Polyvinyl polypyrrolidone
| Structural formula | |||||||
|---|---|---|---|---|---|---|---|
|
|||||||
| General | |||||||
| Surname | Polyvinyl polypyrrolidone | ||||||
| other names | |||||||
| CAS number | 9003-39-8 | ||||||
| Monomer | Vinyl pyrrolidone | ||||||
| Molecular formula of the repeating unit | C 6 H 9 NO | ||||||
| Molar mass of the repeating unit | 111.14 g mol −1 | ||||||
| Brief description |
white hygroscopic powder |
||||||
| properties | |||||||
| Physical state |
firmly |
||||||
| safety instructions | |||||||
|
|||||||
| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||
Polyvinyl polypyrrolidone (PVPP, crospovidone or E1202) is a highly cross-linked homopolymer of 1-ethenylpyrrolidin-2-one ( N- vinyl-2-pyrrolidone ). It is insoluble in water and thus differs from the linear form, polyvinylpyrrolidone . PVPP swells considerably on contact with water. It has a complexing and adsorbing effect. These properties make it useful for a number of uses in the food and pharmaceutical technology fields.
synthesis
Insoluble polyvinylpyrrolidone is produced by means of popcorn polymerization from N- vinyl-2-pyrrolidone in a solvent, a highly crosslinked polymer being formed. A free radical polymerization mechanism is assumed, but no free radical initiators have to be added. Rather, the crosslinking is achieved either by adding a small amount of a bifunctional divinyl monomer or by choosing the reaction conditions (presence of an alkali hydroxide, temperatures above 100 ° C) so that bifunctional structures are created in situ [1-vinyl-2 -ethylidenpyrrolidone, ethylene- to -3- ( N -vinylpyrrolidone)], which initiate the polymerization. After the polymerization is complete, they can no longer be detected in the product.
In the case of a polymerization initiated by a free radical-providing starter such as AIBN , the crosslinking is significantly lower. The copolymerization of N- vinylpyrrolidone with crosslinking polyunsaturated compounds gives low crosslinked copolymers.
Syntheses of PVPP starting from linear polyvinylpyrrolidone are mentioned in the literature. PVPP produced in this way also has a low degree of crosslinking . It is obtained, for example, by gamma irradiation of linear PVP, by treatment with persulfate , by treatment with hydrazine and hydrogen peroxide or with α, ω- diolefins in the presence of peroxides .
use
pharmacy
In the manufacture of pharmaceuticals, insoluble polyvinylpyrrolidone is used as a disintegrant (disintegrant) for tablets because of its swelling capacity and also has good binding properties. As a result, the tablets have high abrasion resistance and disintegrate quickly and completely on contact with water without the formation of slime.
Another use is to improve the solubility of poorly soluble active ingredients and to stabilize suspensions, e.g. B. of antibiotic and antacid preparations .
food industry
As a food additive (E 1202), PVPP is only approved in the EU for food supplements in tablet or dragee form. PVPP is also used as a technical auxiliary in the beverage industry. As a stabilizing agent, it binds unwanted tannins and polyphenols in wine , beer and juices, which are then filtered out with it.
Since the new version of the Beer Tax Law in 1993, this is fining of the beer admissible and meets the so-called purity law .
medicine
Because of its adsorptive properties, cross-linked PVP can also be used as an anti-diarrheal agent (commercial products such as Bolinan (F), Poly-Karaya (F)).
properties
Cross-linked PVP is practically insoluble in water, dichloromethane and ethanol 96%. The substance swells strongly on contact with water. Because of its insolubility in water, a molar mass cannot be determined. Crosslinked PVP does not differ in the IR spectrum from the linear form, which is why it is assumed that the crosslinking is mainly physical. X-ray structure analyzes gave no indications of crystalline structures. The high density of cross-linking is attributed to the strong entanglement of the polymeric structures.
Pharmaceutical grades of cross-linked PVP are in the form of powder or flakes that are white to yellowish-white and hygroscopic. The proportion of water-soluble substances in the product must not exceed 1.5%. The pharmacopoeia lists two types of powdered PVPP depending on the degree of fineness: Type A (not crushed, particle size approx. 50–300 µm) and Type B (micronized). For use as a tablet disintegrant, the water-binding capacity (corresponds to the ratio of the mass of the swollen powder to the initial mass of the dry powder sample and is usually between 3 and 9), the flow behavior of the powder and the particle size distribution determined by laser diffraction are important. For the use of cross-linked PVP as a suspension stabilizer, the sedimentation volume is a quality feature that is determined over 24 hours on a sample suspension in a 100 ml measuring cylinder.
Individual evidence
- ↑ a b Datasheet Polyvinylpyrrolidone, average MW 58,000 at AlfaAesar, accessed on January 7, 2020 ( PDF )(JavaScript required) .
- ^ A b F. Haaf, A. Sanner, and F. Straub: Polymers of N-Vinylpyrrolidone: Synthesis, Characterization and Uses . Polymer Journal, Vol. 17, No. I (1985), pp. 143-152 ( PDF ).
- ^ R. Voigt: Pharmaceutical technology. For studies and work. 11th edition. Deutscher Apotheker Verlag 2010, page 287.
- ^ A b V. Bühler: Kollidon - Polyvinylpyrrolidone excipients for the Pharmaceutical Industry . BASF, 2005. p. 186 ( PDF ).
- ↑ Norddeutscher Rundfunk: Beer: Diluted Purity Law , from October 13, 2017.
- ↑ Provisional Beer Act . In: Bundesgesetzblatt 1993 Part I. S. 1400. online at archiv.jura.uni-saarland.de: Federal Law Gazette Model Project Part I and Part II, October 1990 to December 1997.
- ↑ ansm.sante.fr/Produits-de-sante/Medicaments , accessed on February 5, 2020.
- ↑ "Crospovidone". European Pharmacopoeia , 9th Edition (2016), p. 2175 f.