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...
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...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.
The experiment was not a success, there was percent yield of 1,423%. With a percent yield that is relatively high at 1,423% did not conclude a successful experiment, because impurities added to the mass of the actual product. There were many errors in this lab due to the product being transferred on numerous occasions as well, as spillage and splattering of the solution. Overall, learning how to take one product and chemically create something else as well as how working with others effectively turned out to be a
The experiment of Diels-Alder reactions, in particular the furan and maleic anhydride as used in my experiment, observed the exo product as oppose to the exo product. This shows the tendency for the stereochemistry of the Diels-Alder to yield an exo product in preference to the endo product. To determine the stereochemistry, a melt temperature of the product was taken and compared to literature values. The melt temperature for the product was roughly around 113oC, corresponding to the exo Diels-Alder product of furan and maleic anhydride. When compared to the class data of melting ranges, the melting temperature from the reaction was relatively consistent to the majority. Based off this, the assumption can be made that the Diels-Alder prefers
The goal of this two week lab was to examine the stereochemistry of the oxidation-reduction interconversion of 4-tert-butylcyclohexanol and 4-tert-butylcyclohexanone. The purpose of first week was to explore the oxidation of an alcohol to a ketone and see how the reduction of the ketone will affect the stereoselectivity. The purpose of first week is to oxidize the alcohol, 4-tert-butylcyclohexanol, to ketone just so that it can be reduced back into the alcohol to see how OH will react. The purpose of second week was to reduce 4-tert-butylcyclohexanol from first week and determine the effect of the product's diastereoselectivity by performing reduction procedures using sodium borohydride The chemicals for this lab are sodium hypochlorite, 4-tert-butylcyclohexanone
2-ethyl-1,3-hexanediol. The molecular weight of this compound is 146.2g/mol. It is converted into 2-ethyl-1-hydroxyhexan-3-one. This compounds molecular weight is 144.2g/mol. This gives a theoretical yield of .63 grams. My actual yield was .42 grams. Therefore, my percent yield was 67%. This was one of my highest yields yet. I felt that this was a good yield because part of this experiment is an equilibrium reaction. Hypochlorite must be used in excess to push the reaction to the right. Also, there were better ways to do this experiment where higher yields could have been produced. For example PCC could have been used. However, because of its toxic properties, its use is restricted. The purpose of this experiment was to determine which of the 3 compounds was formed from the starting material. The third compound was the oxidation of both alcohols. This could not have been my product because of the results of my IR. I had a broad large absorption is the range of 3200 to 3500 wavenumbers. This indicates the presence of an alcohol. If my compound had been fully oxidized then there would be no such alcohol present. Also, because of my IR, I know that my compound was one of the other 2 compounds because of the strong sharp absorption at 1705 wavenumbers. This indicates the presence of a carbonyl. Also, my 2,4-DNP test was positive. Therefore I had to prove which of the two compounds my final product was. The first was the oxidation of the primary alcohol, forming an aldehyde and a secondary alcohol. This could not have been my product because the Tollen’s test. My test was negative indicating no such aldehyde. Also, the textbook states that aldehydes show 2 characteristic absorption’s in the range of 2720-2820 wavenumbers. No such absorption’s were present in my sample. Therefore my final product was the oxidation of the secondary alcohol. My final product had a primary alcohol and a secondary ketone
2. A test tube was then filled with 35ml of yeast and placed in the
We finally took 1ml of the 0.01% solution from test tube using the glucose pipette and adding it to test tube 4, we then used the H2O pipette and added 9ml of H2O to test tube 4 creating 10ml of 0.001% solution.
The alcohol starting material, 2-methylcyclohexanol, was dehydrated through an E1 elimination by using of phosphoric acid as a catalyst. After a purification by simple distillation, which removed the alkene product and the by-product water from the reaction mixture, the methylcyclohexene products were analyzed by percent yield, boiling point, IR spectroscopy, and two chemical tests, Br2 in CCl4 and Jones test. By performing the simple distillation using pyrolysis, 85% of phosphoric acid and 2-methylcyclohexanol were added into the boiling flask, where the product from the collecting flask was condensed by the ice, and washed with the saturated sodium chloride. The weight of the product was determined and the percent yield of the product was
SE/TC is .413 and is not preferred because it is under 70% 7) The P/BV of 4.98
In this lab 4-tert-butylcyclohexanone is reduced by sodium borohydride (NaBH4) to produce the cis and trans isomers of 4-tert-butylcyclohexanol. Since the starting material is a ketone, NaBH4 is strong enough to perform a reduction and lithium aluminum hydride is not needed. NaBH4 can attack the carbonyl group at an equatorial (cis) or axial (trans) position, making this reaction stereoselective. After the ketone is reduced by the metal-hydride, hydrochloric acid adds a proton to the negatively charged oxygen to make a hydroxyl group. The trans isomer is more abundant than the cis based on the results found in the experiment and the fact that the trans isomer is more stable; due to having the largest functional groups in equatorial positions.
The actual amount of crude product was determined to be 3.11 grams. The percent yield of the crude product was determined to be 67.75 %. The actual amount of pure product formed was found to be 4.38 grams. The percent yield of the pure product was determined to be 95.42%. Regarding the thin layer chromatography, the line from the solvent front is 8 centimeters.
Theoretical yield is the maximum amount of product that can be produced during a reaction (French et al. 83). The numbers used to find theoretical yield must be those of the limiting reagent (French et al. 83). Because parts of the material used are inevitably lost during experiments, the actual yield will be smaller than the theoretical yield (French et al. 83). To test the efficiency of the reaction, calculate the percent yield as shown below:
-443.08 x (100.1 / 2.51) = -17670.2 J.mol. 1. H = -17.67 kJ.mol. 1.
Alcohol, which is the nucleophile, attacks the acid, H2SO4, which is the catalyst, forming oxonium. However, the oxonium leaves due to the positive charge on oxygen, which makes it unstable. A stable secondary carbocation is formed. The electrons from the conjugate base attack the proton, henceforth, forming an alkene. Through this attack, the regeneration of the catalyst is formed with the product, 4-methylcyclohexene, before it oxidizes with KMnO4. In simpler terms, protonation of oxygen and the elimination of H+ with formation of alkene occurs.
So how much distilled water should I add to the jug to make the resulting mixture 50/50? Here's where some critical thinking