Search

Drilling muds with less environmental impact are highly desired over conventional diesel-based mud systems, especially in light of the emerging strict environmental laws. In this article, a novel oil-in-water (O/W) emulsion drilling fluid formulated with a methyl ester extracted from Indian mango seed oil was evaluated. The effect of the weight percent of different constituents of the emulsion/suspension including the oil phase, bentonite, and polyanionic cellulose polymer on the rheology and the fluid loss was examined. The methyl ester oil phase/mud system displayed superior physical, chemical, rheological and filtration properties relative to the diesel and the mango seed oil. Eco-toxicity of the methyl ester and diesel (O/W) emulsion mud systems was assessed using the acute lethal concentration test. The Indian mango methyl ester (O/W) emulsion mud displayed much less impact on fish population. Flow characteristics collected from the flow model at 85 °C suggested excellent shear thinning behavior of the Indian mango methyl ester (IMME) (O/W) emulsion mud. Moreover, the IMME (O/W) emulsion displayed strong pseudoplastic behavior, an attractive feature in a drilling mud, with increasing clay content and polymer concentration. The methyl ester mud was thermally stable over a wide range of the constituent concentrations. Furthermore, a particle size analysis revealed that engineered drilling muds targeting suspension of particles with certain size range can be formulated by changing the volume fraction of the methyl ester in the mud system. [ABSTRACT FROM AUTHOR]

Medicinal chemistry of heterocycles especially β-lactams have been an important discovery in today’s mankind. β-Lactam nucleus is structural feature and core of the biological activity of one of most successful classes of therapeutics to date characterized by a broad spectrum of activity and low toxicity. It constitutes classes of drugs that includes the antibiotics like penicillins, cephalosporins, clavulanic acid, monobactams and also shows wide range of important biological activities such as anti-cancer, anti-inflammatory and anti-malarial. The monocyclic β-lactams and their hetero-substituted conjugates are also applied for the synthesis of many classes of compounds which include taxol derivatives, alkaloids and amino acids. Antimicrobial resistance is one of the major and growing concerns in hospital and community acquired infections and new anti-microbial agents are therefore urgently required. So now, the organic chemists have focussed on the modification of existing molecules for the synthesis of new compounds having diverse pharmacological activities with broad spectrum activity. Monocyclic β-lactams are stable to hydrolysis by β-lactamases in comparison to other β-lactams and thus are attractive platform for searching anti-bacterial agents. The discovery of differently substituted 3-alkyl/aryl β-lactams having significant anti-microbial activities have given insight that substitution at C-3 and C-4 of β-lactam ring affects the biological activity of the ring. So, keeping this in mind and synthetic utility of β-lactams here we have made an attempt towards the feasibility and efficiency of 3-(p-substituted-phenylthio)-β-lactams towards Lewis acid functionalization reactions. In our previous works, we have explored the synthetic utility of cis-3-chloro-3-phenyl/benzyl/methylthio-β-lactams as suitable substrate for the Lewis acid catalysed nucleophilic substitution. The current work is designed to explore the effect of electronic changes at phenylthio group at C-3 on the products profile in the Lewis acid catalysed nucleophilic substitution reactions. The synthetic utility 3-(4′-substitutedphenylthio)-azetidin-2-ones towards Lewis acid catalyzed C-3 functionalization reactions have been studied. [ABSTRACT FROM AUTHOR]