93-60-7Relevant articles and documents
GC-FID-based quantification of the sum of the three forms of vitamin B3 from animal liver
H?mmerle, Michael,Hekmat, Omid,Le, Minh Hien
, (2020)
Vitamin B3 (nicotinic acid, nicotinamide) is an essential water-soluble vitamin and cellular energy metabolism depends on the vitamin B3-derived cofactors. Inaccessible covalently-linked nicotinic acid in food such as maize can cause vitamin B3 deficiency in animals since maize is also deficient in tryptophan, the precursor of nicotinic acid. A sensitive and reproducible GC-FID-based method for the quantification of the sum of the three forms of vitamin B3 from animal liver was developed. Free nicotinic acid, free nicotinamide and nicotinamide moiety of NAD+/NADP+ (and their riboside precursors) were simultaneously derivatized as methyl nicotinate. Reaction time and temperature and the extraction procedure for methyl nicotinate were optimized. Starting from wild boar liver, removal of proteins, solvent exchange, derivatization, and chloroform extraction resulted in sufficient enrichment and baseline separation of methyl nicotinate. The within-laboratory reproducibility of the full procedure was determined with RSD 3 standards. The overall recovery for the full procedure was 16% but very consistent (RSD = 7%), enabling determination of apparent vitamin B3 concentrations for relative quantitative comparison.
Metal analyses in environmental and pharmaceutical samples by capillary electrophoresis with methyl 3-amino-3-(pyridin-3-yl)propanoate dihydrochloride as a new ion-pairing reagent
Belin, Gamze Kavran,Guelacar, Fazil Osman
, p. 2322 - 2332 (2005)
Separation and determination of some common metal ions was achieved with methyl 3-amino-3-( pyridin-3-yl)propanoate dihydrochloride (MAPP) as an ion-pairing reagent and pyridine as a detectable counter-ion for indirect UV detection at 254 nm. The effects of the complexing reagent and chromophore concentrations, applied voltage, and organic solvent content on the separation were investigated. The optimized separation was carried out in a running electrolyte containing 16 mM MAPP and 20 mM pyridine at pH 4.0 and was successfully applied to the qualitative and quantitative analysis of Li +, Na+, Mg2+, Ca2+, Ba2+, Ni2+, and Zn2+ in pharmaceutical vitamin preparations and various water samples.
Minisci-Type Alkylation of N-Heteroarenes by N-(Acyloxy)phthalimide Esters Mediated by a Hantzsch Ester and Blue LED Light
Kyne, Sara Helen,Li, Jiacheng,Siang Tan, Suan,Wai Hong Chan, Philip
supporting information, (2022/01/11)
A synthetic method that enables the Hantzsch ester-mediated Minisci-type C2-alkylation of quinolines, isoquinolines and pyridines by N-(acyloxy)phthalimide esters (NHPI) under blue LED (light emitting diode) light (456 nm) is described. Achieved under mild reaction conditions at room temperature, the metal-free synthetic protocol was shown to be applicable to primary, secondary and tertiary NHPIs to give the alkylated N-heterocyclic products in yields of 21–99%. On introducing a chiral phosphoric acid, an asymmetric version of the reaction was also realised and provided product enantiomeric excess (ee) values of 53–99%. The reaction mechanism was delineated to involve excitation of an electron-donor acceptor (EDA) complex, formed from weak electrostatic interactions between the Hantzsch ester and NHPI, which generates the posited radical species of the redox active ester that undergoes addition to the N-heterocycle.
Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents
An, Ju Hyeon,Kim, Kyu Dong,Lee, Jun Hee
supporting information, p. 2876 - 2894 (2021/02/01)
Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).
Method for preparing carboxylic ester compounds by oxidizing and breaking carbon-carbon bonds of secondary alcohol compounds
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Paragraph 0074-0075; 0092, (2021/06/02)
The invention discloses a method for preparing carboxylic ester compounds by oxidizing and breaking carbon-carbon bonds of secondary alcohol compounds. The method comprises the following steps: adding a secondary alcohol compound, an additive and a nitrogen-doped mesoporous carbon loaded monatomic catalyst into a fatty primary alcohol solvent, putting into a pressure container, sealing, introducing oxygen source gas with a certain pressure, controlling the pressure of the oxygen source gas to be 0.1-1 MPa and the reaction temperature to be 80-150 DEG C, and obtaining a product after the reaction to be the carboxylic ester compound. The nitrogen-doped mesoporous carbon-loaded monatomic catalyst adopted by the invention is high in activity, the highest separation yield of the carboxylic ester compound as a reaction product reaches 99%, the method is wide in application range, the reaction conditions are easy to control, the catalyst can be recycled, the post-treatment is simple, and the method is suitable for industrial production.