SU503906A1 - The method of obtaining levoglucosan - Google Patents

Description

one

This invention relates to an improved preparation method. levoglucosan.

A known method for producing levoglucosane is obtained by prehydrolysis of plant material in the presence of mineral, washing with water, drying and subsequent vacuum-hermetic decomposition of the formed lellolignin.

The main disadvantages of the famous cnoco6aii. relates that the output of ZO-4O% I can only be obtained by washing the cello lignin with distilled or demineralized water, which makes it difficult; application from; Western method in industry. ; In the proposed method for producing levoglucosane, the plant material is subjected to prehydrolysis in the presence of mineral acids, the formed cello lignin is washed with water until pH 2, O-4, O is dried and subjected to vacuum thermal conversion. Alignment followed by separation of the target product in a known manner.

Carrying out the process under the specified conditions makes it possible to use for

washing the natural technical water. The output of 40-50%.

Example 1. 10O g of absolutely icyxoro cello lignin obtained in the process of prehydrolysis of birch wood% of the form of sheps with particles of a size of 3-15 mm, is placed in a glass and filled with ZOO ml go- hot distilled water. Diffusion: washing is carried out at 80 ° C for one hour. Then, the liquid is decanted and the sample of cellulose is poured with ZOO ml of fresh water. Washing is continued in this way until pH 2.9. Washed cello lignin high / dry in dry air and dry condition. With a vacuum thermal decomposition of this: cello lignin in a laboratory glass apparatus at a residual pressure of 10 mm Hg. and a temperature of 450 ° C., the yield of levoglucosane was 54.0% of the decomposed cellulose.

Example 2. Ce lignin washed with distilled water, according to example 1, to a pH of 4.6. Drying and vacuum thermal decomposition of washed cel lignium is carried out according to Example 1. The yield of levoglucosane was composed of 43.8% of decomposed cellulose. Example 3; Cellolignin according to example 1 is washed with natural water to a pH of 2.6. Natural water has the following characteristics: chromaticity 27 °, transparency more than 30 cm, ammonia 1.2 mg / l, iron 0.4 mg / l, nitrogen nitrates and nitrite not detected, chlorides 9.0 mg / l, oxidability 15.4 mg / l. Drying and vacuum thermal decomposition of the washed cellulose is carried out according to example 1. The yield of levoglucosane is 52.3% of the disintegrated cellulose. Example 4. Cellolignin according to example 1 is washed with natural water to a pH of 4.9. Natural water has the characteristics of example 3. Drying and vacuuming hermetic decomposition of the washed cellolignin is carried out as in example 1. The yield of levoglucosane is 30.6% of the decomposed cellulose. Example 5. Cellolignin according to example 1 is washed with natural water to a pH of 2.4. Natural water has the following characteristics; chromaticity is 5 °, transparent. more than 30 cm, ammonia - traces, iron 2.7 mg / l, nitrogen of nitrates and nitrites - not detected, chlorides 191.0 mg / l, oxidability 6.0 mg / l. Drying and vacuum decomposition of the washed cellulose is carried out according to Example 1. The yield of levoglucosane is 43.2% of the decomposed cellulose. Example 6. Cellolignin according to example 1 is washed with natural water to a pH of 4.5. Natural water has a characteristic as in Example 5. Drying and vacuum thermal decomposition of the washed cellulose is carried out as in Example 1. The yield of left glucose is 11.9% of the decomposed cellulose. The method of obtaining levoglucosan by prehydrolysis of plant material in the presence of Mineral acids, washing the formed cello lignin with water, drying it and vacuum thermal decomposition, followed by isolation of the target product in a known manner, so that in order to increase the yield of the target product, washing the cellulose with water is carried out to a pH of 2.0-4.0.