Hydroxyethyl cellulose

Cellulose and hydroxyethyl celluloses ( R = CH ₂ CH ₂ OH) with increasing molar degree of substitution from top to bottom
and display information about the image Cellulose
and display information about the image Hydroxyethyl cellulose, low degree of substitution
and display information about the image Hydroxyethyl cellulose, medium degree of substitution
and display information about the image Hydroxyethyl cellulose, high degree of substitution

Hydroxyethyl celluloses (HEC, also Hyetellose, Ethylose, Tylose H 300, UNII-8136Y38GY5) are cellulose ethers that are used as water-soluble, highly effective thickeners and binders. With small added amounts it results in a transparent, stable solution. HEC are water-soluble, yellowish-white, odorless and tasteless powders and are used in the construction sector (construction paints, for construction adhesives HEMC) and as a component of toothpaste.

Molecular formula

R = CH ₂ CH ₂ (OCH ₂ CH ₂ ) nOH,

Areas of application

Construction area

It can be used for water-soluble applications

Tinting paint
Exterior color
Solid color
Interior paint
Lime emulsion paint
Glue paint
Powder paint
Silicate paint
Silicone resin paint
Wall glaze
Cement paint

Dispersion tile adhesive (HEMC)
Dispersion joint filler (HEMC)
Dispersion adhesive (HEMC)
Synthetic resin plaster (HEMC)
Gloss filler (HEMC)

Pharma and Cosmetics

Component of toothpaste, e.g. B. Aminomed or Elmex jelly
Pharmaceutical excipient

Extraction and presentation

For the preparation of hydroxyethylcelluloses is alkali cellulose with ethylene oxide etherified . The OH group reacts preferentially on C-2 of the glucose units. Furthermore, ethylene oxide is also attached to hydroxyethyl groups that have already formed, so that polyglycol groups are formed. They are cheaper to make than methyl or hydroxypropyl cellulose. Manufacturers are Dow Chemical (formerly Union Carbide, "Cellosize"), Shin-Etsu ("Tylose H") and Ashland Inc. ("Natrosol HEC"), with production facilities in the USA and Brazil.

Since not all hydroxyl groups react in this reaction, mixtures are formed with different degrees of substitution . The degree of substitution of the individual starch components within a polymer can also vary.

classification

Hydroxyethyl celluloses are characterized by their average degree of substitution (DS) and their molar degree of substitution (MS). Commercially available HEC have degrees of substitution of 0.85 to 1.35 (DS) or 1.5 to 3 (MS).

properties

Yellowish white powder or granules
Water-soluble from about 1 mol of ethylene oxide per mol of glucose, also soluble in some organic solvents if they contain water
Viscosity is not very sensitive to changes in the pH value and to electrolytes

Individual evidence

↑ ^a ^b ^c ^d ^e entry on hydroxyethyl celluloses. In: Römpp Online . Georg Thieme Verlag, accessed on February 25, 2015.
^ European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 6th edition, 2008, pp. 2806–2808, ISBN 978-3-7692-3962-1 .

[roempp-1] ↑ ^a ^b ^c ^d ^e entry on hydroxyethyl celluloses. In: Römpp Online . Georg Thieme Verlag, accessed on February 25, 2015.

[EuropäischesArzneibuch-2] European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 6th edition, 2008, pp. 2806–2808, ISBN 978-3-7692-3962-1 .