Tautomeric Equilibrium Modeling: Stability and Reactivity of Benzothiazole and Derivatives

Lucie A Bédé,Lamoussa Ouattara,Mawa Koné,Guy R M Koné,El Hadji S Bamba,Simplice C S Ouattara

doi:10.5539/ijc.v11n1p84

Abstract

Benzothiazoles are organic compounds with multiple biological activities. Due to their biological interests, these are synthesized on a large scale at the industrial level and used in various fields. Their release into waters causes environmental problems which leads to public health problems. Finding solution which can help for their degradation become necessary.   That is the reason why a theoretical study of the reactivity of five benzothiazole derivatives has been initiated in order to understand some aspect of their biodegradation.   The calculations were carried out in gaseous and aqueous phase with B3LYP functional associated with bases 6-311G(d) and 6-31+G(d).   The results revealed that the thione tautomer of the MBT derivative is more stable than the thiol form. These results are in agreement with previous experimental work which showed that the thiones forms in MBT metal complexes are the most stable. Moreover, the study of the reactivity based on the computation of the global indices of reactivity reveals that the benzothiazoles BT, OBT and MBT are the most reactive. The most electrophilic is BT and the least electrophilic is MTBT. In addition, the thermodynamic parameters and the energy barriers predict a possibility of coexistence of tautomers ol and one of OBT derivative. Fukui dual descriptors have shown that the carbon C2 of BT is the most electrophilic. In substituted derivatives, it is the C6 carbon that is the most electrophilic. N3 nitrogen remains the most nucleophilic site in all the studied molecules.

Highlights

Benzothiazole derivatives have a wide range of biological activities such as anticancer, analgesic, anti-inflammatory, antimicrobial, antimalarial, anticonvulsant (Venkatesh & Pandeya, 2009) (Pritesh, Jagath et al, 2012) (Nadeem, Arpana et al, 2007) (Mishra, Gautam et al, 2010) (Hout, Azas et al, 2004)
Benzothiazoles are organic compounds with multiple biological activities. Due to their biological interests, these are synthesized on a large scale at the industrial level and used in various fields. Their release into waters causes environmental problems which leads to public health problems
The results revealed that the thione tautomer of the MBT derivative is more stable than the thiol form

Summary

Introduction

Benzothiazole derivatives have a wide range of biological activities such as anticancer, analgesic, anti-inflammatory, antimicrobial, antimalarial, anticonvulsant (Venkatesh & Pandeya, 2009) (Pritesh, Jagath et al, 2012) (Nadeem, Arpana et al, 2007) (Mishra, Gautam et al, 2010) (Hout, Azas et al, 2004). They are used in large quantities in very different fields such as agriculture, detergent industry, paper industry, automotive industry and pharmaceutical industry (Herrero, Borrull et al, 2013) (Herrero, Borrull et al, 2014) (Speltini, Sturini et al, 2016) (Markiewicz, Björklund et al, 2017) Due to their varied applications, they are synthesized on a large scale at the industrial level These high production of chemicals constitute a real environmental problem (Herrero, Borrull et al, 2014). Their discharge into runoff is likely to affect the functioning of ecosystems, posing a major environmental and public health problem

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Results