Gas chromatographic analysis of tautomerizing amidines

The formation of C-N bonds with aryl amines is one of the most widely studied reactions in organic chemistry. Despite this, it is still highly challenging, often requiring expensive, precious metal-based catalysts. Here we report an easy catalyst-free methodology for constructing C-N bonds. The method, which proceeds via the in situ formation of closed ring amidinium ions, allows the preparation of a series of symmetrical and/or unsymmetrical aryl diamines in notably high yields (82-98%) and purity and with a variety of different substituents. The methodology is shown successful for the preparation of aryl diamines having para- and/or meta-substituted carboxyl, nitro, bromo, methoxy, or methyl groups. This green synthetic pathway, which is catalyst free, requires only three steps, and proceeds without the need for purification. Further, it is a new sustainable, economically viable method to achieve an otherwise challenging bond formation.

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“…13 C NMR (100.61 MHz, DMSO- d 6 , 298 K) δ = 148.9, 130.8, 125, 122, 121.1, 118.1. Reported without complete data set elsewhere. − …”

Section: Methodsmentioning

confidence: 99%

Catalyst-Free Synthesis of Aryl Diamines via a Three-Step Reaction Process

Bulut

Queen

2018

J. Org. Chem.

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“…It has been found that in the case of series of amidines containing one variable substituent at any of three sites, at the amino and imino nitrogen atoms and at the amidino carbon atom, their pKa values obey the Hammett It has been also shown that the p value for N'N'-dimethylacetamidines is higher than that of N'N'-dimethylformamidines containing the same set of variable substituents." Thus the hypothesis has been proposed that the p value for substitution at one site depends on polar effects of substituent at the second site, and that the pKa values of amidines containing two substituents, one at the imino nitrogen atom and the second at the functional carbon atom, obey equation (1) where oIm and oF are constants of the substituents on the phenyl ring at the imino nitrogen atom and the functional carbon atom, respectively. The term p represents the mutual interaction of substituents at the imino nitrogen atom and at the amidino carbon atom.…”

mentioning

confidence: 99%

“…This implies that on the other hand electron-donating substituents at the imino nitrogen atom increase the sensitivity of the amidino group to substitution at the amidino carbon atom. All the correlations have predictive value, but the best results are obtained for equation (1) taking into account the mutual interactions between substituents and when o-for the NO, group on the phenyl ring at the amidino carbon atom is used instead of o.…”

mentioning

confidence: 99%