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Journals / Eskişehir Osmangazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi / 2007 / Cilt: 20 - Sayı: 1

A theoretical study on proton-loss behavior of some monoazo derivatives

Bazı monoazo türevlerinin proton-verme davranışları üzerinde teorik bir inceleme

Hüseyin BERBER
Cemil ÖĞRETİR
Pages
113–135
Publication Date
2022-10-18
DOI
—
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AI Summary & Key Takeaways

AI Insight
⚡ TL;DR(Too Long; Didn't Read)

The first deprotonation for all seems to take place at the para positioned phenolic hydroxyl group.

📌 3 Key Takeaways

🎯
Objective & Hypothesis:The deprotonation acidity constants, (pKa) of five monoazo derivatives were calculated by using the semi-empirical PM3 method and the obtained pKa values were compared with the experimental ones.
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Key Findings & Data:Taking into account of the best fit results, the deprotonation centers and deprotonation patterns were determined.
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Conclusion & Impact:The first deprotonation for all seems to take place at the para positioned phenolic hydroxyl group.
🔬Design:Research Article
📍Scope:Comprehensive Sample
⚙️Variables:Domain Parameters

Abstract

The deprotonation acidity constants, (pKa) of five monoazo derivatives were calculated by using the semi-empirical PM3 method and the obtained pKa values were compared with the experimental ones. Taking into account of the best fit results, the deprotonation centers and deprotonation patterns were determined. Using the calculated acidity constants the equlibrium constants, for keto-enol tautomerizm KT, were calculated. The evaluation of the toutomeric equlibrium constant volues revealed that the enol forms are more stable. It was observed that both deprotonation takes place on the aromatic ring which has two phenolic hydroxy groups. Whith the exception two molecules which deprotonates at phenolic hydroxy group located at ortho position of the other aromatic ring. The first deprotonation for all seems to take place at the para positioned phenolic hydroxyl group.

Özet

Bes monoazo bilesiginin asitlik sabitleri, pKa, yarı-empirik PM3 yöntemiyle hesaplanmıs ve elde edilen asitlik sabitleri ile deneysel olarak elde edilmis olanlar arasındaki uyum arastırılmıstır. Uyumun en iyi oldugu durumlar seçilerek proton-verme merkezleri ve mekanizmaları saptanmaya çalısılmıstır. Bulunan asitlik sabitleri kullanılarak keto-enol tautomerik denge sabitleri teorik olarak, KT dengeleri, hesaplanmıs ve incelenen tüm monoazo bilesikler için enol formlarının daha kararlı oldugu gözlenmistir. Birinci proton-verme iki hidroksil grubu içeren aromatik halkanın para-konumundaki protonunu vermesi, ikinci proton-verme ise aromatik halkanın orto-konumundaki fenolik hidroksil grubundan olmaktadır. Ancak diger halkada orto konumunda hidroksil grubu içeren iki molekülün farklı mekanizma ile proton verdigi gözlenmistir.

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Cite This Article

BERBER, H., ÖĞRETİR, C. (2022). A theoretical study on proton-loss behavior of some monoazo derivatives. Eskişehir Osmangazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi, Cilt: 20 - Sayı: 1, 113–135. https://ajindex.com/articles/505882

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