Exp. 5 – Preparation of Synthetic Banana Oil – Flashcards

Synthesis Isopentyl Acetate (banana oil) from Isopentyl Alcohol, Acetic Acid, Sulfuric Acid, and Heat With purity of <10% Alcohol and <2% Acetic Acid

Isopentyl Alcohol + Acetic Acid [H2SO4, Heat](reversible)--> Isopentyl Acetate + H20

1.An Ester Banana Oil 2.Need to use Fischer Esterification RXN (reversible organic reaction)

1. Organic Reaction - Heating Under Reflux 2. Separation - Separatory Funnel Drying 3. Purification - Distillation 4. Analysis - IR, 1H NMR, and GC

Because the reaction is reversible and has the ability to go back towards the reactants once the product has been reached

Isopentyl Alcohol - more expensive, not easily removed

Acetic Acid Cheaper and easier to remove

Catalyst - will not be used up in reaction Will speed up reaction time (and allow reaction to occur easier) by lowering activation barrier Reaction is reversible. If we put stress (through catalyst) on the reagents, this will push equilibrium toward products --> which will give us highest yield and purity of product About 12% eqv. to Isopentyl alcohol because it is not going to be used up in the experiment - only need a small amount to lower activation energy and kickstart reaction

No

It needs to be heated because it is endothermic (the product is higher energy than the starting materials, creating an activation barrier that must be over come) Use Reflux

Because reaction is reversible (and high activation barriers), will not to reflux for longer to make sure product doesn't go back to starting materials and we get highest yield and purity of product possible

1. Top = Organic (Isopentyl Alcohol and Acetate both have lower densities than water); Bottom = aqueous (MORE dense) 2. Additional extraction process - will pull water soluble materials (focuses specifically on acids) to aqueous layer 3. Sodium Bicarbonate will turn acids into salts, which will pull them into the aqueous layer (will remove any left over acids from organic layer) Do this AFTER water wash because water should remove most of the acids. Sodium Bicarbonate has a byproduct of CO2 gas... if you do not wash with water first (and vent frequently) will cause tiny "eruption/ volcano" in funnel.

1. Because reversible reaction and water is a by product; need to remove water from product before heating again (for distillation) otherwise the reaction will run in the reverse and go back to the starting materials 2. Sodium Sulfate - salt that will absorb water like sponge; can then pipet off organic product

1. Both are liquids, cannot recrystallize 2. Use a thermometer 3. Bulb just below the side arm of 3 way adapter; Too LOW = thermometer reads HIGH; distills too LOW (material distilling below and between temp.) Too HIGH= thermometer reads LOW; distills too HIGH (material distilling above and between temp.) 4. Look at its boiling point 5. Thermowell; because the boiling points are above 100 degrees C and water only gets to 100 degrees C

1. Use GC to calculate % composition

1. Allows us to separate organic molecules in a mixture based on boiling points and a molecule's affinity from the coating inside of the column (stationary phase) 2. Qualitative data about components of our mixture; gives % composition 3. 1 microliter of product (amt. varies) - do not want ANY air bubbles -Chart Speed: 2cm./1 min. -Be sure to mark "Time of Injection" 4. RT: how long it takes for the specific compound of the mixture to get through the column and reach detector (a) from "TIME OF INJECTION" to the top of peak (in cm) TIMES X cm./1 min. --> gives you time in MINUTES Peak Area: [H x W(at 0.5 H)] (cm) Percent Composition: [area of peak 1 / total area under all peaks added together] x 100 DO NOT NEED to include anything that eludes BEFORE TWO minutes 5. Helium (mobile phase) - its inert

Identify certain functional groups in a molecule

Identify specific structure of molecule to confirm if actual product was made 1. Number of Peaks 2. Position of Peaks 3. Intensity of Peaks 4. Multiplicity of Peaks

Decrease in product yield and purity (due to reversible nature of reaction)

Decrease in product yield because without the catalyst, rate of reaction would be very slow and 1 hr reflux would not be long enough

Nothing because this reagent is used in excess OR it could end up in product, causing product to reverse back to starting materials; decreasing product yield and purity

Decrease purity of product

The thermometer will read LOW but will distill ABOVE and between the desired temperature Generating impurities