Journal: Journal of Pharmacy Research

Article Id: JPRS-PC-00001646
Title: Synthesis, characterization and antibacterial activity of new 5-ethoxy-2-mercapto benzimidazole derivatives
Category: Pharmaceutical Chemistry
Section: Research Article
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    Background: In this study, new derivatives were synthesized from 5-ethoxy-2-mercapto benzimidazole by alkylation, acylation, Schiff base formation and vilsmier-haack reaction (ring closure), and in a good yield. Methods:  The reaction of 5-ethoxy-2-mercapto benzimidazole with different types of alkyl halides to produce S-alkyl derivatives (thioether),1a-c.  The reflux of the parent compound with ethyl bromoacetate, afforded the thioester form of 5-ethoxy2-mercapto benzimidazole derivative, and by treating with benzoyl chloride, lead to the formation of the N-benzoyl thioester form 2. The formation of the thiazolo ring-containing compound 3 was done by equimolar reflux of aliphatic ketone and 5-ethoxy-2-mercapto benzimidazole.The compounds 4a-d  were prepared by the reaction of the parent compound with p-substituted phenacyl bromides, then by addition of 2,4-dinitrophenyl-hydrazine produced the Schiff bases 5a-d.  The pyrazole derivatives 6a-d produced by using vilsmier-Haack reaction, by the treatment of 5a-d with phosphorous oxychloride and DMF. New series of compounds 7a-d and 8  were obtained by the reaction of 4a-d with benzoyl chloride and acetic anhydride, respectively. The antimicrobial activity was evaluated by using Agar Diffusion Well Assay. The four types of bacteria used to evaluate the in-vitro antibacterial activity were Staphylococcus aureus, Streptococcus agalactiae, Pseudomonas aeruginosa and Proteus mirabilis. All the titled compounds characterized and identified by elemental microanalysis, I.R, and 1HNMR spectroscopic study. It was found that all the results showed good agreements with the proposed chemical structures of the synthesized compounds. Results:  All the new compounds have distinctive and highest antibacterial activity against Gram-positive bacteria, especially 6b showed the maximum antibacterial activity against Staph. aureus at a concentration of 100µg/ml,  while the compound 7b exhibited the maximum antibacterial activities against both Gram-positive and Gram–negative bacteria at a concentration of 100µg/ml. Conclusion: The results illustrated good preliminary antibacterial activity of the new 5-ethoxy-2-mercapto benzimidazole derivatives, especially 6b and 7b, against Gram-positive and Gram-negative bacteria.

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    Author(s) Name:

    Raad H. Turkey1 and Ammar Abdul Razzak M. Kubba2,*

    Affiliation(s) Name:

    1Ministry of health-Karbala Health Directorate, Pharmacy Department
    2College of Pharmacy-Dept. of Pharmaceutical Chemistry, Bab-Almuadam,Baghdad-Iraq.

    *Corresponding author.
    Dr. Ammar A.Razzak Mahmood Kubba
    College of Pharmacy-Dept. of Pharmaceutical Chemistry,

    Received on:22-09-2016; Revised  on:  27-10-2016; Accepted on: 16-12-2016  

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    Raad H. Turkey1 and Ammar Abdul Razzak M. Kubba2,*

    Title:Synthesis, characterization and antibacterial activity of new 5-ethoxy-2-mercapto benzimidazole derivatives
    Journal:Journal of Pharmacy Research
    Vol(issue):10 (December)
    Page No: (814-824)
  • Experimental Methods Keywords

    Methodology:Schiff base, vilsmier-haack reaction
    Research Materials:Benzimidazole derivatives, 5-ethoxy-2-mercapto benzimidazole


Benzimidazole derivatives 5-ethoxy-2-mercapto benzimidazole Schiff base vilsmier-haack reaction

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