Polymethylated pyridines

Since methyl pyrldlnes are readily available from ring formation reactions, the methylation reaction is useful, primarily, as a means of preparing polymethyl pyridines especially 2,1 -, 2,5-and 2,6-lutidine and 2,l, 6-collldine. 

In order to evaluate fluoroheteroaromatic compounds as intracellular pH probes, R.A.J. Smith and co-workers prepared monofunctionalized polymethylated pyridines. To this end, radical Minisci-type substitution reactions were used on substituted pyridines. Reaction of hydroxymethyl radicals with A/-methoxy 2,4- and 2,6-dimethylpyridinium salts gave 2,4,6-substituted hydroxymethylpyridines. Similar reactions with 2,3,5,6-tetramethylpyridine and derivatives failed, but substitution at the 4-position could be achieved using a carbamoyl radical to yield 2,3,5,6-tetramethyl isonicotinamide, which suggested that steric and reactivity restrictions can be overcome by appropriate choice of the reactive radical intermediate. 

The polymethylated pyridines (lutidines, collidines) are used as solvents or anticorrosion agents, or can be converted into pyridine by dealkylation at temperatures between 700 and 800 °C. 

Paal-Knorr synthesis, 4, 118, 329 Pariser-Parr-Pople approach, 4, 157 PE spectroscopy, 4, 24, 188-189 photoaddition reactions with aliphatic aldehydes and ketones, 4, 232 photochemical reactions, 4, 67, 201-205 with aliphatic carbonyl compounds, 4, 268 with dimethyl acetylenedicarboxylate, 4, 268 Piloty synthesis, 4, 345 Piloty-Robinson synthesis, 4, 110-111 polymers, 273-274, 295, 301, 302 applications, 4, 376 polymethylation, 4, 224 N-protected, 4, 238 palladation, 4, 83 protonation, 4, 46, 47, 206 pyridazine synthesis from, 3, 52 pyridine complexes NMR, 4, 165... 

Cellulose Esters Epoxy Resins Lignins Polystyrene Poly (2-vinyl pyridine) Polyvinyl Chloride Polymethyl methacrylate Polyphenylene Oxide Phenolics Polycarbonate Polyvinyl Acetate, etc. Polyvinyl butyral SBR rubber, etc., etc. 

In contrast with the azoles, diazoles and their benzo derivatives tend to react with dichlorocarbene to yield the tris(diazolyl)methanes, presumably via the initial formation of the N-dichloromethyl derivative [6, 13]. Only in more activated polymethyl derivatives does reaction occur at a ring carbon atom. In a similar manner (7.7.1.B), 2-chloropyridine and 2-chloroquinoline react with dichlorocarbene at the ring nitrogen atom to yield, after nucleophilic displacement of the chloro group, the 1 -dichloromethyl-2-oxo derivatives (13-25%) [14] (Scheme 7.38). 2-Chlorobenzothiazole reacts in an analogous manner, but other pyridine and quinoline derivatives fail to react. It is also noteworthy that the dichloromethyl group is unusually stable and is not converted into the formyl group. 

The loss of a methyl group when polymethylated 8-azaxanthines were refluxed in pyridine has been briefly noted. ... 

Polydimethylsiloxane, hydroxyethoxypropyl-terminated Polydimethylsiloxane, trimethylsiloxy-terminated Polyethylene Polyethylene wax Polyglyceryl-2 isostearate Polymethyl-3,3,3-trifluoropropylsiloxane Potassium caprate PPG-40 Propylene glycol dimethyl ether Propylene glycol laurate Propylene glycol stearate Pyridine Pyridinium propyl sulfobetaine (N-Pyrrolidonepropyl) methylsiloxane-dimethylsiloxane copolymer Silicone... 

Signal intensity versus mtz plots all give readily interpretable MS suitable for structural analysis and chemical identification of the polymer being examined. End-group analysis can be performed. A high detection sensitivity is achievable. The following polymers were examined by Schrimmer and Li [50] PS, polyvinyl pyridine, PS-2-vinyl pyridine, polyethylene glycol (PEG), and polymethyl methacrylate. 

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