Nucleophilic Substitution SN1-SN2

In reference to the collision theory, molecules act as small spheres that collide and bounce off each other, transferring energy among themselves when the collide. In order for a reaction to occur, there must be collisions between molecules. Through experimentation, factors are discovered that influence the reaction rates of chemical reactions include the concentration of reactants, temperature, surface area, the physical state of reactants, and a catalyst. This experiment regarding the factors that affect reaction rate tests the effects of increased concentration and

The Diels-Alder reaction was discovered and named after the Nobel Prize winning scientists Kurt Alder and Otto Diels in 1928. Such a reaction occurs when a diene with two adjacent double bonds is mixed with a dienophile consisting of a double bond in order to create a cyclohexene. The diene must be in the s-cis conformation in order for the electron transfer to engage correctly. If the diene in question is in s-trans conformation then the access to the molecules is limited, thus, no reaction can occur. The dienophile we used was maleic anhydride. Maleic anhydride possesses high electron withdrawing characteristics which caused a very quick reaction. The reaction will

The objective of this laboratory experiment is to study both SN1 and SN2 reactions. The first part of the lab focuses on synthesizing 1-bromobutane from 1-butanol by using an SN2 mechanism. The obtained product will then be analyzed using infrared spectroscopy and refractive index. The second part of the lab concentrates on how different factors influence the rate of SN1 reactions. The factors that will be examined are the leaving group, Br – versus Cl-; the structure of the alkyl group, 3◦ versus 2◦; and the polarity of the solvent, 40 percent 2-propanol versus 60 percent 2-propanol.

In this lab experiment we determined the kinetic rate constant for a solvoysis reaction and observed how a change in polarity of the solvents affects the reaction rate. For the specific reaction that we did in the lab we actually measured the formation of HCl since the rate of

Ans. Dipole moments of Fluoro-Cyclohexane have increased by a factor of 611.6 as compared to cyclohexane.

(b) Calculate the initial rate of absorption ofC12H26Sfrom a 1 mM solution at 20 °C ifits initial sticking coefficient is 1×10–6.6.A gas phase reaction between atomA and a diatomic molecule BC has a positive activationenergy to reach a collinear transition state. Describe how the reaction to form AB occurs.Suggest a plausible explanation for why the product AC is not formed.7.Calculate thecollision rateof waterwith a surface ifthe surfaceis exposed to (a) water vaporwith a pressure of 1 atm and (b) liquid water?The system is held at 350 K.8.The forward and reverse rate constants have been measured for the gas-phase reactionH2(g) +I2(g)2HI(g).The reaction is bimolecular in both directions with Arrhenius parametersA=4.45×105dm3mol–1s–1,Ea=170.3kJ mol–1(forward reaction)A'=5.79×101dm3mol–1s–1,Ea' =117.6kJ mol–1(reverse reaction)Computek,k' (rate constant for the reverse reaction),K,ΔrG°,ΔrH°, andΔrS° at

OMRI is based on the Overhauser effect that enhances the amplitude of the NMR signal of the solvent water protons while the ESR transition of the dissolved paramagnetic solute is saturated [9,19-22]. The enhancement of the proton polarization, of the NMR signal of the 1H nuclei (I = 1/2) of water molecules with couplings to an unpaired electron spin S = 1/2 of a dissolved free radical [43,44], is defined as:

Furthermore, this experiment demonstrated why and how Dichloromethane, a commonly used solvent, is used in many Organic Chemistry

The lines in Figures 6 (A) to 6 (F) indicate predicted values, using fitted rate constants for the reaction. The rate constant valueswere found to increase as expected as the temperature was increased. The activation energies were determined from the temperature dependency of the rate constants to be 831, 2494, 3076 and 2660 J/molfor hydrazone, tryptophol, cinnoline derivative, and polyindole formation, respectively(Table 2). The values indicate the amount of energy required to cross the energy barrier so that,the reaction can takes place. The activation energy for hydrazone formation is low(Table 2) indicating that, the reaction takes place at lower temperatures buttheactivation energy barrier is higherfor tryptophol formation.

Correspondingly, primary alkyl halides are the least likely to react. Additionally, the solvent has the ability to stabilize the carbocation. A polar protic solvent is favored as it will form hydrogen bonds to further stabilize the carbocation intermediate. Overall, SN1 reactions are widely dependent on the formation of a stable carbocation intermediate. Since SN1 reactions are dependent on the formation of the carbocation, and that step occurs separately from the nucleophilic addition, the rate of the reaction is not typically affected by the nature or concentration of the nucleophile.

The amount measured are merely estimates, as there are always uncertainty of 0.2 mL, which is a significant amount when dealing with small amounts of solution. Next, the rate constant at 40°C would be 5.0152 s-1 by using the equation found in the graph of ln absorbance versus time: y=3.2527(1/40) + 4.933 = 5.0152 s-1. Nevertheless, to the study the rate of the chemical reaction and how it is affected by concentration of the reactants, the rate constant, and activation energy is important. According to the chemist, Kim Davis, increasing the temperature increases the rate of the reaction because by increasing the temperature of a system the average kinetic energy of its constituent particles are increasing. As the average kinetic energy increases, the particles move faster, collide more frequently, possessing greater energy when they collide, therefore increasing the rate of the reaction. Moreover, concentration increases the rate of the reaction because the more reactant particles that collide per unit of time, the more often a reaction can occur. As a result, this experiment fostered knowledge on the relationships between the variables of the rate

The overall aim of this experimental investigation is to further research and investigate the factors of temperature and concentration and how these two elements can alter or change the speed or rate of a reaction. The aim will be investigated thoroughly, with multiple experiments being conducted to ultimately fulfil this aim, with as much detail and data as possible so an in-depth conclusion can be delivered.

As mentioned above, the initial addition (CHClBr+NO2→ CHClBrNO2 a) is barrierless and extremely exothermic. Considering the lower energy barriers for subsequent reactions, a, once formed, will isomerize or dissociate to the products. The energy information in the initial addition process is critically important for such case in the kinetic calculations. However, IRC calculation can not be conducted for the barrierless reaction. Since the electronic interaction between C in CHClBr and N in NO2 plays a significant role in this process, the energy profile of the association can be obtained by the relaxed scan, in which the C-N distance in a is fixed from r=2.2 to 3.6 Å in a step size of 1.0 Å and remaining geometries are optimized at B3LYP/6-31+G(d) level using tight convergence criteria. Subsequently, CASPT2 method is utilized to calculate the single point energies. Here, the energy of the reactants at r=10 Å are set to be zero for CASPT2 method. In order to account for the dynamic electron correlation, the CASPT2(16,11)/aug-cc-pVTZ energies are scaled by a factor of 1.18, corresponding to the ratio of the dissociation energies of a calculated at CCSD(T)/6-311++G(d,p) level (-45.17 kcal/mol) and the CASPT2(16,11)/aug-cc-pVTZ level (38.29 kcal/mol). Both of the results with ZPE correction are shown in Figure 3. Figure 3 confirmed our assumption that a is formed barrierlessly via carbon-to-nitrogen approach. Based on the energy information

The approach described above is novel and original because we are integrating the high level of programmability of DNA with natural catalysts, which are very significant to progress in many different scientific fields. Such integration enables coupling of enzymes to circuits that are capable of decision making and self-regulation, leading to an unprecedented level of control of catalytic reactions. To achieve our objectives, we will develop methods to systematically design, model and test both dynamic and structural components. We will also create software and mathematical tools that can predict the dynamic behavior of individual catalytic modules and multi-modular circuits.

The percentage removal of fluoride ion and amount adsorbed (in mg/g) were calculated using the following equations.