The Dehydration of Cyclohexanol to Form Cyclohexene

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The Dehydration of Cyclohexanol to Form Cyclohexene

In order to dehydrate Cyclohexanol it is required that a dehydration

agent, in this case phosphoric acid, be added and for the mixture to

be distilled with the Cyclohexene being taken off between 343K and

363K. This reaction gives the formula:

In order to keep the experiment at a manageable size 0.1 mole of

Cyclohexanol was used along with 4cm3 of concentrated Phosphoric acid.

0.1 mole of Cyclohexanol x 100.2 = 10.2

100.2

0.962 = 10.4 cm3

However because the measuring cylinder only measured to the nearest

1cm3 ,10cm3 had to be used instead. This volume was placed into a 50cm3

pear shaped and the 4cm3 of phosphoric acid was added slowly while

shaking the flask. The flask was then attached to the rest of the

apparatus as shown below;

Because the boiling point of Cyclohexene is 356K and for water it

is373K it was decide best to reflux the mixture between the 343K and

368K or 70oC and 90oC as read off the thermometer. Because of this all

products collected in the vented receiver below 340K were discarded.

In order that water was not present inside the vented receiver or any

other component of the apparatus before the experiment began, all

components were cleaned with acitone. Once the experiment had been set

up the mixture was heated with a Bunsen burner to a temperature of

around 363K where it was kept in order to increase the speed at which

the Cyclohexene was collected in the vented receiver. The temperature

was measured with a thermometer with the mercury tip placed at the

entrance to the condenser in order to be most accurate for the

temperature of the gas be...

... middle of paper ...

...ol were used and therefore the yield should really be taken

on 0.096 moles instead, giving a yield of 72.5%

The measuring cylinder used to measure out the 0.096 moles of

Cyclohexanol was only accurate to the nearest 1cm3 therefore it is

quite possible that 9.5cm3 of Cyclohexanol was measured out which is

0.091 moles, giving a yield of 76% or based on 10.5 cm3, a yield of

69.0%. The balance was only accurate to the nearest 0.01g and

therefore the weight of Cyclohexene produced could instead have been

5.655g which, working on 0.091 moles of reactant, gives a yield of

76.7%. On the other hand the weight might have been 5.645 which,

working on 1.008 moles of reactant, gives a yield of 68.9%.

From this we can se that the maximum yield for the experiment is

around 77% which is reasonable for an experiment of this nature.

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