A Manual of the Chemistry of the Carbon Compounds

258 TEE CHEMISTRY OF
Monofai'min C8H61 >ynffR ls f° rm ed by heating glycerin with
oxalic acid. It is an oily liquid, soluble in water. Oti heating this
solution, monofonnin is resolved into glycerin and formic acid.
Monaeetin C8H6 \ }cr J? |V an oily liquid, which is soluble in water
and possesses an ethereal smell, is formed by heating glycerin with
acetic acid to 100°; while by heating the mixture to 200°, diacetin
( OH
CSH5 -j ,QQ JJ QV ia obtained, an oily liquid boiling at 280°. When
this body is heated with a very large excess of acetic acid to 250°, it
is couverfced into tviacetin CJH^OCJHJO^, a liquid which is insoluble
in water and boils at 286°. This compound exists in the oil contained
iu the seeds of the common spindle-tree (Jfotonymw mropceus),
and has also been produced by heating propenyl tribromide witli
silver acetate.
The three bvtyrins are oily neutral liquids; tributyrin is found in
butter, together with trieapronin, tricapnjlin, and tricaprin; trimyristin
occurs in nutmeg-butter.
Monopabnitin melts at 49°, dipalmittn at 59°; both compounds are
produced by heating glycerin with palmitic acid in sealed tubes. By
using a large excess of palmitic acid and heating the mixture to 250°
for twenty-four hours, tripalmitin is formed, a compound occurring
in many fats. It is prepared by exposing olive oil to a stroug cold,
and subjecting the solid mass to a strong pressure to remove liquid
trioleia Tripalmitin crystallizes from alcohol iu pearly scales, melting
at 61°,
Tristearin occurs in almost all solid fats, and may be extracted
from beet* or mutton suet by means of ether. After being purified by
repeated crystallizations, it is obtained in pearly crystals welting at
66°*5 and solidifying to an auiorpjious mass.
Lecithine C/JB^NPO,,.—Tlus complicated derivative of glycerin -
phosphoric acid is found widely distributed in the animal organism,
occurring iu the brain, in the nerves, in the yolk of eggs, in the bloodcorpuscles,
&c. It is most conveniently prepared by exhausting the
yolk of eggs with a mixture of alcohol and ether. The solution ia
gently heated until all the ether has volatilized, and alcohol added to
the residue, by which fats are precipitated. The solution is filtered
and platinum tetrachloride is added; a yellow precipitate having the
composition 2(C4aHg3NPO8Cl) + PW3L is formed, which is decomposed
by hydrogen sulphide. The lecithine hydroohloride thus
obtained is dissolved in a mixtuie of alcohol and ether, and the solution
shaken with silver oxide, aud, after filtration, again treated with
hydrogen sulphide in order to precipitate silver which has gone in
solution.
Pure lecithine is a wnx-like, indistinctly crystalline mass, soluble
in alcohol and ether; iu watev it softens and becomes gelatinous, but
does not dissulve. It combines uor nnlv with nc.\