US EPA

1469156 

Journal Article 

Theoretical Study of Strong Basicity in Aromatic Diamines 

Fujiwara, E; Omoto, K; Fujimoto, H 

1997 

Yes 

Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904 

62 

21 

7234-7238 

English 

11671834 

10.1021/jo970689z 

WOS:A1997YC65700038 

https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000494543&doi=10.1021%2fjo970689z&partnerID=40&md5=06ab3d6db50f1c8e08614d66a4904d82
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The basic strength of NH(3), NH(2)(CH(3)), NH(CH(3))(2), and N(CH(3))(3) has been evaluated by generating for each species the orbital that plays the dominant role in electron delocalization to an attached proton. The theoretically determined strength has been found to correlate well with the calculated value of proton affinity. The analysis has then been extended to a so-called "proton-sponge" compound, 1,8-bis(dimethylamino)naphthalene. The major component of the orbital of the diamine that captures the proton has been demonstrated to be an in-phase combination of two lone-pair orbitals. The out-of-phase combination elevated in energy by a strong antibonding interaction between two lone pairs of electrons is not necessarily the source of the exceptionally high basicity. The electrostatic interaction has been shown to be the major origin of stabilizing the protonated system, but the location of the captured proton is governed by electron delocalization. A similar conclusion has also been derived for 4,5-bis(dimethylamino)fluorene.