Proton sponge

As a proton sponge is called certain aromatic diamines which unusually high basicity own. Therefore, these results that the close-set amine groups with a mono-protonation of the destabilizing overlaps of the nitrogen - pairs of electrons and the strong steric reduce voltage. The strong N – H – N hydrogen bond also reduces the steric tension.

Examples

1,8-bis ( N , N -dimethylamino) naphthalene

1,8-bis ( N , N -dimethylamino) naphthalene was synthesized in 1968 by Roger Alder at the University of Bristol and marketed by Sigma-Aldrich under the trade name Proton Sponge . This compound is a diamine with the two dimethylamino groups on the same side of the arene in the peri position .

The compound has a dissociation constant pK _a of 12.1 for the conjugate acid in aqueous solution and is one of the strongest known amine bases. Because of the steric hindrance of the groups, the molecule is a weak nucleophile. Because of this combination of properties, it is used in organic synthesis as a highly selective non-nucleophilic base.

Other examples are:

use

Proton sponges are used in organic synthesis to deprotonate organic compounds. They are used as a membrane in low-temperature fuel cells .

literature

Heinz A. Staab, Thomas Saupe: "Proton Sponge" Compounds and the Geometry of Hydrogen Bridges: Aromatic nitrogen bases with unusual basicity. In: Angewandte Chemie. 100, 1988, pp. 895-909, doi : 10.1002 / anie. 19881000704 .
Ralph Puchta, Andreas Scheurer: Are metalloproton cryptands possible? , Z. Naturforsch., 2010, 65b, 231 - 237. doi : 10.1515 / znb-2010-0303

Individual evidence

^ ^A ^b F. Gerson, E. Haselbach, G. Plattner: Radical anion of 1,8-bis (dimethylamino) naphthalene ("proton sponge") . (abstract) In: Chem. Phys. Lett. . 12, No. 2, December 1971, pp. 316-319. doi : 10.1016 / 0009-2614 (71) 85074-1 .
↑ A. Szemik-Hojniak, W.Rettig, I. Deperasinska: The forbidden emission of protonated proton sponge . In: Chem. Phys. Lett. . 343, No. 3, August 3, 2001, pp. 404-412. doi : 10.1016 / S0009-2614 (01) 00690-X .
^ RW Alder: Strain effects on amine basicities . In: Chem Rev.. . 89, 1989, pp. 1215-1223. doi : 10.1021 / cr00095a015 .
↑ University of Stuttgart: Student research project on proton sponge membranes for fuel cells

[Gerson_1971-1] A ^b F. Gerson, E. Haselbach, G. Plattner: Radical anion of 1,8-bis (dimethylamino) naphthalene ("proton sponge") . (abstract) In: Chem. Phys. Lett. . 12, No. 2, December 1971, pp. 316-319. doi : 10.1016 / 0009-2614 (71) 85074-1 .

[Szemik-Hojniak_2001-2] A. Szemik-Hojniak, W.Rettig, I. Deperasinska: The forbidden emission of protonated proton sponge . In: Chem. Phys. Lett. . 343, No. 3, August 3, 2001, pp. 404-412. doi : 10.1016 / S0009-2614 (01) 00690-X .

[3] RW Alder: Strain effects on amine basicities . In: Chem Rev.. . 89, 1989, pp. 1215-1223. doi : 10.1021 / cr00095a015 .

[4] University of Stuttgart: Student research project on proton sponge membranes for fuel cells