher density) layer on bottom and the Organic layer on top. Separate the Aqueous phase into a waste beaker
Extract Organic phase twice with 5% Sodium Bicarbonate to remove excess acid. Discard Aqueous phase into waste beaker
Extract Organic phase twice with Saturated Sodium Chloride to remove excess water. Discard Aqueous phase into waster beaker
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
04/21/23 10
Elements of the Experiment (Con’t)
Dry Product– Dry crude ester (organic layer) with Anhydrous Sodium Sulfate (less than 1 gram)
Mass of Product
Percent (%) Yield
Refractive Index corrected for temperature
Infrared (IR) Spectrum
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
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Procedure
Measure out ~10 mL of Glacial Acetic Acid to the nearest 0.1 mL and compute the mass from the volume and density
Weigh the Isopentyl Alcohol in the vial to the nearest 0.001 g
Mix the reagents in a Beaker, swirling gently to ensure complete solution
If necessary, heat gently to help dissolution of reactants
Carefully add 1.0 mL concentrated Sulfuric Acid to the mixture mixing (swirling) quickly
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
04/21/23 12
Procedure (Con’t) Set up a “Reflux” Apparatus using a 50 mL round
bottom flask Add a “Corundum” or “Teflon” (not calcium
carbonate) boiling chip and heat the mixture under “Gentle” reflux for 50 – 60 minutes
Cool the mixture to Room Temperature Liquid/Liquid Extraction
Pretest the Separatory Funnel to ensure that the stopper and the stopcock assembly do not leak
Add about 50 mL distilled water to the funnel Shake vigorously for about 10 seconds Adjust stopper or stopcock as necessary and
repeat Drain water from funnel
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil) Procedure
Liquid/Liquid Extraction (con’t)
Transfer the reaction mixture to the Separatory Funnel using a short neck stem funnel
Note: Do not transfer boiling chip to funnel
Rinse reaction vessel with 10 mL Distilled Water and add to mixture in separatory funnel
Mix phases by shaking and venting
Remove the lower aqueous layer and put it aside for later disposal04/21/23 13
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
04/21/23 14
Procedure (Con’t)
Liquid/Liquid Extraction (Con’t)
Extract the upper organic layer with 10 mL aqueous Sodium Bicarbonate (NaHCO3) to remove excess Acid.
Note: The reaction between any residual acid and Sodium Bicarbonate produces CO2
gas and could be under considerable pressure in the separatory funnel.
Hold the stopper firmly, invert the funnel, and release the stopcock very slowly so the venting of the gas is controlled
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
04/21/23 15
Procedure (Con’t)
Liquid/Liquid Extreaction (Con’t)
Remove the lower aqueous layer and add to previous waste aqueous solution
Repeat the NaHCO3 extraction a second time
Perform a third extraction of the upper organic layer in the Separatory Funnel with 10 mL of saturated Sodium Chloride to remove excess water
Remove the lower aqueous layer and add to previous waste aqueous solution
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
04/21/23 16
Procedure (Con’t)
Liquid/Liquid Extraction (Con’t)
Repeat the Sodium Chloride extraction a second time
Transfer the organic layer containing the crude ester to a small, clean, Erlenmeyer flask
Instructor will add 1.0 g of Anhydrous Sodium Sulfate
Note: If mixture does not appear to dry (drying agent will clump), add a little more Sodium Sulfate
Synthesis of Isopentyl (Amyl) Acetate Ester
(Banana Oil)
04/21/23 17
Procedure (Con’t)
Allow the mixture to settle
Decant the dried sample into a pre-weighed 100 mL beaker, leaving all solid material in the flask
Reweigh the beaker and determine the mass of product
Determine percentage yield
Measure the Refractive Index and correct for temperature
Obtain the IR Spectrum