Handbook of the polariscope and its pracitcal applications / adapted from the German editon of H. Landolt, by D.C. Robb and V.H. Veley.

  • Hans Heinrich Landolt
Date:
1882
Catalogue details

Licence: Public Domain Mark

Credit: Handbook of the polariscope and its pracitcal applications / adapted from the German editon of H. Landolt, by D.C. Robb and V.H. Veley. Source: Wellcome Collection.

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    The direction of rotation in derivatives, in relation to that in the parent substance, follows no fixed rule. Most derivatives exhibit their rotatory power in the same direction as the parent substance, particularly when no real alteration of molecular constitution has taken place. This is seen in the conversion of active acids and alkaloids into their salts. Still there are exceptions here, as we find that malic acid, which is left-rotating when free, is right-rotating in its neutral salts, especially in the double salt of antimony and ammonium, from which, after precipitation of the antimony with sulphuretted hydrogen, a left-rotating solution of acid malate of ammonia is obtained (Pasteur1). Again, right-rotating para-lactic acid has left-rotating zinc and calcium salts (Wislicenus3). But even in more profound reactions the original direction is generally main- tained. Thus, dextro-tartaric acid gives dextro-malic acid; from dextro-camphor we get dextro-camphoric acid; from lsevo-camphor, lsevo-camphoric acid ; dextro- and kevo-borneols give respectively dextro- and laevo-camphors; and left-rotating amygdalin gives left- rotating amygdalic and mandelic acids (Bouchardat3). Neverthe- less, some derivatives do exhibit rotatory power in a direction contrary to that of the parent substance, as in the following instances:— Dextro-camphoric acid gives left-rotating camphoric anhydride (Montgolfier4) ; dextro-para-lactic acid gives left-rotating ether-anhy- drides (Wislicenus3); the active compounds derived from kevo-amyl- alcohol (amyl chloride, amyl iodide, amyl cyanide, diamyl, ethyl-amyl, amylamine, amyl valerate, valerianic aldehyde, valerianic acid, and capronic acid) are all right-rotating; left-rotating santonic acid, with nascent hydrogen passes into right-rotating hydrosantonic acid (Cannizarro5); left-rotating terebenthene hydrochlorate, heated with stearate of soda, gives left-rotating terecamphene. By saturating the latter with hydrochloric acid we get right-rotating camphene hydrochlorate, from which, by heating with water, left-rotating cam- phene, but with rotatory power much feebler than at first, can be recovered (Biban6). Again, mannite, with weak lsevo-rotatory power, gives both right- and left-rotating derivatives. Of these nitro-mannite, mannite hexacetate, amorphous mannitan, nitro- 1 Pasteur: Ann. Chim. Phys. [3] 31, 67. 2 Wislicenus: Liebig1 s Ann. 167, 322 8 Bouchardat: Comptes Pend. 19, 1174. 4 Montgolfier: Jahresb. fur Chem. 1872, 569. 5 Cannizarro: Jahresb. fur Chem. 1876, 619. 6 Biban; Bull. Soc. Chim. [2], 24, 10.