6-chloro-2-picolinic acid

C7H7N02 picolinic acid, methyl ester 2459-07-6 389.15 33.344 1,2 10755 C7H8CIN 3-chloro-N-methyl aniline 7006-52-2 504.88 44.353 2... 

Our synthesis began with picolinic acid, which was treated with thionyl chloride in the presence of LiBr according to the procedure of Sundberg to provide the 4-chloro acid chloride, which was then treated with diisopropylamine to provide diisopropyl amide 45 (Scheme 12). Ortho-lithiation of this species with LDA and trapping with iodine provided compound 46. Unfortunately, this compound also proved to be... 

The universal synthetic method used to prepare an Ir(C N)2(LX)-type complex is shown in Fig. 5. Dimer complex [Ir(C N)2Cl]2 is readily prepared from reaction of the ligand precursor and IrCl3-nH20 [79], and chloro-ion ligands can be subsequently replaced with an LX chelate. The most studied ancillary ligand LX is acac, but it can be varied with other monoanionic bidentate ligands, such as picolinic acid, N-methylsalicylimine [23], 2-(5-phenyl-4//-[l,2,4]triazol-3-yl)-pyr-idine [28], 2,2,6,6-tetramethyl-3,5-heptanedionate, 1-phenyl-4,4-dimethyl-1,3-pen-tanedionate, l,3-diphenyl-l,3-propanedionate, pyrazolyl, pyrazolyl-borate [80], and (2-pyridyl) pyrazolate derivatives [81]. 

When picolinic acid is heated with thionyl chloride, 4-chloro- or 4,6-dichloro-, and even some 4,5,6-trichloro-picolinic acid result, according to the severity of the conditions 5 Isonicotinic acid gives 2-chloro-isonicotinic acid" " . Quaternary complexes are probably involved in these reactions ... 

The total consumption of 2-methylpyridine (a-picoline) in 1980 has been estimated at 12,000 tons [81CI(L)23]. Half is produced for the U.S. market, whereas the demand in both Western Europe and Japan lies between 2000 and 2500 tons per annum. A significant outlet for 2-methylpyridine is in the production of 2-chloro-6-(trichloromethyl)pyri-dine, which is used as a nitrification inhibitor in agricultural chemistry and in the manufacture of the defoliant 4-amino-2,5,6-trichloropicolinic acid. The major commercial outlet for 2-methylpyridine is, however, its use as a starting material for the production of 2-vinylpyridine [Eq.(7)]. 

The reaction between heteroaromatic iV-oxides and 2-chloro, 5-dihydroimidazole 955 results in a formal ureida-tion of the heteroaryls. This reaction was extended to 2- and 4-picoline iV-oxides for the synthesis of 956 and 957, respectively (Scheme 232) <2002JHC911>. The 2-bromine of nitronyl nitroxide 958 is easily displaced with sodium azolides to give spin-labeled azoles (imidazole, pyrazole, triazole) 959 which are prone to hydrolysis to hydroxamide acid anion 960 <2004T99>. 

Other kinetic studies of complexation using relaxation techniques can be found in Bridger et al. (1983) [hydroxo and chloro complexes of Fe(III)], Bridger et al. (1982) [complexation of Fe(III) by picolinic and dipicolinic acids], Strahm et al. (1979) (complexation of aqueous iron chloride), and Patel and Taylor (1973) (complexation of magnesium pyrophosphates). 

Moreover, the operation can also be accelerated by employing a catalyst (cuprous chloride) in solution in an organic solvent (such as a-picoline), and by raising the temperature. Above 160 0, however, large amounts of by-products are formed 1-chloro butadiene, hydrochloric acid and especially polymers. Thus, to prevent these side reactions it is preferable to maintain a low thermal level, 105 to 125°C, and distill under partial vacuum (about 20 kPa absolute), in the presence of an inhibitor intended to prevent polymerizations from developing (phenothiazine). For a once-through conversion of 1,4-dichloro 2-butenes of about 80 per cent, molar selectivity of the 3,4-isomer exceeds 75 per cen t. 

A newly-developed herbicide based on p-picoline is fluazifop-butyl (ICI, Ishi-hara Sangyo Kaisha). 2-Chloro-5-trichloromethylpyridine, which is obtained by chlorination, is used to produce this herbicide through fluorination with HF/SbFs to give 2-chloro-5-trifluoromethylpyridine, which then undergoes nucleophilic substitution with p-hydroxyphenoxypropionic acid butyl ester. 

Cyanopyridines have been reduced to aminoethylpyridines by a variety of methods, 2- And 4-cyanopyridine are reduced with sodium borohydride to 2-and 4-aminomethylpyridine, respectively. In acidic solutions, the polaro-graphic reduction of 4-cyanopyridine yields 4-aminomethylpyridine. Hydrogenation of 6-chloro-5-cyano-4-methoxymethyl-3-nitro-2-picoline over palladium-charcoal in aqueous hydrochloric acid gives 3-amino-5-aminomethyl-4-methoxymethyl-2-picoline hydrochloride. 3-Amino-5-aminomethyl-2,4-lutidine is prepared in good yield by the catalytic reduction (Pd—C in methanol) of 6-chloro-3-cyano-2,4-dimethyl-3-nitropyri-dine. The hydrogenation of 3-( S-pyridylmethoxy)propionitrile over Raney Nickel yields 3-[(3-aminopropoxy)methyl] pyridine. ... 

Photochlorination of 2-picoline (X-112) at 50 to 150° produces 3-chloro-2-trichloromethylpyridine (X-113) and 3,6-dichloro-2-trichloromethyl-pyridine (X-114). Hydrolysis with concentrated nitric acid gave a 95% yield of the corresponding 2-carboxylic acids. Continued photochlorination affords a perchlorinated trichloromethylpyridine (X-llS), which, after ammonolysis and boiling in sulfuric acid, afforded picloram (X-116). ... 

Preparation of substituted pyridinecarboxyUc acid 1-oxides by means of H-abstraction is reported by Abramovitch and others. Thus, treatment of the lithium derivative of 4-chloropyridine-l-oxide or 4-chloro-3-methylpyridine-l-oxide with CO2 gave the corresponding 4-chloro- and 4-chloro-5-methylpicolinic acid-1-oxides. Under the same conditions, 4-picoline-l-oxide gave the 2,6-di-carboxylic acid. 

Nitro-3-picoline (MI-368) is hydrolyzed on standing to l-(3 -methyl-4 -pyridyl)-3-methyl-4-pyridone and 3-methyl-4-pyridone. 4-Nitropyridine and benzyl bromide give iV-benzyl-3,5-dibromo-4-pyridone (MI-369) in 33% yield. The quaternary salt first formed is hydrolyzed to the 4-pyridone. Oxidation of hydrogen bromide by the nitrous acid product provides the bromine and water. The yield is increased to 71%by the addition of bromine. 3,5-Dibromo-4-chloro-pyridine and benzyl bromide in base also give XII-369. Similarly, 3-methyl-4-nitropyridine and benzyl bromide give W-benzyl-3-bromo-5-methyl-4-... 

Czuba has studied 3-nitramines in some detail. " Nitramines of the four chloro-3-aminopyridines, 3-amino-5-ethoxypyridine, 5-aminonicotinic acid, 5-aminopicolinic acid, 3-amino- and 5-amino-2-pyridinesulfonic acids, 3-amino-4-picoline and 5-amino-3-picoline have been prepared. Attempts to prepare nitramines from the four 3-aminopyridinols were unsuccessful. However, 3-amino-5-ethoxypyridineforms the nitramine that reacts in sulfuric acid to give 5-ethoxy-3-pyridinol. ... 

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