(2) Put the purified chitosan into a reaction bottle with stirring, add a certain amount of 20%NaOH solution and isopropanol, stir at room temperature for 60 minutes, then drop the isopropanol solution of chloroacetic acid, react at room temperature for 5 hours, then neutralize it with dilute hydrochloric acid to pH 7, precipitate the product with acetone, filter, wash it with 85% methanol solution until there is no chloride ion, then wash it with anhydrous methanol, and vacuum dry it at 60℃ to obtain the product.
(3) Add two abalone chitosan into 200mL n-butanol, stir and swell for 20min at room temperature, add 10mol/L NaOH solution for 50mL for 40min in six times, stir for 40min after the last addition to obtain basic chitosan, then add 24g solid chloroacetic acid for 5min five times, stir and react at 55~75℃ for 3h, and then add/. Adjust the pH value to 7 with glacial acetic acid, filter, wash with 300ml of 70% methanol for several times, drain, wash with 300 ml of absolute ethanol for several times, and vacuum dry at 60℃ to obtain the product. The reaction temperature of carboxymethylation was 55℃, 60℃, 65℃, 70℃ and 75℃ respectively, and the yield was 3 1. The highest values at 65℃ are 33.8g, 36.58g, 34.0g and 33.2g respectively.
(4) Soak chitin in 40% ~ 60% NaOH solution. Reacting at a certain temperature for 5-5h, then adding chloroacetic acid under stirring, and reacting at 0-70 DEG C for 0. The mass ratio of alkali to acid is controlled at (1.2 ~1.6):1.5 ~ 5 hours. The method can also prepare carboxymethyl chitosan.
(5) Firstly, alkalize 15g chitosan in 50%(w/w) NaOH solution, then add 150mL isopropanol and stir, add 18g chloroacetic acid, react at 65℃ for 2h, neutralize with acid, wash with 70% methanol for many times, then dissolve in water and precipitate with acetone.
(6) Suspend 3g powdered chitosan in 100mL NaOH solution with concentrations of 25%, 30%, 35% and 40% respectively, add 5g mixed solution of chloroacetic acid and glacial acetic acid (molar ratio:1), and react at 30℃ every/kloc-.
(7) dissolve 10g chitosan in1000ml1%1%acetic acid solution, add 200mL sodium chloroacetate (chloroacetic acid is neutralized with sodium hydroxide solution) and 150ml 50% sodium hydroxide solution, and stir intermittently at room temperature for 4 hours. 、
(8) The preparation of carboxymethyl chitosan by ultrasonic method can significantly shorten the reaction time and improve the degree of substitution of carboxymethyl. 0. Mix 5g chitosan with 5mL isopropanol and 10ml 30 %NaOH solution, then add chloroacetic acid dissolved in 10ml isopropanol (the mass ratio of chitosan to chloroacetic acid is 1: 4 ~ 5), shake for a few minutes in a triangular flask, put it in an ultrasonic cleaner, and heat it to 60℃ with water as oscillation medium. Add 40 ml of water to the viscous substance, fully stir and dissolve, neutralize to pH 7 with 1000 hydrochloric acid, filter out insoluble substances, add a proper amount of methanol to the filtrate for precipitation, filter, wash with anhydrous ethanol, and dry at 100℃ to obtain the product.