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The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.
The aromatization of an additional ring in 4,12-Dihydrogen-4,8,12-triazatriangulene is utilized by Al-Yassiri and Puchta to get a representative for a new class of Δ-shaped proton sponges. [8] This compound has a calculated proton affinity of 254 kcal/mol (B3LYP/6-311+G**) and is therefore between 1,8-Bis(dimethylamino)naphthalene and HMPN.
According to calculations, ortho-diethynylbenzene dianion is the strongest superbase and has a proton affinity of 1,843.987 kJ/mol (440.723 kcal/mol). [1] The meta isomer is the second-strongest, and the para isomer is the third. All three are readily able to accept any proton to its ethynyl tails, from almost any compound.
Proton affinity: a measure of basicity in the gas phase. Stability constants of complexes : formation of a complex can often be seen as a competition between proton and metal ion for a ligand, which is the product of dissociation of an acid.
Organic superbases are charge-neutral compounds with basicities greater than that of proton sponge (pK BH + = 18.6 in MeCN)." [1] In a related definition: any species with a higher absolute proton affinity (APA = 245.3 kcal/mol) and intrinsic gas phase basicity (GB = 239 kcal/mol) than proton sponge. [6]
The broad definition, used generally throughout history, is that chemical affinity is that whereby substances enter into or resist decomposition. [ 2 ] The modern term chemical affinity is a somewhat modified variation of its eighteenth-century precursor "elective affinity" or elective attractions, a term that was used by the 18th century ...
The electron affinity of molecules is a complicated function of their electronic structure. For instance the electron affinity for benzene is negative, as is that of naphthalene, while those of anthracene, phenanthrene and pyrene are positive. In silico experiments show that the electron affinity of hexacyanobenzene surpasses that of fullerene. [5]
The water molecule is amphoteric in aqueous solution. It can either gain a proton to form a hydronium ion H 3 O +, or else lose a proton to form a hydroxide ion OH −. [7] Another possibility is the molecular autoionization reaction between two water molecules, in which one water molecule acts as an acid and another as a base. H 2 O + H 2 O ...