Oxidation of Cyclohexanol to Cyclohexanone
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.
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.
“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). “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).
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.
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
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
Absorbance was defined as: log I_o/I where I_o is incident light and I is the transmitted light. Fluorescence emission spectrum is different from fluorescence excitation spectrum because it records different wavelengths of chemical s...
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
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 IR spectrum that was obtained of the white crystals showed several functional groups present in the molecule. The spectrum shows weak sharp peak at 2865 to 2964 cm-1, which is often associated with C-H, sp3 hybridised, stretching in the molecule, peaks in this region often represent a methyl group or CH2 groups. There are also peaks at 1369 cm-1, which is associated with CH3 stretching. There is also C=O stretching at 1767 cm-1, which is a strong peak due to the large dipole created via the large difference in electronegativity of the carbon and the oxygen atom. An anhydride C-O resonates between 1000 and 1300 cm-1 it is a at least two bands. The peak is present in the 13C NMR at 1269 and 1299 cm-1 it is of medium intensity.
This week’s lab was the third and final step in a multi-step synthesis reaction. The starting material of this week was benzil and 1,3- diphenylacetone was added along with a strong base, KOH, to form the product tetraphenylcyclopentadienone. The product was confirmed to be tetraphenylcyclopentadienone based of the color of the product, the IR spectrum, and the mechanism of the reaction. The product of the reaction was a dark purple/black color, which corresponds to literature colors of tetraphenylcyclopentadienone. The tetraphenylcyclopentadienone product was a deep purple/black because of its absorption of all light wavelengths. The conjugated aromatic rings in the product create a delocalized pi electron system and the electrons are excited
Experimental and Computation Vibration-Rotation Spectroscopy for Carbon Monoxide Through the Use of High-Resolution Infrared (IR) Spectra
A spectrum is a group of light wavelengths that are ordered in relation to their wavelength length. The electromagnetic spectrum consists radio waves, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays. (1)Specifically, this lab looks at the visible light part of the spectrum because one of the colors in the visible light spectrum is shine through the sample. The visible light spectrum consists of colors of red, orange, yellow, green, blue, indigo, and violet. The color chosen to be shine through the sample is affected by the color of sample when mixed with the indicator Ammonium Vanadomolybdate (AMV). The color on the color wheel that is opposite of the solution’s color is the color that is shined through the
UV-254 nm, 15 V, 60 Hz, 0.16 A). Masses were taken on a Mettler AE 100. Rotary
in 5cm³ of water and add 4cm³ of ethanol. We had tom pour this mixture
An Investigation into the Decomposition of Hydrogen Peroxide Aim: To investigate the rate of decomposition of H2O2 with different amounts of catalyst (MnO2). Hypothesis: When H2O2 and a catalyst are mixed together, the catalyst would break down H2O2 into water and oxygen. This will result in bubbles being produced. With the data of these oxygen bubbles, the rate at which H2O2 decomposed could be found out. 2H2O2 (l) à2H2O + O2 The controlwould be to maintain the same temperature (room temperature) and to use the same amount of hydrogen peroxide (10ml) in all the tubes.
The system involved in this lab was L-dopa as a substrate, enzyme was Tyrosinase, and the product was Dopachrome. Tyrosinase is commonly known as polyphenol oxidase, an enzyme that present in plant and animal cell (#1 Boyer). In plant cell, the biological function if Tyrosinase is unknown, but its presence is readily apparent. Tyrosinase is also involved in the browning of fruits, tubers, and fungi that have been damaged. In mammalian cell, Tyrosinase is involved in melanin synthesis, which gives skin its color. It will act on the substrate L-dihydroxyphenylalanine (L-Dopa) and convert to Dopachrome, which is the product that has color, and it can measure at 475nm using the Spectrophotometer. This work based on the Beer-Lambert’s Law (A=εlc), A stands for Absorbance, ε is extinction coefficient or the molar absorptivity (M-1 cm-1), and l is the path length (distance) that light passes through the sample (cm), c is a concentration of solution (M) (#3 Ninfa, Ballou, Benore). Beer- Lambert Law predicts a linear relationship between absorbance and the concentration of a chemical species being analyzed. It states that the absorbance (A) of a sample solution is directly proportional to the concentration (c) of the absorbing colored
The sample was subjected to steam distillation as illustrated in Figure 1. A total of 50ml of distillate was collected while recording the temperature for every 5.0 ml of distillate. The distillate was transferred into a 250ml Erlenmeyer flask and 3.0 g of NaCl was added. The flask was cooled and the content was transferred into a 250-ml separatory funnel. Then 25.0ml of hexane was added and the mixture was shaken for 5 minutes with occasional venting. The aqueous layer was discarded and the organic layer was left inside. About 25.0ml of 10% NaOH was then added and the mixture was shaken as before. The aqueous layer was collected and then cooled in an ice bath. It was then acidified with enough 6.00 M HCl while the pH is being monitored with red litmus paper. Another 25.0 ml of hexane was added and the mixture was shaken as before. The hexane extract was saved and a small amount of anhydrous sodium sulfate was added. The mixture was then swirled for a couple of minutes then filtered. A small amount of the final extracted was tested separately with 1% FeCl3 and Bayer’s reagent.
J. Clayden, N. Greeves, S. Warren, P. Wothers. Organic Chemistry. 8th ed. 2007, Oxford University Press, p. 1186-1191.
Investigating the Effect of the Enzyme Catalyse On Hydrogen Peroxide Introduction The aim of this experiment is to determine the effects of varying enzyme (catalyse) on Hydrogen Peroxide. Hydrogen Peroxide + Catalyse à Water + Oxygen 2H2O2 à H2O + O2 + Heat Apparatus & Diagram [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE] Bung Potato Hydrogen Peroxide Water Collected Oxygen Delivery Tube Measuring Cylinder [IMAGE] Using the Equipment Safely It is important that we use the apparatus carefully, as safety will be an issue throughout the whole experiment. We will wear goggles and an apron or lab coat to protect our eyes and clothes. As we are using enzymes and Hydrogen Peroxide we need to be extra careful, ensuring they don't come into contact with our eyes, skin or clothes. Catalyse is an enzyme found in all living cells.