Acetic acid can be used in the preparation of varnishes.
Acetic acid and sulfuric acid are, respectively, an organic carboxylic acid and an inorganic or “mineral” acid. The combination of glacial acetic acid and sulfuric acid, one of the strongest simple acids, resulted in one of the first two known “superacids.” This term superacid was introduced by chemists Hall and Conant in 1927 and refers to two groups by definition. Any acid stronger than 100% sulfuric acid is a Brönsted superacid, while any acid stronger than anhydrous aluminum trichloride is a Lewis superacid. Combining acids from these two groups resulted in the strongest known superacids, including the famous “magic acid” made up of fluorosulfonic acid and antimony pentafluoride.
Acetic acid can be used in a variety of chemical reactions.
Because it is a moderately weak acid, it may seem that the combination of acetic acid and sulfuric acid should result in a liquid of intermediate acidity. This is not the case, because this action does not simply result in the formation of a solution; instead, a reaction occurs between the two substances. To understand the reaction between acetic acid and sulfuric acid as fully as possible, it is necessary to focus closely on the actual structure of a carboxyl group.
The oxygen atoms within the carboxyl group (-COOH), although adjacently attracted, are not bonded to each other. In fact, the leftmost oxygen atom is bonded only to the carbon atom, forming a carbonyl group (-C=O), while the oxygen on the right is bonded only to carbon and hydrogen atoms, -C -OH. This allows us to visualize the reaction CH 3 COOH + H 2 SO 4 → CH 3 C (OH) 2 + . For clarification purposes, this structure can also be written: CH 3 C (OH) (OH). In theory, one molecule of acetic acid protonated by sulfuric acid would result in the production of HSO 4 -, whereas if a second molecule of acetic acid is protonated by this remaining bisulfate anion, the mechanism is CH 3 COOH + HSO 4 – → CH 3 CO(OH) 2 + SO 4 -2 .
Once protonated, this structure is thought to change in several ways, including the restoration of a carbonyl group, and the second branch becomes -C-OH 2 + . Acetic acid structures modified in one way or another would be joined in polymer-like segments with one of three substances: sulfuric acid molecules, HSO 4 ions, or SO 4 -2 ions. What has been definitively determined is that the stoichiometric ratio of acetic acid and sulfuric acid for the best behavior of the superacid is, in the protonation phase, 2:1, at the level of formation of the final product or segment, the ratio changes to 2 :1:3 .