4.0 Discussion : 4.1 Hypothesis The hypothesis of the reaction, there was similarity by comparing the compound in case nitrogen was neutral and protonated. Table (1) illustrated that there was clearly different in the energy between two cases of that compound by 119 kJ/mole with basis set 6-311+G(d,p) and 128 kJ/mole with basis set 6-31 G(d) and similarly in level of theory(B3LYP). Therefore, the protonated nitrogen of the HALS molecule had higher energy than the neutral nitrogen through the potential energy of the reaction. Accordingly, the hypothesis that was reported becomes incorrect against to the calculation result found it from Gaussian program. 4.2 The aim of calculation the activation energy The objective of this report is to calculate the activation energy for the molecule of HALS reaction using GAUSSIAN 09 via the WebMO interface. There have been assumed that the transition state can be obtained through the reaction as in (Scheme3). By using the program and format (opt=(TS,calcfc,noeigen) freq=noraman) , the structure was optimized and formed as a ring shape in order to be able to transfer Hydrogen from Carbon to nitrogen in the molecule. It also was attempted re-drawing some of the N-O and O-C bond lengths/angles to try and get that final H down closer to the N. Consequently, the result of transferring hydrogen directly to nitrogen was slightly very weak resulting from the frequency output (the first one is negative) given a quite low number by -252 (cm-1). Beside that, it was animated the molecule from the program and did not look like a H- transfer is going to N (Figure 3 (A)). That is because the strongly effect of methyl group located surrounding into two sides of nitrogen led not to... ... middle of paper ... ... The aim of this report was to compute the activation energy of the HALS molecule. Based on that , the transition state was not determine correctly while followed steps by using different format on it. Moreover, the energy of protonated nitrogen in the molecule was higher than where it was neutral. There also were different value in enthalpy of reaction with changing (R=H) level of theory and basis set. It can be suggested that changing the mechanism of HALS molecule can contribute stabilization obtaining transition state. 6.0 Acknowledgment I would like to thank my supervisor, Dr. Stephen Blanksby for the available advice and support he has given me in the writing of this report. I would also like to thank my demonstrator David Marshall for his encouraged and guidance in carrying out the transition state of my report.
The percent yield of products that was calculated for this reaction was about 81.2%, fairly less pure than the previous product but still decently pure. A carbon NMR and H NMR were produced and used to identify the inequivalent carbons and hydrogens of the product. There were 9 constitutionally inequivalent carbons and potentially 4,5, or 6 constitutionally inequivalent hydrogens. On the H NMR there are 5 peaks, but at a closer inspection of the product, it seems there is only 4 constitutionally inequivalent hydrogens because of the symmetry held by the product and of this H’s. However, expansion of the peaks around the aromatic region on the NMR show 3 peaks, which was suppose to be only 2 peaks. In between the peaks is a peak from the solvent, xylene, that was used, which may account to for this discrepancy in the NMR. Furthermore, the product may have not been fully dissolved or was contaminated, leading to distortion (a splitting) of the peaks. The 2 peaks further down the spectrum were distinguished from two H’s, HF and HE, based off of shielding affects. The HF was closer to the O, so it experienced more of an up field shift than HE. On the C NMR, there are 9 constitutionally inequivalent carbons. A CNMR Peak Position for Typical Functional Group table was consulted to assign the carbons to their corresponding peaks. The carbonyl carbon, C1, is the farthest up field, while the carbons on the benzene ring are in the 120-140 ppm region. The sp3 hybridized carbon, C2 and C3, are the lowest on the spectrum. This reaction verifies the statement, ”Measurements have shown that while naphthalene and benzene both are considered especially stable due to their aromaticity, benzene is significantly more stable than naphthalene.” As seen in the reaction, the benzene ring is left untouched and only the naphthalene is involved in the reaction with maleic
The ratios for NaBH4, MPV, and L-selectride are 24.2:75.8, 43.6:56.3, 91.3:.86 respectively. According to analysis of the 1H-NMR spectrum, it is shown that the trans product formed over the cis. The mechanism for L-selectride is very similar to that of NaBH4, but NaBH4 primarily yields the more trans isomer whereas the L-selectride primarily the cis isomer. The reason for this is because in NaBH4, the hydride is not being blocked when convert to OH so it’s free to do a top attack to make a lot more of the the trans isomer. Whereas the L-selectride has bulky groups that block from the carbonyl oxygen which means that it must perform bottom attack and because of this, the isomer that gets made is the cis at 91%. In MPV, the proton is free to attack the carbonyl oxygen in a frontside attack to give more of the trans isomer The MPV reaction using aluminum isopropoxide gives reversible reduction of ketones and aldehydes and the cis or trans can revert back to starting ketone. Each step in the mechanism is reversible so the reaction is driven by the formation of the more stable product which favored thermodynamic. Overall, the stereoselectivity of reaction is affected how the hydride is opened was when it was attacking the carbonyl
In terms of kinetics, specifically speaking, the rate of reaction as determined by the concentration, reaction orders, and rate constant with each species in a chemical reaction. By using the concentration of the catalyst and the temperature, the overall reaction rate was determined. The rate constants of K0, Kobs, and Kcat can be derived via the plotting of the absorption at 400nm of p-nitrophenol vs. the concentration of the catalyst imidazole. Lastly, the free energy of activation, G, that is necessary to force the reactant’s transformation of the reactant to the transition state structure will be determined by using the equation G = H – TS derived from the Eyring plot. Introduction: The purpose of the experiment is to study the rate of reaction through varying concentrations of a catalyst or temperatures with a constant pH, and through the data obtained the rate law, constants, and activation energies can be experimentally determined.
The article begins by establishing the credibility of the authors. Their professional competency is established through the acknowledgement of their professional affiliations. These professional affiliations and subsequent status increases their credibility in terms of their authority and knowledge on the subject. Lisa...
In this experiment, four elimination reactions were compared and contrasted under acidic (H2SO4) and basic (KOC(CO3)3) conditions. The acid-catalyzed dehydration was done on 2-butanol and 1-butanol; a 2ᵒ and 1ᵒ alcohol, respectively. The base-induced dehydrobromination was performed on 2-bromobutane and 1-bromobutane; isomeric halides. The stereochemistry and regiochemistry of the four reactions were analyzed by gas chromatography (GC) to determine product distribution (assuming that the amount of each product in the gas mixture is proportional to the area under its complementary GC peak. The three butene products have been verified that they elute in the following order: 1-butene, trans-2-butene, and cis-2-butene.
Please list the references and clinical resources that you use in your review of this document. These references should support any clinical or extensive revisions or additions that you make. Aside from known common best practices, references are required. We reserve the right to request additional references. References and resources used:
The reaction of (-)-α-phellandrene, 1, and maleic anhydride, 2, gave a Diels-Alder adduct, 4,7-ethanoisobenzofuran-1,3-dione, 3a,4,7,7a-tetrahydro-5-methyl-8-(1-methylethyl), 3, this reaction gave white crystals in a yield of 2.64 g (37.56%). Both hydrogen and carbon NMR as well as NOESY, COSY and HSQC spectrum were used to prove that 3 had formed. These spectroscopic techniques also aided in the identification of whether the process was attack via the top of bottom face, as well as if this reaction was via the endo or exo process. These possible attacks give rise to four possible products, however, in reality due to steric interactions and electronics only one product is formed.
Sroufe. L. A., Egeland, B. E., Carlson, E. A., & Collins, W. A. (2005). The development of the
This memo examines the strengths and weaknesses of my presentation on March 19, 2010. In addition, the memo discusses my goals for improvement in future presentations as well as a review of Aly Sherali’s presentation.
Hydrogen is a tasteless, odorless, colorless gas. Hydrogen is found in group 1 and period 1 on the periodic table. Hydrogen is classified as a nonmetal on the periodic table. The symbol for hydrogen is represented by an H, its atomic number is 1, and its atomic weight is 1.0079. The hydrogen atom consists of one proton, which has a positive charge, and one electron, which has a negative charge. The term hydrogen comes from two Greek words meaning water-former. Henry Cavendish, an English scientist, discovered it in 1766. Named by Lavoisier, hydrogen is the most abundant of all elements in the universe. The sun and many other stars consist of mostly hydrogen. It is the third most abundant element on earth. It is estimated that hydrogen makes up more than 90% of all the atoms or three quarters of the mass of the universe. Hydrogen plays an important part in powering the universe though both the proton-proton reaction and carbon-nitrogen cycle. Hydrogen occurs in almost all organic compounds. Many of the compounds found in plant and animal tissues are organic. Production of hydrogen in the U.S. alone now amounts to about 3 billion cubic feet per year. Some of the methods that hydrogen is prepared by are steam on heated carbon, decomposition of certain hydrocarbons with heat, action of sodium or potassium hydroxide on aluminum, or displacement from acids by certain metals. Hydrogen may be condensed to a liquid that boils at -257.87°C and freezes at -259.14°C. Hydrogen ...
Abstract is a condensed version of the full report; this was well formulated by using headings instead of single paragraph style, thus looked uncluttered (Macnee, 2004). The purpose had c...
7- When describing the properties of JNJ 40279486, the authors highlight the selectivity of the compound over the hERG channel. Explain wh...
Aside from the prepared research questions, the researchers also asked Ms. Bernadette Dimaculangan, area chair of NSTP of DLSL, other questions related to the topic of the research. The other questions and Dimaculangan’s corresponding answers are listed in Table 6 below.
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
Sigfusson, Thorsteinn I. "Pathways to Hydrogen as an Energy Carrier." Philosophical Transactions: Mathematical, Physical and Engineering Sciences 365.1853 (2007): 1025-42. Web.