Understanding the factors affecting the activation of alkane by Cp'Rh(CO)2 (Cp' = Cp or Cp*). (25/78)

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Trifluoroacetic anhydride-catalyzed oxidation of isonitriles by DMSO: a rapid, convenient synthesis of isocyanates. (26/78)

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Determination of dihydroxyacetone and glycerol in fermentation process by GC after n-methylimidazole catalyzed acetylation. (27/78)

A gas chromatographic method that accurately measures glycerol and dihydroxyacetone from a fermentation broth is described in this paper. The method incorporates a sample derivatization reaction using n-methylimidazole as catalyst in the presence of acetic anhydride. Resulting derivatives are separated on a DB-5 capillary column and flame ionization detector. Results show that 10 muL n-methylimidazole and 75 muL acetic anhydride are sufficient to complete the acetylation for glycerol and dihydroxyacetone at room temperature for 5 min. The present method exhibits good linearity at a concentration range of 1-100 g/L with excellent regression (R(2) > 0.9997). The limits of detection are 0.025 and 0.013 g/L for dihydroxyacetone and glycerol, respectively. The method has been successfully applied to the monitoring and control of the fermentation process, and recoveries are in the range of 95.5-98.8% with relative standard deviations below 1%.  (+info)

A facile synthesis of highly functionalized 4-arylcoumarins via Kostanecki reactions mediated by DBU. (28/78)

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Cytotoxicity of new 5-phenyl-4,5-dihydro-1,3,4-thiadiazole analogues. (29/78)

A series of 5-phenyl-4,5-dihydro-1,3,4-thiadiazoles were synthesized and their cytotoxicity was examined against four human cancer cell lines, e.g. lung cancer (A549), ovarian cancer (SK-OV-3), skin cancer (SK-MEL-2), and colon cancer (HCT15). The title compounds were synthesized by condensation of thiosemicarbazide with substituted benzaldehydes, followed by cyclization with acetic anhydrides in good yields. Most of the compounds exhibited significant suppressive activity against the growth of all of the cancer cell lines. The 4-hydroxy analogue of 5-phenyl-4,5-dihydro-1,3,4-thiadiazole (2h) was most active in the inhibition of growth of the SK-MEL-2 cell line, with an IC(50) value of 4.27 microg/ml; followed by compound 2a (IC(50) 5.16 microg/ml). The compounds 2j, 2h, and 2b, bearing 3-methoxy-4-hydroxy-, 4-hydroxy- and 4-methyl substituents in the C-5 phenyl ring respectively, exhibited the highest activity against the SK-OV-3 (IC(50) 7.35 microg/ml), HCT15 (IC(50) 8.25 microg/ml) and A549 (IC(50) 9.40 microg/ml) cell lines, respectively. A structure-activity relationship study revealed that an optimal electron density on the C-5 phenyl ring of 1,3,4-thiadiazoles is crucial for their cytotoxic activity against the human cancer cell lines used in the present study.  (+info)

Acetylation of alphaA-crystallin in the human lens: effects on structure and chaperone function. (30/78)

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Preparation and physical properties of chitosan benzoic acid derivatives using a phosphoryl mixed anhydride system. (31/78)

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Synthesis and characterization of 5-nitro-2-nitratomethyl-1,2,3,4-tetrazole: a high nitrogen energetic compound with good oxygen balance. (32/78)

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