On oxidation with chromic or nitric acids, or potassium permanganate, it yields nicotinic acid or (3-pyridine carboxylic acid, C 5 H 4 N CO 2 H; alkaline potassium ferricyanide gives nicotyrine, C10H10N2, and hydrogen peroxide oxynicotine, C10H14N20.
It gives rise to various decomposition products such as pyridine, picoline, &c., when its vapour is passed through a red-hot tube.
By passing the vapour of this compound through a red-hot tube, it yields the isomeric a0- pyridylpyrrol, the potassium salt of which with methyl iodide gives a substance methylated both in the pyridine and pyrrol nuclei.
By distillation over lime, the methyl group is removed from the pyridine ring, and the resulting a- pyridyl-Nmethylpyrrol gives i-nicotine on reduction.
Rhombic sulphur may be obtained artificially by slowly crystallizing a solution of sulphur in carbon bisulphide, or, better, by exposing pyridine saturated with sulphuretted hydrogen to atmospheric oxidation (Ahrens, Ber., 1890, 23, p. 2708).
Thus benzene, (CH) gives thiophene, (CH) S, from which it is difficultly distinguished; pyridine, (CH) N, gives thiazole, (CH) N S, which is a very similar substance; naphthalene gives thionaphthen, C 11 S, with which it shows great analogies, especially in the derivatives.
Similarly a CH group may be replaced by a nitrogen atom with the production of compounds of similar stability; thus benzene gives pyridine, naphthalene gives quinoline and isoquinoline; anthracene gives acridine and a and 3 anthrapyridines.
Six-membered ring systems can be referred back, in a manner similar to the above, to pyrone, penthiophene and pyridine, the substances containing a ring of five carbon atoms, and an oxygen, sulphur and nitrogen atom respectively.
Pyridine gives origin to: pyridazine or ortho-diazine, pyrimidine or metadiazine, pyrazine or para-diazine, osotriazine, unsymmetrical triazine, symmetrical triazine, osotetrazone and tetrazine.
A-pyrone condenses with the benzene ring to form coumarin and isocoumarin; benzo-'y-pyrone constitutes the nucleus of several vegetable colouring matters (chrysin, fisetin, quercetin, &c., which are derivatives of flavone or phenyl benzo-y-pyrone); dibenzo--ypyrone is known as xanthone; related to this substance are fluorane (and fluorescein), fluorone, fluorime, pyronine, &c. The pyridine ring condenses with the benzene ring to form quinoline and isoquinoline; acridine and phenanthridine are dibenzo-pyridines; naphthalene gives rise to a-and /3-naphthoquinolines and the anthrapyridines; anthracene gives anthraquinoline; while two pyridine nuclei connected by an intermediate benzene nucleus give the phenanthrolines.
In the aromatic compounds there is no regularity between the increments due to the introduction of methyl groups into the benzene nucleus or side chains; the normal value of 20 0 -21° is exhibited, however, by pyridine and its derivatives.
Normal values of K were given by nitrogen peroxide, N204, sulphur chloride, S 2 C1 21 silicon tetrachloride, SiC1 4, phosphorus chloride, PC1 3, phosphoryl chloride, POC1 31 nickel carbonyl, Ni(CO) 4, carbon disulphide, benzene, pyridine, ether, methyl propyl ketone; association characterized many hydroxylic compounds: for ethyl alcohol the factor of association was 2.74-2.43, for n-propyl alcohol 2.86-2.72, acetic acid 3.62 -2.77, acetone 1 .
Pyrrol is readily converted into pyridine derivatives by acting with bromoform, chloroform, or methylene iodide on its potassium salt, t3-brom-and O-chlorpyridine being obtained with the first two compounds, and pyridine itself with the last.
It is a reddish amorphous mass, insoluble in alcohol, and when distilled yields picoline (methyl pyridine) (A.
The amount of eugenol in oil of cloves can be estimated by acetylation, in presence of pyridine (A.
Other forms are: d- and l-gulose, prepared from the lactones of the corresponding gulonic acids, which are obtained from d- and /-glucose by oxidation and inversion; d- and l-idose, obtained by inverting with pyridine d- and l-gulonic acids, and reducing the resulting idionic acids; d- and l-galactose, the first being obtained by hydrolysing milk sugar with dilute sulphuric acid, and the second by fermenting inactive galactose (from the reduction of the lactone of d, l-galactonic acid) with yeast; and d- and l-talose obtained by inverting the galactonic acids by pyridine into d- and l-talonic acids and reduction.
When l-gulonic acid is heated with pyridine, it is converted into l-idonic acid, and vice versa; and d-gulonic acid may in a similar manner be converted into d-idonic acid, from which it is possible to prepare d-idose.
Lastly, when d-galactonic acid is heated with pyridine, it is converted into talonic acid, which is reducible to talose, an isomeride bearing to galactose the same relation that mannose bears to glucose.
The crude anthracene cake is purified by treatment with the higher pyridine bases, the operation being carried out in large steam-jacketed boilers.
The crystallized anthracene is then removed by a centrifugal separator and the process of solution in the pyridine bases is repeated.
In the first category there are two varieties: - (T) A mixture of ioo litres of spirit and 22 litres of a mixture of 4 parts of wood-naphtha and 1 of pyridine bases; this spirit, the use of which is practically limited to heating and lighting purposes, may be mixed with 50 grs.
Of lavender or rosemary, in order to destroy the noxious odour of the pyridine bases.
(2) A mixture of loo litres of spirit, 14 litres of the naphtha-pyridine mixture described above, 4 litre of methyl violet solution, and from 2 to 20 litres of benzol; this fluid is limited to combustion in motors and agricultural engines.
Konigs, expressed the opinion that the alkaloids were derivatives of pyridine or quinoline.
This view has been fairly well supported by later discoveries; but, in addition to pyridine and quinoline nuclei, alkaloids derived from isoquinoline are known.
(1) Pyridine group. Piperine; conine; trigonelline; arecaidine; guvacine; pilocarpine; cytisine; nicotine; sparteine.
It can also be used for the synthesis of pyridine derivatives, since A.
Hantzsch has shown that aldehydes condense with aceto-acetic ester and ammonia to produce the homologues of pyridine, thus: R R [[Rooc Ch 2 Cho Ch 2 Coor Rooc C - Ch - C Coor]] + + 1 = Ii II +3H20.
The 1 5 diketones of this type, when heated with aqueous ammonia, form pyridine derivatives.
Those in which the keto groups are in combination with phenyl residues give pyridine derivatives on treatment with hydroxylamine, thus benzamarone, C 6 H 5 CH[CH(C 6 H 5) CO.
In practice, the crude anthracene is purified by solution in the higher pyridine bases, after which treatment it is frequently sublimed.
It also occurs with pyridine and its homologues in bone-oil.
Only two are known containing the hydroxyl group in the pyridine nucleus, namely, carbostyril (a-oxyquinoline), which is formed by the reduction of ortho-aminocinnamic acid with ammonium sulphide (L.
Alkaline potassium permanganate oxidizes it to pyridine tricarboxylic acid (236).
It crystallizes from water in needles or prisms and in the anhydrous state melts at 253-254° C. Potassium permanganate oxidizes it to pyridine tricarboxylic acid (234).
The transformation of piperidine into pyridine by W.
Hofmann had shown that conine on distillation with zinc dust gave a-propyl pyridine (conyrine).
This substance when heated with hydriodic acid to 300° C. is converted into a-propyl piperidine, which can also be obtained by the reduction of a-allyl pyridine (formed from a-methyl pyridine and paraldehyde).
PYRIDINE, C 5 H 5 N, an organic base, discovered by T.
The amount of pyridine produced in most of these processes is very small, and the best source for its preparation is the "light-oil" fraction of the coal-tar distillate.
Pyridine is a colourless liquid of a distinctly unpleasant, penetrating odour.
On the constitution of the pyridine nucleus, see K6rner, Gior.