9004-57-3 Ethyl cellulose

Details:

Chemical Properties white to slightly yellowish powder
Chemical Properties Ethylcellulose is a tasteless, free-flowing, white to light tan-colored powder.
Uses ethyl cellulose is a binder, film former, and thickener. It is used in suntan gels, creams, and lotions. This is the ethyl ether of cellulose.
Uses Film-former in coatings, hot-melt adhesives and transfer inks and as a plastic coating for a variety of substrates.
Uses In the manufacture of plastics and lacquers. Pharmaceutic aid (tablet binder).
Uses Used as a binder and filler in dry vitamin preparations, as a component of protective coatings for vitamin and mineral tablets, and as a fixative in flavoring compounds. It is a cellulose ether containing ethyoxy groups attached by an ether linkage and containing an anhydrous basis of not more than 2.6 ethoxy groups per anhydroglucose unit.

Production Methods Ethylcellulose is prepared by treating purified cellulose (sourced from chemical-grade cotton linters and wood pulp) with an alkaline solution, followed by ethylation of the alkali cellulose with chloroethane as shown below, where R represents the cellulose radical:
RONa + C2H5Cl→ROC2H5+NaCl
The manner in which the ethyl group is added to cellulose can be described by the degree of substitution (DS). The DS designates the average number of hydroxyl positions on the anhydroglucose unit that have been reacted with ethyl chloride. Since each anhydroglucose unit of the cellulose molecule has three hydroxyl groups, the maximum value for DS is three.
Preparation Ethyl cellulose is prepared by reacting cellulose with caustic to form caustic cellulose, which is then reacted with chloroethane to form ethyl cellulose. Plasticgrade material contains 44-48% ethoxyl.
Although not as resistant as cellulose esters to acids, it is much more resistant to bases. An outstanding feature is its toughness at low temperatures.

Pharmaceutical Applications Ethylcellulose is widely used in oral and topical pharmaceutical formulations.
The main use of ethylcellulose in oral formulations is as a hydrophobic coating agent for tablets and granules.Ethylcellulose coatings are used to modify the release of a drug, to mask an unpleasant taste, or to improve the stability of a formulation; for example, where granules are coated with ethylcellulose to inhibit oxidation. Modified-release tablet formulations may also be produced using ethylcellulose as a matrix former.
Ethylcellulose, dissolved in an organic solvent or solvent mixture, can be used on its own to produce water-insoluble films. Higher-viscosity ethylcellulose grades tend to produce stronger and more durable films. Ethylcellulose films may be modified to alter their solubility, by the addition of hypromellose or a plasticizer. An aqueous polymer dispersion (or latex) of ethylcellulose such as Aquacoat ECD (FMC Biopolymer) or Surelease (Colorcon) may also be used to produce ethylcellulose films without the need for organic solvents. Drug release through ethylcellulose-coated dosage forms can be controlled by diffusion through the film coating. This can be a slow process unless a large surface area (e.g. pellets or granules compared with tablets) is utilized. In those instances, aqueous ethylcellulose dispersions are generally used to coat granules or pellets. Ethylcellulose-coated beads and granules have also demonstrated the ability to absorb pressure and hence protect the coating from fracture during compression.
High-viscosity grades of ethylcellulose are used in drug microencapsulation.
Release of a drug from an ethylcellulose microcapsule is a function of the microcapsule wall thickness and surface area.
In tablet formulations, ethylcellulose may additionally be employed as a binder, the ethylcellulose being blended dry or wetgranulated with a solvent such as ethanol (95%). Ethylcellulose produces hard tablets with low friability, although they may demonstrate poor dissolution.