Glycoazodyes

An unprotected alcohol group of either the sugar or the dye is reacted with an n-carbon, terminal dibromoalkane in a solution of potassium hydroxide and 18-crown-6 ether, using non-anhydrous tetrahydrofuran as the solvent.

The potassium hydroxide produces an alkoxide ion from the alcohol while the 18-crown-6 ether acts as a phase-transfer agent.

A terminal Bromo group is eliminated, and a bond is formed between the oxygen of the alcohol and the carbon of the alkane.

At this stage, the terminal Bromo group that remains may react under the same conditions with the free alcohol of a corresponding sugar or dye.

The point of the amide bond is controlled by protecting the alcohol groups on the sugar and allowing the free amine to react.

[3] A variety of fabrics such as wool, silk, nylon, polyester, polyacrylic, polyacetate, and polyurethane may be dyed with Glycoazodyes under moderate temperatures and pressures in aqueous solutions.

[4] Minor variations in absorption spectra occur when Glycoazodye solutions are prepared, using water, acetone, or methanol solvents.

[1] Converting a parent azo dye to a Glycoazodye may produce a small hypsochromic shift in the absorption spectra.

The increased hydrophilicity of Glycoazodyes allows for the elimination of surfactants, mordants, and salts, during the dyeing process and permits the aqueous dying of a variety of textiles at moderate temperatures and pressures.