Liquid State FTIR Spectroscopy of Lignins

Good lignin solvents (e.g., acetone/water, dioxane/water, pyridine, ethylene chloride/ethanol, and acetic acid) exhibit strong IR bands and therefore are not commonly used for solution state IR investigations. An exception is chloroform. 

It is a good solvent for acetylated lignins and exhibits only a small band around 1210cm-1 and a broad band between 780-720cm-1. 

Sodium hydroxide solutions have a degree of accessibility for FTIR spectroscopy similar to that of water (Fig. 5.2.4). A negative band at 1625 cm-1 (attributable to water) is typical when alkaline solutions are measured against water. 

---