Why is sulfuric acid a strong acid

As we show later, we believe this value to be greatly overestimated, by roughly a factor of 4. The difference in deprotonation enthalpy between a particular alkylogue of sulfuric acid and the corresponding i. The deprotonation enthalpy of each alkylogue of sulfuric acid should reflect some residual negative hyperconjugation between the reaction center and the bonds of the attached alkyl carbon.

The basic idea of the BLW method is to reduce the number of Slater determinants for a VB function, thus dramatically reducing the computational costs. In the BLW method, we partition the molecular system into several blocks or fragments or groups , and limit the block-localized MOs BL-MOs to expand within only one block and to be doubly occupied in closed-shell cases.

BL-MOs in the same block are constrained to be orthogonal like in MO methods, but among different blocks they are non-orthogonal like in VB theory. For each alkylogue, the alkyl chain was in the all- anti conformation. This ensures that the torsional strain in each alkyl chain is minimized and that artifacts imposed by the addition of an alkyl chain are consistent from one alkylogue to another.

The dashed curve represents the function derived from the nonlinear least-squares fit of the data, as explained later in the Discussion section. They all lie within a 1. This is explained by the fact that with greater polarizability, the negative charge that is produced in the alkoxide anion enjoys greater internal solvation.

As Higgins and Bartmess 49 point out, this is due to the ability of the alkyl chain to bend, allowing for more effective internal solvation when the chain becomes long enough. Such an effect is not reflected by our calculated numbers because all of the calculated geometries have an extended, all- anti alkyl chain.

In fact, for the purpose of our alkylogue method, the geometries with the extended alkyl chains are preferable because, when computing the difference in deprotonation enthalpies between corresponding alkylogues of sulfuric acid and ethanol, artifacts due to differences in this internal solvation are avoided.

For instance, strong acids can accelerate the synthesis and hydrolysis of carbonyl compounds. With carbonyl compounds such as esters, synthesis and hydrolysis go through a tetrahedral transition state, where the central carbon has an oxygen, an alcohol group, and the original alkyl group. Strong acids protonate the carbonyl, which makes the oxygen positively charged so that it can easily receive the double-bond electrons when the alcohol attacks the carbonyl carbon; this enables ester synthesis and hydrolysis.

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