EP0006790B1 - 1,2,3,4,4a,9a-hexahydroanthracen-9,10-dion, its preparation and its application in the delignification of lignocellulosic material - Google Patents

Abstract

A new industrial product, namely 1,2,3,4,4a,9a-hexahydro-9,10-anthracene-dione, is disclosed together with a process for its preparation and its use in conventional alkali metal hydroxide cook or Kraft cook processes for the delignification of lignocellulose materials.

Description

The present invention relates, as a new industrial product, to hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10, a compound which can be considered as a hydrogenated anthraquinone: hexahydro-1, 2,3,4,4a, 9a anthraquinone. It also relates to a process for the preparation of hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 by hydrogenation of tetrahydro-1,4,4a, 9a anthraquinone. It also relates to the use of hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 in the delignification of lignocellulosic materials.

The hydrogenated compounds of anthraquinone have, to date, been obtained by hydrogenation of anthraquinone or by addition of a diene on benzoquinone or naphthoquinone. These methods make it possible to synthesize different compounds but none of them corresponds to hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10.

The Applicant has now found that 1,2,3,4,4a hexahydro-9,10 anthracene-dione-9,10 can be obtained with good yields by catalytic hydrogenation of 1,4,4a-tetrahydro, 9a anthraquinone . In accordance with the process according to the invention, the hydrogenation is carried out in the liquid phase, the 1,4,4a-tetrahydro, 9a anthraquinone being in solution in one of the solvents commonly used for hydrogenations.

Examples of such solvents that may be mentioned include aliphatic, cycloaliphatic or aromatic hydrocarbons, ethers, tetrahydrofuran, dioxane, alcohols. Generally, all solvents which do not contain a functional group which can be hydrogenated under the reaction conditions can be used.

The catalyst is chosen from those usually used in hydrogenation. Mention may be made, for example, of those based on nickel, such as Raney nickel, those based on precious metals such as palladium or platinum.

The hydrogenation reaction can be carried out over a wide temperature range from 20 to 200 ° C. It is preferred to operate between 60 and 130 ° C. The hydrogenation can be carried out at atmospheric pressure but it is then slow. It is therefore preferable to operate under pressure. There is no upper limit of the hydrogenation pressure which is preferably chosen between 10 and 50 bars. The hydrogenation is continued until the theoretical amount of hydrogen corresponding to the formation of hexahydroanthracene-dione has been absorbed.

The concentration of 1,4,4a-tetrahydro, 9a anthraquinone in the reaction medium can also vary within wide limits. There is no lower limit of this concentration but for reasons of productivity it is preferably greater than 10% by weight. For practical reasons it is less than 50% by weight. The preferred concentration is between 15 and 40%.

During the catalytic hydrogenation of tetrahydro-1,4,4a, 9a anthraquinone according to the invention, it forms, alongside hexahydro-1,2,3,4,4a, 9a anthracene-dione- 9.10 which is the predominant product, variable amounts of an isomer, tetrahydro-1,2,3,4 anthracene-diol-9,1 0 which can be separated by the usual methods such as distillation or recrystallization. A particularly convenient means of separation is based on the difference in the solubility characteristics of the two compounds. Thus by choosing for hydrogenation a selective solvent of 1,2,3,4,4a hexahydro, 9a anthracene-dione-9,10 it is possible to separate the 1,2,3,4 tetrahydro anthracene- dio) -9.10 by simple filtration and collecting the hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 by cooling or concentration of the solution. However, for most applications of hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 and in particular for the delignification of lignocellulocic materials, it is not necessary to separate the tetrahydro -1,2,3,4 anthracene-diol-9,10.

The present invention also relates to the application of hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 to the delignification of lignocellulosic materials such as wood, straw, linen, alfa, bagasse, etc. .... for the production of pulp.

The preparation of paper pulps from lignocellulosic plant materials generally includes a cooking stage with alkaline detergents intended to dissolve non-cellulosic impurities, in particular the lignin present in greater or lesser proportion depending on the plant species. Proteins, gums, hemicelluloses can also be eliminated by the alkaline cooking treatment. Depending on the conditions under which this treatment is carried out, the cellulose may or may not undergo a certain chemical degradation which modifies its qualities and alters its mechanical properties, which is detrimental to its paper use.

Thus the soda baking process which consists in acting a caustic soda lye (Na OH) sand another additive at high temperature and pressure on wood shavings, generally leads to paper pulp of weak characteristics with a poor yield .

The addition of alkali sulfide to soda liquor has long been recognized as beneficial and has given rise to the universally used Kraft or so-called "sulfate" process which provides the largest share of pasta chemicals used around the world. Unfortunately, Kraft cooking with sulphide sulphide gives rise to volatile sulphide compounds which generate atmospheric pollution and despite all the precautions taken to avoid this pollution, it is often very difficult to avoid it economically. ''

Studies have shown that the degradation reaction of cellulose in an alkaline medium was due to the presence of a reducing group at the end of the cellulose chain. It is at this level that the alkaline attack induces the cut-off reaction (or "peeling" reaction see SVENSK PAPPERSTIDNIG, N ° 9, May 15, 1966-p. 311). The addition of polysulfide or redox compounds prevents the degradation reaction from occurring, either by reduction of the terminal aldehyde group to the alcohol group, or by oxidation of this group to the carboxylic acid.

It has thus been proposed to add sulfonated derivatives of anthraquinone to washing soda lye (patent RDA 98549 of 20.06.1973) but by operating in this way one does not completely avoid the problems of pollution. In US Patent No. 4,012,280 of 03/15/1977, it has been proposed to add to the soda lye, a sulfur-free quinone derivative such as anthraquinone, causing no pollution problem atmospheric.

The Applicant has now found that it is possible to advantageously replace these quinone compounds with hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,1 0. This compound makes it possible to obtain, during '' cooking with soda, pasta with mechanical properties close to those of Kraft pasta with yield and neighboring kappa indices. The same compound used in Kraft (or "sulphate") cooking makes it possible to significantly lower the Kappa index of pasta without altering its mechanical properties. For identical Kappa indices, higher yields can be obtained than the reference Kraft pulp. Under the same conditions, anthraquinone leads to pastes with lower mechanical characteristics. These results can be obtained in the case of cooking with soda for soda rates of between 10 and 30% by weight of soda relative to the dry plant, the cooking temperatures being between 130 and 200 ° C. The amount of hexahydro-1,2,3,4,4a, 9a antracene-dione-9,1 0 to be used can be between 0.01 and 10% preferably between 0.05 and 2% by weight relative dry vegetable.

In the case of Kraft cooking, the level of active alkali can be between 10 and 30% by weight of soda relative to the dry vegetable and the sulfidity between 15 and 35% relative to the active alkali. The cooking temperature can be between 130 and 200 ° C and the level of adjuvant between 0.01 and 10%, preferably between 0.05 and 2% by weight relative to the dry vegetable.

The examples which follow illustrate, without limiting it, the present invention.

Example 1

100 ml of toluene, 21.2 g of 1,4,4,4-tetrahydro, 9a anthraquinone and 0.2 g of a catalyst based on carbon are introduced into a stainless steel autoclave equipped with heating and stirring devices. palladium deposited on charcoal, containing 5% palladium. The mixture is heated to 100 ° C. and hydrogen is introduced under a pressure of 30 bars. The reaction is continued for 4 hours while maintaining the pressure between 20 and 30 bars. After cooling, 7 g of an insoluble product in the form of green crystals, melting at 206-208 ° C. with molecular weight 214, are separated by filtration, the NMR and IR spectra of which show that it is tetrahydro-1 , 2,3,4 anthracene-diol-9,10. By concentrating the filtrate, 14 g of a product melting at 80-88 ° C (F: 89-91 ° C after recrystallization from hexane) consisting of 1,2,3,4,4a hexahydro are obtained. , 9a anthracene-dione-9,10 practically pure:

Example 2

The procedure is as in Example 1 but starting the reaction at 30 ° C. No significant absorption of hydrogen is observed. It is then heated for 30 minutes at 40 ° C., the temperature at which absorption of hydrogen begins to appear. The reaction is continued for 30 minutes at 50 ° C, 150 minutes at 60 ° C and 45 minutes at 100 ° C. 2.4 g of tetrahydro-1,2,3,4 anthracene-diol-9,10 are collected by filtration and by concentration of the solution 18.7 g of hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10.

Examples 3 to 5

The procedure is as in Example 1 but at different temperatures and for different times. The results are summarized in the following table:

Example 6

The procedure is as in Example 1 but using as catalyst 2 g of a nickel catalyst obtained by alkaline attack of 4 g of a nickel-aluminum alloy containing 50% nickel. The reaction is carried out at 60 ° C. for 5 1/2 hours under a hydrogen pressure of 30 bars. After having separated the catalyst, 1 g of tetrahydro-anthracene-diol and 19.2 g of hexahydro-anthracene-dione are collected.

Example 7

The procedure is as in Example 1, but with 63.6 g of 1,4,4a tetrahydro, 9a anthraquinone, 150 cc of touene and 0.4 g of palladium catalyst. After 3 hours of reaction at 80 ° C. at 100 bars, 7 g of tetrahydro-1,2,3,4 anthracene-diol-9,10 and 56 g of hexahydro-1,2,3,4,4a are collected. , 9a anthracene-dione-9,10.

Example 8

The procedure is as in Example 1 but with 424 g of 1,4,4a tetrahydro, 9a anthraquinone, 2 liters of toluene and 4 g of catalyst. After 2 hours of reaction there is no longer absorption of hydrogen. 28.5 g of tetrahydro-1,2,3,4 anthracene-diol-9,10 containing the catalyst are collected by filtration and, after concentration of the solution, 402 g of hexahydro-1,2,3,4, 4a, 9a anthracene-dione-9,10.

Example 9

• - paramètres constants:
  • ^* taux de soude: 22% en poids par rapport au végétal sec,
  • ^* rapport liqueur/végétal: 4
  • * température de cuisson: 170°C
  • ∗ temps de montée à la température de cuisson: 90 min.
  • * temps de cuisson: 90 min.
• - paramètre variable:
  • * taux d'adjuvant: 0―0,1% ―0,5% ― 1 % en poids par rapport au végétal sec.

Landes maritime pine shavings are subjected to cooking in an autoclave with a soda liquor. The cooking conditions are as follows:

• - constant parameters:
  • ^* soda content: 22% by weight compared to the dry vegetable,
  • ^* liquor / vegetable ratio: 4
  • * cooking temperature: 170 ° C
  • ∗ cooking temperature rise time: 90 min.
  • * cooking time: 90 min.
• - variable parameter:
  • * rate of adjuvant: 0―0.1% ―0.5% - 1% by weight compared to the dry vegetable.

After cooking, the pasta obtained is washed, disintegrated and classified on a 0.3 mm grid (Vewerk binder).

• - le rendement brut et le rendement en pâte classée,
• - sur les pâtes écrues, l'indice Kappa suivant la norme française NFT 12018.

On the pasta we determine:

• - the gross yield and the yield of classified pulp,
• - on unbleached pasta, the Kappa index according to French standard NFT 12018.

• - le pH,
• - la consommation en soude.

On liqueurs after cooking:

• - pH,
• - consumption of soda.

The reference unbleached pasta and those obtained with 0.5% adjuvant in cooking, are refined in the Jokro mill.

The sheets for physical tests are made with the Rapid Kothen form. their grammage is approximately 70 g per m2.

• - longueur de rupture : norme AFNOR NFQ 03004
• - indice d'éclatement : norme AFNOR NFQ 03014
• - indice de déchirure : norme AFNOR NFQ 03011
• ― résistance au pllage : norme AFNOR NFO 03001.

The following mechanical characteristics are determined:

• - breaking length: AFNOR standard NFQ 03004
• - burst index: AFNOR standard NFQ 03014
• - tear index: AFNOR standard NFQ 03011
• - resistance to pleating: standard AFNOR NFO 03001.

The cooking results are given in Table 1.

It is found that the addition of hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 accelerates delignification and makes it more selective. The greater the effect, the greater the amount of adjuvant.

With 0.5% soda cooking becomes as efficient as conventional Kraft cooking from the point of view of delignification.

Example 10

A comparison test with 0.5% anthraquinone was carried out under the same operating conditions as in Example 9. The result obtained is given in Table II. It is found that hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 has the same effect as anthraquinone.

The mechanical characteristics of the unbleached pasta obtained after cooking with sodium hydroxide in the presence of 0.5% of adjuvant are compared with those of a conventional Kraft paste (Table III). It can be seen that the quality of the doughs obtained using hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 is very close to the quality of conventional Kraft dough.

Example 11

• -paramètres constants:
  • ^* taux d'alcali actif: 22% en poids par rapport au végétal sec,
  • ∗ sulfidité: 25% par rapport à l'alcali actif,
  • ∗ rapport liqueur/végétal: 4,
  • ∗ température de cuisson: 170°C,
  • * temps de montée à la température de cuisson: 90 min.
  • * temps de cuisson: 120 min.
• paramètre variable:
  • * taux d'adjuvant: 0―0,1 % ―0,5%― 1 % en poids par rapport au végétal sec.

Landes maritime pine shavings are subjected to autoclave cooking with a sodium hydroxide liquor under the conditions below:

• - constant parameters:
  • ^* active alkali level: 22% by weight relative to the dry plant,
  • ∗ sulfidity: 25% compared to the active alkali,
  • ∗ liquor / vegetable ratio: 4,
  • ∗ cooking temperature: 170 ° C,
  • * cooking temperature rise time: 90 min.
  • * cooking time: 120 min.
• variable parameter:
  • * adjuvant level: 0―0.1% ―0.5% - 1% by weight compared to the dry vegetable.

After cooking, the same operations as those described in Example 9 are carried out on the pasta and the cooking liquors.

The results are collated in Table IV.

It is noted that the addition of hexahydro-1,2,3,4,4a, 9a anthracene-dione-9,10 increases the kinetics and the selectivity of the delignification during a Kraft cooking. Under the operating conditions used, this effect results in a decrease in the Kappa index of the pasta without reduction of the cooking yield when the level of adjuvant uses, increases.

Example 12

A comparison test with 0.5% anthraquinone was carried out under the same operating conditions as in Example 11. The results of the cooking operations are listed in Table V.

BOARD. VI Mechanical characteristics of refined unbleached pasta: at 40 ° SR Kraft cooking with 0.5% additive

Control 6 HAD Anthraquinone IK = 31.7. IK = 24; 2 IK = 24.3 Yd = 44.9% Yd = 44; 8% Yd = 44% Break length, m 7 130 7 000 5 8 ₅ 0 Resistance to bending 1 854 1 917 985 Index of burst 5.71 5.55 4.48 Tear index 904 847 808

The introduction of adjuvants reduces the Kappa index of a maritime pine Kraft pulp from 32 to 24. The effect of hexahydro-1,2,3,4,4a, 9a anthracene-dione-9, 10 is more favorable than that of anthraquinone for which a relatively significant degradation is observed.

Claims (10)

1. 1,2,3,4,4a,9a-hexahydro-anthracene-9,1 0-dione.

2. Process for the preparation of 1,2,3,4,4a,9a-hexahydroanthracene-9,10-dione, characterised in that 1,4,4a,9a-tetrahydroanthraquinone is subjected to a catalytic hydrogenation in liquid phase and the 1,2,3,4-tetrahydro-anthracene-9,10-diol and the 1,2,3,4,4a,9a-hexahydro-anthracene-9,10-dione thus obtained are separated.

3. Process as claimed in 2), in which the hydrogenation reaction is effected at a temperature of between 20°C and 200°C, preferably between 60°C and 130°C.

4. Process as claimed in 2) and 3), in which the hydrogenation is effected at a pressure of between 10 and 50 bars.

5. Process as claimed in 2), in which the hydrogenation catalyst is a catalyst based on nickel or precious metal.

6. Process as claimed in 2), in which the 1,2,3,4-tetrahydro-anthracene-9,10-dio! is separated by distillation or recrystallization.

7. Process as claimed in 2), in which the 1,2,3,4-tetrahydro-anthracene-9,10-diol is separated by filtration, the liquid phase comprising a solvent of 1,2,3,4,4a,9a-hexahydro-anthracene-9,10-dione.

8. Process as claimed in 7), in which the solvent is toluene.