ARTHUR
L.
ALLEWELT and WILLIAM R. WATT
Research and Development Division, American Viscose Corp., Marcus Hook, Pa.
N e w Method for Preparing Cellulose Thiourethanes A, product believed to be a thiourethane derivative of cellulose has been found. It i s a soft white fibrous substance, containing nitrogen and sulfur, formed by reaction o f zinc cellulose xanthate and primary amines.
PREPARATION
of cellulose thiourethanes is the subject of numerous patents ( I , 4-77). Cellulose derivatives containing sulfur and nitrogen and assumed to have a thiourethane structure were prepared by Lilienfeld ( 9 ) more than 30 years ago. Lilienfeld found these derivatives to be soluble in dilute caustic and capable of being shaped into “transparent solid flexible forms such as threads, films or plates.” This interesting property of the derivative and its chemical composition prompted further study and led to the work described herein. Alkali-soluble cellulose derivatives containing thiourethane groupings have been obtained by reaction of zinc cellulose xanthate with an amine in aqueous media. The starting material was an alkaline solution of sodium cellulose xanthate (viscose), the material used in commercial spinning of rayon. Viscose was added to a solution of a zinc salt. whereupon a pale yellow fibrous precipitate of zinc cellulose xanthate formed. The precipitate was filtered off, washed, and added to an aqueous solution of an amine. Two or three days were allowed for reaction between the zinc xanthate and amine at room temperature. The product of the reaction was a cellulose derivative containing nitrogen and sulfur. Steps in the reaction are
2 CellOC
f
Zn*+ =
cellulose xanthate and goes on to react with the amine. Like most xanthic acids (73), there i s some tendency for cellulose xanthic acid to decompose into the parent hydroxyl compound and carbon disulfide. Thus, there is competition between the alternate reaction paths as shown by the arrows in the following reaction:
14.0
yo nitrogen
- 297 _
162
1 and DS = n+ 1’ The degree of substitution of the prod-
+ CS. ,
I
/ s\ COCell
CellOCY S
H20 =
[CeHO
