Publication detail

Structure of Azo Coupling Products from N-Alkylenaminones Derived from Acetylacetone and Benzoylacetone in Solid Phase and in Solution

Year: 2007

Type of publication: článek v odborném periodiku

Name of source: New Journal of Chemistry

Publisher name: Royal Society of Chemistry

Place: Cambridge

Page from-to: 429-438

Titles:

Language	Name	Abstract	Keywords
cze	Struktura azokopulovaných N-alkyl enaminonů odvozených od acetylacetonu a benzoylacetonu v pevné fázi a v roztoku	Reakcí substituovaných benzendiazonium-tetrafluoroborátů s N-alkyl 4-aminopent-3-en-2-ony resp. 3-amino-1-fenylbut-2-en-1-ony byla připravena řada produktů azokopulace. Struktura a tautomerie reakčních produktů byla studována pomocí single crystal X-ray study a pomocí NMR spektroskopie v roztoku deuteriochloroformu. Produkty azokopulace na 4-methylaminopent-3-en-2-ony (3a?i) existují v roztoku CDCl3 jako směs E/Z izomerů, kde izomer Z silně převažuje. Majoritní izomer je směsí enamino-azo a imino-hydrazo tautomerů, kde prvně jmenovaný převažuje. Obsah azoformy závisí na substituci benzenového jádra diazoniové soli a klesá v pořadí OMe > Me > Br > NO2. Přechod od 4-methylaminopent-3-en-2-onů k 3-methylamino-1-phenylbut-2-en-1-onům nemá na polohu tautomerní rovnováhy prakticky žádný vliv. V pevné fázi vždy převažuje azoforma, substituenty na diazoniové soli a na dusíku N3 nemají na polohu tautomerní rovnováhy významný vliv. Produkty azokopulace vždy existují ve formě jediného izomeru Z. Všechny struktury měřené v pevné fázi se sestávají ze směsi amino?diazenyl a imino?hydrazon tautomerů v poměru 82/18 k 91/9 %.	azokopulace, N-alkylenaminony, X-Ray, NMR
eng	Structure of Azo Coupling Products from N-Alkylenaminones Derived from Acetylacetone and Benzoylacetone in Solid Phase and in Solution	A series of azo coupling products have been prepared by reaction of substituted benzenediazonium tetrafluoroborates with N-alkyl 4-aminopent-3-en-2-ones or 3-amino-1-phenylbut-2-en-1-ones. The structure and tautomerism of the reaction products were studied by means of single-crystal X-ray study and by NMR spectroscopy in deuteriochloroform solution. The azo coupling products obtained from 4-methylaminopent-3-en-2-ones (3a?i) exist in CDCl3 solution as E/Z isomer mixtures with the Z isomer strongly predominating. The major isomer is a mixture of enamino?azo and imino?hydrazo tautomers with the former predominating. The proportion of the azo form depends on substitution of the benzene ring of the diazonium salt and decreases in the order of MeO > Me > Br > NO2. The position of tautomeric equilibrium is practically unaffected by switching from 4-methylaminopent-3-en-2-ones to 3-methylamino-1-phenylbut-2-en-1-ones. In the solid phase, the azo form always predominates; substitution of diazonium salt and at N3 nitrogen does not significantly affect the position of the tautomeric equilibrium. The azo coupling products always exist in the form of a single Z isomer. All determined structures, in the solid state, consist of a mixture of the two tautomeric forms, amino?diazenyl and imino?hydrazone, in ratios ranging from 82/18 to 91/9 %. The weighed superimposition of both the hydrogen-bonded N1 N2?C1 C2?N3H/ HN1?N2 C1?C2 N3 heterodienic fragments, however, do not allow to clarify the effects of the para-substituents at the N1-phenyl ring both on the N1 N3 hydrogen-bond distances and on the bond lengths in the heterodienic systems within the series 3a?c,f and 4a?c,e,f.	azo coupling, N-alkylenaminones, X-Ray, NMR

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