Abstract: Abstract In this paper, an acetyl bromide procedure was used to determine the lignin content of cottonseed coat, and the acetylation reaction of lignin has been investigated. The results indicated that the optical progress conditions were as follows: acetyl bromide volume fraction 30%, reaction temperature 80℃,reaction time 60min, and perchloric acid concentration 0.69mol/L. On that basis, the lignin content of cottonseed coat measured by acetyl bromide procedure is 19.40%. Compared to Klason method, the acetyl bromide procedure not only simple and rapid, but also has an advantage in reproducibility and accuracy.

Key words: cottonseed coat, lignin, acetyl bromide, acetylation reaction