RU2339648C1 - Method for obtaining cellulose dinitrates out of lignocellulose material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method for obtaining cellulose dinitrates out of lignocellulose material uses source lignocellulose material consisting of cellulose, lignin and hemicelluloses without preliminary separation of components, with preliminary autohydrolysis explosion. Reaction is performed in sequence with trifluoracetic acid at 25°-30°C for 60-180 minutes and with nitric acid after activisation for 15-90 minutes at reagent mass ratio of lignocellulose material to acids of 1:50. Invention allows full use of whole lignocellulose material. Cellulose nitrates feature wider range of properties. High molecular products obtained by the claimed method include 10 to 12% of nitrogen, is soluble by 100% in acetone and by up to 70% in alcohol-ether mix.

EFFECT: reduction of end product cost, implementation of waste-free technology.

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Description

The invention relates to the field of chemical technology and is intended to produce cellulose dinitrates, which can be used for the manufacture of ionizing radiation detectors, test diagnostics of various diseases, biological indicators, solid rocket fuel and other modern types of products.

Known methods of nitration of cellulose - one of the main components of lignocellulosic material with trifluoroacetic and nitric acids [Kasko N.S. Synthesis of chemically homogeneous cellulose 2,3-dinitrates / N.S. Kasko, O.A. Panchenko // Chemistry of plant raw materials, 1197. - No. 2. - P.46] by sequentially treating isolated or isolated cellulose, trifluoroacetic, and then nitric acids. The reaction is carried out at a temperature of 30 ° C for 15 minutes, resulting in products with a nitrogen content of 10 to 12% and solubility in acetone and alcohol-ether mixture up to 100%. The disadvantage of this production method is that the initial raw material is cotton cellulose or selected wood pulp, for which wood is treated in several stages: delignification, mercerization, cooking, bleaching, which makes the production of the final product more expensive. Of the known technical solutions, the closest in scientific and technical essence to the claimed object - the prototype is a method for producing cellulose nitrates from wood [RU Patent - No. 2174984C2 RA, IPC C08B 5/02 Method for producing cellulose nitrate. / A.I. Galochkin, N.S. Kasko, I.N. Ergina; BI No. 29; publ. 10/20/2001. - 5 p.]. In this way, cellulose trinitrates are obtained by esterification of wood with nitric acid in a mixture with trifluoroacetic acid at a temperature of 30 ° C for 15 minutes. Get products that are completely soluble in acetone and sparingly soluble in the alcohol-ether mixture, with a nitrogen content of up to 14%.

Common features of the prototype and the present invention are that trifluoroacetic and nitric acids and lignocellulosic raw materials are used to produce cellulose tri- and dinitrates.

The aim of the invention is to obtain cellulose dinitrates directly from lignocellulosic raw materials: deciduous and coniferous wood waste, as well as agricultural waste by sequential treatment of trifluoroacetic and nitric acids, completely soluble in acetone and alcohol-ether mixture with a nitrogen content of 10 to 12%.

The obtained nitrates are used as nitrates obtained from isolated cellulose, as well as for further modification with various reagents to obtain new polymeric materials with improved properties. For example: films of nitrate-propionate cellulose ether have increased heat resistance, density and strength compared to films of cellulose nitrate.

The essence of the invention lies in the fact that lignocellulosic raw materials are exposed to trifluoroacetic and then nitric acids. Lignocellulosic raw materials consisting of cellulose, lignin and hemicelluloses, without preliminary separation into components, as well as raw materials consisting of deciduous and coniferous wood waste, previously subjected to explosive autohydrolysis, are used as a starting material. Explosive autohydrolysis is a process of treating wood with water vapor under pressure, resulting in the destruction of bonds between the main components of wood. Pretreatment is carried out for 3-5 minutes at a temperature of 220 ° C and a pressure of 3 MPa. The impact of trifluoroacetic and then nitric acids is carried out at a temperature of 25-30 ° C for a duration of 60 to 180 minutes with a mass ratio of reagents of lignocellulosic raw materials: acids 1:50.

The result is cellulose nitrates highly soluble in acetone and in an alcohol-ether mixture. These esters are cellulose dinitrates.

The invention provides the use of all lignocellulosic raw materials, reduces the cost of obtaining the final product - cellulose dinitrate, realizes the possibility of waste-free technology.

The advantages of the claimed invention are that lignocellulosic raw materials are used in the nitration reaction: wood of various species and its waste, annual plants, etc., and not just cellulose - one of the components of this material. In addition, the present invention uses trifluoroacetic acid to partially destroy the morphological structure of wood and increase the availability of hydroxyl groups of the main components of ligno-carbohydrate raw materials for the active reagent, allowing the cellulose to maintain the polymer state. The advantages in using lignocellulosic material are:

- firstly, from the point of view of the availability of feedstock, waste from forestry production compared to cellulose is unrivaled, which significantly reduces the cost of the final product;

- secondly, there is no need to separate lignocellulosic raw materials into main components, which allows realizing the possibility of non-waste technology - cellulose, lignin, hemicelluloses are nitrated and used in the future, which will significantly affect the environmental situation in the logging and timber processing industries, as well as at enterprises for the chemical processing of wood;

- thirdly, nitrates of lignocellulosic material have a wider range of properties than cellulose nitrates.

The implementation of the invention is achieved as follows: a sample of air-dry crushed lignocellulosic raw materials: wheat straw, as well as waste wood (aspen, birch, pine) with a fraction of 0.15 ÷ 0.35 mm, previously subjected to explosive autohydrolysis, are placed in a reaction flask containing 67 ml of trifluoroacetic acid, and incubated for 60 to 180 minutes at a temperature of 25-30 ° C, after activation, nitric acid was added in small portions in a flask and thermostated at 30 ° C for 15 to 90 minutes with a mass ratio of lignocellulosic raw materials : acids 1:50.

The invention allows to obtain cellulose nitrates structurally and molecularly homogeneous. The resulting mass is stabilized with ammonia, filtered on a glass porous filter, washed with large portions of hot and cold water and dried in air. The composition of the obtained products is identified by analysis of the nitrogen content and solubility in acetone and alcohol-ether mixture, as well as by IR spectra. The properties of the obtained products are described in table 1.

Example 1 — A weighed portion of air-dried lignocellulosic raw materials (aspen wood, 0.55 mm fraction) weighing 1.0 g was placed in a reaction flask containing 67 ml of trifluoroacetic acid and kept at 25 ° С for an hour, then 33 ml of nitric acid were added acid, bring the temperature to 30 ° C and incubated for 30 minutes with constant stirring. At the end, the reaction mass is stabilized with ammonia and filtered through a filter, washed with large portions of hot and cold water, and dried in air. The resulting cellulose dinitrate contains 11.0% nitrogen. The solubility in acetone is 87%, and in the alcohol-ether mixture 30%.

Cellulose dinitrate contains a free hydroxyl group at the sixth carbon atom, is structurally and molecularly homogeneous.

Example 2 - Nitration was carried out under conditions similar to example 1, but used vegetable raw materials subjected to explosive autohydrolysis (3-5 min at a temperature of 220 ° C and a pressure of 3 MPa) (table 2).

High molecular weight products are obtained that contain from 10 to 12% nitrogen, are dissolved in 100% acetone and up to 70% in an alcohol-ether mixture.

Tables

Table 1 Nitrogen content (%) in nitration products obtained by sequential modification of polymers in the wall of a plant cell with trifluoroacetic and nitric acids The duration of aging in trifluoroacetic acid, min The duration of nitration, min fifteen thirty 60 90 60 10.9 ± 0.3 11.0 ± 0.3 11.6 ± 0.3 11.9 ± 0.3 90 11.2 ± 0.3 11.3 ± 0.3 11.5 ± 0.3 11.8 ± 0.3 120 11.0 ± 0.3 11.3 ± 0.3 11.3 ± 0.3 11.6 ± 0.3 150 11.0 ± 0.3 11.1 ± 0.3 11.1 ± 0.3 11.6 ± 0.3 180 10.9 ± 0.3 11.2 ± 0.3 11.1 ± 0.3 11.6 ± 0.3

table 2 Properties of nitration products of wood subjected to explosive autohydrolysis obtained by the sequential action of trifluoroacetic and nitric acids Wood The nitrogen content (N),% Solubility Degree of polymerization Acetone,% Alcoholic mixture,% Aspen 11.6 ± 0.3 96 ± 2.0 68 ± 2.0 400 ± 2.0 Birch 11.5 ± 0.3 98 ± 2.0 70 ± 2.0 480 ± 2.0 Pine 11.3 ± 0.3 98 ± 2.0 60 ± 2.0 450 ± 2.0

Claims (1)

The method of producing cellulose dinitrates from lignocellulosic raw materials, which consists in the fact that the cellulose-containing material is sequentially exposed to trifluoroacetic acids and then nitric at a temperature of 25-30 ° C, with a mass ratio of reagents lignocellulosic raw materials - acids: 1:50, characterized in as the starting material, lignocellulosic raw materials are used, consisting of cellulose, lignin and hemicelluloses, without prior separation into components subjected to explosive autohydrolysis, and the interaction of dressed sequentially with trifluoroacetic acid for 60-180 minutes, then with nitric acid for 15-90 minutes.