Novel chitin-based materials were synthesized and the adsorption behavior of typical acid dyes to the resulting polymers has been evaluated. The successful synthetic reaction was confirmed by the infrared spectroscopic measurements. By the reaction of alkalichitin with tosyl chloride, the corresponding tosylchitin was synthesized as a soluble and reactive precursor. Next, aminodeoxychitin was synthesized by the reaction of the tosylchitin with ammonia. Similarly, 2 '-aminoethylamino- and 6 '-aminohexylaminodeoxychitins were synthesized by reacting the tosylchitin with ethylenediamine and hexamethylenediamine, respectively. It has been confirmed that the adsorption abilities of these polymers for acid dyes were significantly high, and also that one of the aminodeoxychitins showed a high adsorption ability for Cu2+ ion. On the basis of the adsorption data of acid dye on the aminodeoxychitin, the tosylchitin and the original chitin, the amino group contents at C-6 and C-2 positions were estimated. The aminodeoxychitin and aminoalkylaminodeoxychitins could be applicable to the adsorbent for anionic dyes and Cu2+ ion along with a precursor for further novel derivatives. (c) 2007 Wiley Periodicals, Inc.