A lack of global political will to mobilise resource to fight tuberculosis is major challenge in ending tuberculosis. The polyherbal formulations are best alternative, as they are economic, ...environmentally friendly and easily available than modern drugs. In present study, a polyherbal suspension with extracts of C. longa, A. indica and O. sanctum was developed and characterized. The developed suspension was found satisfactory with respect to odour, colour, taste, pourability, pH, viscosity, zero microbial count, particle size, percentage ease of disposability, aesthetic characteristic, sedimentation, zeta potential and does not show the crystal growth, polyherbal formulation exhibited significantly inhibited the growth of H37Rv and MIC is also comparable to those of standard agents.
N-Alkylation of anilines by dimethyl carbonate (DMC) catalyzed by onium salts has been demonstrated. The work presented here shows that a simple catalytic system consisting of onium salts in the ...presence of a small amount of water is extremely effective in enhancing the DMC mediated
N-alkylation of anilines to dialkylated products. The effect of reaction conditions, on the synthesis of
N,
N-dimethyl aniline (NNDMA) from aniline and DMC has been investigated. Under the optimized conditions highest yield of NNDMA obtained was 99.8%, which is the best reported for liquid phase
N-alkylation of aniline using DMC. The role of water in enhancing the yield of NNDMA is explained and a reaction-networking scheme is constructed, which summarizes the chemistry behind liquid phase
N-alkylation of anilines by DMC. The catalyst has been shown to recycle up to five times and at the end of fifth recycle almost 98% of NNDMA yields were obtained.
Onium salts in the presence of a small amount of water are excellent catalysts for selective
N,
N-dialkylation. Side products such as carbamates formed during this reaction are hydrolyzed to
N-alkylated anilines thereby increasing the selectivity for alkylated products. Reaction network has been proposed which explains the chemistry of
N-alkylation by DMC. The reusability of catalyst has been demonstrated.
▪
Synthesis of carbamates from substituted ureas and organic carbonates has been demonstrated using di-
n-butyltin oxide (DBTO) as a catalyst. Reactivity pattern of ureas indicated that substituents on ...ureas have no significant effect on the carbamate yields. While, the carbonate reactivity pattern seems to be following the rule that is expected based on the leaving group ability of alkoxides and phenoxide to form carbamate observed in aminolysis of carbonates, it has been shown that basicity of reacting urea plays a vital role in the catalytic activity of this reaction. The effect of reaction parameters such as temperature, catalyst loading, solvent, concentration of reactants, etc. were investigated for synthesis of methyl methyl carbamate (MMC). The Arrhenius activation energy for the reaction between dimethyl urea (DMU) and dimethyl carbonate (DMC) was found to be 7.57
kcal/mol. A reaction mechanism has been postulated explaining the role of DBTO in the synthesis of carbamate from urea and carbonate.
Synthesis of carbamates from substituted ureas and organic carbonates has been demonstrated using n-dibutyl tin oxide (DBTO) as a catalyst. In a typical case 91% yield of N-methyl methyl carbamate have been obtained.
▪
