Laboratory Methods of Organic Chemistry - Sciencemadness Dot Org

394 OCTA-ACBTYLCBLLOBIOSB
solved in a basin in 15 c.c. of 20 per cent ammonia solution and the
solution is evaporated to dryness. The ammonium mucate is stirred
with 20 c.c. of glycerol in a distilling flask and the mixture heated.
At 170° the reaction begins and the bulk of the pyrrole distils between
180° and 210°. (If the temperature is raised to 300° a little
more pyrrole is obtained.) The substance is dissolved in a little
ether, dried, and fractionated. Boiling point of pure pyrrole 131°.
Yield 2-3 g.
A splinter of pine wood which has been dipped in concentrated
hydrochloric acid is coloured red by the vapour from a boiling mixture
of pyrrole and water
7. OCTA-ACETYLCELLOBIOSE AND CELLOBIOSE
Octa-acetylcellobiose. 1 —Pure cotton wool (20 g.) is added in
portions with good stirring to a cooled mixture (about -10°)
of acetic anhydride (75 c.c.) and concentrated sulphuric acid
(8 c.c.) (use a wide-mouthed flask with a ground joint). The temperature
of the liquid during this time must not exceed 10°. From
time to time the mass, which gradually liquefies, is pressed with a
glass rod until, after a few hours a viscous solution is formed. The
tightly closed flask is then placed in a thermostat at 30°. After
about five days the solution becomes coloured and crystals of cellobiose
acetate begin to separate. During the succeeding five days the
separation of crystals increases greatly. After the flask has been
placed in the ice-chest the deposition of crystals is completed in five
more days. Now filter the contents of the flask at the pump, and
wash with a little cold glacial acetic acid until the wash liquor passing
through is colourless (the wash liquor is not to be combined with the
mother liquor). In order to remove completely adherent sulphuric
acid or sulpho-acetic acid the crystalline mass is suspended in
water for several hours and finally dried at 70°. The yield of
already rather pure cellobiose acetate amounts, on the average,
to 11-12 g.
For recrystallisation the cellobiose acetate is dissolved in four or
five times its weight of chloroform, filtered, and the solution treated
with three volumes of methanol. After boiling the mixture for a
short time, the cellobiose acetate crystallises on cooling in beautiful
1 Oat, Annakn, 1913, 398, 332; K. Hess and H. Friese. Annalen, 1927, 456, 49.