n–π Electron donor–acceptor complexes. II. Aliphatic amines with dinitrobenzenes

Abstract

903 (1985). The interaction of several aliphatic amines as n-donors and dinitrobenzenes (DNB) as T-acceptors has been studied in n-hexane. The formation of electron donor -acceptor (EDA) complexes is proposed to explain the spectroscopic behaviour of the mixtures. The stability constants (K,) for these complexes have been calculated by an iterative procedure. For a given acceptor, the donor strength of RNH, > R,NH > R,N was found. This order is explained by considering the role that steric effect may play in the EDA complex formation. On the other hand, the fact that for a given donor K, follows the order I ,2-DNB > I ,3-DNB > I ,4-DNB, and that I ,2-DNB reacts with primary amines, led to the proposal of orientational complexes. These EDA complexes may be considered intermediates in aromatic nucleophilic substitution reactions. On a CtudiC I'interaction de pluseurs amines aliphatiques, comme donneurs tz et dinitrobenzens (DNB), comme accepteurs T, dans n-hexane. On propose la formation de complexes electron-donneur -accepteur (EDA) pour expliquer le comportement spectroscopique des melanges. La constante de stabilite (K,) pour ces complexes a Cte calculee au moyen d'une itCrature. Pour un accepteur donne, on a observC que la force du donneur etait RNHz > RzNH > R,N. Cela s'explique en considCrant le role que jouent les effects steriques dans la formation de complexes EDA. D'ailleurs le fait que K,, pour un donneur donne, ait I'ordre I ,2-DNB > I ,3-DNB > 1,4-DNB et que I ,2-DNB reagisse avec amines primaires, conduit a proposer des complexes orientationnels. Ces complexes EDA peuvent etre consideris des intermediaires dans les reactions de substitution nucl6ophilique aromitique.

Self‐catalysis and molecular complexes in aromatic nucleophilic substitution reactions: Reaction between 1,3,5‐trinitrobenzene and 1,8‐diazabicyclo [5.4.0] undec‐7‐ene in toluene

“…which are well known, but have not been fully investigated in systems reacting by an SNAr mechanism. 5 , 6 Recently, the presence of a particular charge-transfer complex has been indicated to be active in the SNAr reaction pathway by MNDO calculations. Our previous findings agree well with the presence of molecular complexes in the pathway of the SNAr reactions.…”

Donor–Acceptor Complex Enables Alkoxyl Radical Generation for Metal‐Free C(sp3)–C(sp3) Cleavage and Allylation/Alkenylation

“…After visible-light-induced electron transfer, [22] the N-alkoxyphthalimide radical anion is formed and eliminates phthalimides to generate the alkoxyl radical. After visible-light-induced electron transfer, [22] the N-alkoxyphthalimide radical anion is formed and eliminates phthalimides to generate the alkoxyl radical.…”

n-π Electron donor–acceptor complexes. III. Aliphatic amines with dicyanobenzenes. Electric and steric effects of the N-substituents on complex formation

“…However, the fact that 1,3-DCB gives the greater value of K (Table 1) can be explained only if orientational complexes are proposed (2). In this case, there will be a preferential approach of the donor to the region of the smallest electronic density in the benzene ring.…”

“…complexes have a 1:l stoichiometry, as in the n-T systems previously studied (1,2). Problems of solubility prevented experiments in the presence of an excess of DCB, as were carried out for the benzonitrile systems.…”

“…Continuing our work involving the interactions between ' n-electron donors with IT-electron acceptors (1,2), in the presence investigation we wish to report the study of EDA : (Electron Donor-Acceptor) complexation between aliphatic amines and 1,2-, 1,3-, and 1,4-dicyanobenzenes (DCB) in n-hexane as solvent.…”