Pectic acid from wood

In the isolation of hemicelluloses from plant materials containing relatively large amounts of hemicelluloses and small amounts of insoluble pectic materials, as in hardwoods, the powdered material is first extracted with organic solvents and hot water. The hemicelluloses are then removed by two extractions with a cold 4% solution of sodium hydroxide. The material is made neutral with dilute hydrochloric acid and washed with water. It is then extracted successively with a hot. 05 N solution of hydrochloric acid and a cold 5% solution of ammonium hydroxide. This procedure removes only a part of the hemicelluloses and pectic materials from a wood since lignin protects the underlying hemicelluloses from the alkaline solution or is combined with them. - To overcome this difficulty the wood is suspended in water and treated with chlorine gas. - - The subsequent addition of a large volume of... 

On treating wood from maritime pine with boiling water, Roudier and Eberhard obtained a mixture which could be resolved into four polysaccharides by fractionation with alcohol, acetone, and calcium chloride, giving a pectic acid, an arabinogalactoglucuronoxyloglycan, a galactomannan, and an araban. 

Uronic acids and pectic material have partly or mainly been dissolved and removed from commercial boards on pressurized refining. On heating wood they will contribute considerably to CO2 release (33). Organic acids such as formic and acetic acid are also split off from side chains of wood polymers. 

A new dialdose dianhydride derivative has been obtained from an acid hydrolysate of the water-soluble pectic fraction of wobaku wood by successive treatment with methanolic hydrogen chloride and acetic anhydride-pyridine. The compound was the 1,2 1, 2 dianhydride of 3,4-di-0-acetyl-j3-L-rhamno-pyranose and methyl 3,4-di-0-acetyl-o -D-galactopyranosyluronate. This is the first report of a dianhydride containing two different sugar residues. 

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