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Detection And Identification of Drugs of Dependence
Published in S.J. Mulé, Henry Brill, Chemical and Biological Aspects of Drug Dependence, 2019
Color reactions for this group of compounds primarily concern reactions associated with primary, secondary, and tertiary amines. It is possible through reaction of sympathomimetic amines44 with benzoyl chloride, p-nitrobenzoyl chloride, benzenesulphonyl chloride, picric acid, and ammonium reineckate to differentiate dexam-phetamine, amphetamine, methamphetamine, and ephedrine by color and microcrystal tests. A dark red color may be obtained45 when a sample solution in CC14 is treated with ethanolic quinhydrone, indicating a diamine. Primary amines give a gold color; secondary and tertiary amines do not react.
Scombrotoxin
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Other detection methods for histamine in fishery products have not been validated for regulatory use but are frequently used for research purposes. The main advantages of these methods are use of more recent technologies, broader quantification range, and multiplexing. Numerous HPLC methods have been developed that use separation by reversed-phase HPLC and rely on derivatization (91–95) or UV detection of the histidine imidazole ring (94,96). More recently, liquid chromatography-mass spectrometry has been applied for detection of histamine (97–99). The most frequently used derivatization reagents for histamine determination are dansyl chloride, fluorescamine, benzoyl chloride, and OPA (100). Other popular detection methods include enzyme-based screening (101,102), capillary electrophoresis (103), paper electrophoresis (104,105), thin-layer chromatography (106,107), and gas chromatography-mass spectrometry (108,109).
Future Strategies for Commercial Biocatalysis
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Robert E. Speight, Karen T. Robins
Another example of a cascade, that highlights its complexity and benefits, is the production of the naturally occurring antiviral compound, (S)-tembamide, using a one-pot, four step, sequential chemoenzymatic cascade (Schrittwieser et al., 2013; Schrittwieser et al., 2018; Rios-Lombardia et al., 2018). The first step of the cascade was a chemical azidolysis step, followed by enzymatic asymmetric reduction, palladium catalysed hydrogenation and then acylation (Fig. 1.8). Organic azide was generated in situ by a halogen-azide exchange reaction to produce the azido ketone from the corresponding halo ketone. The alcohol dehydrogenase was added directly to the vessel, after completion of the azidolysis step, producing the chiral azido alcohol from the azido ketone. The solution from the azidolysis step led to a slight decrease in the alcohol dehydrogenase activity, which could be compensated for by increasing enzyme loading. Next, the pH of the aqueous reaction mix was increased to pH 9 for the lignin-stabilised palladium nanoparticle azide hydrogenation of the azido alcohol. In addition to the 1,2-amino alcohol an unexpected by-product, 2,2-dimethyloxazolidine, was formed by the reaction of the amino alcohol with acetone, a by-product of the enzyme reduction step. Removal of acetone by carrying out the bioreduction under reduced pressure solved this problem. After the completion of the palladium catalysed hydrogenation, benzoyl chloride in MTBE was added directly to the alkaline reaction mixture to produce (S)-tembamide in an overall yield of 73% over four steps and an enantiomeric excess of >99%. One-pot, four step chemoenzymatic synthesis of (S)-tembamide.Adapted from Schrittwieser et al. (2013).
Dyhidro-β-agarofurans natural and synthetic as acetylcholinesterase and COX inhibitors: interaction with the peripheral anionic site (AChE-PAS), and anti-inflammatory potentials
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Julio Alarcón-Enos, Evelyn Muñoz-Núñez, Margarita Gutiérrez, Soledad Quiroz-Carreño, Edgar Pastene-Navarrete, Carlos Céspedes Acuña
Compound 4 (1.49 mmol) was dissolved in 250 µL of anhydrous pyridine were heated at 70 °C and under stirring with 1.49 mmol of CH3COCl and 0.75 mmol of 4-dimethylamino pyridine (DMAP) for 1 h. The resulting mixture was diluted with water, allowed to stand for 30 min, extracted with EtOAc and dried with anhydrous sodium sulphate. Removal of the solvent gave a residue which crystallised from n-hexane in the form of a colourless fine needle of 5 (yield 99%). Compounds 6 and 7 were prepared in the same manner using furoyl chloride (C5H3ClO2) and benzoyl chloride (C7H5ClO) respectively (95% and 97% yield respectively). The final purification of all the products for analysis was carried out by recrystallization.
Design, synthesis and biological activity evaluation of a new class of 2,4-thiazolidinedione compounds as insulin enhancers
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Zou Huiying, Chen Guangying, Zhou Shiyang
The benzoic acid (1a, 12.03 g, 0.10 mol) was put into 500 ml round bottom flask, then 200 ml of methylene chloride (CH2Cl2) was used as the solvent and 10 drops of N,N’-dimethyl formamide (DMF) used as a catalyst for the reaction were added. The flask was placed in the ice water bath (≤10 °C), and a magnetic mixer was used to stir until the reaction liquid became clarified. The thionyl chloride (SOCl2, 11.25 ml, 0.15 mol) was constantly dropped into the flask under stirring, and the drop speed rate and the reaction temperature were controlled (≤10 °C and ≥20 min). After the reactants were added, the reaction lasted for 6–10 h under reflux. The methylene chloride and excessive thionyl chloride were removed under vacuum. The mixture was dried to get the crude product of benzoyl chloride (2a). The crude product was obtained by atmospheric distillation, the product was collected at 198 °C, and the pure product of benzoyl chloride (2a) as a colourless transparent liquid was obtained. The general method was used to synthesise compounds 2c and 2e as all were colourless transparent liquid. And the general method was used to synthesise crude compounds 2b, 2d and 2f, the crude products were recrystallised with hexane, filtered and dried in vacuum to give pure products of compounds 2b, 2d and 2f as all were of white crystal.
Comparing the dopaminergic neurotoxic effects of benzylpiperazine and benzoylpiperazine
Published in Toxicology Mechanisms and Methods, 2018
Daniel P. Katz, Mohammed Majrashi, Sindhu Ramesh, Manoj Govindarajulu, Dwipayan Bhattacharya, Subhrajit Bhattacharya, Aimen Shlghom, Chastity Bradford, Vishnu Suppiramaniam, Jack Deruiter, C. Randall Clark, Muralikrishnan Dhanasekaran
Synthesis of Benzylpiperazine and Benzoylpiperazine: A mixture of benzaldehyde (1 g, 0.01 mol) and piperazine (1.43 g, 0.0165 mol) in methanol was stirred for half an hour. Then sodium cyanoborohydride (2.1 g, 0.033 mol) was added and the mixture was allowed to stir for half an hour. The reaction was quenched by adding ice/water mixture and stirring the mixture for 20 min followed by extracting the final product using dichloromethane (3 × 30 ml). The combined organic extract was dried with anhydrous magnesium sulfate, filtered and evaporated to yield yellow oil. The oil was dissolved in anhydrous diethyl ether, and hydrochloric acid was added to form the hydrochloride salt. Benzoyl chloride (1.4 g, 0.01 mol) was dissolved in dichloromethane and the solution was dripped slowly over the piperazine solution over 10 min. The mixture was allowed to stir for 15 min. The solution was evaporated under reduced pressure to yield light yellow oil. The oil was dissolved in anhydrous diethyl ether, and hydrochloric acid gas was added to form the hydrochloride salt (Figure 1).