PT89376A - METHOD FOR PREPARING A TWO-AMINO ACID COPOLYMER AND A CUTANEOUS WOUND COATING AGENT - Google Patents

Description

60.546 Ref: 630731-1

-3 JM.18S

Description of the object of the invention that DELALAFDE S.A., French, industrial, with headquarters at 32, rue Henri Regnault - 92400 COURBSVOIE France, wishes to obtain in Portugal for: " PROCESS FOR THE PREPARATION OF A COPOLYMER OF TWO ACIDS c < -MEDIA OF A CU-TINE WOUND COATING TEETH " 15

The present invention relates to a novel process for the synthesis of a two-acid copolymer comprising the preparation of a mixture of the N-carboxy-anhydride in a X-amine acid and F-carboxy-anhydride in a second λ-amino acid, followed by the copolymerization of that mixture. It also relates to the copolymer obtained by this process.

According to known processes of this type the F-carboxy-anhydrides of the first and second α-amino acids (i) are obtained by the separate preparation of the F-carboxy-anhydride of the first X-amine acid and the F-carboxy anhydride of the second " -amined acid by the separate reaction of a phosgene on the first amino acid and on the second amino acid, then (ii) by mixing, after possible purification, the two F- carboxy-anions thus obtained. Due to the distinct preparation of the two F-carboxy-anhydrides thus obtained, such known processes

-3 M13SS 60,546

Ref: 6307E1-1 cease the execution of two parallel production chains each comprising a reactor equipped with various accessories (agitator, temperature measuring means, reflux device, various preparations for the reagents, flow regulating means phosgene, means for evacuating the reaction mixture), N-carboxy-anhydride purification medium 3 and means for transferring said N-carboxy-anhydride to the polymerization reactor. The implementation of these procedures therefore necessarily calls for complex and, at the outset, costly equipment. In addition, it is often difficult to program all operations performed with this equipment, so that there is synchronism between the two parallel production chains. Such difficulty arises from the complexity of the equipment used, but also from the fact that the reaction of one amino acid with phosgene may require a longer duration than that of the other amino acid. It will frequently follow, with the known processes described above, that the operations relating to one of the N-carboxy-anhydrides are terminated before those relating to the other N-carboxy-anhydride, so that N-carboxy- the anhydride obtained first should be stored for a more or less prolonged period before being used for copolymerization. Or it has been found that these N-carboxy anhydrides are poorly preserved and are sensitive to various agents, especially moisture, which necessitates taking precautions which further complicate the equipment and the synthesis of said N-carboxy-anhydrides. The present invention has the object of overcoming the aforementioned drawbacks and for this purpose proposes a process as defined in the first paragraph of this description, characterized in that the mixture of the N-carboxy-anhydrides of the first and second- 6307E1-1 -3 JAH.i

1 5 10 15

A process according to any one of the preceding claims, characterized in that the amino acid is obtained by the action of a phosgene on a mixture of a first and second S-amine acid having neighboring reaction rates to phosgene. Indeed, it will be understood that by properly selecting the starting amino acids, namely, those having comparable reaction rates relative to phosgene, it is possible to have them react simultaneously with phosgene, in a single reactor and therefore a single production chain is hence sufficient to obtain the desired N-carboxy anhydrides, which not only greatly simplifies the equipment to be installed for the synthesis of the desired copolymer, but also avoids any risk of degradation of the N-carboxy anhydrides, since the latter are obtained simultaneously and the temporary storage of one or the other is no longer necessary. The first and second amino acids are advantageously comprised of β-amine acids whose carbon atom in the β-position is in the form and whose amino group in c < It is particularly preferred that one of the acids is leucine, in particular L-leucine, and that the other acid is constituted by glutamic acid whose carboxyl function furthest from the amine function is esterified by a methyl or benzyl group, namely L-glutamic acid or the methyl or benzyl ester of L-glutamic acid. The mixture of the first and second α-amino acids intended to react with phosgene advantageously comprises 40-60 mol-% of one such amino acid and 60-40 mol-% of the other. The reaction of the d-aminated acids can be carried out in an organic solvent and mention may be made of dioxane or tetrahydrofuran by way of example. - 3 - 30 1 10 15 iB - * - * · 000 01 - I L · ρο «20 25 30 60.546Ref: 6307E1-1 -3 M. i38

Q

Prior to the copolymerization of the resulting N-carboxy-anhydrides, it is desirable to subject them to an appropriate treatment to reduce their content in chlorinated derivatives, preferably to a value less than 0.1%, which derivatives are produced in the course of the reaction of phosgene with the Î ± -amino acids. Such a treatment is described hereinafter in the context of the preparations given for the purposes of illustration of the invention. The N-carboxy-anhydride mixture is then subjected to the copolymerization reaction, advantageously at moderate temperatures, in a suitable solvent, such as dioxane and in the presence of a copolymerization initiator such as a tertiary amine (triethylamine, tributylamine , triethanolamine, etc.), optionally in the presence of a lithium salt (for example, chloride or nitrate) or a strong base such as an alkali metal (for example, sodium methylate). The ratio between the sum of the number of moles of the N-carboxyhydrides and the number of moles of the copolymerization initiator is a function of the initiator used and the desired viscosity of the copolymer. Thus, in the case where the initiator is tributylamine, a proportion in the range of from 25 to 200 leads to obtaining a copolymer having an intritical viscosity appropriate to the uses described below and for which this copolymer is intended. Likewise, when the initiator is comprised of sodium methylate, a ratio in the range of 100 to 1000 leads to obtaining an appropriate copolymer. The copolymer obtained by performing the process described above is isolated by sinking the reaction mixture into a large excess of water. In doing so, the copolymer precipitates in the form of a very voluminous, very hydrophobic fibrous product. - 4 - 35 60,546 Ref: 6307E1-1 -3 MI9S9

15

Mod. 71. 10 000 βχ · 4-87 20 25

This copolymer finds its application essentially as a coating medium for repairing skin wounds, burns and graft extraction areas, coating means which promotes healing by securing, even to dryness or cure, the protection of these wounds and zones against external aggressions, whether mechanical or microbial.

In view of this use, the copolymer is prepared in a form appropriate to its thin layer deposition on the part to be protected. Thus, this copolymer may, for example, be prepared in the form of a thin film or a powder, or be incorporated into a gel. From this copolymer, it is possible in particular to make a thin film by means of the well known technique of phase inversion, as will be described more fully below. Such a film is generally translucent, flexible and non-porous, has a thickness of preferably between 300 and 750 Âμm and is permeable to oxygen, water vapor and certain disinfectant solutions which may be wished to apply through such a film. film. In order to obtain such a film, it is desirable for the copolymer to have an intrinsic viscosity at 30 ° C in dichloroacetic acid of from 0.5 to 3 dl / g. After curing or healing, the film, the powder or the gel are withdrawn or removed spontaneously from the area over which they have been applied.

The following preparations are given by way of illustration of the invention.

Preparation of methyl L-glutamate / L-Glu (OMe) /

1.25 liters of methanol is placed in a 2 liter reactor. They are poured into it afterwards, at one - 5 - 30 15

Mod. 71 - 10 000 βχ - 4-87 20 25 -3 JM 1SS9 60,546

Ref: 6307E1-1 temperature below 20 ° C, 100 ml of acetyl chloride. After dissolution and under the same conditions of temperature, 148 g of L-glutamic acid are added in one portion. is stirred at room temperature for 24 hours. 125 ml of pyridine is then poured into the obtained mixture at a temperature below 20 ° C. A precipitate forms and is further stirred for 48 hours at room temperature. The precipitate is collected by filtration, washed twice with ethanol and once with ether then dried under vacuum and yields 174 g (yield: 86.56%) of the expected ester as a white solid. of a white product.

Elemental analysis

Found (%) Calculated (%) C: 45.22 - 45.23 44.72 H: 7.14 - 7.16 6.88 N: 8.46 - 8.46 8.69 CCM: eluent: BuOH / CH3C00H / H2O: 4/1/1

Preparation of a mixture of the N-carboxy-anhydrides of L-leucine and methyl L-glutamate

In a 2 liter reactor equipped with a 2 liter non-return system, a gas inlet allowing a significant flow of phosgene and argon, a soda cooler, a soda receiver and an active carbon column , 65.5 g of L-leucine (0.5 mol), 80.5 g of methyl L-glutamate (0.5 mol) and 1600 ml of anhydrous dioxane previously passed through alumina are charged to the the peroxides it may contain. The suspension obtained is purged by means of argon for 30 minutes. A stream is then passed - 6 - 35 60,546 Ref: 6307E1-1 -3 JAN. tssb

phosgene by vigorously stirring the mixture. The temperature inside the flask is brought to 40 ° C. After 6 hours, the reaction mixture becomes homogeneous. The solution is then flushed with argon for at least 48 hours at 40 ° C, in order to eliminate the maximum amount of chlorinated derivatives dissolved in the solution. Evaporate in vacuo and dilute the residue with 20 liters of anhydrous dioxane for 2 liters portions. It is found in the distillate that the amounts of chlorinated derivatives decrease progressively.

The solution in the dioxane is evaporated in vacuo and the residue is taken up with 800 ml of dry hexane. There is crystallization of a product on which, after vacuum drying, a potentiometric dosage of the chloride ions is carried out. If the chloride ion content is higher than 0,4%, the residue is recovered with dioxane. Otherwise, a final treatment with the theoretical amount of Ag0 0 in solution in the dioxane should allow the content of chloride ions to be lowered to less than 0.1. The condition necessary to obtain, in the next step, a copolymer suitable for the thin du-film film production. Finally, about 140 g (yield: 81.39%) of the expected ready-for-copolymerization mixture is obtained.

Preparation of L-leucine copolymer and methyl L-glutamate

In a 2 liter reactor equipped with a powerful stirrer, 137 g of a prepared mixture as indicated above and 2000 ml of anhydrous dioxane are introduced. The obtained solution is brought to a temperature of 40 ° C under argon. 16 ml of a 0.1 M solution of sodium methylate in dioxane or 8 ml of a 1 M solution of tributylamine in dioxane are then introduced in one portion. At the end of 4 hours of stirring the polymerization reaction starts at -78 ° C.

Mod. 71 - 10 000 βχ - 4-87 20 25 60.546 Ref: 6307S1-1 -3 Jü.i5b9 and the solution becomes progressively more viscous. The mixture is allowed to stir for 3 days and the characteristic band of the N-carboxy-anhydrites disappears at 1785 cm -1 in IV. The polymerization time depends on the amount of chlorinated derivatives present in the medium and the amount of initiator of the polymerization used. For a content of chlorine derivatives of less than 0,1%, a mole ratio of the mixture of the N-carboxy-anhydrides in the initiator of 100 in the case of the use of tributylamine or 500 in the case of the use of sodium methylate is particularly convenient to obtain a copolymer suitable for use as a film. The viscous solution of the copolymer in dioxane is then slowly poured into a vessel containing 10 liters of water. The copolymer is contacted with water, the precipitate is collected by filtration, dried in air on paper and the drying is terminated in vacuo. There is thus obtained 85 g of a white product having the following characteristics: intrinsic viscosity at 30øC in dichloroacetic acid: 1.79 dl / g. Eluent analysis: Found% Calculated (%) C: 56.04 - 56.17 56.23 N: 7.99 - 7.96 7.83 N: 10.48 - 10.42 10.93 (Calculated percentages are determined for an equimolar amount of L-leucine and Methyl L-glutamate). rotary power: = 44 ° (c = 1% in dichloroacetic acid) at 20 ° C for the sodium D range. High pressure liquid chromatography:

Claims (2)

L-leucine and L-glutamic acid after a 48 hour hydrolysis in concentrated HCl at 100 DEG C. ° C: L-leucine: 44% L-glutamic acid: 56% Production of a thin film from the L-leucine copolymer is Methyl L-glutamate A collodion of the copolymer is started in a very polar organic solvent, such as N-methyl pyrrolidone, N-dimethylacetamide, N-dimethylformamide, dimethylsulfoxide or difluoro or trifluoroacetic acid. After pouring, at the desired thickness (500 μm for example), of the collodion obtained on a glass plate, the plate supporting the copolymer is immersed in successive baths of water, to coagulate the collodion and to wash the resulting film. This film is detached from the glass plate and immersed in a bath containing 75% PEG 600 and 25% saline to impregnate the film with a view to its preservation. After being placed in an impermeable sachet, everything is sterilized by irradiation such as Y-rays. The deposit of the first application for the invention described above was carried out in France on 6 January 1988 under No. 5,888,664. A process for the synthesis of a copolymer of two β-amines comprising the preparation of a mixture of the N-carboxy-anhydride of a first A-amine acid and the N-carboxy-anhydride of a second amine acid, followed by the copolymerization of said mixture, characterized in that said mixture is obtained by the action of phosgene on a mixture of first and second α-amines having neighboring reaction rates in relation to phosgene. The process according to claim 1, wherein the first and second acids are p < -amino acids having the carbon atom in the β-position is in the form of C1-4 and the amino group in C4 is in the form of N, 3. The process according to claim 1 or 2 , characterized in that one of the Î ± -amino acids is leucine. A process according to any one of the preceding claims, characterized in that one of the β-amines is glutamic acid or glutamic acid whose carboxyl function is more distanced of the amino function is esterified by a methyl or benzyl group A process according to any one of the preceding claims, characterized in that said mixture of the first and second amino acids comprises from 40 to 60 mol% of one of the The present invention relates to a process for the preparation of a coating agent for cutaneous wounds, skin areas undergoing repair, burns, and the like. of graft withdrawal areas, characterized in that a copolymer prepared according to the previous claims is incorporated. 7. A process as claimed in claim 7, wherein the coating agent obtained is in the form of a thin film, a powder or a gel. Lisbon, Mad. 71 - 10 000 «x - 4-87 20 25 By DELALANDE S.A. 11 35