Nomenclature Generic:
Acetylenic diols
Acetylenic glycols
Acetylenic surfactants
Examples:
Dimethyloctynediol or 3,6-dimethyl-4-octyne-3,6-diol
2,4,7,9-Tetramethyl-S-decyn-4,7-diol
Description
The products are difficult and expensive to make from acetylene. Acetylenic surfactants are often in the form of free-flowing powders, manufactured by the adsorption of an active surfactant onto finely divided silica.
The hydroxyl groups may also react with ethylene oxide. Ethoxylation of hydroxyl groups increases water solubility without loss of surface-active properties, but the products become liquid and lose steam volatility.
General properties
1. Crystalline solids (rare with non-ionics):
Dimethyl octynediol is a white odorless crystalline solid, m.p. 50°C.
2. Solubility:
Low solubility in water unless ethoxylated; soluble in alcohols and glycols; soluble in polar solvents, e.g., ketones.
3. Functional properties:
Low foam, reduces foam of anionic and nonionic whilst increasing wetting; excellent wetting agents at low concentrations; in combination with other surfactants, there is a synergistic effect giving even better wetting; low molecular weight products are volatile with steam, so can be easily removed from the system; reduces viscosity of vinyl plastisols and starch solutions.
4. Disadvantages:
Expensive on an active basis compared to commodity surfactants, but in some applications, very small quantities of active are needed and therefore can compete on a cost/efficiency basis; very low solubility in water unless ethoxylated; unstable to acids.
Application
1. Shampoos:
Dimethyl octynediol is used as a solubilizer and clarifier for shampoos.
2. Surface coatings:
Wetting agent, particularly for aqueous systems of industrial coatings on oil-contaminated steel to give better coverage and good recoat ability; defoamer and pigment dispersing agent.
3. Oil field chemicals:
Corrosion inhibitors
4. Agricultural chemicals:
Additive to wettable powders to give low foam, good wetting and increased re-dispersability.
Specification
Appearance, white waxy solid with sharp melting point (usually 100% active), liquid (50-75% active in alcohols or glycols) or free-flowing powder (adsorbed on silica, approx. 5% active); cloud point, < 100°C, likely to be an ethylene oxide adduct.
