P-picoline

Water 2-methylpiperidine Water 3-metliylpipericline Water 4-methylpiperidine Water P picoline Water aa-Iutidine Glycerol m-toluidine. ... 

P-Picoline may serve as an important source of nicotinic acid [59-67-6] for dietary supplements. A variety of substituted pyridines may be prepared from acrolein (75—83). 

Compound (27) may also be obtained dkecdy by oxidation of P-picoline (3) or by exhaustive oxidation of 5-ethyl-2-methylpyridine (7), followed by decarboxylation of the initially formed pyridine-2,5-dicarboxyhc acid [100-26-5] (28) (eq. 8) (30). 

Acrolein and ammonia give P-picoline (3, R — H) (eq. 17). Acrolein, ammonia, and acetaldehyde give pyridine (1) (eq. 19). Acrolein, ammonia, and propionaldehyde give (3) (eq. 20) (52—56). Reactions are performed in the vapor phase with proprietary catalysts. 

Acrolein (CH2=CHCHO) can be substituted for formaldehyde and acetaldehyde in the above reaction to give similar results, but the proportion of (3) is higher than when acetaldehyde and formaldehyde are fed separately. Acrolein may be formed as one of the first steps to pyridine (1) and P-picoline (3) formation. There are many variations on the vapor-phase synthesis of pyridine itself. These variations are the subject of many patents in the field. 

The relative production volumes of pyridine compounds can be ranked in the following order pyridine (1) > P-picoline (3) > a-picoline (2)> niacin (27) or niacinamide (26)> 2-vinylpyridine (23)> piperidine (18). U.S. and Japanese production was consumed internally as well as being exported, mainly to Europe. European production is mosdy consumed internally. Growth in production of total pyridine bases is expected to be small through the year 2000. 

The piedominant use of P-picoline (3) is as a starting material for agrochemicals and pharmaceuticals. For example, it is used to make insecticides such as chlorpyrifos (43), food additives such as niacin (27) and its amide (26), and herbicides such as fluazifop-butyl [69806-50-4] (63). 

Nicotinic acid is prepared in good yield by the oxidation of p picoline with potassium permanganate ... 

Trigonelline is present in green coffee (1 %),15 but it is rapidly decomposed on roasting so that only about 0.1% trigonelline is present in a deeply roasted coffee.161 The products of trigonelline breakdown are evident in roasted coffee and include nicotinic acid and its methylester, pyridine, and p-picoline (Figure 17).3... 

The data in Table 3 also show that the N-H BDE of aniline (9b) and the C-H BDE of P-picoline (9c) are quite similar and are calculated to differ by only 0.1 kcal/mol at the BVWN5/AUG-cc-pVTZ level of theory. This is also true for cases other than 9b versus 9c as shown by the calculated enthalpies in Table 4.77 The isodesmic reaction in Table 4 gives the difference between the N-H BDEs of RNH2 and the C-H BDEs of comparable R CH3 species. For R=R =Ph, the calculated difference in BDEs between aniline (9b) and toluene is only 0.3 kcal/mol and for R=R =H, the N-H BDE in NH3 is computed to be only 1.4 kcal/mol larger than the C-H BDE in CH4. The latter energy difference is close to the experimental value of 3.7 kcal/mol.76 Thus, the results in Table 4 show that the N-H BDEs of primary amines are, in general, nearly... 

P-parinaric acid, physical properties, 5 33t P-pentenoic acid, physical properties, 5 3 It P-peroxylactones, 18 484 Beta phase titanium, 24 838 in alloys, 24 854-856 properties of, 24 840, 941 P-phellandrene, 24 493 P-picoline, 21 110 from acrolein, 1 276 uses for, 21 120 P-pinene, 3 230 24 496-497 major products from, 24 478 /-menthol from, 24 522 as natural precursor for aroma chemicals, 3 232 terpenoids from, 24 478-479 P-propiolactone, polymerization of, 14 259 P-quartz solid solution, 12 637—638 Beta ratio, in filtration, 11 329—330 Beta (P) rays, 21 285 P-scission reactions, 14 280-281 P-skytanthine, 2 101 P-spodumene solid solution, 12 638-639 P-sulfur trioxide, 23 756 P-sultones, 23 527 P-tocopherol, 25 793 P-tocotrienol, 25 793 P-vinylacrylic acid, physical properties, 5 33t... 

Lutidine (rejective) from 2.5- lutidine, 2,4-lutidine, a-picoline, P-picoline, AgNa-5.1Y 2,4-Xylidine [23]... 

Uses Intermediate in the manufacture of many chemicals (e.g., glycerine, 1,3,6-hexanediol, P-chloropropionaldehyde, 1,2,3,6-tetrahydrobenzaldehyde, P-picoline, nicotinic acid), pharmaceuticals, polyurethane, polyester resins, liquid fuel, slimicide herbicide anti-microbial agent control of aquatic weeds in irrigation canals and ditches warning agent in gases. 

Byproducts of large industrial-scale processes are valorized for instance, in the DuPont process for adiponitrile, the byproduct a-methylglutaronitrile is upgraded to p-picoline and further to niacinamide. 

For production of niacinamide in the past, methylethylpyridine was oxidized with nitric acid to yield niacin, and P-picoline was treated with air and ammonia to produce the nitrile that was then hydrolyzed to niacinamide. A more modern process can produce both niacin and niacinamide from a single feedstock, either P-picoline or 2-methyl-5-ethylpyridine by oxidative ammonolysis, a combination of oxidation and animation. 

Common Name 3-Methylpyridine Synonym p-picoline, 3-picoline Chemical Name 3-methylpyridine, p-picoline CAS Registry No 108-99-6 Molecular Formula C5H4NCH3 Molecular Weight 93.127 Melting Point (°C) ... 

Deactivation during the hydrogenation of 2-methylglutaro-nitrile to p-picoline... 

The reaction scheme of the conversion of MGN into p-picoline in the presence of hydrogen over supported group VHI metals is presented in Figure 1 and is supported by the literature [3]. 

Since the reaction conditions for the one-reactor synthesis of p-picoline from MGN are a compromise between hydrogenation and dehydrogenation, and since very reactive compounds are involved, several unwanted reactions were expected to take place, in addition to those indicated in Figure 1. For instance, intermolecular condensations may take place which yield heavy compounds. These compounds, depending on the reaction conditions, adsorb on the metal surface leading to deactivation. 

Figure 3a compares the total conversion for these catalysts and shows that activity and catalyst life increase with metal loading. The p-picoline selectivity, however, seems to be strongly correlated with conversion, independent of the metal loading (Figure 3b). The results indicate that in this low Pd loading range the distance between the metal particles is large enough for the particles to behave independently from each other. As a consequence, all catalysts have a similar deactivation pattern.

In Figure 4 the results of two catalysts with similar Pd loading, but different dispersion are compared. Conversion (a) and P picoline selectivity (b) increase with metal dispersion. At the same time the dimer selectivity (c) decreases, indicating that intermolecular condensation reactions are suppressed by the higher (de)hydrogenation activity of catalyst C6. 

Figure 4. Effect of metal dispersion on conversion (a), p-picoline selectivity (b) and dimer selectivity (c).

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