Method for preparing solvent system capable of dissolving cellulose under room temperature condition

Abstract

The invention discloses a method for preparing a solvent system capable of dissolving cellulose under a room temperature condition. The solvent system is composed of ionic liquid and dimethyl sulfoxide, wherein anions in the ionic liquids are acetate ions, cations are N-R1 and N-R2 imidazole cations; in the formula, R1 is methyl or ethyl, R2 is ethyl, allyl or butyl. The method comprises the following preparation steps: mixing and fully dissolving N-methylimidazole or N-ethylimidazole and the dimethyl sulfoxide; slowly dripping bromo-hydrocarbon R2Br under an ice bath condition to react; heating to carry out a reflux reaction at a temperature of 40-70 DEG C; and adding a saturated lead acetate or silver acetate solution, stirring to react, filtering precipitate, and removing water in filtrate through a rotary evaporation method to prepare the solvent system. The method disclosed by the invention has the advantages that the preparation method is short in reaction time, free of pollution and high in synthesis efficiency and conversion rate; and the solvent system can dissolve a large amount of non-activated or non-pretreated cellulose under the room temperature condition.

Description

technical field [0001] The invention relates to a preparation technology of a cellulose solvent system, in particular to a preparation method of a solvent system capable of dissolving cellulose at room temperature. Background technique [0002] As one of the most abundant renewable resources on earth, cellulose and its derivatives are widely used in the fields of food, medicine, composite materials, textiles and energy. During the production process, the cellulose needs to be dissolved first. However, natural cellulose has a high degree of crystallinity and a large number of hydrogen bonds in and between molecules, which makes it difficult to dissolve in water and common organic solvents. With the efforts of many researchers, people have discovered a variety of solvent systems for dissolving cellulose. These solvent systems mainly include: NaOH / CS 2 system, protonic acid system, DMAc / LiCI, TBAF / DMSO, DMF / N 2 o 4 , LiC1O 4 ·3H 2 O, LiSCN 2H 2 O and NMMO systems. Amo...

AI Technical Summary

Problems solved by technology

Second, the preparation process of these ionic liquids is cumbersome and the efficiency is low

Microwave heating can greatly shorten the reaction time, but the reaction conditions are difficult to control, and it is easy to cause the decomposition of the product

Ultrasound-assisted synthesis of ionic liquids still requires heating and still requires a long reaction time

In addition, in the synthesis methods of these ionic liquids, an excess of a raw material is generally required, and an organic solvent needs to be used to remove unreacted raw materials after the reaction, which not only increases the cost, but also brings additional pollution

Third, the viscosity of the ionic liquid solution of cellulose is relatively high

Patent CN 101215725A discloses a mixed solvent composed of ionic liquid 1-butyl-3-methylimidazolium acetate (BMIMAc) and dimethyl sulfoxide (DMSO), which can dissolve cellulose at room temperature, but The solvent is prepared by adding dimethyl sulfoxide (DMSO) to 1-butyl-3-methylimidazolium acetate (BMIMAc), while 1-butyl-3-methylimidazole acetate ( The preparation process of BMIMAc) is loaded down with trivial details, and needs to use a large amount of organic solvents