Synthesis of heterocycles : Synthesis of 4H-1,4-benzothiazines

A new synthesis of fluorinated 4H-1,4-benzothiazines is being reported for the first time, obtained by condensing O-aminobenzenethiol with fluorinated β-diketones. An oxidative cyclisation mechanism, involving an intramolecular nucleophilic attack in an intermediate enamine system is suggested.     

A ~35 kDa polypeptide from insect cells binds to yeast ACS like elements in the presence of ATP

Background  

The S. cerevisiae origin recognition complex binds to the ARS consensus sequence in an ATP dependent fashion. Recently, the yeast Cdc6 has been reported to have DNA binding activity. Conservation of replication proteins among different species strongly supports their functional similarity. Here we report the results of an investigation into the DNA binding activity of human Cdc6 protein. Cdc6 was expressed and purified from baculovirus infected Sf9 (Spodoptera frugiperda) insect cells as GST fusion protein (GST-Cdc6) and its DNA binding activity was tested.     

Technical and economic evaluation of different reactors for methanotrophic cultures for propylene oxide production

A two-stage process for the manufacture of propylene oxide is described. The preliminary economics based on use of methanol as a regeneration factor has resulted in a production cost of $12.10/lb of propylene oxide based on propylene oxide production rate of 40 mg/g-cell/h in conventional reactor. Increasing the propylene oxide production from 40 to 500 mg/g-cell/h resulted in a cost reduction from $12.10 to 5.8/lb of propylene oxide. The granular-activated, carbon-fluidized bed reactor (GAC-FBR) absorbs the propylene oxide and when saturated is eluted with ethyl acetate, and the bed is regenerated by steam to drive off the residual solvents. The estimated manufacturing costs are approx 59% lower (from $12.10/lb in conventional reactors to $5.00/lb for GAC-FBRs) for products that are highly inhibitory such as epoxides. In the GAC-FBR reactor, enhancing the propylene oxide production rate from 120 to 1500 mg/g-cell/h has resulted in the cost reduction to $2.00/lb. Enhancing the production capacity from 1 million lb to 10 million lb/yr has further reduced the cost of production to $1.00/lb.     

Biological-chemical treatment of soils contaminated with exploration and production wastes

Oil-gas exploration and production (E&P) soils contaminated with total petroleum hydrocarbons (TPHs) have been tested for degradation by two different treatments: biological and chemical. Biological treatment includes the use of native microorganisms for transformation of the various hydrocarbons found in E&P soils. Degradation of TPH of 80 and 86%, was achieved for two different soils, respectively in control experiments. The effect of growth stimulants such as glucose, acetic acid, and valeric acid was examined on TPH degradation. Incorporation of inducer (valerate) enhanced the degradation up to 89 and 93%, for the two soils, respectively. A large portion (> 41%) of contaminant in one soil was comprised of compounds in the carbon range of C₁₀-C₁₆ and < 7% constituted carbon range of C₂₄-C_28. The degradation of C₁₀-C₁₆ compounds was higher (> 98%) as compared to C₂₄-C₂₈ compounds (< 75%). Likewise, the degradation rate was also higher (58 mg/kg/d) for lower compounds as compared to higher carbon range compounds (6.7 mg/kg/d). Experiments conducted on chemical treatment included the effect of chelators on stabilization of H₂O₂, comparative studies between buffer and water (used for soil preparation), and the effect of pH on TPH degradation. The rate of oxygen evolution from H₂O₂ was significantly reduced with use of either chelated iron or phosphate buffer using naphthelene as a model compound. Chemical treatment demonstrated a higher degradation of TPH from contaminated soils at pH 4.0 as compared to a pH of 7.0. More degradation was obtained with slurry prepared in phosphate buffer as compared to deionized water.