The Acetylation of Silk Fibroin by the Action of Ketene. Part II

Abstract

1. The study of the behavior of ketene towards silk fibroin has been continued. 2. The rate of absorption of ketene by fibroin increases with rise of temperature, and with increase of the concentration of ketene exposed to the fibre. 3. That ketene combines with the phenolic group of typosine, and the free α-amino groups in fibroin is evidenced by the failure of completely ketenized silk to respond to the characteristic Millon and Ninhydrin tests of protein respectively. 4. More ketene is absorbed by fibroin than can be accounted for by addition only in the known. phenolic and free amino groups. The results of acetyl analyses of fibroin, saturated with ketene, indicate the presence of other unidentified groupings in the protein molecule capable of combining with ketene. 5. The degree of acetylation of degummed silk fibroin reaches a maximum or limiting value of about 7% of acetyl groups. 6. Exhaustive treatment of silk fibroin with ketone gas produces a tan coloration of the fibre.

Reaction of silk fibroin with diazomethane

“…The acid chlorides and anhydrides were used for this purpose by Abderhalden and Brockmann [3, 4J, but they were found to produce appreciable deterioration of the• fibers. Ketene was used by Kise and Carr [5,6] with far more satisfactory results, although on prolonged treatment with this reagent. the fiber was colored tan and some degradation occurred.…”