ORGANIC CHLORINE STRUCTURES IN CHLOROLIGNIN

Hydrolysis of organic chlorine in two chlorolignin preparations (1 kD < MW < 10 kD and MW > 10 kD) was studied at 80-degrees-C in alkaline m edia representing increasing dechlorinating power: 1) 2 M NaOH under a rgon atmosphere, 2) 0.1 % hydrogen peroxide in 2 M NaOH, and 3) 2 M KO H after treatment of the substrate with singlet oxygen. Organic chlori ne was classified based on its reactivity during alkaline hydrolysis: type 1 - hydrolyzable under non-oxidative conditions; type 2 - hydroly zable in alkaline hydrogen peroxide; type 3 - susceptible to alkaline hydrolysis following singlet oxygen attack, and type 4 - resistant to all three treatments. Hydrolysis of 12 chlorolignin model compounds wa s studied under the same conditions in attempt to identify the four ty pes of organic chlorine. The following classes of structures were iden tified: type 1 - aliphatic chlorine (unless sterically hindered), chlo roquinones, and a portion of chlorocatechol structures; type 2 - the r emaining portion of the chlorocatechol structures; type 3 - chlorinate d monohydric phenols and more reactive non-phenolic chloroaromates; ty pe 4 - non-phenolic chloroaromatic structures and, possibly, stericall y hindered aliphatic chlorine. Both chlorolignins contained about 1.3 mmol/g of organic chlorine. The ration of hydrolyzable (types 1 to 3) to non-hydrolyzable chlorine (type 4) was higher in medium-than in hig h-molecular-weight chlorolignin (0.9 and 0.6, respectively).The major portion of hydrolyzable chlorine is type 1 and the smallest portion is type 3.