To prepare an alkene, cyclohexene, by the dehydration of an alcohol, cyclohexanol, and better understand the processes that take place during this reaction. Introduction:
One of the common ways of preparing an alkene is through the dehydration of an alcohol. In this experiment cyclohexanol is dehydrated to prepare cyclohexene while using sulfuric acid as a catalyst.
A bromine test can be later done to ensure that the end product is an alkene.Procedure:
The procedure given on pages 24-25 in the CH102 Lab Manual 2012 was followed with a few modifications as follows. Steps 6 and 7 were interchanged, that is, first 10cm³ of 3M aqueous sodium hydroxide solution was transferred to a separating funnel to which the distillate was added so that incase the funnel was leaking no distillate would be lost. Some changes were also made to step 12. Instead of gravity filtration using cotton wool, decantation was used to filter the cyclohexene into a pre-weighed conical flask. Data and Observation:
Reference: Aylward.G,Findlay.T,2008,SI Chemical Data ,John Wiley & Sons Australia,LTD,6th ed, pp92-98.
Reference (for density of cyclohexanol): Aylward.G,Findlay.T,2008,SI Chemical Data, John Wiley & Sons Australia,LTD,6th ed, p92.
Color of sample (cyclohexanol)Clear solution
Color of BromineBrownish red
Color of Bromine + sample (after reaction)Clear
Mass of cyclohexene = flask and cyclohexene – flask
= 49.0107g – 39.1276g = 9.8831g
Mr (cyclohexene) =10H + 6C
Moles (cyclohexene) = mass/Mr