1906, 39, p. 2486) showed that the difference in the rotations of the natural and synthetic d-conine is not due to another substance, iso-conine, as was originally supposed, but that the artificial product is a stereo-isomer, which yields natural conine on heating for some time to 290°-300°, and then distilling.
MANDELIC ACID (Phenylglycollic Acid), C 8 H 8 O 3 or C 6 H 5 CH(OH) COOH, an isomer of the cresotinic and the oxymethylbenzoic acids.
An isomer of cinnamic acid known as allo-cinnamic acid is also known.
According to the above formula the critical temperature is given by 8aA/54b, and as the critical temperature is approximately proportional to the boiling-point, both being estimated on the absolute scale of temperature, we may conclude that the larger value of b corresponds to the lower boilingpoint, and indeed the isomer corresponding to the left-hand formula boils at 74°, the other at 114°.
Consequently, of each pair of isomers we may establish beforehand which is the more stable; either in particular circumstances, a direct change taking place, as, for instance, with maleic acid, which when exposed to sunlight in presence of a trace of bromine, yields the isomeric fumaric acid almost at once, or, indirectly, one may conclude that the isomer which forms under greater heat-development is the more stable, at least at lower temperatures.
Ladenburg (Ann., 1875, 179, p. 163) to be symmetrical trimethyl benzene; terephthalic acid, the remaining isomer, must therefore be the para-compound.
Benzoflavin, an isomer of chrysaniline,1`is also a dye-stuff, and has been prepared by K.
Jorgensen in the second dinitrotetramminecobalt chloride, [Co(NO 2) 2 (NH 3) 4 ]Cl, designated as flavo - whereas the older isomer of Gibbs was distinguished as croceo-salt.
The remaining isomer, pivalic or trimethylacetic acid, (CH3)3C C02H, melts at 35° and boils at 163°.
Atropine is optically inactive; hyoscyamine, possibly a physical isomer, which yields atropine when heated to 108.6°, is laevorotatory.
The third isomer (sarcolactic acid) is found in meat extract (J.
Metaor iso-xylene, the most important isomer, may be prepared by nucleus-synthetic reactions, or by distilling mesitylenic acid, C 6 H 3 (CH 3) 2 CO 2 H, an oxidation product of mesitylene, C 6 H 3 (CH 3) 3, which is produced on the condensation of acetone, with lime; this reaction is very important, for it orientates meta-compounds.
For an isomer, isocampholactone (the lactone of trimethyl-2.2.
Homo-pyrocatechin is an isomer (CH 3: OH: OH= I: 3 : 4), found as its methyl ether (creosol) in beech-wood tar.
Van't Hoff and others have established, corresponds to the presence of one or more asymmetric atoms of carbon - that is, atoms directly united to elements or radicles all different from one another - and in every case there exists an isomer that rotates the plane of polarization to the same degree in the opposite direction.