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Fumaric acid has pK a values of approximately 3.0 and 4.5. By contrast, maleic acid has pK a values of approximately 1.5 and 6.5. The reason for this large difference is that when one proton is removed from the cis isomer (maleic acid) a strong intramolecular hydrogen bond is formed with the nearby
A metal ion in aqueous solution or aqua ion is a cation, dissolved in water, of chemical formula [M(H 2 O) n] z+.The solvation number, n, determined by a variety of experimental methods is 4 for Li + and Be 2+ and 6 for most elements in periods 3 and 4 of the periodic table.
Solutions of metal aquo complexes are acidic owing to the ionization of protons from the water ligands. In dilute solution chromium(III) aquo complex has a pK a of about 4.3, affording a metal hydroxo complex: [Cr(H 2 O) 6] 3+ ⇌ [Cr(H 2 O) 5 (OH)] 2+ + H + Thus, the aquo ion is a weak acid, of comparable strength to acetic acid (pK a of about ...
As a solvent, hexafluoro-2-propanol is polar and exhibits strong hydrogen bonding properties. Testament to the strength of its hydrogen-bonding tendency is the fact that its 1:1 complex with THF distills near 100 °C. It has a relatively high dielectric constant of 16.7. It is also relatively acidic, with a pKa of 9.3, comparable to that for ...
At shorter distances, the barrier between the two energy minima is low enough that the hydrogen is equally bound as a low-barrier, or single-well hydrogen bond. A Low-barrier hydrogen bond (LBHB) is a special type of hydrogen bond. LBHBs can occur when the pKa of the two heteroatoms are closely matched, which allows the hydrogen to be more ...
In general, pK a values in water and organic solvent diverge significantly when the anion is capable of hydrogen bonding. For instance, in the case of water, the values differ dramatically: the pK a in water of water is 14.0, [15] while the pK a in DMSO of water is 31.4, [16] reflecting the differing ability of water and DMSO to stabilize the ...
Guanidinium chloride is a weak acid with a pK a of 13.6. The reason that it is such a weak acid is the complete delocalisation of the positive charge through 3 nitrogen atoms (plus a little bit positive charge on carbon). However, some stronger bases can deprotonate it, such as sodium hydroxide:
For instance, hydrogen fluoride, whether dissolved in water (= 3.2) or DMSO (= 15), has values indicating that it undergoes incomplete dissociation in these solvents, making it a weak acid. However, as the rigorously dried, neat acidic medium, hydrogen fluoride has an H 0 {\displaystyle H_{0}} value of –15, [ 1 ] making it a more strongly ...