Ethoxylation

Ethoxylation of various reactants

The ethoxylation is the addition of ethylene oxide (oxirane) to compounds such as alcohols , phenols , amines or carboxylic acids .

execution

For ethoxylation, the raw material is treated with a catalyst , e.g. B. potassium hydroxide , and treated with ethylene oxide. The mixture is heated to temperatures between 80 and 150 ° C. under nitrogen pressure at approx. 5 bar.

A mixture with a relatively wide degree of ethoxylation is obtained. By choosing suitable catalysts, e.g. B. alkaline earth salts, the distribution of the chain lengths can be narrowed. So-called "narrow range ethoxylates" are then obtained.

Reaction example

Ethoxylation of an alcohol:

${\displaystyle \mathrm {ROH+OH^{-}\longrightarrow RO^{-}+H_{2}O} }$

${\displaystyle \mathrm {RO^{-}+C_{2}H_{4}O\longrightarrow RO{\mathord {-}}C_{2}H_{4}O^{-}} }$

${\displaystyle \mathrm {RO{\mathord {-}}C_{2}H_{4}O^{-}+C_{2}H_{4}O\longrightarrow R(O{\mathord {-}}C_{2}H_{4})_{2}O^{-}} }$

${\displaystyle \mathrm {\longrightarrow \longrightarrow {\xrightarrow {+H^{+}}}R(O{\mathord {-}}C_{2}H_{4})_{n}OH} }$

In the ethoxylation of amines, the addition of ethylene oxide to nitrogen generally does not need to be catalyzed, since it is nucleophilic enough.

application

The ethoxylates thus obtained are produced on a large scale and used for a variety of purposes, e.g. B .:

Ethoxylates of fatty alcohols , castor oil , sorbitans (esterified with fatty acids), alkylphenols , fatty amines or fatty acids are used as nonionic surfactants or as raw materials for anionic surfactants . By ethoxylating polypropylene glycol (PPG), block copolymers ( Pluronics ) are obtained, which are also used as nonionic surfactants.

Base-catalyzed ethoxylation of ethanediol ( ethylene glycol ) or ring-opening polymerization of ethylene oxide with water as the starter molecule gives polyglycols whose low molecular weight homologues (also etherified and / or esterified ) are used as solvents. Higher homologs are used e.g. B. as a lubricant, for the production of hydraulic fluids or as a binder.

Web links

• Patent from Henkel KGaA