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Chemoenzymatic Approaches towards (S)-Duloxetine
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Danish Shahzad, Muhammad Faisal, Aamer Saeed
Ou Zhimin et al. revealed an efficient approach for (S)-duloxetine 1 synthesis. The synthetic approach initiated from (S)-3-chloro-1-(thiophen-2-yl)propan-1-ol 9a, which in turn is asymmetrically synthesized by reduction of 3-chloro-1-(thiophen-2-yl)propan-1-one 7 in membrane reactor with liquid-based immobilized Candida pseudotropicalis 104 (Scheme 5.8) (Zhimin et al., 2012). The optimum diameter of the liquid-based capsules, the pH value of the potassium phosphate buffer, and the shaking speed are 2 mm, pH 6.6~7.2, and 160 r/min, respectively. Conversion of 9a is reached at 100% while ee of 9a is reached at >99.5% in continuous reduction of 7 (12 g/L) for 10 days (Scheme 5.8). The reaction of 9a with NaI followed by treatment with methylamine afforded amine 12. Nucleophilic substitution reaction of amine 12 with 1-fluoronaphthalene in NaH afforded (S)-duloxetine 1. Following benefits can be gained through this biotransformation (i) Use of liquid-core immobilized cells not only being recyclable but are much more efficient as compared to solid-core immobilized cells or free cells, (ii) Liquid-based capsules have improved mass transfer attainment than classical solid-based capsules. They offer easy mass transfer of substrates, products and nutrients. This contributes to the achievement of high density cells and the enhancement of substrate transformation, and (iii) Continuous reduction approach can relieve the inhibition from a high concentration substrate and ee % of 9a is not affected by different reduction conditions when compared to batch reduction strategy (Zhimin et al., 2012). Synthesis through immobilized Candida pseudotropicalis.
Monitoring of polycyclic aromatic hydrocarbons (PAHs) in smoke of charcoal grilled meat-restaurants in Amman, Jordan
Published in Toxin Reviews, 2022
Sharif H. Arar, Sarya G. Ikbarieh, Mohammed H. Kailani, Mahmoud A. Alawi
Three blank samples were used for PAHs recovery experiment. Each blank filter was divided into two halves. The first half was extracted and cleaned-up according to the above-mentioned method. While, the second half of each blank sample was spiked with the concentrations of 50, 250, and 750 ppb of PAHs and the internal standard (1-fluoronaphthalene); to give a final concentration in each sample of 1 ppm in 350 µL. The results show that the recoveries were ranged between of 80–99% for the 50 ppb concentration; 81–100% for the 250 ppb concentration and 82–101% for the 750 ppb concentration. All recoveries were found within the acceptable range for trace analysis (80–120%) (Gonzalez and Herrador 2007).
Determination of polycyclic aromatic hydrocarbons (PAHs) in carbon black-containing plastic consumer products from the Jordanian market
Published in Toxin Reviews, 2018
Mahmoud A. Alawi, Rana A. Abdullah, Ibrahim Tarawneh
The residues from the extraction step were added to the C18 solid phase extraction (SPE) apparatus and eluted with 23 ml n-hexane. The eluant was evaporated at 40 °C and 335 mbar to ca. 1 ml, then to dryness using a gentle stream of nitrogen. The residue was dissolved in 1 ml n-hexane containing 1 µg/mL internal standard (1-fluoronaphthalene), and then 1 µL was injected onto the GC/MS column.
Levels of polyaromatic hydrocarbons (PAHs) in sediment samples from selected Jordanian dams
Published in Toxin Reviews, 2021
Sharif Arar, Mahmoud Alawi, Ali Alnawaiseh, Mohanad Masad
The eluate was evaporated at 40 °C and 335 mbar to ca. 1 ml, then to dryness using a gentle stream of nitrogen. The residues were dissolved in 0.5 ml n-hexane containing 1 µg/ml internal standard (1-fluoronaphthalene) then 2 µl were injected onto the GC/MSD-column (CPET 1999).