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The preparation of cyclohexene from cyclohexanol

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Title: The preparation of cyclohexene from cyclohexanol. Objectives: To prepare cyclohexene from cyclohexanol by an elimination method and to test for unsaturation in product. To introduce the method of purification for an organic liquid. Introduction: The acid-catalyzed dehydration of an alcohol is an important method for the preparation of an alkene. It is also an example of an elimination reaction, which proceeds by a first order mechanism via an intermediate carbocation. In this experiment, cyclohexanol is dehydrated to cyclohexene n the presence of concentrated phosphoric acid: Distillation is employed in this experiment to synthesize and purify cyclohexene. The principle of distillation as a separation method is based on the difference in boiling points of substances. The identity and purity of the product can be checked by infrared spectroscopy and gas chromatography. Apparatus: Conical flask x 3 250cm3 beaker x 1 50cm3 pear-shaped flask x 1 Spatula x 1 Filter funnel x 1 150? thermometer x 1 Oil bath x 1 Test tubes x 2 Hot plate x 1 Screw cap adaptor x 1 Condenser x 1 Ice bath x 1 Still head x 1 Aluminium foil x 1 piece Filter paper x 1 Dropper x 1 Stir bar x 1 ...read more.


As the result, almost none of water can dissolve in the cyclohexene so we can extract out the all-high purity synthesized cyclohexene. This is a separation called solvent extraction or salting out. Since the anhydrous sodium sulphate is a very good dehydrating agent, it is used to remove the water in the mixture with cyclohexene. As we add excess amount of anhydrous sodium sulphate into the mixture, the water can be absorbed by it and the remains are the cyclohexene and the rest of the anhydrous sodium sulphate solid. After filtration, the remained dehydrating agent can be filtered out so the dry organic cyclohexene can be obtaine 6. What is the percentage yield of cyclohexene in your experiment? The mass of the extracted dry cyclohexene = (Mass of conical flask with extracted dry cyclohexene - mass of dry empty conical flask) = 46.62 -42.16 = 4.46 g No. Of moles of extracted dry cyclohexene = Mass / molar mass = 4.46 / [(1.008) (10) + (12.01) (6)] = 0.0543 Density of cyclohexanol = Mass/volume So, the mass = Density x volume = 0.948 x 15 = 14.22g No of moles of used cyclohexanol = Mass / molar mass = 14.22/ [(12.01) ...read more.


6. It should be lubricating the glass joints evenly, using only a small amount of lubricant. 7. Clamp the apparatus at a suitable position, with the movable parts uppermost and firmly but not too tight. 8. Place the thermometer bulb in the correct position; adjust the position of the thermometer by unscrewing the adapter, sliding the thermometer through the ring and then retightening it. 9. Set up a water condenser by checking that the rubber tubing is of sufficient length, fitting the rubber tubing by lubricating with a little water, running water into the condenser from the lower end, and controlling the rate of flow of water so that the tubing is not disloged, and the rate is geared to the boiling point of the distillate. 10. Don't let the rubber too close to the heater. Otherwise, the rubber will be broken. 11. Check that the system is not a closed one, the joints are well fitted and the system is not tilted, 12. The anti-bumping granules are added when the liquid is cold. Conclusion: The cyclohexene can prepared from cyclohexanol by an elimination method and tested that it was unsaturated. Also the purification of the product by adding sodium chloride and anhydrous sodium sulphate is worked. 1 ...read more.

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