Purpose The purpose of the experiment is to identify and understand reactions under kinetic and thermodynamic control. A reaction under kinetic and thermodynamic control can form two different types of products. A reaction under kinetic control is known to be irreversible and the product is formed quickly. A reaction under thermodynamic control is known to require rigorous conditions. It is also reversible. The final product is more stable than the product made by kinetic control. The chart below shows the two types of reaction coordinates: The green line shows kinetic control, whereas the blue line shows thermodynamic control. (*SM = starting materials, TS = transition state, P = product) This experiment will help identify which compound …show more content…
The expected melting point of Semicarbazone of Cyclohexanone is 166°C.1 The assumed product is Semicarbazone of Cyclohexanone. Observed temperature being lower than the expected may indicate a contamination or an impurity. The low temperature result was shown to be more accurate than the room temperature result. Perhaps, in the room temperature, there was more of a mix in the products (i.e. containing both Semicarbazone of Cyclohexanone and Furaldehyde). This is reinforced by the pale yellow colour observed, when Semicarbazone of Cyclohexanone is supposed to be white. Room temperature result could be close to the eutectic point. This is kinetic control, as it is formed much quicker than the product of the high temperature reaction. To fix the problem of lower than expected melting point could be have a set temperature as to how cold the low temperature should be (e.g. …show more content…
The expected melting point of Semicarbazone of 2-furaldehyde is 202°C.1 It is implied that the product of the high temperature reaction is Semicarbazone of 2-furaldehyde. This is thermodynamic control. If under normal conditions, when the nucleophilic nitrogen attacks, it will attack the cyclohexanone. If under rigorous conditions, the nitrogen will attack 2-furaldehyde. This is due to the carbon on cyclohexanone being secondary (i.e. more stable) than the primary carbon of 2-furaldehyde. The trend observed is thermodynamic control seem to effect primary carbons, whereas, kinetic control seem to effect secondary carbons. Under thermodynamic control the intermediate seems the most unstable. The kinetic controlled intermediate seems the least unstable of the two. Some improvements to the experiment might be using Na Acetate or Na Citrate as buffers instead of KHPO4. The pH ranges are 4.5-5.5 and 4.7-5.5, respectively. This range falls closer to the ideal pH of 5, then KHPO4 (pH
The experiment of Diels-Alder reactions, in particular the furan and maleic anhydride as used in my experiment, observed the exo product as oppose to the exo product. This shows the tendency for the stereochemistry of the Diels-Alder to yield an exo product in preference to the endo product. To determine the stereochemistry, a melt temperature of the product was taken and compared to literature values. The melt temperature for the product was roughly around 113oC, corresponding to the exo Diels-Alder product of furan and maleic anhydride. When compared to the class data of melting ranges, the melting temperature from the reaction was relatively consistent to the majority. Based off this, the assumption can be made that the Diels-Alder prefers
This experiment was divided into two main steps. The first step was the addition of bromine to trans-stilbene. Trans-stilbene was weighted out 2.00g, 0.0111mol and mixed with 40ml of glacial acetic acid in 100ml Erlenmeyer flask on a hot bath. Pyridinium hydrobromide perbromide of 4.00g, 0.0125mol was added carefully into the flask.
Results: Through a melting point reading, it was determined that the product obtained was 2,4-Dibromoanisol mp 55-58 C. The products obtained by my partners, were determined to be: (p-bromoacetanilide mp 160-165 C) and (2,4,6 tribromoaniline, mp of 108-110 C) respectively.
As a result, the laboratory experiment was determined to be successful and the two product samples obtained and completed calculations displayed that overall bromide was a stronger nucleophile as the chloride ion was more electronegative than bromide, which allowed it to hold electrons in closerE. In conclusion, since bromide is less electronegative and has more electrons, it was able to share the unpaired electrons more easily than chlorideA. These results were expected, as the alkyl bromide would be the major product of procedure A as it followed the SN2 mechanism which was based on nucleophile strength and the product from procedure B would be a near-equal mixture as it followed the SN1 reaction mechanismC. The methods used during this experiment allowed for a successful completion and determination of the better nucleophile, but other additions and observations would have been interesting and beneficial as well. A possible examination of the two sample products collected using pH tested values or observation of sample spotted chromatography paper under a
The overall objective of this experiment was to perform a Wittig reaction from creating an ylide and mixing it with a carbonyl (C=O) compound, cinnamaldehyde. The completion of the reaction was confirmed ultimately from the initial TLC analysis. Since TLC separates the components of the spotted material, as long as the retention factor values were different for cinnamaldehyde, the starting reagent, and the product(s), it was evident that some of the reaction had gone to completion. However, as seen in Figure 3, there was some blurred area between the product spots. This indicated that there still existed some impurities, most likely the starting reagent, which was affecting the movement of the compounds through the solvent, petroleum
The percentage yield gained was 70% from the Fischer Esterification reaction, which evaluates to be a good production of yield produced as the reaction is known to be reversible where conditions such as the concentration of the reactants, pressure and temperature could affect the extent of the reaction from performing. These white crystalline crystals were tested for impurity by conducting a melting point analysis and taking spectrospic data such as the IR spectra, HNMR and CNMR to confirm the identification of the product. These spectrospic methods and melting point analysis confirmed the white crystalline crystals were benzocaine.
" This means that therefore the enthalpy change of a reaction can be measured by the calculation of 2 other reactions which relate directly to the reactants used in the first reaction and provided the same reaction conditions are used, the results will not be affected. We have the problem set by the experiment to determine the enthalpy change of the thermal decomposition of calcium carbonate. This is difficult because we cannot accurately measure how much thermal energy is taken from the surroundings and provided via thermal energy from a Bunsen flame into the reactants, due to its endothermic nature. Therefore, using the enthalpy changes obtained in reaction 1 and reaction 2 we can set up a Hess cycle.
Introduction The purpose of this experiment was to investigate the relationship between thermal energy and chemical reactions. A calorimeter is a metal container that is insulated for the purpose of conservation during a chemical process. In the calorimeter, a stirring rod and a thermometer place to keep track of the heat changes occurring during the experiment. Calorimetry was used in the experiments to measure the absorbed heat in a chemical process.
Acetamide 80 Maleic Acid 135 Vanillin 81 Urea 134 M-toluic Acid 113 4-acetamidophenol (or acetaminophen) 171 Benzoic Acid 122 Hydroquinone 172 Benzamide 128 Table 2: Collected Melting Point (mp) Data Sample Temperature (℃) at 1st Sign of Melting Temperature (℃) when Fully Melted
From looking at the results I can conclude that when the pH was 3 and
The aim of this experiment was to investigate the affect of the use of a catalyst and temperature on the rate of reaction while keeping all the other factors that affect the reaction rate constant.
Mixed melting point was used to confirm the identity of the product. The smaller the range, the more pure the substance. When the two substances are mixed; the melting point should be the same melting range as the as the melting range obtained after filtering. If the mixed melting point is lower one taken from the crystals, then the two substances are different.
I decided to experiment with pHs within the range pH 2 to pH7, as I
On further cooling the χT curve shows a sudden increase to 1.23 cm3.K.mol-1 at T=21 K followed by a sharp decrease down to 0.71 cm3.K.mol-1 at 5 K. The χT maximum de...
To control the rates of chemical reactions is imperative to the continued existence of our species. Controlled chemical reactions allow us to move forward in society, constantly. We find new ways to provide light and heat our homes, cook our food, and pursue in crafts that benefit our society. There are, however, just as there are advantages, disadvantages to the efficiency of controlling the rate of reactions, which in some cases can be fatal to our scientific development and progression. The growth of humankind necessitates that we must be able to control the rate of chemical reactions.