Presentation on theme: "OXIDATION OF 9-FLUORENOL"— Presentation transcript:
1 OXIDATION OF 9-FLUORENOL Experiment 19:OXIDATION OF 9-FLUORENOL
2 Objectives:To synthesize a ketone from a secondary alcohol using household bleach.To monitor the reaction progress using TLC analysis.To purify product using simple extraction.To analyze the purity of the product using TLC and melting point analysis.To characterize reactants and products using IR analysis.
3 Before coming to lab… Review these techniques: TLC analysis Acid-base ExtractionDrying over MgSO4Melting Point Analysis
4 Typical oxidation vs. Green oxidation Typical oxidation using chromium compoundGreener oxidation using household bleach
5 Forming the oxidizing agent… NaOCl + CH3CO2H HOCl + CH3CO2NaSodium acetic hypochlorous sodiumHypochlorite acid acid acetateSodium hypochlorite is the main ingredient in bleach.It must first be converted to hypochlorous acid in order to oxidize the alcohol.HOCl is a source of a positive Cl, which has 2 fewer electrons than a chloride anion.Remember, oxidation is the loss of H or the addition of O.
6 From reaction of bleach CHEMICAL EQUATIONFrom reaction of bleachwith acetic acid!
7 PROPOSED MECHANISM13. Water abstracts a proton from the oxygen bearing the chlorine…1. Bleach is reacted with acetic acid to produce hypochlorous acid.232. Electropositive chlorine atom undergoes nucleophilic attack by oxygen of alcohol to form O-Cl bond…4. …followed by another attack on the proton of the carbon bearing the oxygen.45. Both electrons from the C-H bond form the p bond of the carbonyl, and a chlorine atom is eliminated to form the neutral product ketone.5Although complex, the mechanism results in the exchange of a Cl+ with a H+ on oxygen, followed by subsequent elimination of HCl to form the ketone.
8 OVERVIEWReact alcohol, acetic acid, and bleach dissolved in acetone to synthesize product.Follow the reaction progress using TLC analysis.Neutralize acid and perform extraction to purify product and isolate from unreacted starting materials.Evaporate solvent to yield solid product.To reweigh to obtain product mass and calculate % yield.Perform melting point analysis to identify and determine product purity.
9 Why are the Rf values different? The 9-fluorenol can DONATE hydrogen bonds to the silica gel on the TLC plate, resulting in a lower TLC Rf value!The 9-fluorenone can ACCEPT hydrogen bonds, but not donate to the silica gel on the TLC plate, resulting in a higher TLC Rf value!
10 Why does the color change? More conjugatedLess conjugatedThe more conjugated a compound is, the higher the wavelength of light it absorbs.The visible region of the spectrum is the nm wavelength range.If a compound absorbs light close to 400 nm, it will appear as a yellow color.
11 EXPERIMENTAL PROCEDURE (SYNTHESIS) Add Fluorenol to 50 mL flask with stir bar.Add acetone and stir of until dissolved.Add acetic acid and bleach while stirring. Place a small cork in top of flask to reduce decomposition of bleach.Stir 10 minutes.Perform TLC experiment to check for completion.If oxidation is incomplete, add more acetic acid and bleach, react for 10 additional minutes and repeat TLC experiment.If oxidation is complete, proceed to purification steps.Complete reaction!!!RCTSTDYOUR RXNPRODSTD
12 EXPERIMENTAL PROCEDURE (PURIFICATION) Transfer liquid to separatory funnel.Extract product into diethyl ether 2X.Wash organic layer with 5% NaHCO3 and Saturated NaCl.Transfer organic layer to clean flask.Dry over MgSO4.Transfer liquid to preweighed 150 mL beaker w/3 boiling chips.125 mL150 mL
13 EXPERIMENTAL PROCEDURE (PURIFICATION) Prepare a tap water bath using your 400mL beaker.Place the water bath on a hotplate and heat the water on a setting of 3 (NO HIGHER) until just above room temp.Remove water bath from hotplate.Slowly place the 150mL beaker containing diethyl ether into the water bath to evaporate the liquid solvent.If the solution boils too rapidly, remove it immediately until it ceases to boil!150 mL400 mL
14 EXPERIMENTAL PROCEDURE (PRODUCT ANALYSIS) Place LABELED 150mL beaker in oven for 10 minutes to dry. Reweigh.Repeat if %yield is greater than 100%!Reweigh to obtain final product mass and calculate % yield.Perform melting point analysis.YOUR NAME HERE
15 Table 19.1 Theoretical yield (g) Actual yield (g) % yield Calculate based on 9-fluorenol ONLY! Bleach is used in excess!Actual yield (g)(Beaker + product weight) – (empty beaker weight)% yield(Actual yield/theoretical yield) X 100Melting Range (oC)Compare to lit value of 81-85oC.Product AppearancePhysical state and color of product
16 Table 19.2 Atom Economy (%) Cost per Synthesis ($) Cost per gram ($/g) Should be calculated based on 9-Fluorenol and hypochlorous acid (HOCl), NOT bleach (NaOCl)Review Experiment 13 for calculation.Cost per Synthesis ($)Remember to calculate COST PER SYNTHESIS using 9-Fluorenol, bleach, acetic acid and acetone.Cost of stock bottles on p. 167!Cost per gram ($/g)COST PER SYNTHESIS/ACTUAL YIELD
17 Table 19.3 Compound TLC Rf values Standards Sample 9-fluorenone Rf values are UNITLESS!Rf values are 2 decimal places ONLY!If more than one TLC experiment is performed, record data from final TLC plate!9-fluorenol
18 IR SpectroscopyRemember to concentrate on the types of bonds that indicate the CONVERSION from reactant to product!30413196103130601716
19 Table 19.4 Functional Group Base Values (cm-1) 9-fluorenol 9-fluorenoneOH stretchC-O stretchC=O stretchsp2 CH stretch
20 Acetic acid is corrosive! SAFETY CONCERNSDIETHYL ETHER IS EXTREMELY FLAMMABLE! NEVER place diethyl ether directly on a hotplate!Acetic acid is corrosive!
21 WASTE MANAGEMENT“LIQUID WASTE” container: any/all liquid waste from extraction and TLC experiment.“SOLID WASTE” container: any/all solid waste from synthesis and purification.BROKEN GLASS box: Place used TLC and melting point capillaries.
22 CLEANING Clean all glassware with soap, water, and brush if necessary. Rinse all glassware with wash acetone before returning to lab drawer.DO NOT return any glassware to lab drawer dirty or wet.
23 LABORATORY NOTEBOOK (Pre-lab) OBJECTIVE (Must clearly state…)What compounds will be made and howHow the compounds will be purifiedHow the purity of the product will be determinedCHEMICAL EQUATIONInclude the chemical equation from the top of page 161.TABLE OF PHYSICAL DATA (Complete the following table using a site listed on WWW Links ONLY. Wikipedia is unacceptable!)REFERENCE TO PROCEDURE (Must include…)full title including edition and author namespage numbers where actual procedure can be foundCompoundMW (g/mol)mp(oC)bp(oC)d (g/mL)HAZARDS9-fluorenol182.22XNone known9-fluorenone180.2181-85Acetic acidAcetoneHypochlorous acid52.46Diethyl ether
24 LABORATORY NOTEBOOK (In-lab) DATA/CALCULATIONSInitial weight of 9-fluorenol usedTLC diagram (s) with all cm measurementsInitial weight of 150 mL beakerFinal weight of 150 mL beaker + productFinal product weightPhysical state and color of productTheoretical yield calculationPercent yield calculationAtom economy calculationCost per synthesis and cost per gram calculationsGive at least one TLC Rf value calculationEXPERIMENTAL PROCEDUREIn paragraph form, describe the procedure that you actually followed during the lab.Paragraph must be written in PAST TENSE, PASSIVE VOICE.Include any volumes or weights of chemicals used during the experiment.Include any observations or errors that occur (if any).