Oxidation of Certain Methylpyridines to Pyridine Carboxylic Acids

Black, Gordon S.; Depp, E. A.; Corson, B. B.

doi:10.1021/jo01153a003

Cited by 91 publications

(34 citation statements)

References 21 publications

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“…The following improvements were achieved, when compared to the literature (Xiao et al 2008;Black et al 1949;Singer and McElvain 1955): 1. The volume of water was reduced from 50 to 25 mL/g of the starting material; this modification eliminated the concentration under vacuum step, which allows an easier scale up.…”

Section: Synthesis Of Pyridine-26-dicarboxylic Acidmentioning

confidence: 86%

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Pre-treatment of the paper pulp in the bleaching process using biodegradable chelating agents

Pinto¹,

Ascenso

Barros

et al. 2013

Int. J. Environ. Sci. Technol.

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The aim of this work was to study the application of two biodegradable chelating agents, pyridine-2,6-dicarboxylic acid (PDA) and methylglycinediacetic acid (MGDA), in the treatment of the pulp, prior to hydrogen peroxide bleaching. Such compounds must remove transition metals (Mn, Fe and Cu) from pulp, that catalyze the degradation of hydrogen peroxide, and Ca, which is also problematic due to the formation of precipitates that accumulate in the equipment. Computer simulations were first performed to study the best conditions for metal complexation, and optimum pH was defined as 5-5.5 for PDA and 6.5-7 for MGDA. Metals removal from the pulp, as well as the subsequent bleaching process (Q-P1-Paa-P2), were tested experimentally, and performances were compared to ethylenediaminetetracetic acid (EDTA). PDA removed both Mn and Ca efficiently, leaving most Mg in the pulp after first chelation stage, while MGDA had a lower Ca removal, even using a higher pH and concentration. Residual hydrogen peroxide and kappa number after peroxide stages showed a similar bleaching efficiency between the studied compounds and EDTA.

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Section: Synthesis Of Pyridine-26-dicarboxylic Acidmentioning

confidence: 86%

“…In general, the global yield is low or there is a necessity of complex purification processes. The present experimental protocol was developed based on the works of Xiao et al (2008), Black et al (1949) and Singer and McElvain (1955) where 2,6-dimethylpyridine is oxidized with potassium permanganate (Fig. 2).…”

Section: Synthesis Of Pyridine-26-dicarboxylic Acidmentioning

confidence: 99%

Pre-treatment of the paper pulp in the bleaching process using biodegradable chelating agents

Pinto¹,

Ascenso

Barros

et al. 2013

Int. J. Environ. Sci. Technol.

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“…Silica gel (Acros, 0.035-0.07 mm) was used for preparative column chromatography. Tris(2-(N-methylamino)ethyl)amine (2) 19 and 2-carboxy-6-methylpyridine 58 were prepared according to literature procedures. The perchlorate salts Ln(ClO 4 ) 3 .xH 2 O (Ln ) La-Lu, x ) 6-8) were prepared from the corresponding oxides (Rhodia, 99.99%) and dried according to published procedures.…”

Section: Methodsmentioning

confidence: 99%

Connecting Terminal Carboxylate Groups in Nine-Coordinate Lanthanide Podates: Consequences on the Thermodynamic, Structural, Electronic, and Photophysical Properties

et al. 2003

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The hydrolysis of terminal t butyl-ester groups provides the novel nonadentate podand tris{2-[N-methylcarbamoyl-(6-carboxypyridine-2)-ethyl]amine} (L13) which exists as a mixture of slowly interconverting conformers in solution. At pH ) 8.0 in water, its deprotonated form [L13 − 3H] 3-reacts with Ln(ClO 4 ) 3 to give the poorly soluble and stable podates [Ln(L13 − 3H)] (log( 110 ) ) 6.7−7.0, Ln ) La−Lu). The isolated complexes [Ln(L13 − 3H)](H 2 O) 7 (Ln ) Eu, 8; Tb, 9; Lu, 10) are isostructural, and their crystal structures show Ln(III) to be nine-coordinate in a pseudotricapped trigonal prismatic site defined by the donor atoms of the three helically wrapped tridentate binding units of L13. The Ln−O(carboxamide) bonds are only marginally longer than the Ln−O(carboxylate) bonds in [Ln(L13 − 3H)], thus producing a regular triple helix around Ln(III) which reverses its screw direction within the covalent Me−TREN tripod. High-resolution emission spectroscopy demonstrates that (i) the replacement of terminal carboxamides with carboxylates induces only minor electronic changes for the metallic site, (ii) the solid-state structure is maintained in water, and (iii) the metal in the podate is efficiently protected from interactions with solvent molecules. The absolute quantum yields obtained for [Eu(L13 − 3H)] (Φ Eu tot ) 1.8 × 10 -3 ) and [Tb(L13 − 3H)] (Φ Eu tot ) 8.9 × 10 -3 ) in water remain modest and strongly contrast with that obtained for the lanthanide luminescence step (Φ Eu ) 0.28). Detailed photophysical studies assign this discrepancy to the small energy gap between the ligand-centered singlet ( 1 ππ*) and triplet ( 3 ππ*) states which limits the efficiency of the intersystem crossing process. Theoretical TDDFT calculations suggest that the connection of a carboxylate group to the central pyridine ring prevents the sizable stabilization of the triplet state required for an efficient sensitization process. The thermodynamic and electronic origins of the advantages (stability, lanthanide quantum yield) and drawbacks (solubility, sensitization) brought by the "carboxylate effect" in lanthanide complexes are evaluated for programming predetermined properties in functional devices.

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“…For instance, KMnO 4 has been employed in the synthesis of niacin (187) from b-picoline (186) [161]. Selective oxidation of the methyl group of disubstituted pyridine 188 has been achieved using SeO 2 as the oxidizing agent of choice to give carboxylic acid 189 [162].…”

Section: Reactions With Oxidizing Agentsmentioning

confidence: 99%

Six‐Membered Heterocycles: Pyridines

González‐Bello

Castedo

2011

Modern Heterocyclic Chemistry

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Figure 16.5 Examples of agrochemical pyridine derivatives and their applications.1434j 16 Six-Membered Heterocycles: Pyridines IR DataThe pyridine IR spectrum is quite similar to the corresponding vibrations of benzene. Pyridine has C-H stretching frequencies in the range 3020-3070 cm À1 as well as C¼C and C¼N stretching frequencies at 1590-1660 cm À1 and near 1500 cm À1 . N J 2,3 = 4-6 J 2,4 = 0-2.5 J 2,5 = 0-2.5 2 3 4 5 6 J 2,6 = 0-0.6 J 3,4 = 7-9 J 3,5 = 0.5-2 1436j 16 Six-Membered Heterocycles: Pyridines R + Metal catalyst ∆ R = alkyl, vinyl, aryl Scheme 16.2 16.

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Oxidation of Certain Methylpyridines to Pyridine Carboxylic Acids

Cited by 91 publications

References 21 publications

Pre-treatment of the paper pulp in the bleaching process using biodegradable chelating agents

Pre-treatment of the paper pulp in the bleaching process using biodegradable chelating agents

Connecting Terminal Carboxylate Groups in Nine-Coordinate Lanthanide Podates: Consequences on the Thermodynamic, Structural, Electronic, and Photophysical Properties

Six‐Membered Heterocycles: Pyridines

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