Acetate by Azeotropic Distillation of Water & Organic Chemistry Lab Report
 Post Lab Report Format (typed, printed, page numbered, single spacing) (make sure to put Your Name and Your Partner’s Name together)Title (n-Butyl Acetate by Azeotropic Distillation of Water)Purpose (why we did the exp.)Chemical Structure (make sure to put the reference) You can draw your own structure with free software (any chemical structure drawing software is ok. However, put the name of the software below the structures)Safety Information/Physical Data (physical properties of compounds)Procedure (Your own paragraph form (3rd person))Clean-Up (how to clean up the wastes)Observational Data PresentationFinal mass of n-Butyl Acetate? Color of the product? IR? Briefly explain IR of the product. (See the attached IR in this announcement) % yield?Discussion (in PARAGRAPH FORM)Le Chatelier’s principle? How do Acetic acid and 1-butanol react? Why Dowex ion-exchange resin? Dean-Stark azeotropic esterification apparatus?Why 3 M sodium hydroxide solution (NaOH)? Why aqueous sodium chloride solution (brine)? sodium sulfate (Na2SO4)?Explain IR data. Any possible error?References (ACS format for discussion)Side reaction: N/A% yield: show your calculation work.Mechanisms: N/AAnalysis of TLC/IR/NMR: show the IR again and explain the IR of n-Butyl Acetate in detail.Post Lab Questions: N/AChapter 40: Exp. 1 n-Butyl Acetate by Azeotropic Distillation of Water O OOHDowex ion-exchange resin+ + H2OOH ©Dr. Wang O
  • Roles of chemicals
Dowex ion-exchange resin: a solid acid catalyst which can be easily removed from the liquid product by filtration. It can be considered as a safer (but less potent) solid variant of the concentrated sulfuric acid, which is a strongly corrosive, acidic, and oxidizing reagent in liquid form.
  • Background: Le Chatelier’s principle
Le Chatelier’s principle states that if a change is imposed on a system at equilibrium, the position of the equilibrium will shift in a direction that tends to reduce that change. If the above reaction is run under normal conditions and equilibrium is reached, there will always be some unreacted starting acetic acid and 1-butanol (or nbutanol) and theoretically the yield can never reach 100%. If we can somehow continuously remove water, however, the equilibrium will be disturbed and more and more n-butyl acetate together with water will be formed to compensate that change. If water can be completely removed then in theory 100% yield of n-butyl acetate could be obtained. In practice water removal is achieved with the Dean-Stark apparatus (FIG. 40.2, page 519) on macroscale. On microscale we can deliberately tilted the reaction apparatus to achieve the same water removal effect (FIG. 40.1).
  • Modified procedure
Prepare a sand bath of about 120 oC. Place a 5-mL round-bottomed, short-necked flask in a small beaker on a balance and zero the reading. Use pipette to carefully add ~0.60 g of acetic acid and 0.74 g of 1-butanol. Record the exact balance reading on your notebook. Weigh ~0.10 g of Dowex 50WX8-400 ion-exchange resin on a weighing paper and pour the solid into the flask. Try to get close to the specified weight, but if you measure a little bit more or less chemical than what is needed go with it. If there is any uncertainty as to whether you need to redo the operation please first check with Dr. Wang. Take the flask back to your hood, and then add one piece of boiling stone to the flask. Set up the microscale Dean-Stark azeotropic esterification apparatus according to Fig 40.1 on page 519, and bring the mixture to boil. Make sure the opening of the reflux condenser is pointing toward one far corner of your hood instead of yourself. Thus if the reaction gets out of control, the hot mixture will not shoot on you or your labmates. You may need to adjust the bath temperature or scrap the sand away (or around) the reaction flask to reflux in a manner such that the vapors condense about one-third of the way up the empty distilling column, which is functioning as an air condenser. Note that the vapor that1distills is a ternary azeotropic mixture of 1-butanol, n-butyl acetate, and water with a constant boiling point of 90.7 oC. Once you see continuous condensation of liquid in the upper sidearm begin timing and let the reaction proceed for 30 minutes. Carefully lift the apparatus out of the sand bath, allow it to cool, and tip the apparatus to upright position so that all liquids flow back into the flask. Ignore the small droplets which won’t flow down. Disconnect the apparatus.Remove the liquid from the reaction flask with a Pasteur pipette into a test tube #1. Leave the solid ion-exchange resin behind. Add to the test tube #1 1 mL of 3 M sodium hydroxide solution (NaOH), and mix the liquids thoroughly by pulling the two layers into a long (9 inches) Pasteur pipette and expelling them back into the test tube. Note that the product should form the top layer because its density (0.882 g/mL) is lower than that of the sodium hydroxide solution (1.13 g/mL). Be careful to avoid getting any liquid splashed onto your hand. Do this for about 1 minute. Allow the layers to separate completely and then draw off the bottom layer into another test tube (#2). The purpose of the sodium hydroxide wash is to remove any residual acetic acid. To the remaining liquid in test tube #1 add 1 mL of saturated aqueous sodium chloride solution (brine), and mix the liquids thoroughly with the previously used pipette. Note that the product should still form the top layer because of brine’s even higher density (1.20 g/mL). Allow the layers to separate completely and then draw off the top layer into another clean test tube (#3). Add enough sodium sulfate (Na2SO4) to tube #3 and shake the mixture until the solid can freely move around and the liquid becomes totally clear. Gently shake the mixture periodically for ~3 min. Put a small Erlenmeyer flask (or beaker) on the balance and zero the reading. Use a clean and dry pipette to transfer the clear liquid in test tube #3 into the flask (or beaker) on the balance. Make sure no Na2SO4 get transferred. Record the exact product mass into your notebook. In experiments involving liquid-liquid extraction, it is good practice to save all layers until you are sure that the product is in hand. Determine the weight of your product and then submit the sample to Dr. Wang for IR analysis. The product is volatile and should NOT be poured into the liquid organic wastes container until you have received your printed IR spectrum. In your lab report compare the IR spectrum of your product to those of the two starting materials and rationalize whether your reaction has worked or not.Cleaning up. Decant n-butyl acetate into the liquid organic wastes container. Everything else could be rinsed with soap water and flushed down the sink. Wash all dirty glassware with soap water and finally rinse with a small amount of acetone.2word image 1885word image 1886
Order a unique copy of this paper
(550 words)

Approximate price: $22