2014年12月28日 · Note that an oxonium ion is simply an ion in which an oxygen carries a positive formal charge. Many oxonium ions exist. One of which is hydronium ion. The hydronium ion corresponds to the strongest acid able to exist in water for significant periods of time because a stronger acid will be immediately deprotonated by some base in the system.

2014年4月9日 · The pKa of H3O^+ is 0.0. The pKa of water is 14.0. As a simple proof, the pKa of the Na+ ion in water is 13.9

2018年1月7日 · You can think of the bromonium ion as a carbocation that has been stabilised by interaction with a nearby bromine atom. You have seen a similar effect - this 'oxonium ion' was an intermediate, for example, in the $\ce {S_N1}$ substitution of MOM chloride on …

2023年6月8日 · The question was marked duplicate to What is the pKa of the hydronium, or oxonium, ion (H3O+)?, and the answer disregarded auto-protonation of water as a thermodynamic process while citing Reference 2 (1998).

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2016年4月18日 · Mesomeric stabilization There is also a mesomeric stabilization between the resulting carbocation and a Oxonium-Ion in the S N 1-Mechanism. Steric Hindrance: In my opinion, through the planar region around the anomeric C (planar ether), there is no steric hindrance -> S N 2 possible. Temperature: high temperature -> S N 1 preferred.

2017年4月20日 · For the acid catalyzed opening of epoxides, the epoxide is first protonated to form the oxonium ion. I read in some textbooks that the $\ce{H2O}$ molecule, which acts as a nucleophile attacks in a $\mathrm{S_N2}$ concerted mechanism.

On the other hand, the oxonium ion is resonance stabilised, which would indicate that it is protonated in preference to the double bonds. Which reasoning is correct? And more importantly, in these situations how are we supposed to predict which factor dominates?

2020年6月1日 · Now deciding between hydroxy oxygen and alkene is a bit tougher task. Let us assume that proton attacked hydroxy oxygen and it formed oxonium ion, now it can be removed as water and a cation can be formed there. After formation of cation there is nothing to do and it will be waiting for the hydroxy component of water to get attacked by.

At low concentrations of a conjugate acid/base pair in aqueous solutions, the Henderson-Hasselbalch equation gives a good approximation of the ratio of acid and base: $$ \frac{[\ce{A-}]}{[\ce{AH}]}...