Formation of an Alkene by Alcohol Dehydration Lab Report Balanced Chemical Equation for the Main Reaction Contrivance The eager-catalyzed dehydration of unimportant and tertiary alcohols involves non-isolable carbocation intermediaries. In the primary tread of the of the reaction contrivance beneath, a phosphoric eager catalyst adds a proton to the oxygen speck of the alcohol to contrive an oxonium ion. The OH is converted to a reconstruct leaving collection as the unequivocal impute on the oxygen weakens the carbon-oxygen association. The carbon-oxygen association breaks during fevering giving infiltrate an transient carbocation.
Without a nucleophile, the carbocation middle loses a proton from a carbon and contrives a carbon-carbon envelop association from the carbon-hydrogen electrons. The contriveation of a carbocation middle from the missing of a leaving collection classifies this as an Elimination Reaction. Table of Reagents Pertinent Safety Inshape The phosphoric eager in this lab is a corrosive eager. Caution must be used to not get the eager in adjunction delay husk or clothes. Gloves must be decrepit occasion address it. If there is a throw-off, bathe the area delay comprehensive amounts of infiltrate.
Cyclohexanol, and especially cyclohexene, are very flammable liquescents. Do not use an notorious flash as a spring of fever delay these substances. Outline of the Procedure Add 20 mL of cyclohexanol and 5 mL of 85% phosphoric eager to a 50-mL round-bottom flask parallel delay 1 or two outburst chips Swirl the flask gently to wholely mix the laminas and conglutinate this into a single-minded essential-tendency shaft Fever the flask until essential-tendency begins and sloth leaks the combination, powerful the fevering so that the latitude of the essential-tendency mist does not go overhead 100-105 degrees C.
Cool the receiver in an ice bath to contract the missing of leakate to evaporation Continue the essential-tendency until merely 5-10 mL of high-outburst redundancy is left in the flask Suffer the flask to propitious and disresemble the trappings
Transfer the leakate to a separatory funnel and weaken it delay 10 mL of saturated sodium chloride discerption, then parch off inferior aqueous lamina Add 5 mL of 10% sodium carbonate to discerption to counterpoise any eager, gently weaken the combination, and parch off the inferior aqueous lamina again Pour the surpassing lamina into a dry, neat Erlenmeyer flask Add 1-2 g of anhydrous calcium chloride, and suffer the flask to pause for 15-20 detaileds delay intermittent remarkable Neat and dry the condenser, essential-tendency flask and adapters for the developed essential-tendency Decant or depurate the dry cyclohexene from the calcium chloride into a dry essential-tendency flask and set up a single-minded essential-tendency trappings Add 1-2 outburst chips to the flask and leak the cyclohexene, collecting the liquescent that boils betwixt 79 and 85 degrees C in a detailed graduated cylinder Data and Observations The point of this lab is to synthesize cyclohexene from cyclohexanol using phosphoric eager. This ward had difficulties maintaining the latitude of the essential-tendency mist betwixt 100-105 degrees C. the leakate recovered that was betwixt 79 and 85 degrees C was discarded. The receiver was placed in an ice bath to contract evaporation. A whole of 21 mL was attentive. Results and Discussion Volume of cyclohexene: 2. 8 mL Weight from density of cyclohexene: (0. 810 g/mL) / (2. 8 mL) = *0. 29 g cyclohexe*ne Percentage render of cyclohexene: 20 mL x 0. 960 g/mL = 19. 2 g = 0. 192 mol 0. 192 mol x 82 g/mol = 15. g x 1mL/0. 81 g = 19. 4 mL (Theoretical Yield) 2. 8 mL/19. 4 mL x 100 = 14. 4% Render (but of palliable tendency) In a detailed trial tube, add 5 drops of cyclohexene to 1 mL of 0. 5% aqueous potassium permanganate discerption The discerption rancid brown forthafter a while and then contriveed a ebon, inspissated dive delayin 1 detailed 1 mL of a 2% discerption of bromine in carbon tetrachloride The discerption forthafter a while rancid serene, and remained that way throughout the lab Conclusions The dehydration of alcohols is one of different methods to result alkenes. This dehydration may be wellbred using a solid azoic eager such as sulfuric and phosphoric eager.
The primary tread in this transshape is protonation of the hydroxyl collection by the eager rendering an palliable leaving collection. Next infiltrate is eliminated from the atom resulting in a carbocation middle, which then eliminates a proton to contrive an alkene. Questions Name and describe the construction of the alkenes that sway be obtained by eager-catalyzed dehydration of 2-methylcyclohexanol 3-methyl-3-hexanol What would be the best alcohol to use in an eager-catalyzed dehydration to order 1, 3-dimethylcyclopentene? The most appropriate alcohol to use is 2*, 5*-dimethylcyclopentanol. Write equations to profession the products that contrive in the reactions of cyclohexene delay potassium permanganate and bromine.