Potential energy hydrogen chloride

With the potential energies shown on a common scale we see that the transition state for formation of (CH3)3C is the highest energy point on the diagram A reaction can proceed no faster than its slowest step which is referred to as the rate determining step In the reaction of tert butyl alcohol with hydrogen chloride formation of the... 

FIGURE 4 12 Potential energy diagram for the reaction of tert butyl alcohol and hydrogen chloride according to the SnI mechanism... 

This assumption is no longer valid in its place the wave mechanics provides the simple explanation that the repulsive forces arise from the interpenetration of the atoms. As a simple example, we may consider the hydrogen ion and the chloride ion according to the wave mechanics the potential energy of these two ions at a distance R apart, assuming that no deformation occurs, is6... 

FIGURE 4.7 Potential energy diagram for proton transfer from hydrogen chloride to te/t-butyl alcohol. 

The reaction between ammonia and methyl halides has been studied by using ab initio quantum-chemical methods.90 An examination of the stationary points in the reaction potential surface leads to a possible new interpretation of the detailed mechanism of this reaction in different media, hr the gas phase, the product is predicted to be a strongly hydrogen-bonded complex of alkylammonium and halide ions, in contrast to the observed formation of the free ions from reaction hr a polar solvent. Another research group has also studied the reaction between ammonia and methyl chloride.91 A quantitative analysis was made of the changes induced on the potential-energy surface by solvation and static uniform electric fields, with the help of different indexes. The indexes reveal that external perturbations yield transition states which are both electronically and structurally advanced as compared to the transition state in the gas phase. 

B-9. To which point on the potential energy diagram for the reaction of 2-methylpropene with hydrogen chloride does the figure shown at the right correspond ... 

We may conclude that many-body forces are not important for the structure of solid hydrogen chloride (for further details see Sections 4.3 and 5). The energy of interaction in the dimer and in the solid fit very well into our relations. This is more a test of our assumptions of binary potentials in equations 8 and 18 than a limit on the role of many-body forces because the only available value was derived from cluster calculations based on the assumption of pairwise additivity. From the concepts and data discussed in this section it is obvious that an accurate description of clusters and condensed phases formed from polar molecules like HF and H20 which are both characteristic hydrogen bond donors and acceptors, requires a proper consideration of many-body forces. 

Karpfen, A., Bunker, P. R., and Jensen, P., An ab initio study of the hydrogen chloride dimer the potential energy surface and the characterization of the stationary points, Chem. Phys. 149, 299-309(1991). 

Quantum chemical computations of potential energies surface sections along the reaction pathway (PEES) for interaction of typical electrophiles (halogensilanes HaSiX (X = F, Cl, Br, I), trimethylchlorosilane [48,49], acetyl chloride [51]) and nucleophiles (hydrogen halides HX (X = F, Cl, Br, I), water, aliphatic amines, aliphatic alcohols [52], amino acids [53] and substituted phenols [54]) with the silica OH group in a cluster approach using semiempirical AMI, NDDO, MNDO and MNDO/H methods were performed. Representative PEES is shown in Fig.l. 

The mechanism for the reaction of ferf-butyl alcohol with hydrogen chloride presented in Figure 4.7 involves a sequence of three elementary steps. Each step has its own transition state, and the potential energy diagram in Figure 4.13 for the overall process is a composite of the energy diagrams for the three steps. 

---