5006-66-6Relevant articles and documents
Bioelectrochemically accelerated microbial conversion of nicotinic acid to 6-hydroxynicotinic acid on microorganism-immobilized column electrolytic flow system
Torimura, Masaki,Yoshida, Hideto,Kano, Kenji,Ikeda, Tokuji,Nagasawa, Toru,Ueda, Teruhisa
, p. 295 - 296 (1998)
Nicotinic acid (NA) is efficiently hydroxylated into 6-hydroxynicotinic acid (6HNA) by Pseudomonas fluorescens TN5-immobilized column electrolytic method using K3Fe(CN)6 as an extracellular electron transfer mediator, in which the conversion rate was sufficiently accelerated compared with the aerobic oxidation. The NA conversion system was applied to the continuous-production of 6HNA in 100% yield and the absolute determination of NA in flow-injection analysis.
A 6 - chloro nicotinic acid preparation method and separation and purification method
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Paragraph 0035; 0039-0092, (2017/08/24)
The invention discloses a preparation method and a separation and purification method for 6-chloronicotinic acid, belonging to the field of fine chemical engineering. The preparation method comprises the following steps: by taking low-cost DL-malic acid as a raw material, carrying out a cyclization reaction and an ammonification reaction, thereby obtaining 6-hydroxynicotinic acid; by taking 6-hydroxynicotinic acid as a raw material, carrying out a chlorination reaction, thereby obtaining 6-chloronicotinic acid. The reaction conditions are simple, operation is easy, the environmental pollution is slight, and the yield is high. The purification method disclosed by the invention comprises the following step: refining crude 6-chloronicotinic acid by virtue of methanol and activated carbon to finally obtain 6-chloronicotinic acid with the purity of more than 99.5 percent. The requirement of a medical intermediate on the purity is met. The method disclosed by the invention has the advantages of reasonable design, low cost and high economic benefits and has wide application prospects.
Photochemistry of the three carboxypyridines in water: A pH dependent reaction
Rollet, Florence,Richard, Claire,Pilichowski, Jean-Francois,Aboab, Bettina
, p. 2253 - 2261 (2007/10/03)
The photochemistry of ortho, meta and para-carboxypyridines (pK a1 = 1.0-2.1 and pKa1 = 4.7-5.3) in aqueous medium was studied by laser-flash photolysis and product studies. At pH a1, hydroxylated compounds are produced with low quantum yields. Within the pH range 4-7, ortho and meta isomers undergo dimerization together with decarboxylation with a quantum yield showing a very sharp maximum around pKa2 (φmax = 0.09 and 0.01, respectively) while the para isomer is photostable. End-of-pulse transients assigned to triplet states were detected by laser-flash photolysis at pH a1 and pH > 4. Additionally, the carboxypyridinyl radicals were detected as secondary intermediates at pH a1 and 4 a1. This is in favour of an electron transfer reaction between triplet and starting compound producing a charge transfer species. The radical anion would escape as carboxypyridinyl radical while the radical cation may add water at pH a1 yielding the OH-adduct radical or may undergo decarboxylation at pH > 4. The high quantum yield of phototransformation of the ortho isomer at pH > 4 is due to an easy decarboxylation process. A reaction scheme is proposed accounting for the dependences of φ on both the pH and the carboxypyridines concentration. This study points out the distinct pattern of reactivity of carboxypyridines depending on the ionisation state of starting compounds and isomeric substitution.
