Synthesis of 7.7-Dichlorobicyclo [4.1.0]Heptane †Phase...

Abstract The preparation of 7.7-dichlorobicyclo [4.1.0]heptane which is also known as 7,7-dichloronorcarane was done by reacting cyclohexene , chloroform and a base( 50% aqueous sodium hydroxide) with benzyl triethylammonium chloride. The latter being a water soluble phase transfer catalyst (PTC).reaction was performed at room temperature and was distilled at atmospheric pressure. The mechanism of action of the above mentioned PTC is described in the text along with the mechanism for the addition of a dichlorocarbene. The percentage yield obtained was 38.80%. This is considerably low due to an unfortunate spillage of the product at the stage of semi- micro distillation. Introduction Phase transfer catalysts (PCT) are used to†¦show more content†¦The vigorous stirring also increases the turbulence in the reaction flask which facilitates collisions between the primary reactants. This is needed for the reaction to occur at an optimum rate. Hence, the rate constants of the reaction increase as stirring speed increases. 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. It was during this stirring time that the action of the PTC is significant. The mechanism of action of the PTC is illustrated and explained below. 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. As seen above, benzyl triethylammonium chloride undergoes a nucleophillic substitution with NaOH. The hydroxyl group f rom the base displaces the chloride group on the PTC which results in the formation of a quaternary ammonium hydroxide. The PTC is now able to transport the OH ion to the organic phase where it can react with chloroform. The three step mechanism describing the formation of 7.7-dichlorobicyclo [4.1.0]heptane is illustrated and explained below. In step one, the hydroxyl group