These reactions a and b are illustrated below. The percentage yield however was low If the reaction mixture was not stirred at high speeds, the reaction will not proceed to yield maximum product in the given time and will result in low percentage yields.
When the waiting period had elapsed, 15 ml of saturated sodium chloride and 15ml of hexane was slowly added to the reaction mixture. An Infrared and Gas chromatography analysis was done on the product for identification purposes.
The three step mechanism describing the formation of 7. The mechanism of action of the PTC is illustrated and explained below. A reflux condenser and a dropping funnel were then set up over the flask. It was necessary to stir the reaction intensely to ensure that the organic and aqueous layer in the reaction flask is well mixed, hence promoting mass transfer of the OH ion to the Chloroform molecule at the phase interface.
The gas chromatogram had two peaks and this could be due to the possibility of obtaining an impure product. The mixture was then transferred to a separating funnel and the lower aqueous layer was separated and discarded. Conclusion The synthesis of 7.
The organic layer was washed with two portions 25 ml of deionised water and was dried with anhydrous magnesium sulphate. As seen above, benzyl triethylammonium chloride undergoes a nucleophillic substitution with NaOH. Experimental Synthesis of 7. It was during this stirring time that the action of the PTC is significant.
These spectra are attached at the end of this report. CH2 bending and stretching peaks were identified in the region cm This is important since an accumulation of water can result in undesired reactions between chloroform or carbine with water.
It follows that this anion then slowly releases a chloride group to form the dichlorocarbene mechanism 2.
Here the PTC can also transport the chloride ions back to the aqueous phase via a base-induced? The distillate was then discarded and the remaining liquid was transferred to semi micro distillation apparatus where the product was distilled used a Bunsen burner.
After the addition of all the reactants, the reaction flask was placed under reflux, warmed and stirred vigorously for 40 minutes.
The carbine then attacks the double bond of cyclohexene to finally produce 7. This is needed for the reaction to occur at an optimum rate.
The water subsequently moves into the aqueous layer keeping the water content in the organic layer low. The vigorous stirring also increases the turbulence in the reaction flask which facilitates collisions between the primary reactants.
How to cite this page Choose cite format: The IR spectra were analyzed and the C-Cl bond was identified in the region cm The base used in this reaction is a strong one NaOH which dissociated completely in the aqueous phase to give an excess of OH ions which is needed for the generation of the dichlorocarbene in the organic phase.
The remainder 9ml of aqueous NaOH solution was then added drop wise over the next 20 minutes while the reaction mixture was to refluxing.
A distillation apparatus was set up and the solvents from the dried organic layer were distilled off using a steam bath.
Hire Writer Therefore the actual yield of product recovered was quiet low which resulted in a final percentage yield of only In step one, the hydroxyl group transported into the organic layer via the PTC deprotonates the chloroform molecule to form water.
Nevertheless the rest of the experiment was carried out with as much precision as possible.
Hence, the rate constants of the reaction increase as stirring speed increases.Phase Transfer Catalysis Addition To Dichlorocarbene To Cyclohexene also known as 7,7-dichloronorcarane was done by reacting cyclohexene, chloroform and a base(50% aqueous sodium hydroxide) with benzyl triethylammonium chloride.
The phase transfer base catalyzed generation of dichlorocarbene and its subsequent addition to cyclohexene is markedly influenced by the introduction of an alcohol or carboxylate.
Generally an added alcohol will facilitate the reaction while carboxylate ion retards the reaction. The current work. The authors have developed a procedure for the addition of dichlorocarbene to cyclohexane to give dichloronorcarane.
2,2-Dichlorobicycloheptane from cyclohexene and dichlorocarbene by phase transfer catalysis - Journal of Chemical Education (ACS Publications).
In LAB. Phase-Transfer Catalysis: Addition of Dichlorocarbene to Cyclohexene why did we need to stir themixture vigorously during the reaction.
The latter being a water soluble phase transfer catalyst (PTC).reaction was performed at room temperature and was distilled at atmospheric pressure. are in different phases. The reaction catalyzed in this experiment is the addition of a dichlorocarbene to cyclohexene.
The dichlorocarbene must first be generated in solution and this is done. The latter being a water soluble phase transfer catalyst (PTC). reaction was performed at room temperature and was distilled at atmospheric pressure.
are in different phases. The reaction catalyzed in this experiment is the addition of a dichlorocarbene to cyclohexene.
The dichlorocarbene must first be generated in solution and this is done.Download