Experiment N | Kinetics of the Depolymerization of Diacetone Alcohol via Basic Catalysis | | Ingrid Tafur -5672578 | 2/11/2011 |
CHM233O
Partner: Laura Marrongelli
Demonstrator: Cheryl McDowall
Objective
The rate constant of the depolymerization of diacetone alcohol via basic catalysis was determined by monitoring the change in volume as a function of time at constant temperature of a pseudo first order reaction where the species in excess was sodium hydroxide. This was accomplished by using a dilatometer as the apparatus and following both methods: isolation and initial rates in conjunction.
Introduction
Depolymerization is the process in which a compound is converted into one of a smaller molecular weight and of
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This increases the volume density. The volume of one molecule of diacetone alcohol is not the same as the effective volume of two molecules of acetone. Recall, that the rate constant is temperature dependent. Thus, the temperature must remain constant. The reagents and reaction occur submerged in a thermal water bath at 27C.
Figure 1 : The apparatus a dilatometer submerged in a constant water temperature at 27C.
As a result of volume being directly proportional to concentration, equation four becomes ln(vt- v∞)=-kobst (5)
Where v∞ is the volume at infinity, which is related to the starting amount of reagent. It is found when the reaction goes to completion and plateaus. vt is the volume at each reading from the dilatometer.
To find the rate constant of the reaction, the logarithm is taken for both sides of the equation in equation 3. This is known as the method of initial rates, the rate is measured at the beginning of the reaction for several different initial concentrationsii. log(kabs)=logk+mlog[OH-] (6)
In order to determine the rate constant ‘k’, three different hydroxyl-dependent observable k are needed and so a solution of NaOH must be made from the standard solutions given. To precisely know the concentration of the new molar NaOH concentration, a back titration standardization must be performed. To calculate the new molar
The objective of this lab was to create a ketone through an oxidation reaction using a using a secondary alcohol and oxidizing agent in order to use that ketone in a reduction reaction with a specific reducing agent to determine the affect of that reducing agent on the diastereoselectivity of the product. In the first part of this experiment, 4-tert-butylcyclohexanol was reacted with NaOCl, an oxidizing agent, and acetic acid to form 4-tert-butylcyclohexanone. In the second part of this experiment, 4-tert-butylcyclohexanone was reacted with a reducing agent, either NaBH4 in EtOH or Al(OiPr)3 in iPrOH, to form the product 4-tert-butylcyclohexanol. 1H NMR spectroscopy was used to determine the cis:trans ratio of the OH relative to the tert-butyl group in the product formed from the reduction reaction with each reducing agent. Thin-layer chromatography was used in both the oxidation and reduction steps to ensure that each reaction ran to completion.
Used to see if the temperature of the water is at 37oc – 40oc and if
By extrapolating from the curve, the concentration of the unknown solution is ≈ 1.9mg.mL. The rate of reaction increases linearly with an increase in the substrate concentration.
Rate= k [I-]1[H2O2]. (2.13675*10-5 ) = k [0.015] [0.015] then solve for k. For this trial, k=0.09497.
Alcohol dehydrations are widely used in many industries to produce alkene. In this experiment 2-methylcyclohexanol was dehydrated to three possible products using phosphoric acid as a catalyst. The main tool for this experiment is the Hickman still. First, Drierite was added to the Hickman still so that any excess water formed during the experiment will be absorbed. It also acted as a boiling stone and addition surface to increase surface area. Next, 0.75 mL of 2-methylcyclohexanol is added to the still and right after 1 mL of phosphoric acid is added. The phosphoric acid (H3PO4) acts as a catalyst in order for the reaction to occur. The mixture is heated up to between 120o Celsius and 160o Celsius. If the temperature goes above 165oC then
This reaction is spontaneous for almost all esters but can be very slow under typical conditions of temperature and pressure. The reaction occurs at a much faster rate if there is a significant amount of base (OH-) in the solution. In this lab experiment, the rate of this reaction will be studied using an ester called para-nitrophenyl acetate (PNA), which produces an alcohol,
Condensation reaction is a chemical reaction that joins two reactants to form a larger molecule with the loss of a small molecule, usually water. 1 This reaction is used as a basis for many important process in the plastic/food industry. The most common being the formation of ester, also known as esterification. When a carboxylic acid is reacted with alcohol in the presence of a dehydrating agent, ester and water molecule are formed as products:
Is this a linear relationship? What happens to the initial reaction rate as substrate concentration increases?
9) Trial E: Remove the syringe and empty the beaker. Add a Thermometer to the beaker. Add 200 mL of Room Temperature water to the beaker and heat with a Bunsen Burner until it reaches 100° C. Remove the Bunsen Burner. Repeat Steps 5 & 6.
In this experiment, an alkyne—diphenylacetylene—was prepared by a double dehydrobromination. Potassium hydroxide (KOH) and high heat were used to accomplish this. The precipitate of this reaction was collected by vacuum filtration. It was then washed with water and recrystallized using ethanol. The product was then isolated again before the weight was taken for further analysis of percent yield. The melting point was also taken to identify that it was the desired product.
This experiment was designed by conducting a substitution reaction to construct a complex compound (2-methylphenoxyacetic acid) from two simple parts; also known as synthesis - converting simple molecules into more complex molecules. A purification technique known as crystallization was used to purify the product. Suction filtration was used to filter out the product. The experiment was completed over a three-day experimental period.
Chemical kinetics involving reaction rates and mechanisms is an essential part of our daily life in the modern world. It helps us understand whether particular reactions are favorable and how to save time or prolong time during each reaction. Experiment demonstrated the how concentration, temperature and presence of a catalyst can change the rate of a reaction. 5 runs of dilution and reaction were made to show the effect of concentration on chemical reactions. A certain run from the previous task was twice duplicated to for a “hot and cold” test for reaction rate. The prior run was again duplicated for a test with
2) Calculate the a mean rate constant using orders of reactions and the rate equation allowing for the overall order or reaction to be found.
The purpose of this lab was to synthesize the ester isopentyl acetate via an acid catalyzed esterification (Fischer Esterification) of acetic acid with isopentyl alcohol. Emil Fischer and Arthur Speier were the pioneers of this reaction referred to as Fischer Esterification. The reaction is characterized by the combining of an alcohol and an acid (with an acid catalyst) to yield and ester plus water. In order to accomplish the reaction, the reactants were
The objective of this experiment is to successfully perform a dehydration of 1-butanol and 2-butanol, also dehydrobromination of 1-bromobutane and 2-bromobutane to form the alkene products 1-butene, trans-2-butene, and cis-2-butene. The dehydration reactions react under and acid-catalysis which follows an E1 mechanism. It was found that dehydration of 1-butanol yielded 3.84% cis-2-butene, 81.83% trans-2-butene, and 14.33% 1-butene, while 2-butanol is unknown due to mechanical issues with the GC machine. For the dehydrobromination, with the addition of a