CONCENTRATION METHOD OF AN ORGANIC PEROXIDE

WATER SOLUBLE

FIELD OF THE INVENTION

The present invention relates to a method for concentrating a water-soluble organic peroxide, preferably an alkyl hydroperoxide, by reverse osmosis as well as a method for separating a water-soluble organic peroxide and a water-insoluble organic peroxide.

TECHNICAL BACKGROUND

The manufacture of hydroperoxides is generally carried out by reaction of the corresponding alcohols or alkenes with hydrogen peroxide using acid catalysts such as sulfuric acid. They can also be obtained by air or dioxygen oxidation of the corresponding alkanes. In all of these synthetic processes, unwanted by-products are formed which must be separated from the desired hydroperoxides.

For example, during the synthesis of hydroperoxides by reaction of alcohols or alkenes with hydrogen peroxide in the presence of sulfuric acid, the acid also catalyzes the formation of symmetrical dialkyl peroxides, the latter representing an undesirable impurity.

In order to be able to separate the undesirable by-products from the desired hydroperoxides, it is often necessary to carry out several washes resulting in a solution comprising the dilute hydroperoxides. Thus, once this separation step has been carried out, a reconcentration of the solution comprising the peroxides may be necessary for subsequent applications.

Different methods for concentrating solutions comprising water-soluble organic peroxides, in particular hydroperoxides, are known.

For example, WO 2004/037782 describes a concentration process in which water present in a peroxide formulation is removed using pervaporation technology. Water is removed through a semi-permeable membrane. This process requires vaporizing the water. The effectiveness of this technique is all the greater as the organic peroxide solution is heated, which generates a significant risk in terms of safety. In addition, this process is only suitable for removing small amounts of water.

There is therefore a real need to provide a method for concentrating a solution comprising a water-soluble organic peroxide, in particular a hydroperoxide, which does not require a step of heating the solution containing the water-soluble organic peroxide or the addition of salts or base. can destabilize organic peroxide.

SUMMARY OF THE INVENTION

The invention relates to a method for concentrating a composition comprising at least one water-soluble organic peroxide, said method comprising a step of bringing said composition into contact with a reverse osmosis membrane.

The present invention makes it possible to meet the need expressed above. It more particularly provides a method for concentrating a composition comprising a water-soluble organic peroxide that is effective and safer because it does not require the heating of the organic peroxide or the addition of salts or bases that can reduce the stability of the organic peroxide.

It is known to use the reverse osmosis technique to concentrate hydrogen peroxide. However, this always generates only one phase whatever its concentration in water. On the contrary, it appears that during their concentration, water-soluble organic peroxides, in particular organic hydroperoxides, in solution in water form two distinct phases (an organic phase and an aqueous phase) from a certain concentration of peroxide organic. Surprisingly, it has been discovered that the reverse osmosis technique allows the concentration of a water-soluble organic peroxide despite the appearance of this biphasic system in the immediate vicinity of the reverse osmosis membrane.

The invention is particularly useful for the reconcentration of dilute solutions of water-soluble organic peroxide, resulting from washing stages for example.

BRIEF DESCRIPTION OF THE FIGURE

[Fig.1] Figure 1 shows a schematic view of an apparatus allowing the implementation of the method according to the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now described in more detail and in a non-limiting manner in the description which follows.

In the present description, unless otherwise expressly indicated, all the percentages (%) indicated are percentages by weight.

Concentration of the composition comprising the water-soluble organic peroxide

In a first aspect, the invention relates to a method for concentrating a composition comprising at least one water-soluble organic peroxide, said method comprising a step of bringing said composition into contact with a reverse osmosis membrane.

This contacting step makes it possible to obtain a retentate and a permeate, the water-soluble organic peroxide being concentrated in the retentate.

Within the meaning of the present invention, “a water-soluble organic peroxide” can mean one or more water-soluble organic peroxides. The same is true for the other species mentioned in the present description.

Within the meaning of the present invention, the term "composition" means the composition to be concentrated. Preferably said composition is an aqueous composition.

By “composition to be concentrated”, is meant the composition before being brought into contact with a reverse osmosis membrane.

Within the meaning of the present invention, the term “a water-soluble organic peroxide” means an organic peroxide having a solubility in an aqueous solution, in particular in pure water, greater than or equal to 1 g/l, preferably greater than or equal to 10 g/l, preferably greater than or equal to 30 g/l, more preferably greater than or equal to 45 g/l at the temperature at which the step of bringing the composition into contact with the reverse osmosis membrane is carried out . Advantageously, said water-soluble organic peroxide has a solubility in an aqueous solution, in particular in pure water, of greater than or equal to 1 g/L, preferably greater than or equal to 10 g/L, preferably greater than or equal to 30 g/L. L, even more preferably greater than or equal to 45 g/L, at a temperature of 20 to 25°C.

In particular, the term "a water-soluble organic peroxide" means an organic peroxide having a solubility in the aqueous composition to be concentrated according to the invention, greater than or equal to 1 g/l, preferably greater than or equal to 10 g/l, of preferably greater than or equal to 30 g/l, more preferably greater than or equal to 45 g/l at the temperature at which the step of bringing the composition into contact with the reverse osmosis membrane is carried out. Advantageously, said water-soluble organic peroxide has a solubility in the aqueous composition to be concentrated according to the invention, greater than or equal to 1 g/L, preferably greater than or equal to 10 g/L, preferably greater than or equal to 30 g/L, even more preferably greater than or equal to 45 g/L, at a temperature of 20 to 25°C.

The measurement of the solubility can be carried out by any technique known to those skilled in the art, such as iodomethe, chromatography, or by measuring the total organic carbon (TOC).

Preferably, the solubility is measured by gas chromatography.

Reverse osmosis is a technique for concentrating an aqueous solution comprising one or more species to be concentrated using a membrane allowing the passage of water but not of the species or species to be concentrated. The pressure exerted on the solution to be concentrated forces the water to cross the membrane, and constitutes, once the membrane has been crossed, the permeate while the species or species to be concentrated are retained by the membrane, and therefore represents the retentate. Therefore, said at least one water-soluble organic peroxide is concentrated in the retentate.

By “the water-soluble organic peroxide being concentrated in the retentate”, it is meant that the mass concentration of at least one water-soluble organic peroxide in the retentate is greater than that in the permeate. In addition, the mass concentration of the water-soluble organic peroxide in the retentate is greater than that in the composition before concentration.

Preferably, the method according to the invention does not include the addition of salt and/or base before the step of bringing said composition into contact with a reverse osmosis membrane. In particular, the method does not include a step for adding salt and/or base to the composition to be concentrated.

The reverse osmosis can be carried out using any appropriate membranes, such as membranes of acetate, polyacrylonitrile, polysulfone, polyvinylidene fluoride or polyamides, preferably polyamides.

Advantageously, the composition to be concentrated has a pH less than or equal to 8, preferably less than or equal to 7.5, even more preferably less than or equal to 7.

Preferably, the composition to be concentrated has a pH greater than or equal to 5, more preferably greater than or equal to 6, more preferably greater than or equal to 6.5.

The reverse osmosis, that is to say bringing the composition into contact with the reverse osmosis membrane, can be carried out at a pressure of between 20 and 70 atmospheres, preferably between 25 and 60 atmospheres. In other words, the reverse osmosis can be carried out at a pressure of between 2026 kPa and 7092 kPa, preferably between 2533 kPa and 6079 kPa, or between around 2000 kPa and around 7000 kPa, preferably between around 2500 kPa and around 6000 kPa. Preferably, the pressure increases during the contacting step, so as to keep the flow rate of permeate constant. Even more preferably, the pressure increases as the reverse osmosis progresses but remains within the ranges specified above.

The concentration by reverse osmosis, and therefore in particular the step of bringing said composition into contact with the reverse osmosis membrane, can be carried out at a temperature ranging from 0° C. to 60° C., preferably from 5° C. to 50°C, more preferably from 10°C to 45°C, even more preferably from 15°C to 30°C.

According to embodiments, the mass percentage of water-soluble organic peroxide in the retentate is higher by at least 1.05 times, preferably by at least 1.1 times, preferably by at least 1.2 times, preferably at least 1.3 times, preferably at least 1.5 times, preferably at least 2 times, and even more preferably at least 3 times relative to the mass percentage of water-soluble organic peroxide in the composition before concentration.

In a particularly advantageous manner, the composition is concentrated by reverse osmosis at least until the appearance of two phases in the retentate. In this case, the retentate forms two immiscible phases consisting of a phase concentrated in water-soluble organic peroxide and a dilute phase.

By "phase concentrated in water-soluble organic peroxide" and "phase dilute in water-soluble organic peroxide", it is meant that the mass concentration of water-soluble organic peroxide in said phase concentrated in water-soluble organic peroxide is higher than that in the phase dilute in water-soluble organic peroxide . The phase concentrated in water-soluble organic peroxide corresponds to the phase

organic, and the dilute phase in water-soluble organic peroxide corresponds to the aqueous phase of this two-phase system.

Preferably, the mass percentage of water-soluble organic peroxide in the phase concentrated in water-soluble organic peroxide is higher by at least 2 times, preferably by at least 3 times, preferably by at least 4 times, preferably by at least 5 times, preferably at least 8 times, preferably at least 10 times, and even more preferably at least 15 times relative to the mass percentage of water-soluble organic peroxide in the composition before concentration.

Advantageously, all or part of the dilute phase is recycled with the composition comprising the water-soluble organic peroxide to be concentrated, before the step of bringing into contact with a reverse osmosis membrane. In other words, all or part of the dilute phase is recovered and added to the composition comprising the water-soluble organic peroxide to be concentrated.

Advantageously, the water-soluble organic peroxide is an alkyl hydroperoxide.

By "alkyl hydroperoxide" is meant a compound of formula ROOH in which R represents an alkyl group, linear or branched, cyclic or non-cyclic, unsaturated or functionalized, or an aromatic group, optionally substituted, preferably having from 4 to 10 carbon atoms.

More particularly, R represents:

- an alkyl group, linear or branched, optionally substituted by one or more hydroxy groups, C4-C10, preferably C4-Cs, more preferably C4-C6, or

- a cyclic group containing 5 to 8 carbon atoms, optionally aromatic, optionally

substituted with one or more C1-C3 alkyl groups.

In particular, R can represent a cyclic group comprising from 5 to 8 carbon atoms, optionally aromatic, optionally substituted by one or more C1-C3 alkyl groups, in particular by a Ci group.

More particularly, R can represent a non-aromatic cyclic group comprising from 5 to 8 carbon atoms, optionally substituted by a Ci group.

Preferably, the alkyl hydroperoxide is a tert-alkyl hydroperoxide.

Preferably, R 1 represents a branched C4-C10 alkyl group, preferably C4-Cs, more preferably C4-C6, even more preferably C4-C5.

Preferably, said alkyl hydroperoxide is selected from the group consisting of tert-butyl hydroperoxide, tert-amyl hydroperoxide, hexylene glycol hydroperoxide, tert-octyl hydroperoxide, hydroperoxide tert-hexyl, methylcyclopentyl hydroperoxide and methyl, cyclohexyl hydroperoxide. Preferably, the water-soluble organic peroxide is chosen from the group consisting of tert-butyl hydroperoxide and tert-amyl hydroperoxide, even more preferentially is tert-amyl hydroperoxide.

Preferably, the composition comprising the at least one water-soluble organic peroxide to be concentrated comprises from 1 to 50%, preferably from 1% to 20% by weight of water-soluble organic peroxide relative to the total weight of the composition.

Particularly preferably, the composition comprising the at least one water-soluble organic peroxide to be concentrated is an aqueous solution, preferably comprising from 50 to 99% by weight of water, more preferably from 80 to 99% of water, relative to the total weight of the composition.

Separation of a water-soluble organic peroxide and a dialkyl organic peroxide

According to another aspect, the invention relates to a method for separating at least one water-soluble organic peroxide and at least one water-insoluble compound, comprising the following steps

a) extraction with an aqueous composition of said at least one water-soluble organic peroxide of a composition comprising said at least one water-soluble organic peroxide and said at least one water-insoluble compound;

b) separation of the aqueous phase enriched in water-soluble organic peroxide and of the organic phase obtained in step a); c) concentration of said aqueous phase enriched in water-soluble organic peroxide according to the concentration process as described above.

It should be understood that the aqueous phase subjected to step c) of concentration is equivalent to the composition comprising the water-soluble organic peroxide in the part “Concentration of the composition comprising the water-soluble organic peroxide” above. In particular, all the characteristics of the composition comprising the at least one water-soluble organic peroxide described above in relation to the concentration process can be applied to the aqueous phase subjected to step c) of concentration in the separation process. Likewise, all the characteristics of the concentration process described above can be applied to step c) of concentration of the separation process.

In particular, said composition comprising at least one water-soluble organic peroxide and at least one water-insoluble compound can be obtained during the synthesis of said at least one water-soluble organic peroxide. In this case, the composition obtained may comprise the water-soluble organic peroxide synthesized as well as one or more water-insoluble compounds, preferably one or more water-insoluble organic peroxides, more preferably one or more dialkyl peroxides, as an impurity formed during from the synthesis of water-soluble organic peroxide.

Within the meaning of the present invention, the term "a water-insoluble compound" or "a water-insoluble organic peroxide" means a compound or an organic peroxide having a solubility in an aqueous solution, in particular in pure water, of less than 1 g/L, preferably less than or equal to 0.8 g/l, preferably less than or equal to 0.5 g/l, more preferably less than or equal to 0.1 g/l at the temperature at which step contacting the composition with the reverse osmosis membrane is carried out. Even more preferentially, said water-insoluble compound or said water-insoluble organic peroxide is not at all miscible in water at the temperature at which the step of bringing the composition into contact with the reverse osmosis membrane is carried out. Advantageously,

In particular, the term “a water-insoluble compound or “a water-insoluble organic peroxide” means a compound or an organic peroxide having a solubility in the aqueous phase enriched in water-soluble organic peroxide obtained after step a), of less than 1 g/ L, preferably less than or equal to 0.8 g/l, preferably less than or equal to 0.5 g/l, even more preferably less than or equal to 0.1 g/l at the temperature at which the setting step in contact of the composition with the reverse osmosis membrane is carried out. Still preferentially, said water-insoluble compound or said water-insoluble organic peroxide is not at all miscible in the aqueous phase enriched in water-soluble organic peroxide obtained after step a) at the temperature at which the step of bringing the composition into contact with the reverse osmosis membrane is made. Advantageously, said water-insoluble compound or said water-insoluble organic peroxide has a solubility in the aqueous phase enriched in water-soluble organic peroxide obtained after step a), of less than 1 g/L, preferably less than or equal to 0.8 g/ L, preferably less than or equal to 0.5 g/L, even more preferably less than or equal to 0.1 g/L, and even more preferably is not at all miscible at a temperature of 20 to 25° C.

The separation process according to the invention may comprise a step a′), prior to step a), of synthesis of said at least water-soluble organic peroxide.

Stage a′) of synthesis of the water-soluble organic peroxide can be carried out by any method known to those skilled in the art leading to the formation of water-insoluble compounds, in particular water-insoluble organic peroxides, as an impurity. In particular, step a′) can be carried out by the reaction of at least one alcohol or at least one alkene with hydrogen peroxide in the presence of an acid, preferably sulfuric acid. Such a process results in particular in the synthesis of dialkyl peroxide as impurities.

Preferably, the water-soluble organic peroxide can be prepared in an acid medium.

In this case, the method for preparing the water-soluble organic peroxide consists in particular in reacting hydrogen peroxide (hydrogen peroxide) in the presence of at least one alcohol or at least one alkene in an acid medium.

Preferably, the method for preparing the water-soluble organic peroxide consists in particular in reacting hydrogen peroxide (hydrogen peroxide) in the presence of at least one alcohol or an unsaturated compound in an acid medium.

The reaction can be carried out at a temperature which can range from 10°C to 80°C, preferably from 20°C to 40°C.

Preferably, the reaction is carried out in the presence of one or more mineral or organic acids, in particular one or more mineral acids.

More preferably, the mineral acid is sulfuric acid.

The composition comprising at least one water-soluble organic peroxide and at least one water-insoluble compound (before step a)), may comprise at least 50% by weight of water-soluble organic peroxide, preferably at least 60% by weight of water-soluble organic peroxide , more preferably at least 68% by weight of water-soluble organic peroxide, even more preferably at least 70% by weight of water-soluble organic peroxide relative to the total weight of organic peroxides.

According to embodiments, the composition comprising a water-soluble organic peroxide and a water-insoluble compound (before step a)), comprises from 0.1% to 40% by weight of water-insoluble compound, preferably from 1 to 30% by weight of water-insoluble compound, more preferably from 2 to 22% by weight of water-insoluble compound, even more preferably from 3 to 20% by weight of water-insoluble compound relative to the total weight of water-soluble organic peroxides and water-insoluble compounds.

Preferably, said at least water-insoluble compound is a water-insoluble organic peroxide, more preferably still is a dialkyl peroxide.

By "dialkyl peroxide" is meant a compound of formula RiOO-R2 in which Ri and R2 are identical or different, and independently represent an alkyl group, linear or branched, cyclic or non-cyclic, unsaturated or functionalized, or an aromatic group , optionally substituted, preferably having from 4 to 10 carbon atoms.

Advantageously, R 1 and R 2 , which are identical or different, in particular identical, represent:

- a linear or branched C4-C10, preferably C4-Cs, more preferably C4-C6 alkyl group, optionally substituted by one or more hydroxide groups, or

- a cyclic group comprising from 5 to 8 carbon atoms, optionally aromatic, optionally substituted by one or more C1-C3 alkyl groups, in particular C1.

In particular, R 1 and R 2 can represent a cyclic group comprising from 5 to 8 carbon atoms, optionally aromatic, and optionally substituted by one or more C1-C3 alkyl groups, in particular C1.

More particularly, R 1 and R 2 can represent a non-aromatic cyclic group comprising from 5 to 8 carbon atoms, optionally substituted by a Ci group.

Preferably, the dialkyl peroxide is a di-tert-alkyl peroxide.

Preferably, R 1 and R 2 , which are identical or different, represent a branched C4-C10, preferably C4-C8, more preferably C4-C6 alkyl group, optionally substituted by one or more hydroxide groups.

Preferably, R 1 and R 2 , which are identical or different, represent a branched C4-C10, preferably C4-C8, more preferably C4-C6 alkyl group.

Even more preferentially, the dialkyl peroxide is symmetrical, that is to say that the groups flanking the 0-0 group are identical. In other words, R 1 and R 2 are more preferentially identical and represent a branched alkyl group in C4-C10, preferably in C4-Cs, more preferentially in C4-C6.

As dialkyl peroxide to be separated from the hydroperoxide, mention may be made of di-tertio-butyl peroxide, di-tertio-amyl peroxide, di-3-hydroxy-1,1-dimethylbutyl peroxide, di-tert-octyl, di-tert-hexyl peroxide, di(methylcyclopentyl) peroxide, di(methylcyclohexyl) peroxide. In particular, the dialkyl peroxide is symmetrical, ie the groups flanking the 0-0 group are identical.

More preferentially, the dialkyl peroxide is chosen from the group consisting of di-tertio-butyl and di-tertio-amyl peroxide.

Even more preferably, the dialkyl peroxide is di-tert-amyl peroxide.

Advantageously, the alkyl hydroperoxide and the dialkyl peroxide have identical R, R 1 and R 2 groups.

The characteristics of the water-soluble organic peroxide described in relation to the concentration process above can be applied in the same way to the water-soluble organic peroxide within the framework of the separation process.

Advantageously, said at least one water-soluble organic peroxide, preferably said at least one hydroperoxide, and said at least one dialkyl peroxide have identical R, R1 and R2 groups.

For example, the water-soluble organic peroxide is tert-butyl hydroperoxide and the dialkyl peroxide is di-tert-butyl peroxide.

Alternatively, the water-soluble organic peroxide is tert-amyl hydroperoxide and the dialkyl peroxide is di-tert-amyl peroxide.

Alternatively, the water-soluble organic peroxide is hexylene glycol hydroperoxide and the dialkyl peroxide is di-3-hydroxy-1,1-dimethylbutyl peroxide.

Alternatively, the water-soluble organic peroxide is tert-octyl hydroperoxide and the dialkyl peroxide is di-tert-octyl peroxide.

Alternatively, the water-soluble organic peroxide is tert-hexyl hydroperoxide and the dialkyl peroxide is di-tert-hexyl peroxide.

The process according to the invention comprises a step a) of extraction with an aqueous composition of said at least one water-soluble organic peroxide. This step makes it possible to obtain an aqueous phase enriched in water-soluble organic peroxide and an organic phase.

By “extraction with an aqueous composition”, is meant the addition of an aqueous composition to the composition comprising said at least one water-soluble organic peroxide and said at least one water-insoluble compound, optionally followed by mixing the aqueous composition with the composition comprising said water-soluble organic peroxide and said water-insoluble compound, such that the water-soluble organic peroxide is at least partially transferred to the aqueous phase. The water-insoluble compound is not or poorly soluble in water and most of this compound is not transferred to the aqueous phase and remains in the organic phase.

Advantageously, the aqueous composition used for the extraction, or in other words added in step a), comprises at least 50% by weight of water, preferably at least 70% by weight of water, more preferably at least 90% by weight of water, even more preferably at least 95% by weight of water, even more preferably at least 97% by weight of water and even more preferably at least 99% by weight of water per relative to the total weight of the composition. According to preferred embodiments, the aqueous composition is water.

Preferably, the aqueous composition used for the extraction, or in other words added in step a), has a pH less than or equal to 8, preferably less than or equal to 7.5, even more preferably less than or equal to 7.

Preferably, the aqueous composition used for the extraction, or in other words added in step a), preferably has a pH greater than or equal to 5, more preferably greater than or equal to 6, even more preferably greater than or equal to 6, 5.

Preferably, the salt content of the aqueous composition used for the extraction, or in other words added in step a), is less than or equal to 10 g/l, preferably less than or equal to 5 g/l, of preferably less than or equal to 1 g/l, preferably less than or equal to 0.5 g/l. Preferably, the aqueous composition is devoid of salt and/or of ionized species and/or of base, and/or of acid.

Preferably, the aqueous composition used for the extraction, or in other words added in step a), is devoid of salt such as sodium chloride, potassium chloride or sulphates. This has the advantage of limiting the presence of ions in the aqueous phase, after extraction with said aqueous composition, which would increase the osmotic pressure of the aqueous phase and could destabilize the water-soluble organic peroxide.

By “aqueous phase enriched in water-soluble organic peroxide”, it is meant that the ratio of the mass concentration of said at least one water-soluble organic peroxide to the mass concentration of said at least one water-insoluble compound in the aqueous phase is greater than that of the composition comprising said at least one water-soluble organic peroxide and said at least one water-insoluble compound before step a).

The molar concentrations and/or the mass percentages of the water-soluble organic peroxide and of the water-insoluble compound may

be determined by iodometry, chromatography or by measuring total organic carbon (TOC).

Step a) of extraction can be carried out at a temperature ranging from 0° C. to 60° C., preferably from 5° C. to 50° C., more preferably from 10° C. to 45° C., even more preferably from 15°C to 30°C

Step b) for separating the aqueous phase and the organic phase makes it possible to separate the aqueous phase comprising the major part of the water-soluble organic peroxide from the organic phase comprising the major part of the water-insoluble compound, preferably water-insoluble peroxide , more preferably dialkyl peroxide.

This step b) can be carried out by any means known to those skilled in the art. In particular, step b) can be carried out by decantation, by centrifugation or by coalescence. The separation of stage b) can for example be carried out using a decanter, a centrifuge or a coalescer.

The method according to the invention also comprises a step c) of concentration of said aqueous phase according to the concentration method as described above.

Preferably, the process according to the invention does not comprise the addition of salt and/or base before stage c) of concentration of the aqueous phase. In particular, the method does not include a step for adding salt and/or base to the aqueous phase.

All or part of the permeate obtained in stage c) can be recycled with the aqueous composition, in stage a).

Preferably, the mass percentage of water-insoluble compound, preferably of water-insoluble organic peroxide, preferably of dialkyl in the retentate obtained in step c) is reduced, relative to that in the composition comprising said at least one organic peroxide water-soluble and said at least one water-insoluble compound before step a), at least 50%, preferably at least 60%, preferably at least 68%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 97%, or at least 99%, or at least 99.5%, or at least 99.9%, or at least 99.95%.

Composition

The invention also relates to an aqueous composition containing at least 60% by weight of alkyl hydroperoxide, as defined above, and less than 0.1% by weight of dialkyl peroxide as defined above, the proportions being calculated in weight relative to the total weight of the composition.

Preferably, the aqueous composition contains at least 68% by weight by weight of alkyl hydroperoxide, as defined above, preferably at least 70% and more preferably at least 80% by weight.

Preferably, R represents a branched alkyl group, optionally substituted, in C4-C10, preferably in C5-C10, preferably in Cs-Cs, more preferentially in C5-C6, even more preferentially in Cs.

The alkyl hydroperoxide is preferably selected from the group consisting of tert-amyl hydroperoxide, hexylene glycol hydroperoxide, tert-octyl hydroperoxide and tert-hexyl hydroperoxide.

More preferably, the alkyl hydroperoxide is tert-amyl hydroperoxide (TAHP).

Advantageously, the aqueous composition contains less than 0.08% by weight, preferably less than 0.07% by weight of dialkyl peroxide, preferably less than 0.05% by weight of dialkyl peroxide, preferably less than 0.025% by weight of dialkyl peroxide, more preferably still less than 0.01% by weight of dialkyl peroxide relative to the total weight of the composition.

Preferably, the dialkyl peroxide is selected from the group consisting of di-tert-amyl peroxide, di-3-hydroxy-1,1-dimethylbutyl peroxide, di-tert-octyl peroxide and di-tert-octyl peroxide. di-tert-hexyl.

More preferably, the dialkyl peroxide is di-tert-amyl peroxide.

Advantageously, the aqueous composition contains at least 68% by weight of tert-amyl hydroperoxide (TAHP) and less than 0.1% by weight of di-tert-amyl peroxide (DTA), the proportions being calculated by weight by relative to the total weight of the composition.

The present invention also relates to an aqueous composition rich in alkyl hydroperoxide which can be obtained by the process according to the invention.

Use of composition

The present invention also relates to the use of the composition as defined above for the preparation of crosslinking agent(s) or polymerization initiator(s).

Preferably, the initiator(s) is or are polymerization initiators by the radical route, in particular ethylene under high pressure.

By "high pressure" is meant within the meaning of the present invention, a pressure greater than 50 MPa. Preferably, the pressure varies from 500 bar (50 MPa) to 3000 bar (300 MPa), preferentially from 1200 bar (120 MPa) to 3000 bar (300 MPa), better still from 1200 bar (120 MPa) to 2600 bar (260 MPa).

Preferably, the crosslinking agents or the polymerization initiators are chosen from the group consisting of organic peroxides, in particular peroxyesters, hemi-peroxyacetals and peroxyacetals.

The term "hemi-peroxyacetal" means a compound of general formula (R3)(FU)C(-ORI)(-OOR2), in which:

- Ri represents an alkyl group, linear or branched, preferably C1 -C12, preferably C1 -C4, more preferably Ci, or a cycloalkyl group with R2,

- R2 represents an alkyl group, linear or branched, preferably C1-C12, preferably C4-C12, more preferably Cs, or a cycloalkyl group with Ri,

- R3 represents a hydrogen or an alkyl group, linear or branched, preferably C1-C12, more preferably C4-C12, or a cycloalkyl group with R4,

- R4 represents a hydrogen or an alkyl group, linear or branched, preferably C1-C12, more preferably C4-C12, or a cycloalkyl group with R3.

Preferably R3 forms a cycloalkyl group with R4.

Preferably, when R3 is hydrogen, R4 is an alkyl group, linear or branched, preferably C1-C12, more preferably C4-C12.

EXAMPLES

The following examples illustrate the invention without limiting it.

A hydroperoxide is first brought into contact with demineralised water in a batch reactor. When two phases appear in the reactor, they are separated by decantation to obtain clear solutions. The aqueous phase recovered, containing the hydroperoxide, is then reconcentrated by reverse osmosis. This step is carried out in an apparatus as shown in [Fig.1 ] figure 1.

The product to be treated is stored in a stirred and temperature-controlled container (1). It is then fed into the membrane module (3) by a high pressure pump (2). The permeate separated by the membrane is collected by the outlet (4) of the module (3) and the retentate produced is recycled into the container (1). The pressure regulator (5) is used to control and pressurize the installation. The heat exchanger (6) makes it possible to maintain the temperature of the liquid returning to the container (1).

The membranes used are commercial membranes of the Polyamide type. The membrane surfaces used in the tests are 140 cm 2 and 2.6 m 2 .

The analyzes are carried out by gas chromatography in the different flows (on a GC column: J&W DB-1 (15 meters x 0.530pm -1.50pm of phase, Carrier gas: Helium at 3 ml/min, Injector temperature: 90° C, Detector temperature: 250°C, Temperature gradient: 60°C for 4min then 15°C/min up to 140°C (no pause) then 30°C/min up to 220°C then level off 2min Injection: 2mI).

Example 1

2503 g of aqueous phase containing 14.6% by weight of TBHP is fed into the membrane module, equipped with a Dow Filmtec™ SW30 polyamide membrane (surface: 140 cm 2 , circulation rate of 480 L/h provided by the high pressure pump (2)). The temperature of the aqueous phase is kept constant at 26°C. A pressure increasing from 47 to 53 atmospheres (about 4762 to 5370 kPa) is applied.

The following results are obtained over time.

[Table 1 d

At the end of the test, 1.86 kg of retentate are recovered. After decantation, we recover:

- 178 g of organic phase (phase concentrated in hydroperoxide) containing 70% by weight of TBHP, water: qsp;

- 1680 g of aqueous phase (dilute phase) of composition: TBHP: 14% by weight, water: qsp.

Example 2

201.6 g of a solution of tert-amyl hydroperoxide (TAHP) having the following composition are mixed: TAHP: 85% by weight, di-tert-amyl peroxide (DTAP): 5% by weight, water: qsp, with 2399 g of water. After decantation, 95.5 g of organic phase mainly composed of DTAP and 2505 g of an aqueous phase containing 4.5% by weight of TAHP are obtained. This aqueous phase is fed into the membrane module, equipped with a GE-Suez Water type AD polyamide membrane (membrane area: 140 cm 2 , circulation rate of 480 L/h). The temperature of the aqueous phase is maintained at 25°C-26°C. An increasing pressure of 40 to 47 atmospheres is applied to the membrane (ie approximately 4053 to 4762 kPa).

The following results are obtained over time:

[Table 2j

At the end of the test, 1.873 kg of retentate are recovered.

After decantation, we recover:

- 23 g of organic phase (phase concentrated in hydroperoxide) of composition: TAHP: 85% by weight, DTAP: less than 200 ppm by weight, water: qsp;

- 1,850 g of aqueous phase (dilute phase) of TAHP composition:

4.5% by weight, water: qsp.

Example 3

3.7 kg of a tert-amyl hydroperoxide solution having the following composition: TAHP: 85% by weight, DTAP: 5% by weight, water: qsp, are mixed with 48 kg of water. After separation of the organic phase mainly composed of DTAP, 46.3 kg of an aqueous phase containing 4.8% by weight of TAHP are obtained. This solution is fed into a membrane module, equipped with a Dow Filmtec™ SW30 polyamide membrane (membrane area: 2.6 m 2 , circulation rate of 480 L/h). The temperature of the aqueous phase is maintained at 25°C. An increasing pressure of 40 to 50 atm is applied to the membrane (ie approximately 4053 kPa to 5066 kPa).

The following results are obtained over time:

At the end of the test, 11.9 kg of retentate are recovered.

After decantation, we recover

- 1,980 g of organic phase (phase concentrated in hydroperoxide)

of composition: TAHP: 85% by weight, DTAP less than 200 ppm by weight, water: qsp;

- 9920 g of aqueous phase (dilute phase) of composition: TAHP: 4.8% by weight, water: qsp.

Example 4

In a batch reactor, 1,577 g of water are mixed with 1,155 of DTBP (99% by weight) and 515g of a solution of tert-butyl hydroperoxide (68% by weight, water: qs), After decantation 1388 g of organic phase composed mainly of DTBP and 1854 g of aqueous phase containing 6.7% by weight of TBHP are obtained. This solution is fed into a membrane module equipped with a Dow Filmtec™ SW30 polyamide membrane (area: 140 cm 2 , circulation rate of 480 L/h provided by the high pressure pump (2)) The temperature of the aqueous phase is maintained at 25°C. An increasing pressure of 40 to 50 atmospheres (ie approximately 4053 kPa to 5066 kPa) is applied to the membrane.

The following results are obtained over time:

Table 41

At the end of the test, 245 g of retentate are recovered. After decantation, we recover

- 148 g of organic phase (phase concentrated in hydroperoxide) containing 70% by weight of TBHP, 500 ppm by weight of DI; water: qsp;

- 97 g of aqueous phase (dilute phase) of composition: TBHP: 16% by weight, water: qsp.

CLAIMS

1. Method for concentrating a composition comprising at least one water-soluble organic peroxide, said method comprising a step of bringing said composition into contact with a reverse osmosis membrane.

2. Method according to claim 1, in which the step of bringing said composition into contact with the reverse osmosis membrane is carried out at a temperature ranging from 0° C. to 60° C., preferably from 5° C. to 50° C. °C, more preferably 10°C to 45°C, even more preferably 15°C to 30°C

3. Method according to any one of claims 1 or 2, in which the contacting step is carried out at a pressure of between approximately 2000 and approximately 7000 kPa.

4. Method according to any one of claims 1 to 3, to obtain a retentate forming two immiscible phases consisting of a concentrated phase of water-soluble organic peroxide and a dilute phase of water-soluble organic peroxide.

5. Process according to claim 4, in which all or part of the dilute phase is recycled with the composition comprising the water-soluble organic peroxide to be concentrated.

6. Process for separating at least one water-soluble organic peroxide and at least one water-insoluble compound, comprising the following steps:

a) extraction with an aqueous composition of said water-soluble organic peroxide of a composition comprising said at least one water-soluble organic peroxide and said at least one water-insoluble compound;

b) separation of the aqueous phase enriched in water-soluble organic peroxide and of the organic phase obtained in step a);

c) concentration of the said aqueous phase enriched in water-soluble organic peroxide according to the concentration process as defined according to any one of Claims 1 to 5.

7. Process according to any one of claims 1 to 6, in which said at least one water-soluble organic peroxide is an alkyl hydroperoxide, preferably chosen from the group consisting of tert-butyl hydroperoxide, tert-amyl hydroperoxide, hexylene glycol hydroperoxide, tert-octyl hydroperoxide, tert-hexyl hydroperoxide, methylcyclopentyl hydroperoxide and methyl cyclohexyl hydroperoxide, again preferably chosen from the group consisting of tert-butyl hydroperoxide and tert-amyl hydroperoxide, more preferably still is tert-amyl hydroperoxide.

8. Process according to claim 6 or 7, comprising no addition of salt or base before step c) of concentration of the aqueous phase.

9. Process according to any one of claims 1 to 8, in which the composition to be concentrated as defined according to any one of claims 1 to 5 or the aqueous phase according to any one of claims 6 to 8, has a pH less than or equal to 8, preferably less than or equal to 7.5, more preferably less than or equal to 7.

10. Process according to any one of claims 1 to 9, in which the composition to be concentrated as defined according to any one of claims 1 to 5 or the aqueous phase according to any one of claims 6 to 9, has a pH greater than or equal to 5, preferably greater than or equal to 6, more preferably greater than or equal to 6.5.

11. Method according to any one of claims 6 to 10, in which step b) is carried out by decantation, centrifugation or coalescence.

12. Method according to any one of claims 6 to 1 1, comprising a step a '), prior to step a), of synthesis of said at least one water-soluble organic peroxide.

13. Method according to any one of claims 6 to 12, in which step a′) is carried out by the reaction of at least one alcohol or at least one alkene with hydrogen peroxide in the presence of an acid. , preferably sulfuric acid.

14. A method according to any one of claims 6 to 13, wherein said at least one water-soluble organic peroxide is tert-butyl hydroperoxide and said at least one water-insoluble compound is di-tert-butyl peroxide.

15. A method according to any one of claims 6 to 13, wherein said at least one water-soluble organic peroxide is tert-amyl hydroperoxide and said at least one water-insoluble compound is di-tert-amyl peroxide. .

16. Aqueous composition containing at least 68% by weight of alkyl hydroperoxide in which R represents an alkyl group, linear or branched, optionally substituted by one or more hydroxy groups, C5-C1 0, as defined according to claim 7, and less than 0.1% by weight of dialkyl peroxide, the proportions being calculated by weight relative to the total weight of the composition.

17. Composition according to claim 1 6, characterized in that the content of alkyl hydroperoxide is at least 70% by weight, more preferably at least 80% by weight, relative to the total weight of the composition .

18. Use of the composition as defined in claim 16 or 17 for the preparation of crosslinking agents or polymerization initiators,

preferably chosen from the group consisting of organic peroxides.