Hydroxyethyl Cellulose Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
WEISSES PULVER.
PHYSIKALISCHE GEFAHREN
Staubexplosion der pulverisierten oder granulierten Substanz in Gemischen mit Luft m?glich.
CHEMISCHE GEFAHREN
Zersetzung beim Erhitzen unter Bildung reizender Rauche.
ARBEITSPLATZGRENZWERTE
TLV nicht festgelegt (ACGIH 2005).
MAK nicht festgelegt (DFG 2005).
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Reizt m?glicherweise mechanisch.
LECKAGE
Pers?nliche Schutzausrüstung: Atemschutzger?t, P1-Filter für inerte Partikel. Verschüttetes Material in Beh?ltern sammeln.
R-S?tze Betriebsanweisung:
R23/24/25:Giftig beim Einatmen, Verschlucken und Berührung mit der Haut.
R36/37/38:Reizt die Augen, die Atmungsorgane und die Haut.
S-S?tze Betriebsanweisung:
S26:Bei Berührung mit den Augen sofort gründlich mit Wasser abspülen und Arzt konsultieren.
S36:DE: Bei der Arbeit geeignete Schutzkleidung tragen.
S45:Bei Unfall oder Unwohlsein sofort Arzt zuziehen (wenn m?glich, dieses Etikett vorzeigen).
S24/25:Berührung mit den Augen und der Haut vermeiden.
S22:Staub nicht einatmen.
Beschreibung
Hetastarch, another nonproteinaceous colloid, is a complex mixture of ethoxylated amylopectins
ranging in molecular weight from 10 to 1,000 kDa (average molecular weight, ~450 kDa). When
infused as a 6% solution, hetastarch approximates the activity of human albumin. The larger
molecular weights, however, increase its intravascular residence time as well as its plasma
expansion effects relative to albumin.
Hetastarch is synthetically produced, so it is degraded more
slowly and is less antigenic than other colloids. Despite these advantages, hetastarch is quite
expensive and also has no oxygen-carrying capacity.
Chemische Eigenschaften
Hydroxyethyl cellulose occurs as a white, yellowish-white or
grayish-white, odorless and tasteless, hygroscopic powder.
Verwenden
hydroxyethyl cellulose is a thickener, protective colloid, binder, stabilizer, and suspending agent. It is obtained from wood pulp Copyright 2014 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial Review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. or chemical cotton by treatment with an alkali.
Vorbereitung Methode
A purified form of cellulose is reacted with sodium hydroxide to
produce a swollen alkali cellulose, which is chemically more reactive
than untreated cellulose. The alkali cellulose is then reacted with
ethylene oxide to produce a series of hydroxyethyl cellulose ethers.
The manner in which ethylene oxide is added to cellulose can be
described by two terms, the degree of substitution (DS) and the
molar substitution (MS). The DS designates the average number of
hydroxyl positions on the anhydroglucose unit that have been
reacted with ethylene oxide. Since each anhydroglucose unit of the
cellulose molecule has three hydroxyl groups, the maximum value
for DS is 3. MS is defined as the average number of ethylene oxide
molecules that have reacted with each anhydroglucose unit. Once a
hydroxyethyl group is attached to each unit, it can further react
with additional groups in an end-to-end formation. This reaction
can continue and there is no theoretical limit for MS.
Definition
A starch derivative containing 90% amylopectin.
synthetische
Hydroxyethylcellulose is prepared from alkali cellulose and ethylene oxide. It may be noted that the hydroxyethyl group itself can react with ethylene
oxide so that side-chains of varying length may be present in the product.
Commercial materials generally contain between 1.4 and 2.0 ethylene oxide
residues per glucose residue and have a degree of substitution of about 0.8-1.0.
Allgemeine Beschreibung
Non-ionic water soluble polymer. Aqueous solutions are pseudoplastic. Readily disperses without lumping.
Pharmazeutische Anwendungen
Hydroxyethyl cellulose is a nonionic, water-soluble polymer widely
used in pharmaceutical formulations. It is primarily used as a
thickening agent in ophthalmic and topical formulations,
although it is also used as a binder and film-coating agent for
tablets.It is present in lubricant preparations for dry eye, contact
lens care, and dry mouth.
The concentration of hydroxyethyl cellulose used in a formulation
is dependent upon the solvent and the molecular weight of the
grade.
Hydroxyethyl cellulose is also widely used in cosmetics.
Sicherheit(Safety)
Hydroxyethyl cellulose is primarily used in ophthalmic and topical
pharmaceutical formulations. It is generally regarded as an
essentially nontoxic and nonirritant material.
Acute and subacute oral toxicity studies in rats have shown no
toxic effects attributable to hydroxyethyl cellulose consumption, the
hydroxyethyl cellulose being neither absorbed nor hydrolyzed in the
rat gastrointestinal tract. However, although used in oral pharmaceutical
formulations, hydroxyethyl cellulose has not been
approved for direct use in food products.
Glyoxal-treated hydroxyethyl cellulose is not recommended for
use in oral pharmaceutical formulations or topical preparations that
may be used on mucous membranes. Hydroxyethyl cellulose is also
not recommended for use in parenteral products.
Lager
Hydroxyethyl cellulose powder is a stable though hygroscopic
material.
Aqueous solutions of hydroxyethyl cellulose are relatively stable
at pH 2–12 with the viscosity of solutions being largely unaffected.
However, solutions are less stable below pH 5 owing to hydrolysis.
At high pH, oxidation may occur.
Increasing the temperature reduces the viscosity of aqueous
hydroxyethyl cellulose solutions. However, on cooling, the original
viscosity is restored. Solutions may be subjected to freeze–thawing,
high-temperature storage, or boiling without precipitation or
gelation occurring.
Hydroxyethyl cellulose is subject to enzymatic degradation, with
consequent loss in viscosity of its solutions. Enzymes that catalyze
this degradation are produced by many bacteria and fungi present
in the environment. For prolonged storage, an antimicrobial
preservative should therefore be added to aqueous solutions.
Aqueous solutions of hydroxyethyl cellulose may also be sterilized
by autoclaving.
Hydroxyethyl cellulose powder should be stored in a well-closed
container, in a cool, dry place.
Inkompatibilit?ten
Hydroxyethyl cellulose is insoluble in most organic solvents. It is
incompatible with zein and partially compatible with the following
water-soluble compounds: casein; gelatin; methylcellulose; polyvinyl
alcohol, and starch.
Hydroxyethyl cellulose can be used with a wide variety of watersoluble
antimicrobial preservatives. However, sodium pentachlorophenate
produces an immediate increase in viscosity when added
to hydroxyethyl cellulose solutions.
Hydroxyethyl cellulose has good tolerance for dissolved
electrolytes, although it may be salted out of solution when mixed
with certain salt solutions. For example, the following salt solutions
will precipitate a 10% w/v solution of Cellosize WP-09 and a 2%
w/v solution of Cellosize WP-4400: sodium carbonate 50% and
saturated solutions of aluminum sulfate; ammonium sulfate;
chromic sulfate; disodium phosphate; magnesium sulfate; potassium
ferrocyanide; sodium sulfate; sodium sulfite; sodium thiosulfate;
and zinc sulfate.
Natrosol is soluble in most 10% salt solutions, excluding sodium
carbonate and sodium sulfate, and many 50% salt solutions with
the exception of the following: aluminum sulfate; ammonium
sulfate; diammonium phosphate; disodium phosphate; ferric
chloride; magnesium sulfate; potassium ferrocyanide; sodium
metaborate; sodium nitrate; sodium sulfite; trisodium phosphate;
and zinc sulfate. Natrosol 150 is generally more tolerant of
dissolved salts than is Natrosol 250.
Hydroxyethyl cellulose is also incompatible with certain
fluorescent dyes or optical brighteners, and certain quaternary
disinfectants which will increase the viscosity of aqueous solutions.
Regulatory Status
Included in the FDA Inactive Ingredients Database (ophthalmic
preparations; oral syrups and tablets; otic and topical preparations).
Included in nonparenteral medicines licensed in the UK. Included in
the Canadian List of Acceptable Non-medicinal Ingredients.
Hydroxyethyl cellulose is not currently approved for use in food
products in Europe or the USA, although it is permitted for use in
indirect applications such as packaging. This restriction is due to the
high levels of ethylene glycol residues that are formed during the
manufacturing process.
Hydroxyethyl Cellulose Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
