Ascorbinsure Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
GERUCHLOSE, WEISSE BIS SCHWACH GELBE KRISTALLE ODER PULVER.
CHEMISCHE GEFAHREN
Starkes Reduktionsmittel. Reagiert mit Oxidationsmitteln. Mittelstarke S?ure in w?ssriger L?sung.
ARBEITSPLATZGRENZWERTE
TLV nicht festgelegt (ACGIH 2005).
MAK nicht festgelegt (DFG 2005).
AUFNAHMEWEGE
Aufnahme in den K?rper durch Inhalation des Aerosols und durch Verschlucken.
INHALATIONSGEFAHREN
Nur ungenügende Angaben vorhanden über die Geschwindigkeit, mit der eine gesundheitssch?dliche Konzentration in der Luft beim Verdampfen bei 20°C erreicht wird.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Die Substanz reizt die Augen, die Haut und die Atemwege.
LECKAGE
Verschüttetes Material in Beh?ltern sammeln; falls erforderlich durch Anfeuchten Staubentwicklung verhindern. Reste mit viel Wasser wegspülen. Pers?nliche Schutzausrüstung: Atemschutzger?t, P1-Filter für inerte Partikel.
R-S?tze Betriebsanweisung:
R20/21/22:Gesundheitssch?dlich beim Einatmen,Verschlucken und Berührung mit der Haut.
R36/37/38:Reizt die Augen, die Atmungsorgane und die Haut.
S-S?tze Betriebsanweisung:
S24/25:Berührung mit den Augen und der Haut vermeiden.
S36:DE: Bei der Arbeit geeignete Schutzkleidung tragen.
S26:Bei Berührung mit den Augen sofort gründlich mit Wasser abspülen und Arzt konsultieren.
Beschreibung
Ascorbic acid, a water-soluble dietary supplement, is consumed by humans more than any other supplement. The name ascorbic means antiscurvy and denotes the ability of ascorbic to combat this disease. Vitamin C is the l-enantiomer of ascorbic acid. Ascorbic acid deficiency in humans results in the body’s inability to synthesize collagen, which is the most abundant protein in vertebrates.
Chemische Eigenschaften
White crystals (plates or needles). Soluble in water; slightly soluble in alcohol;
insoluble in ether, chloroform, benzene, petroleum
ether, oils and fats. Stable to air when dry. One
international unit is equivalent to 0.05 milligram of
l-ascorbic acid.
Physikalische Eigenschaften
Appearance: white crystal or crystalline powder, and it is odorless and flavors sour. The color changes yellowish when exposed in the air for a long time. Its aqueous solution is acidic reaction. Solubility: vitamin C is soluble in water, slightly soluble in ethanol, and insoluble in chloroform or ether. Melting point: 190–192? °C.? It would decompose when it melts. Specific optical rotation: +20.5 to +21.5°. Ascorbic acid is two-base acid (the pKa is 4.1 and 11.8). It occurs mainly in the form of sodium salt and calcium salt, and its aqueous solution is strongly acidic reaction. Ascorbic acid is a strong reducing agent.
History
Vitamin C is a general term for compounds having ascorbic acid activity, including ascorbic acid, dehydroascorbic acid, and its isomers.
The understanding of vitamin C has gone through a long and painful process. Although the relationship between scurvy and stored food is obvious, but the
treatments of this disease have been misguided. By 1601, British armed Captain
James Lancaster discovered the disease on the ship of the East India Company and
regarded the scurvy as “rot,” which could be made tissue alkaline.
At the early stage of the nineteenth century, the understanding and treatment of scurvy had developed to a right approach. The exposition of
scurvy etiology and metabolic theory took more than a century.
By the early stage of the twentieth century, inspired by the animal model of beriberi, researchers in the Christchurch Oslo University discovered one animal that
could suffer scurvy accidentally and then established a valuable scurvy animal
model. This experiment demonstrated that the extract isolated from lemon had antiscurvy activity. Until 1932, many research groups obtained the anti-scurvy crystal
from different plants and identified the crystal as ascorbic acid vitamin C. Next year,
the chemical structure of ascorbic acid was elucidated, and then its artificial synthesis was accomplished.
Verwenden
antiscorbutic, antiviral
Indications
Vitamin C (ascorbic acid) is essential for the maintenance
of the ground substance that binds cells together
and for the formation and maintenance of collagen.The
exact biochemical role it plays in these functions is not
known, but it may be related to its ability to act as an
oxidation–reduction system.
Definition
ChEBI: L-ascorbic acid is the L-enantiomer of ascorbic acid and conjugate acid of L-ascorbate. It has a role as a coenzyme, a flour treatment agent, a food antioxidant, a plant metabolite, a cofactor, a skin lightening agent and a geroprotector. It is an ascorbic acid and a vitamin C. It is a conjugate acid of a L-ascorbate. It is an enantiomer of a D-ascorbic acid.
Allgemeine Beschreibung
White to very pale yellow crystalline powder with a pleasant sharp acidic taste. Almost odorless.
Air & Water Reaktionen
May be sensitive to prolonged exposure to air and light. Sensitive to moisture. Soluble in water. Aqueous solutions are oxidized by air in a reaction that is accelerated by alkalis, iron and copper. The rate depends on the pH and on oxygen concentration. Also subject to degradation under anaerobic conditions.
Reaktivit?t anzeigen
L(+)-Ascorbic acid is a lactone. Reacts as a relatively strong reducing agent and decolorizes many dyes. Forms stable metal salts. Incompatible with oxidizers, dyes, alkalis, iron and copper. Also incompatible with ferric salts and salts of heavy metals, particularly copper, zinc and manganese .
Brandgefahr
Flash point data for L(+)-Ascorbic acid are not available; however, L(+)-Ascorbic acid is probably combustible.
Pharmakologie
Vitamin C is considered as a classical enzyme cofactor or antioxidant but also as a transition material in metal ion reaction. And all of these functions of vitamin C are related to the property of antioxidation.
Clinical Use
Vitamin C is indicated for the treatment and prevention of known or suspect deficiency. Although scurvy occurs infrequently, it is seen in the elderly, infants, alcoholics, and drug users.Ascorbate can also be used to enhance absorption of dietary nonheme iron or iron supplements. Ascorbic acid (but not the sodium salt) was historically used to acidify the urine as a result of excretion of unchanged ascorbic acid, although this use has fallen into disfavor. Ascorbate also increases iron chelation by deferoxamine, explaining its use in the treatment of iron toxicity.
Nebenwirkungen
Megavitamin intake of vitamin C may result in diarrhea
due to intestinal irritation. Since ascorbic acid is
partially metabolized and excreted as oxalate, renal oxalate
stones may form in some patients.
Toxikologie
L-Ascorbic acid, or vitamin C, is widely present in plants. The structures of ascorbic acid and dehydroascorbic acid are shown in Figure 10.5. Vitamin C is not only an important nutrient but is also used as an antioxidant in various foods. However, it is not soluble in fat and is unstable under basic conditions. Vitamin C reduces cadmium toxicity and excess doses prolong the retention time of an organic mercury compound in a biological system. Overdoses of vitamin C (106 g) induce perspiration, nervous tension, and lowered pulse rate. WHO recommends that daily intake be less than 0.15 mg/kg. Toxicity due to ascorbic acid has not been reported. Although repeated intravenous injections of 80 mg dehydroascorbic acid was reported to be diabetogenic in rats, oral consumption of 1.5 g/day of ascorbic acid for six weeks had no effect on glucose tolerance or glycosuria in 12 normal adult males and produced no change in blood glucose concentrations in 80 diabetics after five days. The same report noted that a 100-mg intravenous dose of dehydroascorbic acid given daily for prolonged periods produced no signs of diabetes. Ascorbic acid is readily oxidized to dehydroascorbic acid, which is reduced by glutathione in blood.
Sicherheitsprofil
Moderately toxic by
ingestion and intravenous routes. Human
systemic effects by intravenous route: blood,
changes in tubules (including acute renal
failure, acute tubular necrosis). An
experimental teratogen. Other experimental
reproductive effects. Mutation data
reported. When heated to decomposition it
emits acrid smoke and irritating fumes.
l?uterung methode
Crystallise it from MeOH/Et2O/pet ether [Herbert et al. J Chem Soc 1270 1933]. [Beilstein 18/5 V 26.]
Ascorbinsure Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
