Chem 347 Lecture 10e Oxidation of 9-Fluroenonol

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Chem 347 Lecture 10e Oxidation of 9-Fluroenonol Powered By Docstoc
					  Chem 347 Fall 2010                         Prof. Rob Ronald

  Oxidation of 9-Fluorenol – Preparation of 9-Fluorenone
• This experiment will give you an experience
  with running a medium scale reaction and
  purifying the product
  – Learn to set up and run a multigram scale reaction
  – Learn a typical procedure for reaction workup
  – Learn to isolate a crude reaction product
  – Learn to recrystallize on a multigram scale
• The platform we have selected for this
  laboratory exercise is the oxidation of 9-
  fluorenol to 9-fluorenone.
  – 9-Fluorenone is a reagent we use in the first
    semester laboratory to learn about hydride
    reductions.
   Chem 347 Fall 2010                                      Prof. Rob Ronald
• This experiment was developed by Chongjie Zhu and Jia Pan
  from the published procedure.
   – Luca, L. D.; Giacomelli, G.; Porcheddu, A. Organic Letters 2001, 3, 3041-
     3043
• This procedure can be adapted for running relatively large scale
  oxidations of 1° and 2° alcohols to produce aldehydes and
  ketones using an inexpensive and relatively benign oxidant –
  trichloroisocyanuric acid.
   – Trichloroisocyanuric acid is used as a source of chlorine for the
     treatment of the water in swimming pools, and hot tubs, and also as a
     disinfectant in the food industry.
   – The by-products of the reaction are water soluble chloroisocyanuric acids
     and HCl.
• The oxidation procedure of Luca, et.al. uses a stable free
  radical, 2,2,6,6-tetramethylpiperdine-1-oxyl (TEMPO), as an
  oxidation catalyst.
   Chem 347 Fall 2010                             Prof. Rob Ronald

• This is the Zhu-Pan modification of the Luca procedure
  (written in journal style):
  To a stirred mixture of powdered trichloroisocyanuric acid
  (10.0g, 43mmoles) and 9-fluorenol (7.5g, 41mmoles) in
  CH2Cl2 (30mL) in a 50mL round bottomed flask cooled in an
  ice bath was added TEMPO (2,2,6,6-tetramethylpiperdine-1-
  oxyl, 0.032g, 0.21mmoles). After the addition of the catalyst
  the mixture was stirred for 15 minutes and then the ice bath
  was removed and the mixture allowed to warm to room
  temperature. When the TLC showed that the reaction was
  complete the reaction mixture was filtered through a pad of
  Celite. The combined filtrate and rinses were washed with
  5% aq. NaHCO3 (2 x 10mL), 3N HCl (7.5mL), brine, dried
  with anhydrous Na2SO4, and concentrated to a yellow oil
  The crude product was crystallized from MeOH to give
  bright yellow crystals, 6.7g (91%), mp 81-83 °C.
Chem 347 Fall 2010                                                                              Prof. Rob Ronald
     9Fl#1a 09-14-10
     Oxidation of 9-Fluorenol
     Experiment 9/21/2010
     Intended Reaction.




           Reagent                         Mol. Unit     Wt-Vol calc mol/pts      Wt-Vol used mol/pts    Eq/pts
      9-Fluorenol                        182.2   FW        7.50   g    0.0412       7.46   g    0.0409     1.00
      CH2Cl2                               4.0   parts     30.0   mL        4.0     30.0   mL        4.0    4.0
      Trichloroisocyanuric acid          232.4   FW       10.04   g    0.0432       9.98   g    0.0429     1.05
      TEMPO                              156.2   FW       0.032   g    0.00021     0.035   g    0.00022 0.005
      9-Fluorenone                       180.2   FW        7.38   g    calc-obt     8.20   g     111.1% crude
      9-Fluorenone                       180.2   FW        7.38   g    calc-obt     6.72   g      91.1% x-tal

     Purpose/Rationale. The purpose of this experiment is to prepare the title compound using the
     procedure in the reference as modified by Zhu and Pan.
     Reference. Luca, L. D.; Giacomelli, G.; Porcheddu, A. Organic Letters 2001, 3, 3041-3043
     Setup. The reaction was run in a 100mL round bottomed flask fitted with a magnetic stirring bar
     and cooled in an ice bath.
     Reaction.
     Workup.
     Purification.
Chem 347 Fall 2010                                                  Prof. Rob Ronald

  Materials:
  Labware                                   Reagents/Solvents
  3-necked flask (100 mL)               1   9-fluorenol
  Clamp                                 1   Trichloroisocyanuric acid
  Magnetic stirring bar                 1   TEMPO
  Thermometer and thermometer adapter   1   Dichloromethane
  Reflux condenser                      1   NaHCO3 (sat.)
  Ice bath                              1   HCl
  Separatory Funnel (250mL)             1   Brine (sat. NaCl)
  iron ring                             1   Anhydrous Na2SO4
  Erlenmeyer flask (125 mL)             3   Charcoal
  Filtering adapter                     1   Celite
  Tared round bottom flask (250 mL)     1   Methanol
  Hirsch funnel                         1   Hexane
  Suction flask (125 mL)                1   EtOAc
  clamp holder                          1   TLC plates
  Büchner Funnel                        1
  Jar for TLC tank                      1
  TLC spotting pipettes
   Chem 347 Fall 2010                                         Prof. Rob Ronald

• Typical Workup Procedure for a reaction.
• This reaction calls for an additional filtration step that is not
  always used in working up reactions.
   – The crude reaction mixture is filtered through a pad of Celite (5-7mm
     thick) in a Büchner Funnel – filter into a suction flask and be sure to rinse
     the flask out and the also the filter pad with CH2Cl2.
• Transfer the filtered reaction solution to the separatory funnel
  and wash the reaction mixture as directed by the experimental
  procedure
   – Be sure you know which layer contains your product – test if you are
     unsure.
   – Keep the aqueous and organic phases in separate, labeled Erlenmeyer
     flasks.
• After you have washed the organic phase as directed dry it with
  Na2SO4 to remove residual water.
   – Filter the dried solution into a tared round bottomed flask using a funnel
     with a cotton plug in the stem
   – Be sure to rinse to get all the product into the flask
• 9-Fluorenone is colored so if you see colored traces on your
  glassware you are losing your product – RINSE!
   Chem 347 Fall 2010                                         Prof. Rob Ronald

• Concentrate your dried extract using the rotary evaporator.
   – After all the solvent is removed you can weigh the flask to obtain the
     weight of your crude product.
• The crude product may or may not crystallize at this point
• Dissolve the crude product in MeOH
   – You are aiming for about 3-7 parts of solvent for the crystallization
   – If you have trouble getting it to dissolve you can add a little CH2Cl2, but
     remember that will have to be boiled off in order for the product to
     crystallize from the MeOH
• While you are doing this set up a filtering apparatus as
  described in the unit on recrystallization to clarify your crude
  solution
• Once you get it all dissolved remove it from the heat and add
  some charcoal – be careful to add the charcoal slowly.
• Clarify (filter) the solution into the clean suction flask
• Place the suction flask on the hot plate and evaporate some of
  the solvent to concentrate the solution so that it can crystallize
   – Seed the solution if necessary to induce crystallization.
 Chem 347 Fall 2010                       Prof. Rob Ronald

                      Experimental Work
• 1st lab begin by finding a suitable TLC solvent
  system to analyze 9-fluorenol and 9-fluorenone
• Between the 1st and 2nd lab periods set up the
  calculations to run this experiment on a 10g
  scale based on 9-fluorenol.
• 2nd lab set up and organize all the equipment
  you will need for this experiment.
• Obtain the IR spectrum of 9-fluroenol as a
  reference.