CHEM 324 - Lab 22.pdf - Experiment 22 The Synthesis of 7,7-Dichloronorcarne Using a Phase-Transfer Catalyst Hang Tran 40044938 CHEM 324 \u2013 Organic

CHEM 324 - Lab 22.pdf - Experiment 22 The Synthesis of...

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Experiment 22 The Synthesis of 7,7-Dichloronorcarne Using a Phase-Transfer Catalyst Hang Tran 40044938 CHEM 324 – Organic Chemistry III Concordia University Chem 324 – Thursday Afternoon Date Submitted: 17/10/2019
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Introduction The goal of this experiment was to synthesize 7,7-dichloronorcarane from cyclohexene and chloroform with the help of a phase transfer catalyst. This reaction proceeds through a formation of a highly reactive intermediate product, dichlorocarbene, which forms from reacting a strong aqueous solution of sodium hydroxide with 1 . Due to different solubilities of the reagents used in the reaction, a phase transfer catalyst (PTC) is used to allow the reagents to interact at the phase boundary. The PTC used in this experiment is tricaprylmethylammonium chloride, which is a quaternary ammonium cation with long alkyl chains. . Figure 1: Structure of tricaprylmethylammonium chloride Once the reaction occurred, the reaction mixture was clarified and extracted with diethyl ether and sodium chloride. The final product obtained in this reaction is 7,7-dichloronorcarane. Figure 2: Reaction scheme of this experiment An important technique used in this experiment was the rotary evaporator, or Rotovap. This technique allows for evaporation of diethyl ether in the final reaction solution to obtain the crude oil of 7,7-dichloronorcarane. The Rotovap accomplishes the evaporation of the solvent in three ways. Firstly, the solution mixture in a round bottom flask is placed under a vacuum PTC
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chamber which reduces pressure to lower the solvent’s boiling point. Secondly, the solution mixture can be lowered into the Rotovap’s water bath to heat up the reaction and evaporate the solvent. Lastly, the Rotovap continuously spins the round bottom flask to increase the surface area of the solution which also allows for faster evaporation of the solvent 2 . Observations When cyclohexene, chloroform, and tricaprylmethylammonium chloride were mixed together, a clear solution was formed Once NaOH was added, the solution thickened into a yellowish colour Once cyclohexanol was added, the solution turned into a brown/slushy mixture Swirling of the reaction mixture turned it into a light brown, slightly slushy and liquid solution Throughout swirling process, temperature did not go over 50 ° C After 10-15 minutes of swirling, the temperature decreased on its own to about 25 ° C The first wash was done with 50mL of diethyl ether o Bottom layer was a darker brown o Top layer was light brown Second wash was done with 25mL diethyl ether o Bottom layer was a darker brown o Top layer was light brown The organic layer was observed to be very chunky with light brown precipitate Third wash was done with 25mL NaCl o Bottom layer was darker brown o Top layer was chunky brown so distilled water was added to dissolve the solid Fourth wash was done with 25mL NaCl o Bottom layer was a clear, colourless solution o Top layer was a clear, orange/brown solution
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