JPS6335603A - Production of cellulose derivative having aldehyde group and side chain - Google Patents

Abstract

PURPOSE:To produce a cellulose derivative having aldehyde groups as side chains, excellent in physical properties, by treating a cellulose derivative having allyl groups as side chains with an oxidizing agent. CONSTITUTION:A cellulose derivative having aldehyde groups as side chains is produced by treating a cellulose derivative having allyl groups as side chains with an oxidizing agent. It is desirable to use, especially, ozone as said oxidizing agent. It is theoretically possible to produce even a tri-substituted derivative having three aldehyde groups as side chains according to said process. However, the quantitative determination of the aldehyde groups of an aldehydecellulose of a degree of substitution >1 is difficult because it is crosslinked and insolubilized in the stage of isolation from the ozonization reaction solution. However, it is possible even in this case to subject it to the subsequent synthetic reaction without removing the solvent therefrom. On the contrary, an aldehydecellulose of a degree of substitution <1 can be separated and purified so that it can be used for synthesizing a higher derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a cellulose derivative having a β-1,4 glucan skeleton as the main chain and an aldehyde group in the side chain.

[Conventional technology]

A polymer having an aldehyde group as a functional group has an affinity for electron-donating substances. Therefore, it can be used to immobilize adducts with many physiologically active substances such as proteins and peptides, enzymes, and bacterial cells, and to adsorb biological wastes such as urea.
It may be used as an intermediate for ion-exchange polymer synthesis.

When the polymer is cellulose or its derivatives, favorable physical properties such as low toxicity and biocompatibility are expected. A conventional method known for introducing aldehyde groups into cellulose is to oxidize cellulose with periodic acid. However, this method involves cleavage of the anhydroglucose ring, so the aldehyde derivative obtained no longer has β
-1,4 glucan skeleton is not maintained. Therefore, the physical properties are inferior to that of the original cellulose.

[Means for solving problems]

Mechanistically, the oxidation of cellulose with periodic acid generates aldehydes through the oxidation of polyhydric alcohol compounds. There is oxidation of bonds.

That is, by introducing an allyl group as a side chain of cellulose and oxidizing the obtained allyl derivative of cellulose under appropriate conditions, a cellulose derivative having an aldehyde group in the side chain may be obtained.

In the method for producing a cellulose derivative having an aldehyde group in its side chain according to the present invention, the allylated cellulose derivative, which is a precursor of the target product, can be synthesized by various methods.

The present invention relates to a method for producing a cellulose derivative having an aldehyde group in the side chain, which is characterized by treating a cellulose derivative having an allyl group in the side chain with an oxidizing agent, and in particular, using ozone as the oxidizing agent. The present invention relates to a method for producing a cellulose derivative having an aldehyde.

A cellulose derivative having an allyl group as a side chain, which is a precursor of a cellulose derivative having an aldehyde group in a side chain, which is the object of the production method of the present invention, can be synthesized by various methods.

A method for directly allylating cellulose is, for example, described by Kashita (A.
ngew, Chell, 42.549 (1929
)), Kisso (Journal of the Textile Society 21.317 (1965))
, Method et al. (Inter-national Sympo
sium on Wood and PulpingC
hen+1stry, 1.70 (1983)). However, recent studies have found that products with a higher degree of allyl group substitution can be obtained by using cellulose ethers or cellulose esters, which have higher solvent solubility than cellulose, as reported by Chikakatsu et al. (Collection of Abstracts of the 1985 Fiber and Textile Society Annual Conference, p. 102).

The latter method is a method in which a cellulose ether or cellulose ester having a free hydroxyl group is dissolved in a suitable solvent, such as dimethyl sulfoxide, and allylated by reacting with allyl halide in the presence of an alkali and the absence of water. In this case, the higher the amount of alkali relative to the free hydroxyl groups of cellulose ether or cellulose ester, the higher the degree of allyl group substitution is obtained. Furthermore, when cellulose ester is used as a raw material, the ester group is eliminated during the reaction, and a completely allylated cellulose derivative can be obtained. Oxidation of allyl groups present as side chains of cellulose derivatives can be carried out by oxidizing the cellulose derivatives in a suitable solvent,
For example, this can be achieved by dissolving ozone in a mixed solvent of methylene chloride/methanol and bubbling air containing ozone into the solution. This reaction proceeds smoothly at low temperatures and does not involve side reactions.

By the method of the present invention, it is theoretically possible to obtain up to trisubstituted side chain aldehyde groups. However, aldehyde cellulose with a degree of substitution of 1 or more undergoes a crosslinking reaction and becomes insolubilized during isolation from the ozonation reaction solution, making it difficult to quantify the aldehyde groups. However, even in this case, it is possible to carry out the next synthetic reaction of the derivative without removing the solvent. On the other hand, aldehyde cellulose with a degree of substitution of 1 or less can be separated and purified, and can be used in higher-order derivative synthesis reactions.

Example 1 1.0 g of sufficiently dried methylcellulose (DS = 1.6, Wako Pure Chemical Industries, Ltd.) was used as a starting material, added to 60 ml of dimethyl sulfoxide, stirred overnight at 40°C to dissolve, and then cooled to room temperature. Place the solution under nitrogen gas atmosphere,
5.6 g of sodium hydroxide powder was added, and the mixture was stirred for about 1.5 hours until no lumps of sodium hydroxide were observed. Next, Oml of allyl chloride 6 was added, and the mixture was stirred at 70° C. for 14 hours to react under a nitrogen gas atmosphere.

After the reaction was completed, the reaction solution was added to 200 ml of water/chloroform=1/1 (volume ratio) for distribution. The chloroform layer was taken out, washed three times with water, concentrated under reduced pressure, and poured with methanol to form a precipitate.

The resulting precipitate was redissolved in chloroform and precipitated with methanol to obtain 1.0 g of allyl (methyl) cellulose.

Since no absorption maximum near 3450 cm-' is observed in the infrared absorption spectrum (Fig. 1) of the obtained allyl (methyl) cellulose, the above allyl (methyl) cellulose is considered to be a completely allylated product.

Allyl (methyl) cellulose produced above 0, tg
30ml of mixed solvent of methylene chloride/methanol = 571
1 and bubbled with an ozone stream generated from a 100 V ozone generator at a flow rate of 0.51/min at a temperature of -70°C. When passed through the ozone stream, the colorless solution was observed to turn dark blue.

After bubbling ozone for 15 minutes, the ozone was stopped and nitrogen was bubbled, and the dark blue color gradually disappeared and the solution became colorless again. The reaction solution was poured into methanol and the precipitate was collected. 'This stuff is aldehyde (methyl) cellulose.

The infrared absorption spectrum (Figure 1) of the aldehyde (methyl) cellulose has an absorption maximum derived from carbonyl at 1730 cm-', indicating the presence of free aldehyde groups.

The above aldehyde (methyl) cellulose was produced by reacting with hydrazine, and the N content of the hydrazone was quantified, and the original degree of aldehyde group substitution was calculated, and it was found that DS = 0.8
The value of was obtained.

The reaction for the above quantification is as follows.

That is, 0.1 g of aldehyde (methyl) cellulose was mixed with 2.0 g of aldehyde (methyl) cellulose.
4-dinitrophenylhydrazine 2N hydrochloric acid solution 50ml
1 at 60° C. for 24 hours. When the infrared absorption spectrum of the product was measured (Fig. 2 ■), it was found to be 1730 cm-
'The absorption based on >C=0 disappears, and -N=C-(16
Absorption of aromatic ring (near 1590 cm-'), -NH- (near 1500 cm-') appears, and it is recognized from the tailcoat that the aldehyde group is completely converted to phenylhydrazone. In addition, Figure 2■,■
are aldehyde (methyl) cellulose, 2.4-
This is an infrared absorption spectrum of a reaction product with dinitrophenylhydrazine.

The above aldehyde (methyl) cellulose is weakly alkaline (
Dissolve in water at pH=9). However, the same aldehyde (
Heating (methyl) cellulose casting film
For example, at 80°C (day and night), it became insoluble in the weakly alkaline water.

When the dynamic viscoelasticity of the insolubilized film was measured using a Vipron, it was found that the movement of the cellulose skeleton was restricted and that crosslinks between aldehyde side chains were formed. This crosslinking is considered to be a hemiacecool type crosslinking due to aldehyde side chains.

Example 2 In place of methylcellulose in Example 1, sufficiently dried low-acetyl cellulose acetate (DS = 1.75, manufactured by Daicel Chemical Industries, Ltd.) was used as a starting material, and the amount of sodium hydroxide was 4.5 g. The allylation reaction of the cellulose derivative was carried out in the same manner as in Example 1 except for the above. In this case, the amount of alkali relative to the anhydroglucose residue of the starting material is 30 moles.

The obtained allylcellulose is chloroform.

Soluble in solvents such as methylene chloride, benzene, and tetrahydrofuran. It was confirmed from the infrared absorption spectrum and NMR spectrum that the allyl cellulose contained no acetyl group or free hydroxyl group and was triallyl cellulose.

Using the above triallyl cellulose, ozone was applied in the same manner as in Example 1 to obtain aldehyde cellulose.

The solvent was removed from the obtained aldehyde cellulose solution in a methylene chloride/methanol mixed solvent to obtain a film.

This product was insoluble in acidic to alkaline water.

Furthermore, when the dynamic viscoelasticity of the film was measured, it was found that the degree of crosslinking was higher than that of the crosslinked aldehyde (methyl) cellulose film obtained in Example 1.

[Brief explanation of the drawing]

Figure 1 shows the infrared absorption spectra of allyl (methyl) cellulose and hyaldehyde (methyl) cellulose obtained in this example. The reaction product with hydrazine, (■) shows the infrared absorption spectrum of the reaction product obtained by heat treatment. Applicant's agent Kaoru Furuya Figure 2 4000 3200 2400 180
0 j400 1000 600 waves 11 (3-')

Claims (1)

[Scope of Claims] 1. A method for producing a cellulose derivative having an aldehyde group in its side chain, which comprises treating a cellulose derivative having an allyl group in its side chain with an oxidizing agent. 2. The method for producing a cellulose derivative having an aldehyde group in a side chain according to claim 1, wherein the oxidizing agent is ozone.