Picoline was obtained, in impure form, in 1826 by the German chemist
Otto Unverdorben (1806 – 1873), who obtained it by the
pyrolysis (roasting) of bones. He called it
Odorin due to its unpleasant smell. In 1849, the Scottish chemist
Thomas Anderson (1819 – 1874) prepared picoline in pure form, from
coal tar and via the pyrolysis of bones. Anderson also named picoline by combining the Latin words
pix (tar) and
oleum (oil) because coal tar oil was a source of picoline. By 1870, the German chemist
Adolf von Baeyer had synthesized picoline in two ways: by the dry distillation of
acroleïnammoniak (CH2=CH-CH=N-CHOH-CH=CH2) and by heating
tribromallyl (
1,2,3-tribromopropane) with ammonia in ethanol. In 1871, the English chemist and physicist
James Dewar speculated that picoline was methylpyridine. If the structure of pyridine that had been proposed in 1869 by the German-Italian chemist
Wilhelm Körner were correct, that is, if pyridine were analogous to
benzene (a hexagonal ring of alternating single and double bonds), then there should be three isomers of methylpyridine. By 1879, the Austrian chemist
Hugo Weidel had succeeded in isolating and characterizing three isomers of picoline, which he denoted α–, β–, and γ–picoline: α–picoline was the main component of impure picoline; it was accompanied by small quantities of β–picoline; and γ–picoline was produced by Baeyer's dry distillation of
acroleïnammoniak. Weidel then subjected each isomer of picoline to oxidation by
potassium permanganate, transforming each into a
carboxylic acid. He called the acid from α–picoline
Picolinsäure (picolinic acid). He recognized the acid from β–picoline as
Nicotinsäure (
nicotinic acid or "niacin"), which Weidel had discovered in 1873. When Weidel
decarboxylated the carboxylic acid of each isomer – by dry distilling its calcium salt with
calcium oxide – the reaction yielded pyridine, thus showing that picoline was a mixture of three isomers of methylpyridine, as expected. However, Weidel did not determine, for any of the three isomers, the position of the
methyl group in relation to the nitrogen atom of the pyridine nucleus. The structure of niacin, and thus β–picoline, was determined in 1883 when the Czech-Austrian chemist
Zdenko Hans Skraup and Albert Cobenzl repeatedly oxidized β–naphthoquinoline and found niacin among the products, thus proving that β–picoline was 3-methylpyridine. ==Environmental properties==