Calculations ethyl halide reactions

Calculations on ethyl halide reactions include that on the SN2 reaction between ethyl chloride and cyanide ion in DMSO.112 The calculated free energy of activation at the CCSD(T)/6-31+G(2df,2p) level on the B3LYP/6-31G(d)-optimized structure was within 1.5 kcalmol-1 of the experimental value. 

The free energies of activation for the Sn2 reactions between acetate ion and ethyl chloride, bromide, and iodide in DMSO and in water have been calculated at the MP4/CEP-31+G(d)/MP2 level of theory.87 The solvent was accounted for using the PCM method. There was good agreement (<2.6 kcalmol-1) between the calculated and experimental values for the reactions in DMSO and water and the relative reactivities of the halides were predicted correctly in both solvents. However, the rate increases found experimentally when the solvent was changed from water to DMSO were underestimated by up to 4.5 kcalmol-1. 

The effects of a- and 8-phenyl substitution can be calculated from the data of Table 5. The reaction rates for ethyl acetate a-phenyl ethyl-acetate a, /3-diphenylethylacetate are 1 45 130. Thus a phenyl group in the a-position, has a relatively large effect in the /3-position, a much smaller one. This behaviour is also observed with the halides, although in that case the enhancement of rate on a-phenylation is very much larger. 

By means of computer calculations, an attempt has been made to analyze a set of experimental stabilization data in order to extract the individual rate constants for various reactions that may occur during stabilization with metal salts (III). Ethyl j3-aminocrotonate, a representative of an auxiliary stabilizer type, has been shown to react with a model allylic halide (l-bromo-2-butene) via alkylation on C- rather than nitrogen (112). 

When the sodium derivative of acetoacetic ester is warmed with an alkyl halide, the metallic atom is replaced by an alkyl group. The stable form of these substances appears to have the keto structure. The reaction is usually effected by treating an alcoholic solution of acetoacetic ester with the calculated quantity of sodium ethylate, which converts the ester into its sodium derivative —... 

There is evidence that carbocations do play a role in the reaction of some diazonium ions. For example, the products of nucleophilic addition to f-butyl carbocations are essentially the same whether the carbocations are produced from aliphatic amines or from solvolysis of the corresponding alkyl halide. The decomposition of the diazonium ion to form a carbocation should become less favorable as the stability of the carbocation decreases, and the formation of an ethyl cation from ethyldiazonium ion in the gas phase has been calculated to be endothermic by 13.9kcal/mol. The decomposition of a 1° alkyldiazonium ion to N2 and a 1° carbocation in solution may be energetically more favorable, perhaps even exothermic, but it is questionable... 

Abstract - The effects of hydroxylic solvents on AG values for the solvolysis of t-butyl chloride have been dissected into initial-state and transition-state contributions. The AG°t(Tr) values, after correction for the "size or "cavity" effect, are well correlated with values for the Me N" " Cl ion-pair and for a-aminoacids. Similar calculations have been carried out for other alkyl halides and for S 2 i eaction of trie-thylamine with ethyl iodide. Dissections of AH" and AS for these Sj ] and S 2 reactions into initial-state effects are also reported. 

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