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Synthesis of Isopentyl (Amyl) Acetate Ester(Banana Oil)

Overview

SynthesisAcid (H2SO4) catalyzed Fischer Esterificationreaction of a Carboxylic Acid (Acetic Acid) with theHydroxyl group of an Alcohol (Isopentyl [amyl] Alcohol)

This is a Condensation reaction where the moleculesbecome joined through the intermolecular elimination ofwater

Refluxing - Reagents will be Refluxed for about 60 minutes.

Liquid/Liquid Extraction - The product will be washedseveral times with Water, Sodium Bicarbonate, SodiumChloride

Dry Sample

Refractive Index (with temperature correction)

Infrared Spectrum2212/13/201

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The Laboratory Report:

Synthesis Experiment Mass, Moles, Molar Ratio, Limiting Reagent,

Theoretical Yield

Procedures

TitleConcise: Simple Distillation, Dry Sample, IRSpectrum, 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) form

Concise, but complete description

Use your own wordsDont copy book!!


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The Laboratory Report: (Cont)

ResultsNeat, logically designed template to presentresults

Summary experimental results, includingTheoretical Yield results, in paragraph form

Analysis & Conclusions

Limiting reagent

Discuss reaction mechanism in the context of yourexperimental results

Verification of product


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h f l ( l)


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Reagents Product

Acetic Acid Isopentyl (amyl) AcetateMol Wgt - 60.05 g/mole Mol Wgt - 130.19 g/mole

Density - 1.049 g/mL Density - 0.876

Boiling Point - 117.9oC Boiling Pnt - 142oC

% Acid - 100% Ref. Index - 1.4040

Isopentyl (amyl) Alcohol

Mol Wgt - 88.15 g/mole

Density - 0.809 g/mL

Boiling Point - 130.0oC

Sulfuric Acid

Mol Wgt - 98.08 g/mole

Density - 1.84 g/mL

% Acid - 96.5 %

Molarity - 36 moles/Liter

S h f l ( l)


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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

S h i f I l (A l) A E


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Elements of the Experiment

Equilibrium

Reaction equilibrium does not favorformation of the ester

Therefore, an excess of one of the reagents(Acetic AcidCheap!!!) is used to force theequilibrium to product side, i.e., to the right

S th i f I t l (A l) A t t E t


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Elements of the Experiment (Cont)


The reaction mixture is mixed with Distilled Waterand placed in a separatory funnel where the phasesseparate into two layersAqueous (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% SodiumBicarbonate to remove excess acid. Discard

Aqueous phase into waste beaker

Extract Organic phase twice with Saturated SodiumChloride to remove excess water. Discard Aqueousphase into waster beaker



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Elements of the Experiment (Cont)

Dry Product Dry crude ester (organic layer) with

Anhydrous Sodium Sulfate (less than 1 gram)

PurificationSimple Distillation (if so instructed)

Mass of Product

Percent (%) Yield

Refractive Index corrected for temperature

Infrared (IR) Spectrum



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Procedure

Measure out ~10 mL of Glacial Acetic Acid to thenearest 0.1 mL and compute the mass from thevolume and density

Weigh the Isopentyl Alcohol in the vial to the nearest0.001 g

Mix the reagents in a Beaker, swirling gently to ensurecomplete solution

If necessary, heat gently to help dissolution ofreactants

Carefully add 1.0 mL concentrated Sulfuric Acid to themixture mixing (swirling) quickly



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Procedure (Cont)

Set up a Reflux Apparatus using 50 mL roundbottom flask

Add a Corundum or Teflon (not calcium carbonate)boiling chip and heat the mixture under Gentle

reflux for 5060 minutes

Cool the mixture to Room Temperature


Transfer the mixture to a 125 mL SeparatoryFunnel using a Short Neck stem funnel

Note: Do not transfer boiling chip to funnel

Rinse reaction vessel with 10 mL Distilled Waterand add to mixture in separatory funnel



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Procedure (Cont)

Liquid/Liquid Extraction (Cont)

Mix phases by shaking and venting

Remove the lower aqueous layer and put it aside

for later disposal Extract the upper organic layer again with 10 mL

aqueous Sodium Bicarbonate to remove excess Acid

Note: The reaction between the residual acid and

Sodium Bicarbonate produces CO2gas andcould be under considerable pressure in theseparatory funnel. Hold the stopper firmly,invert the funnel, and release the stopcock veryslowly so the venting of the gas is controlled



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Procedure (Cont)

Liquid/Liquid Extreaction (Cont)

Remove the lower aqueous layer and add toprevious waste aqueous solution

Repeat the NaHCO3extraction a second time Perform a third extraction of the upper organic

layer in the Separatory Funnel with 10 mL ofsaturated Sodium Chloride to remove excess water

Remove the lower aqueous layer and add toprevious waste aqueous solution



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Procedure (Cont)

Liquid/Liquid Extraction (Cont)

Repeat the Sodium Chloride extraction a secondtime

Transfer the organic layer containing the crude esterto a small, clean, Erlenmeyer flask

Instructor will add 1.0 g of Anhydrous SodiumSulfate

Note: If mixture does not appear to dry (dryingagent will clump), add a little more SodiumSulfate

S nthesis of Isopent l (Am l) Acetate Este


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Procedure (Cont)

Allow the mixture to settle

Decant the dried sample into a pre-weighed 100 mLbeaker, leaving all solid material in the flask

Reweigh the beaker and determine the mass ofproduct

Determine percentage yield

Measure the Refractive Index and correct for

temperature

Obtain the IR Spectrum


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Purification of Product

If so instructed, purify and determine the boilingpoint of the sample using Simple Distillation (BoilingPoint of Isopentyl Acetate is 142oC)

Transfer purified product to small Erlenmeyer flask

Add ~ 1 g Anhydrous Sodium Sulfate Pre-weigh a small, clean 100 mL beaker

Decant the dried / purified sample into the pre-weighed beaker, leaving all solid material in the flask

Weigh the beak and calculate the mass of the productby difference

Compute % yield

Determine Refractive Index corrected for temperature

Synthesis of Isopentyl (Amyl) Acetate Ester


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Procedure (Cont)

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