When fatty oils are treated with additional glycerol, the triacylglycerol is transesterified into a mixture of fatty acid mono- and diglycerides, resulting in commercial glycerol alkyds. The reaction requires the presence of strong acids or alkalis which remove one of the alcohol groups from the starting glycerol molecule.
Alkyd resins are derived from petroleum or fossil fuels and are used as paints, stains, and varnishes. They are water-based materials that can be thinned with organic solvents such as turpentine or alcohol. As they contain no latex, alkyds are useful for painting metal surfaces.
In chemistry, an alkyd is any ester containing at least two hydroxyl groups bonded to a single carbon atom. Examples include glycerol monostearate, glycerol distearate, and pentaerythritol tetrastearate. Esters with more than four hydroxyl groups are called polyhydroxyalkanes. In general, alkyds are viscous liquids or soft pastes at room temperature that can be made fluid by heating. Alkyds are used in oil paintings, acrylic paintings, and watercolor paintings.
An alkyd is a polyester resin that has been altered by the addition of fatty acids and other ingredients. Polyols and organic acids, such as dicarboxylic acids or carboxylic acid anhydride, and triglyceride oils, are used to make alkyds. These additives give the paint additive qualities such as hardness, toughness, shrink resistance, and durability.
The word "alkyde" comes from two Arabic words meaning alcohol (alcoholates are derived from alcohol) and ether (ethers are derivatives of ethyl). Thus, an alkyd is a polymer with alcohol and ether groups.
Alkyds were first developed in Germany around 1910 by Dr. Franz Kremann. He called his product "ester resins". Later, American companies such as E.I. DuPont de Nemours & Company and The Pennsylvania Colloid Company began manufacturing their own versions of this material. By 1925, alkyds accounted for nearly 100% of all ester resins sold. Today, they account for about 5% of all resin sales.
Alkyds are used in many applications where there is a need for paint products that will dry fast, have good adhesion to various surfaces, and resist weathering. They are also used as surfactants and plasticizers in paints, varnishes, and lacquers.
Alkyl polyglycosides are easily made by reacting an alcohol of the required kind and chain length, generally a fatty alcohol from which the "alkyl" component of the glycoside of interest is formed, with a saccharide reactant (e.g., a monosaccharide such as glucose, xylose, arabinose, galactose, fructose). The reaction can be carried out under acidic or basic conditions with or without a catalyst. Alkyl polyglycosides contain equal amounts of epimeric centers; therefore, they can be separated into their enantiomers by chromatography methods.
The reaction is usually performed in the presence of a catalytic amount of acid or base. Strong acids or bases are necessary because the reaction is endothermic, so excess reagent will lead to poor yields. Lewis acids such as aluminum chloride and titanium(IV) chloride dihydrate are common catalysts for this reaction. Triethylamine has been used as a catalyst for alkoxylation reactions with ethanol.
The product will be soluble in most organic solvents but not water. This makes it useful as a surfactant, replacing natural surfactants such as coconut oil or soybean oil.
Alkyl polyglycosides are used as emulsifiers and detergents in cosmetics and pharmaceuticals. They are also used as additives in asphalt to reduce viscosity. They can also be used as pre-concentrators for gas chromatography.