§ 110. Sugars, C, H12O6.

6

Glucose. Dextrose, C, H12 O + H2O. Dextro-rotatory. Fresh solutions, prepared in the cold, exhibit bi-rotation (§ 27). The following numbers refer to the reduced constant of rotation. The most accurate observations are those of Tollens (§ 38), whence the following formulæ are derived :

Hoppe-Seyler (Med. chem. Untersuchungen I., 163) determined the specific rotation of diabetic sugar by Broch's method, employing a solution in which c= 36.277 anhydrous substance, and found :

In more recent investigations, Hoppe-Seyler (Fresenius, Zeitsch. für analyt. Chem. 14, 305), employing solutions of diabetic sugar with c = 14 to 29, obtained a mean value for [a] = 564 (anhydrous substance).

Hesse (L. A. 176, 102) has investigated the specific rotation of [a] of various glucoses, and found, at t = 15°, the following:

These sugars are therefore identical with one another. Along

with them must also be included amygdalin-sugar, which, with c = 2,

gave [a]p

D

=

49-25 (hydrate).

D

49-25 (hydrate). On the other hand, phlorhizin-sugar (hydrate) showed a lower rotation, viz., with c = 3, [a], 40-9, and with c 6, [a] = 40·08. Another sample gave, with c = 8, [a] = 399; and with c = 10-52, [a] = 39·7. 10·52, [a]D = 397.

174).

=

D

Hesse (L. A. 192,

For the transition tint [a], the following rotation values are recorded:-52, Bondonneau. 52-5, Clerget Listing. 53-2, Dubrunfaut. 551, Pasteur. 56, Berthelot. 57, Schmidt. 57.4, Béchamp. 57.7, Jodin.

Lime reduces the rotatory power. A solution which contained, in 100 cubic centimetres, 0.98 gramme of lime for 6.9 grammes of grape-sugar, gave [a]; = 33.3. Jodin (C. R. 58, 613).

Fruit-sugar. Lævulose, C6H12O6. Lævo-rotatory.

The observations under this head are very incomplete, as the effects of concentration have not been investigated. This substance exhibits a marked decrease of rotation with increase of temperature. For lævulose obtained from invert-sugar by the lime process, Dubrunfaut (C. R. 42, 901) found the following values (c not recorded):

When the temperature exceeds 90°, a chemical change begins in the solutions.

According to Neubauer (D. C. G. 1877, 829), at a temperature of 14°, [a] = 100 (e not given).

Jodin (C. R. 58, 613) gives the following values († not given,

Lime causes a considerable reduction of the rotatory power. A solution with c = 5, giving [a]; = − 106, on the addition of 0·64 lime gave [a] = 63.-Jodin.

Invert-sugar, C6H12O6. Lævo-rotatory.

The rotatory power decreases rapidly with increase of temperature. Dubrunfaut (C. R. 42, 901) found for a solution, the strength of which is not stated :

Tuchschmid's observations (J. P. C. [2] 2, 235) show that an aqueous solution of invert-sugar with c = 17-21 has at 0° Cent. a

(27.9

specific rotation [a] = 27·9, and that this value decreases with increase of temperature according to the formula [a] = − -0.32 t). According to which, at t = 87.2°, rotation will be 0. Alcohol, according to Jodin (C. R. 58, 613), causes an important reduction in the lævo-rotation of invert-sugar, which can, moreover, by the application of heat, be converted into dextro-rotation. Lime also causes a decrease.

According to Maumené (C. R. 80, 1139) different specimens of invert-sugar exhibit similar properties only when in their preparation the proportions of water and acid, the temperature and duration of the action, and the mode of neutralization employed have been strictly identical.

Galactose, C, H12O6. Dextro-rotatory.

Exhibits bi-rotation. According to Fudakowski (Hoppe-Seyler's Med. chem. Untersuchungen I., 164), it is a mixture of two different sugars of unequal rotatory powers.

=

=

-

46.9. Berthelot. Pelouze (A. C. P. [3] 35, 222).

§ 111. Mannite Group.

Mannite, C, H14 O6. Pasteur (C. R. 77, 1192) and Bouchardat (C. R. 80, 120; A. C. P. [5] 6, 100) have shown that in aqueous solutions (c 15) with a tube-length of 3 to 4 metres, this substance gives a left-handed rotation of 0.1° to 0.3°, whence [a]; = 0·03. Vignon (A. C. P. [5] 2, 433), also Müntz and Aubin (A. C. P. [5] 10, 533) consider mannite as inactive.

The addition of various substances to aqueous solutions of mannite renders them optically active, dextro-rotatory in the case of boracic acid, borax, and borate of lime, and more feebly so with chloride and sulphate of sodium; lævo-rotatory in the case of caustic potash, caustic soda, potassium carbonate, potassium, and hydrogen arsenate, lime, baryta, and magnesia. After saturation with acetic acid. the solution either remains feebly lævo-rotatory or shows slight dextrorotation. Sulphuric acid or acetic acid added even in large proportion to mannite solutions produces no activity (Bouchardat, Vignon, Müntz, and Aubin, loc. cit.).

Certain derivatives of mannite are active, as, for example, nitromannite, diacetyl- and hexacetyl-mannite, which are dextro-rotatory, and mannite dichlorhydrin which is lavo-rotatory.

Mannitin is a variable mixture of dextro-rotatory and lævorotatory isomers, the proportions varying with the mode of producBouchardat).

tion.

The mannite obtained by the action of nascent hydrogen on inactive glucose, invert-sugar, dextrose, lævulose (from invert-sugar or inulin) is also inactive, as well as that from manna. But each of them becomes active on addition of borax or conversion into nitromannite Müntz and Aubin).

Treated with ammonium sulphide, nitro-mannite passes into inactive (?) manuite, which by the action of nitric acid becomes once more active. Loir (Bull. sce. chim. 1861, 113). Krecke, loc. cit.

Du'cite is inactive. Biot. Jaquelain (J. B. 1850, 536). The acetyl-derivatives of dulcite and dulcitan rotate feebly to the right. Bouchardat (A. C. P. [4], 27; 68, 145).

Isodulcite, C. H12O; + H2O. Dextro-rotatory.

6 12 5

Water. c = 10·2. [a]; = 7.6. Hlasiwetz and Pfaundler (L. A. 127, 362).

Quercite, C H12 03. Dextro-rotatory.

Water. e 1 to 10. =

6 12

t = 16°. [a]

=

24-3. Temperature without influence. Prunier (Bull. soc. chim. 28, 555, and C. R. 85, 808).

The rotation data given by different observers for substances of this class differ so widely from each other, that they cannot be used as characteristic marks for the substances.

Cellulose, dissolved in cadmium, or zincoxide-ammonia (obtained by treating cellulose dissolved in cupric-oxide ammonia, with cadmium or zinc until a colourless solution is obtained) is inactive. Krecke (Arch. Néerl. VI. 1871). Collodion, according to Krecke, is inactive. According to Schützenberger (L. A. 160, 77) it is dextrorotatory.

Starch boiled for a few hours in water, solution of potash or of chloride of zinc, gives dextro-rotatory liquids. For p = 2-22

to 3.88. [a]; = +211°. Starch solution heated with dilute sulphuric acid at 100°, gives first [a]; =216, but the rotatory power quickly decreases with the formation of dextrin and dextrose. Béchamp (A. C. P. [3] 48, 458).

Glycogen. Dextro-rotatory. Various modifications. [a]; = +140 to 211. Tichanowitsch. Stscherbakoff (J. B. 1870, 848).

5

Inulin. Lævo-rotatory. The data for dahlia- and elecampaneinulin, range from [a]; =26 to 72. The inuloid of Popp (L. A. 156, 190), C, H10 0, + H2O, with c = 2, gives [a]; =- 30.5. The rotatory powers of the aoetic ethers of cellulose, starch glycogen, and inulin have been determined by Schützenberger (L. A. 160, 74).

Dextrin. Dextro-rotatory. The data range from [a];=139 to 213.

Gum Arabic Acid. The varieties of gum arabic met with in commerce, are partly dextro-rotatory, and partly lævo-rotatory. Scheibler (D. C. G. 1873, 618) found, on examination of five samples in aqueous solution with c = 5, the specific rotations for [a]; = +37.3 + 461;288; 29-2; -300 respectively. On heating with dilute sulphuric acid, all these solutions become dextro-rotatory by the formation of gum-sugar (arabinose), C, H12 06

The gum of beet-root is, in general, dextro-rotatory, but at certain seasons and in individual plants it is found to be lævorotatory. Scheibler, loc. cit.

Dextro-rotatory gum is further found in the stag-truffel, and lævo-rotatory gum in couch-grass. Ludwig (J. B. 1869, 791;

1872, 803).

$ 113. Glucosides.

Salicin, C13 H18 O7. Lævo-rotatory.

Water. c = 1 to 3. t = 15o. [a]»

Water. p

=

2.78. [a];

=

=

(65.17 0.63 c). Hesse (L. A. 176, 116).

73.4. Biot and Pasteur (C. R. 34, 607).

Populin, C20 H22 Og. Lævo-rotatory.

Water. p 1. [a];

=

=

53. Biot and Pasteur, loc. cit.

Phlorhizin, Ca H30 011 + 2 H2O. Lævo-rotatory.

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