Question: Draw the mechanism of the reaction you will complete in lab. Use the proper arrow drawing convention to show all bond making and bond breaking steps in the reaction.
Question: Draw the mechanism of the reaction you will complete in lab. Use the proper arrow drawing convention to show all bond making and bond breaking steps in the reaction.
Question: Draw the mechanism of the reaction you will complete in lab. Use the proper arrow drawing convention to show all bond making and bond breaking steps in the reaction.
Question: Draw the mechanism of the reaction you will complete in lab. Use the proper arrow drawing convention to show all bond making and bond breaking steps in the reaction.
Background info:
A substitution reaction takes place when a nucleophile (Nu:) forms a bond with a carbon atom, displacing a leaving group (L).
SN2 reaction Leaving groups are typically weak Bronsted bases that are stable as anions (often halide anions). The precise timing of when the leaving group leaves depends on the structure of the substrate – the molecule bearing the leaving group. Methyl and primary alkyl halides tend to undergo SN2 type reactions. In this type of reaction, the nucleophile attacks the carbon from the side opposite the leaving group and the nucleophile-carbon bond is made simultaneous with the carbon-leaving group bond breaking. SN2 reactions are one-step and there is an inversion of stereochemistry at the carbon bonded to the nucleophile. SN1 reaction If the carbon undergoing substitution is sterically hindered (as is the case with tertiary alkyl systems) or the intermediate carbocation is relatively stable (tertiary alkyl or resonance stabilized systems), SN1 reactions are prevalent. In this case, the nucleophile cannot approach the carbon bearing the leaving group as it would in an SN2 reaction or the carbocation is fairly stable, and the leaving group leaves first, forming a planar carbocation with a formal positive charge on the carbon. Once the carbocation is formed, it is attacked by the nucleophile forming a new bond. Reactivity, in terms of SN1 substitutions, is based on the stability of the carbocation intermediate formed. SN1 reactions are two step reactions where the first step involves the formation of the carbocation and the second step involves the attack of the nucleophile. Because of the achiral nature of the carbocation intermediate, if the carbon bearing the leaving group is chiral, then stereochemistry is lost in an SN1 reaction. The reaction you will be carrying out in lab will convert 9-fluorenol to 9-methoxy fluorene using a nucleophilic substitution reaction.
Obtain a hotplate, 10 mL round-bottom flask, and heat transfer block from the stockroom. Set up a reflux apparatus using a 10 mL round-bottom flask and a water condenser (which can be found in the red kit on your bench). Before attaching the round bottom flask, add your spin bar and 200 mg of 9- fluorenol (pre-weighed) to this flask and place it in your cork ring for safe holding. Measure out approximately 6 mL of methanol into your graduated cylinder. In the hood, slowly add 1.5 mL of concentrated sulfuric acid to the methanol with a transfer pipette (CAUTION: concentrated sulfuric acid is a strong acid. In case of contact with ANY organic material, immediately wash with cold water. Do not leave ‘drops’ of sulfuric acid on the table. Dispose of the transfer pipette in the container in the back of the hood.). The solution will become hot as the sulfuric acid is added (Why?). Return to your bench and pour the H2SO4/MeOH mixture into your flask and reassemble your reflux apparatus. Rinse the graduated cylinder with cold water. Start circulating the water in the water condenser. The water flow should be a slow steady stream and should enter from the bottom of the condenser. Set the reaction flask in the largest hole in the aluminum block and set the thermometer in the smallest hole of the aluminum block using the thermometer clamp. Heat the reaction mixture to about 100ºC while stirring. The solution should boil gently. Heat the solution for a total of 20 minutes, beginning from the time the reaction flask is put on heat. Remove the reaction flask from heat, i.e. unplug and move your hot plate, and allow it to cool to approximately room temperature, but do not detach the flask from the condenser yet. Be careful not to shake the flask when removing it from the heating block because it may start to boil violently. During this time obtain two spotting pipettes. Put a small amount of 9-fluorenol in a disposable culture tube and add enough dichloromethane to dissolve the sample. Once your reaction has cooled, prepare a TLC plate and spot it with 9-fluorenol and your
reaction mixture. Develop the TLC plate in methylene chloride. Visualize your plate using UV light and trace around the spots. Pour your reaction mixture into the waste bottle provided in the hood.
Definition Definition Organic compounds in which one or more hydrogen atom in an alkane is replaced by a halogen atom (fluorine, chlorine, bromine, or iodine). These are also known as haloalkanes.
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