Analysis Of Cyclohexene Lab Report
PREPARING CYCLOHEXENE FROM CYCLOHEXANOL
INTRODUCTION
Alkenes can be prepared in the lab by dehydrating the corresponding alcohol. Concentrated sulphuric and phosphoric acids both act as dehydrating agents. Phosphoric acid is preferred because it gives a higher yield of the alkene. Concentrated H2SO4 reacts with alkenes.
SAFETY
Eye protection must be worn. Concentrated phosphoric acid is corrosive. Mop up spillages immediately with plenty of water.
Cyclohexene and cyclohexanol are highly flammable. Keep away from naked flames. Anhydrous calcium chloride is an irritant.
PREPARATION
1) Weigh out between 9 and 10 grams of cyclohexanol directly into a 250cm3 round-bottomed, quickfit flask. Record accurately the mass of alcohol …show more content…
used.
2) Measure out 4cm3 of concentrated phosphoric acid in a small, glass measuring cylinder.
Add this SLOWLY to the cyclohexanol in the flask and mix thoroughly by swirling cautiously.
3) Add an anti-bumping granule to the flask and set it up in the electric heating mantle with a reflux condenser fixed vertically to the top.
4) Heat the mixture until it boils. Adjust the heat control so that the mixture refluxes gently for about 10 to 15 minutes.
5) Allow to cool, then rearrange the apparatus to allow for distillation of the crude product. Do this by inserting a still head fitted with a thermometer between the top of the flask and the condenser. Attach a 100cm3 round-bottomed flask to the end of the condenser to collect the distillate. …show more content…
SEPARATION
Switch on the heater again and allow the mixture to boil gently so that all the cyclohexene vapour is condensed in the condenser. Collect the distillate that comes across between 70 and 90OC. Switch off the heater when you have finished collecting the distillate.
PURIFICATION
1) Pour the distillate into a separating (tap) funnel and shake it with an equal volume of saturated sodium chloride solution (this has a higher density than ordinary water and allows the two layers to separate more easily).
2) Once the two layers have separated, run off the lower aqueous layer and discard it. Pour the organic top layer (cyclohexene) into a small conical quickfit flask and add a few granules of anhydrous calcium chloride (a drying agent).
3) Stopper and swirl the flask gently until the liquid is clear. (The flask may be left overnight if desired).
4) Decant the cyclohexene from the conical flask into a clean round-bottomed flask and re-distil it, collecting the product in a previously weighed, clean, conical quickfit flask. Collect the liquid which comes over between 81 and 85OC (the boiling point of cyclohexene is 83OC).
5) Re-weigh the flask with the product.
RECORD OF WEIGHINGS
Mass of cyclohexanol used …………………………………………….. grams
Mass of empty conical flask …………………………………………….. grams
Mass of flask with cyclohexene …………………………………………….. grams
Mass of cyclohexene obtained …………………………………………….. grams
TESTS ON THE PRODUCT
1) Burn 1 drop of cyclohexene on a small tuft of ceramic wool in a crucible or combustion spoon.
Note the appearance of the flame.
2) Shake 1cm3 (1 teat pipette full) of bromine water with 3 or 4 drops of cyclohexene in a test tube. Observe what happens.
3) Add 2 or 3 drops of potassium manganate (VII) solution to 2cm3 of bench sulphuric acid in a clean test tube. Add 3 or 4 drops of cyclohexene and shake. Observe what happens.
4) Place 3 or 4 drops of cyclohexene in a clean test tube. Carefully add 2 or 3 drops of concentrated sulphuric acid and observe what happens.
When you have completed your tests, put any remaining cyclohexene into the “Solvents Residues” bottle in the fume cupboard. Rinse used glassware and place it on the wet tray. Clear away all apparatus and leave your bench clean and tidy.
QUESTIONS
1) 1 mole of cyclohexanol (C6H11OH) forms 1 mole of cyclohexene (C6H10).
a) Use your starting mass of cyclohexanol and the appropriate relative atomic masses to calculate the mass of cyclohexene you would expect to get if all the alcohol reacted (this is called the theoretical yield).
b) Calculate your actual yield of cyclohexene as a % of the theoretical
yield.
2) The combustion of cyclohexene:-
a) Suggest four products formed when cyclohexene burns.
b) Write a balanced chemical equation for the complete combustion of cyclohexene in plenty of oxygen.
3) The reaction with bromine water – Br2 (aq):-
a) Write a balanced equation for the reaction of cyclohexene with bromine.
b) Draw the structural formula of the product and give its name.
4) Draw the structural formula of the product formed when concentrated H2SO4 reacts with cyclohexanol. What organic compound is formed when this product is reacted with water?
5) The reactions of cyclohexene with bromine and concentrated H2SO4 are addition reactions. Explain what you understand by this term and say why alkenes readily undergo addition reactions.
INTRODUCTION
Alkenes can be prepared in the lab by dehydrating the corresponding alcohol. Concentrated sulphuric and phosphoric acids both act as dehydrating agents. Phosphoric acid is preferred because it gives a higher yield of the alkene. Concentrated H2SO4 reacts with alkenes.
SAFETY
Eye protection must be worn. Concentrated phosphoric acid is corrosive. Mop up spillages immediately with plenty of water.
Cyclohexene and cyclohexanol are highly flammable. Keep away from naked flames. Anhydrous calcium chloride is an irritant.
PREPARATION
1) Weigh out between 9 and 10 grams of cyclohexanol directly into a 250cm3 round-bottomed, quickfit flask. Record accurately the mass of alcohol …show more content…
used.
2) Measure out 4cm3 of concentrated phosphoric acid in a small, glass measuring cylinder.
Add this SLOWLY to the cyclohexanol in the flask and mix thoroughly by swirling cautiously.
3) Add an anti-bumping granule to the flask and set it up in the electric heating mantle with a reflux condenser fixed vertically to the top.
4) Heat the mixture until it boils. Adjust the heat control so that the mixture refluxes gently for about 10 to 15 minutes.
5) Allow to cool, then rearrange the apparatus to allow for distillation of the crude product. Do this by inserting a still head fitted with a thermometer between the top of the flask and the condenser. Attach a 100cm3 round-bottomed flask to the end of the condenser to collect the distillate. …show more content…
SEPARATION
Switch on the heater again and allow the mixture to boil gently so that all the cyclohexene vapour is condensed in the condenser. Collect the distillate that comes across between 70 and 90OC. Switch off the heater when you have finished collecting the distillate.
PURIFICATION
1) Pour the distillate into a separating (tap) funnel and shake it with an equal volume of saturated sodium chloride solution (this has a higher density than ordinary water and allows the two layers to separate more easily).
2) Once the two layers have separated, run off the lower aqueous layer and discard it. Pour the organic top layer (cyclohexene) into a small conical quickfit flask and add a few granules of anhydrous calcium chloride (a drying agent).
3) Stopper and swirl the flask gently until the liquid is clear. (The flask may be left overnight if desired).
4) Decant the cyclohexene from the conical flask into a clean round-bottomed flask and re-distil it, collecting the product in a previously weighed, clean, conical quickfit flask. Collect the liquid which comes over between 81 and 85OC (the boiling point of cyclohexene is 83OC).
5) Re-weigh the flask with the product.
RECORD OF WEIGHINGS
Mass of cyclohexanol used …………………………………………….. grams
Mass of empty conical flask …………………………………………….. grams
Mass of flask with cyclohexene …………………………………………….. grams
Mass of cyclohexene obtained …………………………………………….. grams
TESTS ON THE PRODUCT
1) Burn 1 drop of cyclohexene on a small tuft of ceramic wool in a crucible or combustion spoon.
Note the appearance of the flame.
2) Shake 1cm3 (1 teat pipette full) of bromine water with 3 or 4 drops of cyclohexene in a test tube. Observe what happens.
3) Add 2 or 3 drops of potassium manganate (VII) solution to 2cm3 of bench sulphuric acid in a clean test tube. Add 3 or 4 drops of cyclohexene and shake. Observe what happens.
4) Place 3 or 4 drops of cyclohexene in a clean test tube. Carefully add 2 or 3 drops of concentrated sulphuric acid and observe what happens.
When you have completed your tests, put any remaining cyclohexene into the “Solvents Residues” bottle in the fume cupboard. Rinse used glassware and place it on the wet tray. Clear away all apparatus and leave your bench clean and tidy.
QUESTIONS
1) 1 mole of cyclohexanol (C6H11OH) forms 1 mole of cyclohexene (C6H10).
a) Use your starting mass of cyclohexanol and the appropriate relative atomic masses to calculate the mass of cyclohexene you would expect to get if all the alcohol reacted (this is called the theoretical yield).
b) Calculate your actual yield of cyclohexene as a % of the theoretical
yield.
2) The combustion of cyclohexene:-
a) Suggest four products formed when cyclohexene burns.
b) Write a balanced chemical equation for the complete combustion of cyclohexene in plenty of oxygen.
3) The reaction with bromine water – Br2 (aq):-
a) Write a balanced equation for the reaction of cyclohexene with bromine.
b) Draw the structural formula of the product and give its name.
4) Draw the structural formula of the product formed when concentrated H2SO4 reacts with cyclohexanol. What organic compound is formed when this product is reacted with water?
5) The reactions of cyclohexene with bromine and concentrated H2SO4 are addition reactions. Explain what you understand by this term and say why alkenes readily undergo addition reactions.