Picolinic acid N-oxide

Peroxomolybdenum-Picolinate N-oxide complex (1). The complex is prepared from Na2Mo04-2H20, H202, picolinic acid N-oxide, and Bu4NOH. It is obtained... 

The indolizine nucleus is readily oxidized. No N- oxides have been isolated so far. In the course of many oxidations, ring fission occurs. The reaction has therefore been used in the past for structural elucidation (B-66MI30800). Thus l-(4-nitrophenyl)indolizine on treatment with perhydrol and acetic acid gave picolinic acid N- oxide and 4-nitrobenzoic acid (Scheme 7). 

C6H5N03 picolinic acid N-oxide 824-40-8 489.15 42.843 2 7020 C6H6N203 6-hydroxy-5-nitro-2-picoline 39745-39-6 377.15 32.218 2... 

Figure 7. Car-Parrinello calculated envelope for the OH stretching mode in picolinic acid N-oxide in the solid state, according to Ref [32].

Picohne s 2.8 g 3-picoline s 2.8 g catalyst s 0.30 g adamantane (internal standard s 0.5 g 1 = 4 h Products 2 isonicotinic acid (4-picolinic acid) 3 4-picoUne N-oxide 4 isonicotinic acid N-oxide 2A nicotinic acid (3-picoUnic acid) 3A 3-picoline N-oxide 4A nicotinic acid N-oxide O others... 

The results for the oxidation of 4- and 3-picoline with these catalysts are shown in Table 21.2. In the case of 4-picoline, the overall conversion falls by an order of magnitude (ca 2.5 times), but more significantly, the selectivity for the target (desired) product (isonicotinic acid) was greatly diminished. Interestingly, substantial amounts (almost tenfold) of 4-picoline N-oxide and isonicotinic acid N-oxide were formed, whereas with the microporous host, containing the redox-active site in high oxidation (Mn ") state, 92% selectivity for the desired isonicotinic acid was maintained. In the case of 3-picoline, the results were even more pronounced there was almost a fivefold decrease in the conversion and virtually no nicotinic acid was produced. 

Oxidation of hydroxymethyl alkylpyridines with the HjOa/HOAc affords N-and C-oxidation products 2 ydroxymethyl-6-methylpyridine (X-210) yielded 6-inethylpicolinic acid-1-oxide (X-211) and 2-hydroxymethyl-6-methylpyri-dine-l-oxide (X-212). Similarly, 2,6-bis(hydroxymethyl)pyridine (X-213) yielded the expected pyridine-1-oxide (X-214) and a small amount of 6-hydroxymethyl-picolinic acid-l-oxide (X-215). On the other hand, permanganate oxidations lead... 

N - Benzyl- N -p icolinoylpiperazine (EGYT-475, 4.88), a compound with potential antidepressant activity, underwent similar hydrolysis. After intravenous administration, picolinic acid (4.89) was one of its major urinary metabolites in rats the other product, A-benzylpiperazine (4.90) was also detected, but at much lower levels, since it was further transformed by A-de-benzylation [55], Since the products of direct hydrolysis of these cyclic tertiary amides (i.e., the corresponding secondary amines) were found at substantial levels, it appears that oxidative A-monodealkylation is not an essential step for hydrolysis in these compounds, in contrast to the findings for A,A-diethylbenzamide. This contradicts the hypothesis [52] (see above) that the steric bulk of the tertiary amide group impedes direct hydrolysis. Here, although the degree of steric bulk is at least comparable, direct hydrolysis clearly takes place. 

Use of the urea-hydrogen peroxide complex and /V,/V -bis(TMS) urea provides an improved method126 for the preparation of bis(TMS) peroxide, TMSOOTMS. In the presence of Fe(m)(picolinic acid)3, bis(TMS) peroxide carries out selective oxidation of alkanes to ketones by a non-radical mechanism. The Fe(III)-Fe(IV) manifold is believed to be responsible127. On the other hand, using FeCU in pyridine, alkyl chlorides are formed through a radical mechanism. Here, the Fe(n)-Fe(IV) manifold has been proposed128. 

Oxidation with nitric acid yields picolinic acid. Structure established by n. m. r. spectrum, by degradation and by synthesis. 

Phthaeaedehyde, 34, 82 Phthalic acid, 32, 67 Phthalic anhydride, 32, 19 Phthalideacetic adi 34,10 PhTHAEIMIDE, N-2-BROMOETHYE-, 32,18 3-Picoline, nitro-, 1-oxide, 36, 53 3-Picoline-l-oxide, 36, 54... 

Clement and Paris [17] have devised a pair of methods for the determination of cobalt in steels, especially materials encountered in the nuclear industry. In the first technique, suitable for the analysis of solutions containing 8 to 160 mM cobalt(II), iron(III) is used to oxidize cobalt(II) in a picolinic acid medium, after which the resulting iron(Il) is titrated po-tentiometrically with a standard solution of cerium(IV). An alternative procedure, for concentrations of cobalt(n) below 8mM, involves a constant-current coulometric titration with electrogenerated cerium (IV) to measure the iron(II) that arises from the original reaction between cobalt(II) and iron(III). 

Phthalic acid, 259 Phthalic anhydride, 104 a-Picoline, 161 a-Picoline N-oxide, 161 Picolinic acid, 16 Picramic acid, 271 Picric acid, 271 Pinacol reduction, 7 Pinosylvin, 31 Piperazines, 322 Piperidine, 33, 291 2-Piperidone, 194 Pivaldehyde, 105 Podophyllotoxin, 337 Podophyllotoxone, 337 Polonovski reaction, 308 Polyisoprenoids, 300-301 Polymethoxybenzophenones, 30—31 Polymethylhydrosiloxane, 294 Polyphosphate ester (PPE), 229-230 Polyphosphoric acid, 227, 231—232 Potassium, 232, 233 Potassium acetate, 96 Potassium amide, 232—233, 310 Potassium azodicarboxylate, 100 Potassium r-butoxide, 26, 45, 47, 77-78, 85, 133, 188, 212, 222, 225, 233-234, 236, 246... 

Figs. 19 and 20 show the infrared spectra of some acid salts and related crystalline compounds. The spectrum in Fig. 19(a) is from an acid salt of Type B, and it approximates to a superposition of the spectra of free acid and neutral salt. The other spectra are all of Hadzi s T5q>e (ii), which is shown in its starkest form in Fig. 19(c) (sodium hydrogen diacetate) with a window near 950 cm h Potassium hydrogen malonate, a Type A structure, has a similar spectrum (20 (a)). The picoline-N-oxide hemi-hydrobromide (19(d)) is a T5q>e A basic salt Cook s basic salt (Sect. XI) is of pseudo-Type A and gives the spectrum (20(b)). Sodium bicarbonate (20(c)) and potassium hydrogen oxalate (20(d)) are acid sdts of intermediate character (see Sect. XV and XVI A). 

Fig. 19. Infrared spectra of some crystalline acid salts and related compounds (a) potassium hydrogen di-p-nitrobenzoate (Type B) (b) rubidium hydrogen di-o-nitrobenzoate (Type A) (c) sodium hydrogen di-acetate (d) a-picoline-N-oxide hemi-hydrobromide...

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