A kind of preparation method of lignin-based carboxylic acid derivative
A technology of cellulose-based carboxylic acid and lignin, which is applied in the field of preparation of lignin carboxylic acid derivatives, can solve the problems of benzene ring destruction, increase of carboxyl group, molecular weight degradation, etc. simple effect
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Embodiment 1
[0034] 1) Mix 1.91g of alkali lignin with 20ml of water to obtain a suspension, and stir evenly;
[0035] 2) Take hydrochloric acid whose mass is 2 times of the lignin mass used, then slowly drop hydrochloric acid into the lignin suspension, stir evenly to obtain a lignin hydrochloric acid solution, the hydrochloric acid concentration of which is 4mol / L, and set aside;
[0036] 3) Take sodium nitrite whose mass is 1 times that of the lignin used, prepare it into a nitrite solution with a concentration of 50%, and quickly add it dropwise to the lignin hydrochloric acid solution obtained in step 2), and stir in a closed manner at a temperature of 30° C. Oxidation reaction 36h;
[0037] 4) 1.24 g of lignin carboxylic acid derivatives were isolated, washed and dried, and the carboxyl content of the oxidation product was detected to be 2.5 mmol / g.
Embodiment 2
[0039] 1) Mix 1.91g of alkali lignin with 20ml of water to obtain a suspension, and stir evenly;
[0040] 2) Take sulfuric acid whose mass is 1 times the mass of lignin used, then slowly drop sulfuric acid into the lignin suspension, stir evenly to obtain lignin sulfuric acid solution, the sulfuric acid concentration of which is 4mol / L for later use;
[0041] 3) Take sodium nitrite whose mass is twice that of the lignin used, and prepare it into a nitrite solution with a concentration of 50%, and quickly add it dropwise to the lignin sulfuric acid solution obtained in step 2), at a temperature of 30° C., airtightly stir, and carry out Oxidation reaction 24h;
[0042] 4) 1.34 g of lignin carboxylic acid derivatives were isolated, rinsed and dried, and the carboxyl content of the oxidation product was detected to be 2.24 mmol / g.
Embodiment 3
[0044] 1) Mix 1.91g of alkali lignin with 40ml of water to obtain a suspension, and stir evenly;
[0045] 2) Take nitric acid whose quality is twice that of the used lignin, then slowly drop nitric acid into the lignin suspension, add water and stir evenly to obtain a lignin nitric acid solution, the nitric acid concentration of which is 0.4mol / L, and set aside;
[0046] 3) Take sodium nitrite whose mass is 0.07 times the mass of lignin used, prepare it into a nitrite solution with a concentration of 50%, quickly add it dropwise to the lignin nitric acid solution obtained in step 2), and carry out the oxidation reaction in a sealed environment at a temperature of 30°C 36h;
[0047] 4) 1.5 g of lignin carboxylic acid derivatives were isolated, rinsed and dried, and the carboxyl content of the oxidation product was detected to be 3.327 mmol / g.
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