Oxidation of Cyclohexanol to Cyclohexanone :: essays research papers fc

Oxidation of Cyclohexanol to Cyclohexanone   Ã‚  Ã‚  Ã‚  Ã‚  The oxidation of cyclohexanol to cyclohexanone involves the removal of hydrogen from the OH group. After separation and purification, an Infrared Spectrum will be run to determine the composition of the recovered material.   Ã‚  Ã‚  Ã‚  Ã‚  Infrared Spectroscopy is a very powerful technique used in the determination of molecular structure and the identification of unknown organic materials. The infrared spectrum yields direct information about the presence or absence of key functional groups. â€Å"The region of the infrared spectrum which is of greatest interest to organic chemists is the wavelength range 2.5 to 15 micrometers which correspond to approximately 4000 to 600cm-1†(Young). â€Å"When atoms or molecules absorb light, the incoming energy excites a quantized structure to a higher energy level. The type of excitation depends on the wavelength of the light. Electrons are promoted to higher orbirtals by ultraviolet or visible light, vibrations are excited by infrared light, and rotations are excited by microwaves† (Tissue).   Ã‚  Ã‚  Ã‚  Ã‚  IR spectroscopy is the measurement of the wavelength and intensity of the absorption of infrared light by a sample. The wavelength of IR absorption bands are characteristic of specific types of chemical bonds.   Ã‚  Ã‚  Ã‚  Ã‚  An IR spectrophotometer is an instrument which is designed to obtain an infrared spectra of a molecule. An IR spectra is obtained by first irradiating a sample with an IR source of light. The light passes through the sample, which can be in solution or contained within a salt plate, and then onto an IR light detector. The spectrum is analyzed by examining at which frequency the peaks occur. Different peak frequencies indicate different types of vibrational motion and hence, different types of chemical bonds. The peak intensities are usually noted as percent transmittance which compares the amount of light absorbed compared to the amount of IR light that was not absorbed. The frequencies are normally listed in wave numbers (in units of reciprocal centimeters). Experiment   Ã‚  Ã‚  Ã‚  Ã‚  The oxidation of cyclohexanol by dichromate occurred in the presence of sulfuric acid which yielded cyclohexanone according to the balanced redox reaction below: 3 + Cr2O7-2 + 8H+ -- 3 + 2Cr+3 + 7H2O In the presence of excess dichromate, cyclohexanol oxidizes to adipic acid. To maximize yield, the following reaction was prevented: 3 + 4Cr2O7-2 + 32H+ -- 3HOOC(CH2)4COOH + 8Cr+3 + 19H2O The addition of methanol reduced the excess dichromate according to the balanced redox reaction below: CH3OH + Cr2O7-2 + 8H+ -- CO2 + 2Cr+3 + 6H2O Recovery of the ketone was by steam distillation; collecting all