Preparation+of+Cyclohexene

= Preparation of Cyclohexene =



Introduction:
Cyclohexene, a cycloalkene, is a colorless liquid that has a pungent odor. In this lab, cyclohexene will be produced by an acid catalyzed elimination reaction. Classically sulfuric acid would be used to complete the process of the E1 reaction, but for this particular lab phosphoric acid will be used which is less corrosive. The reaction takes places using a two-step elimination reaction where phosphoric acid initiates the OH to be removed causing a beta hydrogen to form a double bond in the carbon ring. How else could you word this last sentence, to make it more clear?

To complete the necessary reaction, cyclohexanol is combined with phosphoric acid and then distilled. The distilled liquid washed with water, further purifying the cyclohexene where it is then extracted into a separate collection flask. The collected cyclohexene is put into an Infrared Spectrometer to test its purity.

including the reaction, drawn out, is always a great idea!

Procedure:
The procedure for the experiment can be located at the following link:

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Procedural Changes: -Skip steps 6 and 7.

Data:
To convert from moles of cyclohexanol to grams of cyclohexanol, the following mathematics were performed: your answer ought to have just 2 sig figs.

Cyclohexanol: 7.417 g 85% H3PO4: ~1.75 mL Transformer setting prior to first drop: 40% of maximum voltage First drop: 73.3 degrees Celsius Elapsed time until first drop: 24.0 minutes Transformer voltage after first drop: 50% of maximum voltage Time elapsed until reaction completion: 48.5 minutes H20 wash: 5 mL Boiling point of cyclohexene: 83 degrees Celsius Final mass of product: 3.884 grams cyclohexene


 * = **Peak Number** ||= **1** ||= **2** ||= **3** ||= **4** ||= **5-8** ||
 * = **Postions** ||= 3013.07 ||= 2916.25 ||= 2848.94 ||= 2828.84 ||= In the Fingerprint Region ||
 * = **Bond Decription** ||= alkene

Csp2-H ||= Alkane

Csp3-H ||= Alkane

Csp3-H ||= Not within a Given Range ||=  || knowing that Cyclohexene has this type of bond, this point is close enough to call it so. ||=  ||=   ||=   ||=   || in the rooms as the infrared spec is being done. ||  ||   ||   ||   ||
 * = **Other Comments** ||= This point does not fall into the exact range for an Alkene but
 * Observations: || There is a reverse peak at approximately 2200 that can be attributed to the amount of CO2

__Graph : The graph above is the temperature inside the reflux tube throughout the distillation process.__
When you put graphs into your data, also include data tables to go with each. For instance, in this situation the range of temps over which distillation occurs is important, and I can't tell exactly what the highest temp is that is on the graph. A table of the data used to generate this graph would show it clearly.

Error Analysis:
One possible source of error could have came from the small amount of unknown liquid that was remaining in our reaction flask. This could have been left over from the previous lab. Also, some product remained in the distillation apparatus which was noticed upon dis-assembly leading to lower percent recovered product.

Conclusion/Analysis:
This experiment was to create a knowledge of how to perform an E1, or two step elimination reaction. The distillation process was used in order to purify the cyclohexene, not complete the reaction. From the infrared spectrum of the final product it is clear that the substance was very pure with no strange peaks on the spectrum. The fact that the copper which is used in the reflux condenser added to a more purified product. It allowed the cyclohexene to condense and re-evaporate more giving a higher level of purity.

What can be learned from the distillation temperatures? What can you say about the yield? I am not seeing a % yield calculation anywhere.

__Graph Observations:__
The large dip at the end of the graph is when the probe was removed from the hot reflux tube. The gradual incline from zero around 40 minutes was what was expected and the small dips within the curve can be from the temperature probe moving to the sides and touching the glass.

Sig figs: you can report more precisely in the Post-lab Answer below.

This lab earned the following scores for: format (2/2) style(2/2) data (2.5/3) quality of result (1/1) quality of reported data (0.5/1) conclusion (1/2) error (1/1) PLQ (1.5/2) for a total of 11.5/14. Please note that individual scores may reflect the level of contribution to the report by that person.