2,4,6-Collidine, nitration

The criterion has also been applied qualitatively. Thus, 2,4,6-collidine and 1,2,4,6-tetramethylpyridinium cation can be nitrated under identi-... 

For this series of compounds qualitative information is quite extensive. Application of the criteria discussed in 8.2, in particular comparison with the corresponding methyl quaternary salt, establishment of the rate profile for nitration in sulphuric acid, and consideration of the encounter rate and activation parameters, shows that 2,4,6-collidine is nitrated as its cation. The same is true for the 3-nitration of 2,4- ... 

GLYCOSIDES Bromotrimcthyisilanc-Cobalt(II) bromide, lodonium di-sym-collidine perchlorate. Mercury(Il) nitrate. Silver imidazolale. Siannous chloride-Silver perchlorate. 

Iodine-copper(II) acetate, 267 Iodine-mercury(II) oxide, 267-268 Iodine monochloride, 268-269 Iodine-silver carboxylates, 268 Iodine-silver nitrate, 268 lodoamination, 265-266 Iodocarbamation, 264-265 Iodocarbonates, 263 2 Iodoestradiol, 267 2-Iodoestrone, 267 Iodoiactonization, 263-264 C,-Iodomethylcephalosporins, 273 Iodonium di-svm-collidine perchlorate, 269 19-Iodononadecanic acid, 488 Iodophenylbis(triphenylphosphine)palladium, 269... 

Pyridine itself can be converted into 3-nitropyridine only inefficiently by direct nitration, even with extremely vigorons conditions, however a couple of ring methyl groups facihtate electrophilic substitution snfficiently to allow nitration both collidine (2,4,6-trimethylpyridine) and its M-methyl quaternary salt are nitrated at similar rates under the same conditions, showing that the former reacts via its A -protonic salt. Steric or/and inductive inhibition of M-nitration allows C-3-substitution using nitronium tetrafluo-roborate an example is the nitration of 2,6-dichloropyridine or of 2,6-difluoropyridine using tetramethyl-ammoninm nitrate with trifluoromethansulfonic anhydride. ... 

For the activation of pyridine, more than one alkyl group is necessary. Thus, on nitration picolines suffer extensive oxidation of the side chain, but 2,6-lutidine and 2,4,6-collidine are converted smoothly into the 3-nitro products. 

Both collidine and its quaternary salt are nitrated at similar rates under the same... 

Both collidine and its quaternary salt are nitrated at similar rates under the same conditions, showing that the the former reacts via its N-protonic salt. ... 

Polychromatic reagents Moffat and Lyttle (42) developed a polychromatic ninhydrin reagent. It consisted of (a) ninhydrin (0.2%) in ethanol (50 ml) + acetic acid (10 ml) + 2,4,6-collidine (2 ml) and (b) a solution of copper nitrate (1.0%) in absolute ethanol. The two solutions are mixed in a ratio of 50 3 before use. Krauss and Reinbothe replaced ethanol by methanol (43) and also achieved polychromatic amino acid detection by joint application of ninhydrin and primary, secondary, or tertiary amines. The layers were first sprayed with diethylamine, dried for 3 min at 110°C, cooled, and then sprayed with 0.2% methanolic ninhydrin and heated for 10 min at 110°C, when the spots of amino acids appeared on a pale blue background. Use of ninhydrin (0.27 g), isatin (0.13 g), and triethylamine (2 ml) in methanol (100 ml) gave spots of amino acids on a yellow background. 

The nitration of 2,4,6-collidine in sulphuric acid involves the cation, and... 

---