General structure of a sulphonic acid
Sulfuric acid is an organic acid with the formula R-SO2H wherein a sulfur atom is bound to an organic residue, an oxydrile and, with double bond, to an oxygen. This group has a configuration similar to that of the carboxy group. However, the spatial configuration is not the same as the carboxy group has a flat shape while the sulfuric group is pyramidal (due to the sulfur electronic doublet, similar to that of ammonia nitrogen). In addition, the solfinyl groups have a pKa ranging from 1 to 2, as opposed to the carboxylic acids weighing around 4.
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