- Bioelectrochemically accelerated microbial conversion of nicotinic acid to 6-hydroxynicotinic acid on microorganism-immobilized column electrolytic flow system
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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.
- Torimura, Masaki,Yoshida, Hideto,Kano, Kenji,Ikeda, Tokuji,Nagasawa, Toru,Ueda, Teruhisa
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- A 6 - chloro nicotinic acid preparation method and separation and purification method
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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.
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Paragraph 0035; 0039-0092
(2017/08/24)
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- CYP199A4 catalyses the efficient demethylation and demethenylation of para-substituted benzoic acid derivatives
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The cytochrome P450 enzyme CYP199A4, from Rhodopseudomonas palustris strain HaA2, can efficiently demethylate 4-methoxybenzoic acid via hemiacetal formation and subsequent elimination of formaldehyde. Oxidative demethylation of a methoxy group para to the carboxyl moiety is strongly favoured over reaction at one in the ortho or meta positions. Dimethoxybenzoic acids containing a para-methoxy group were also efficiently demethylated exclusively at the para position. The presence of additional methoxy substituents reduces the substrate binding affinity and the activity compared to 4-methoxybenzoic acid. The addition of the smaller hydroxy group to the ortho or meta positions or of a nitrogen heteroatom in the aromatic ring of the 4-methoxybenzoate skeleton was better tolerated by the enzyme and these analogues were also readily demethylated. There was no evidence of methylenedioxy ring formation with 3-hydroxy-4-methoxybenzoic acid, an activity which is observed with certain plant CYP enzymes with analogous substrates. CYP199A4 is also able to deprotect the methylenedioxy group of 3,4-(methylenedioxy)benzoic acid to yield 3,4-dihydroxybenzoic acid and formic acid. This study defines the substrate range of CYP199A4 and reveals that substrates without a para substituent are not oxidised with any significant activity. Therefore para-substituted benzoic acids are ideal substrate scaffolds for the CYP199A4 enzyme and will aid in the design of optimised probes to investigate the mechanism of this class of enzymes. They also allow an assessment of the potential of CYP199A4 for synthetic biocatalytic processes involving selective oxidative demethylation or demethenylation.
- Coleman, Tom,Chao, Rebecca R.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
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p. 52007 - 52018
(2015/06/25)
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- Photochemistry of the three carboxypyridines in water: A pH dependent reaction
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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.
- Rollet, Florence,Richard, Claire,Pilichowski, Jean-Francois,Aboab, Bettina
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p. 2253 - 2261
(2007/10/03)
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- Demethylation of methoxypyridines with sodium trimethylsilanethiolate
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Demethylation of methoxypyridines was accomplished in 55-87percent yield by use of ca. 1.5-2.5 equivalents of NaSSiMe3 in 1,3-dimethyl-2-imidazolidinone at 120-180 deg C.This method was found applicable to a methoxyquinoline and methoxypyridines containing a second substituent, such as Cl, OMe, and COOMe.
- Shiao, Min-Jen,Ku, Wei-Shen,Hwu, Jih Ru
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p. 323 - 328
(2007/10/02)
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- CONTROLLED, REGIOSPECIFIC OXIDATION OF PYRIDINE CARBOXYLIC ACIDS AND ESTERS WITH ELEMENTAL FLUORINE
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Pyridine carboxylic acid salts or esters in water or water-acetonitrile mixtures were treated with elemental fluorine to give the corresponding 2-pyridones.
- Puy, Michael Van Der,Nalewajek, David,Wicks, Gene E.
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p. 4389 - 4392
(2007/10/02)
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- REINVESTIGATION OF THE REACTION OF NICOTINIC ACID 1-OXIDE WITH ACETIC ANHYDRIDE
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Reinvestigation of the reaction of nicotinic acid 1-oxide (1) with boiling acetic anhydride has revealed that the primary product is not 2-acetylnicotinic acid 1-oxide (3) but 3-acetoxy-4-aza-3-methyl-1(3H)-isobenzofuranone 4-oxide (2), the acetate of the ring tautomer of 3.Reactions of 2 and 3 with phosphorus trichloride and some related reactions are reported.
- Nagano, Hiroyuki,Hamana, Masatomo,Nawata, Yoshiharu,Prachayasittikul, Supaluk,Abdel-Sayed, Ashraf N.,Bauer, Ludwig
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p. 1263 - 1270
(2007/10/02)
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- Process for the production of 2-hydroxypyridines from 2-pyridine carboxylic acid-N-oxides
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Process for the production of 2-hydroxypyridines having the formula: STR1 from 2-pyridine carboxylic acid-N-oxides having the formula: STR2 wherein R is H, a --COOH group, an alkyl group having 1 to 8 carbon atoms or an aryl group and n designates a number between 1 and 4. The N-oxide is converted using lower aliphatic carboxylic acid anhydrides in the presence of a tertiary amine. The conversion product is then hydrolyzed.
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