Researches on Cellulose, 1895-1900Cross, C. F. (Charles Frederick)
Science
Researches on Cellulose, 1895-1900
Cross, C. F. (Charles Frederick)
Cellulose
Phenylhydrazine Furfural
Fixed p.ct. formed p.ct.
Cotton (bleached) 1.73 1.60
Oxycellulose (HClO_{3}) 7.94 2.09
" (HClO) 3.37 1.79
" (CrO_{3}) (1) 7.03 3.00
" (CrO_{3}) (2) 7.71 3.09
" (CrO_{3}) (3) 8.48 3.50
(e) _Constitution of cellulose and oxycellulose._--The results of
these investigations are generalised as regards cellulose (C_6) by the
constitutional formula
CH--CH_{2}
/ | |
(CHOH)_{3} O |
\ | |
CH--O .
The oxycelluloses contain the characteristic group
COH
/
(CHOH)_{3}
\
CH--CO
\ /
O
in union with varying proportions of residual cellulose.
QUANTITATIVE SEPARATION OF CELLULOSE-LIKE CARBOHYDRATES IN VEGETABLE
SUBSTANCES.
WILHELM HOFFMEISTER (Landw. Versuchs-Stat., 1897, 48, 401-411).
To separate the hemicelluloses, celluloses, and the constituents of
lignin without essential change, the substance, after being freed from
fat, is extracted with dilute hydrochloric acid and ammonia, and the
residue frequently agitated for a day or two with 5-6 p.ct. caustic soda
solution. It is then diluted, the extract poured off, neutralised with
hydrochloric acid, treated with sufficient alcohol, and the
hemicellulose filtered, dried, and weighed. The residue from the soda
extract is washed on a filter with hot water, and extracted with
Schweizer's reagent.
When the final residue (lignin) is subjected to prolonged extraction
with boiling dilute ammonia (a suitable apparatus is described, with
sketch) until the ammonia is no longer coloured, a residue is obtained
which mostly dissolves in Schweizer's reagent, and on repeating the
process the residue is found to consist largely of mineral matter. The
dissolved cellulose-like substances often contain considerable amounts
of pentosanes.
According to the nature of the substance, the extraction with ammonia
may take weeks, or months, or even longer; the ammonia extracts of hard
woods (as lignum vitae) and of cork are dark brown, and give an odour of
vanilla when evaporated down. The residues, which are insoluble in
water, but redissolve in ammonia, have the properties of humic acids.
Other vegetable substances, when extracted, yielded, besides humic
acids, a compound, C_{6}H_{7}O_{2}, soluble in alcohol and chloroform,
but insoluble in water, ether, and benzene; preparations from different
sources melted between 200 deg. and 210 deg..
FOOTNOTES:
[4] The original paper is reproduced with slight alterations.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account