Method for preparing acetylated hemicellulose by employing catalysis of iodine

A technology for hemicellulose and catalytic preparation, applied in the field of modified hemicellulose, can solve problems such as toxicity and reduce production cost, and achieve the effects of improving hydrophobicity, reducing production cost and increasing yield

Inactive Publication Date: 2008-05-21
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these reaction media are toxic, and there are no reports on the homogeneous acetylation of hemicellulose in ionic liquids. Using molecular iodine as a new catalyst can improve the efficiency of hemicellulose acetylation and improve the substitution of products. degree, and the ionic liquid can be recycled, which can reduce the production cost

Method used

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  • Method for preparing acetylated hemicellulose by employing catalysis of iodine
  • Method for preparing acetylated hemicellulose by employing catalysis of iodine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] In the first step, 50 g of ground wheat straw was first extracted with toluene-ethanol (2:1, v / v) in a Soxhlet extractor for 6 hours. Then add 1000ml of water and extract at 75°C for 2h to remove water-soluble hemicellulose. The residue was treated with 75 g of sodium chlorite in 1000 ml of water at 75° C. for 2 h (the pH value was adjusted between 3.6 and 3.8 with acetic acid). The solid-liquid ratio of delignified wheat straw and KOH solution is 1:20g·ml -1 Under the condition of 10wt% KOH at 23°C for 10h. The resulting filtrate was adjusted to pH 5.5 with 6 mol / l acetic acid, then precipitated with 3 volumes of 95% ethanol, filtered, washed with acidified 70% ethanol, air-dried for 12 hours and dried at 60°C for 16 hours.

[0026] In the second step, 6.6g of purified hemicellulose (equivalent to xylan hydroxyl mole in 0.1 hemicellulose composition) is placed in a 500ml three-necked reaction flask, and 260g of 1-butyl-3-methylimidazolium chloride ion is added Liqui...

Embodiment 2

[0031] In the first step, 50 g of ground wheat straw was first extracted with toluene-ethanol (2:1, v / v) in a Soxhlet extractor for 6 hours. Then add 1000ml of water and extract at 75°C for 2h to remove water-soluble hemicellulose. The residue was treated with 75 g of sodium chlorite in 1000 ml of water at 75° C. for 2 h (the pH value was adjusted between 3.6 and 3.8 with acetic acid). The solid-liquid ratio of delignified wheat straw and KOH solution is 1:20g·ml -1 Under the condition of 10wt% KOH at 23°C for 10h. The resulting filtrate was adjusted to pH 5.5 with 6 mol / l acetic acid, then precipitated with 3 volumes of 95% ethanol, filtered, washed with acidified 70% ethanol, air-dried for 12 hours and dried at 60°C for 16 hours.

[0032] In the second step, 6.6 g of purified hemicellulose (equivalent to 0.1 moles of xylan hydroxyl groups in hemicellulose composition) is placed in a 500 ml three-necked reaction flask, 260 g of ionic liquid is added, and the reaction is car...

Embodiment 3

[0036] In the first step, 50 g of ground wheat straw was first extracted with toluene-ethanol (2:1, v / v) in a Soxhlet extractor for 6 hours. Then add 1000ml of water and extract at 75°C for 2h to remove water-soluble hemicellulose. The residue was treated with 75 g of sodium chlorite in 1000 ml of water at 75° C. for 2 h (the pH value was adjusted between 3.6 and 3.8 with acetic acid). The solid-liquid ratio of delignified wheat straw and KOH solution is 1:25g·ml -1 Under the condition of 10wt% KOH at 23°C for 10h. The resulting filtrate was adjusted to pH 5.5 with 6 mol / l acetic acid, then precipitated with 3 volumes of 95% ethanol, filtered, washed with acidified 70% ethanol, air-dried for 12 hours and dried at 60°C for 16 hours.

[0037] In the second step, 8.8 g of purified hemicellulose (equivalent to 0.133 moles of xylan hydroxyl groups in the composition of hemicellulose) was placed in a 500 ml three-necked reaction flask, 260 g of ionic liquid was added, and the reac...

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Abstract

The invention discloses a method of applying iodine catalysis to prepare for acetylated hemicellulose. Firstly, KOH solution is used to dispose delignified wheat straw, then, dissolved alkali-soluble hemicellulose in filtrate is processed for purification and separation; subsequently, the hemicellulose after separation is added into 1-butyl-3-methyl imidazole chloride solution, the catalyst iodine with the weight of corresponding 10 percent to 15 percent of the hemicellulose is added, then the acetic anhydride which is 16 to 28 times of xylan hydroxyl in the compositions of the hemicellulose is added to react for 20 to 30 minutes under 90 DEG C to 110 DEG C and cooled, saturated sodium thiosulfate is added into a mixture, and ethanol is used for washing and drying to obtain the acetylated hemicellulose. The invention can obtain the acetylated hemicellulose with high substitution degree; compared with a heterogeneous system, the invention improved the reaction speed by five to ten times, increases the output and reduces the production cost, the hydrophobic nature of the hemicellulose after chemical modification is improved greatly, and the invention can be used for preparing for the degradable food-packing film.

Description

technical field [0001] The invention relates to modified hemicellulose, in particular to a method for preparing acetylated hemicellulose using iodine catalysis. Background technique [0002] A new field opened up by green chemistry—biomass chemistry, is to study the chemical transformation of green plants, that is, to find an effective and cheap method to separate cellulose, hemicellulose and lignin, and then decompose them into glucose monomers , alcohol and other organic chemical raw materials, thereby transforming the huge reserves of green wild plants on the earth into human food and livestock feed, energy and organic chemical raw materials. Among the three main components of plant resources, cellulose is the most utilized by humans, hemicellulose is the least utilized, and lignin is the most difficult to utilize. Hemicellulose is a polysaccharide polymer biosynthesized by trees. It is estimated that 3.5×10 hemicellulose is produced annually by p...

Claims

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Application Information

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IPC IPC(8): C08B37/14
Inventor 任俊莉彭锋孙润仓
Owner SOUTH CHINA UNIV OF TECH
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