The purpose of this lab was for students to familiarize and perfect the simple distillation method to produce 4-Methylcyclohexene and to gain experience using an IR spectroscopy to characterize the product of the reaction in favor of equilibrium.
B.Results and Discussion:
24 mL of 4-methylcyclohexanol, 5mL of phosphoric acid, and 1mL of concentrated sulfuric acid was added to a 250 mL round bottom flask and mixed thoroughly with a magnetic stirrer. A simple distillation set up was installed with a 250mL round bottom flask, jack, stirrer, heating mantle, and variac.
The solution was heated gently with a small heating mantle to distill the crude product while keeping the vapor temperature around 100C or less. The crude product was collected which contained water, 4-methylcyclohexene, and trace acid.
1.Outline a mechanism for the dehydration of 4-methylcyclohexanol catalyzed by phosphoric acid.
2.What major alkene product is produced by the dehydration of the following alcohols? a.Cyclohexanol
3.Compare and interpret the infrared spectra of 4-Methylcyclohexene and 4-Methylcyclohexanol.
4.Identify the C-H out of plane bending vibrations in the infrared spectrum of 4-methylcyclohexne. What structural information can be obtained from these bands?
Properties of 4-Methylcyclohexene
1.Flash point: 154F
2.OSHA recommended personnel exposure level (PEL): 50 ppm (235 mg/cu m)
GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ Fire or Explosion: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back.
Most vapors are heavier than air. They will spread along ground and collect in low confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Those substances designated with “P” may polymerize explosively when heated or involved in a fire.