Dehydration Lab Report

Dehydration refers to a chemical reaction where the reactant loses a water molecule. In the presence of a strong acid like 85% phosphoric acid, an alcohol like-2-methylcyclohexanol can be dehydrated to form an alkene. In this experiment, alcohol was dehydrated by E1 elimination, in order to synthesize cyclohexene. First, alcohol is protonated by the acid. Second, during E1 elimination, a carbocation is formed by the removal of an oxonium ion to yield a secondary and a tertiary carbocation. The receiving flask had a few drops of water before beginning the reaction. Upon the addition of 85% phosphoric acid and sulfuric acid and stirring in the simple distillation the clear solution turned pinkish. Heating began and the pink color of the solution
Upon addition of bromine, the brown color of bromine quickly disappears as the bromine adds to the double bond in the products. Addition of bromine to the fractional distillate caused the bromine to discolor. The addition of bromine to 2-methyl-cyclohexanol remains brown because there is an absence of double bound (saturation). Addition of potassium permanganate caused the solution to turn slightly brown but appeared immiscible as result of the unsaturation product. When analyzing the IR results confirmed the presence of an alcohol group with a distinctive wide peak at 3400 cm-1. The presences of sp3 C-H peaks were found at 2900 cm-1 as well as the C-O functional group at 1250 cm-1 for 2-methylcyclohexanol. When analyzing the functional groups for the alkenes, the presence of a carbon- carbon double bond is observed at 1650 cm-1 as well as the sp2 C-H at 3100 cm-1. Also the prominent peak at 2900 cm-1 for sp3 C-H was observed for the alkenes product. However; there was the presence of an alcohol group in the product with a smaller but still visible peak at 3400 cm-1 as observed in the IR spectrum provided in the result
First peak correspond to methyl cyclohexane with a percentage of 15.81% and a boiling point of 102°C. Second peak corresponds to 3-methyl cyclohexene with a 2.37% and a boiling point of 104°C. Finally, the largest peak corresponds to 1-methycyclohexene with a high percentage of 81.3% and a boiling point of 110°C. The order in which the peaks appear in the GC is based on the retention time. The time taken for a particular compound to travel through the column to the detector is known as its retention time. The lowest alkene percentage is 3-methyl cyclohexene due to its derivation of a secondary carbocation. 1-methycyclohexene has the highest peak percentage due to is derivation of a tertiary carbocation and therefore more substituted alkene. 3-methyl cyclohexene also derivate from a tertiary carbocation, but it is not the least substituted and therefore less percentage is observed. IR and GC spectra are attached and labeled