Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C407/00—Preparation of peroxy compounds
  • C07C407/003—Separation; Purification; Stabilisation; Use of additives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D11/00—Solvent extraction
  • B01D11/04—Solvent extraction of solutions which are liquid
  • B01D11/0492—Applications, solvents used
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/14—Fractional distillation or use of a fractionation or rectification column
  • B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/14—Peroxides

Definitions

• the present invention relates to a process for purifying a mixture containing at least one alkyl hydroperoxide, preferably tert-butyl hydroperoxide or tert-amyl hydroperoxide, and at least one dialkyl peroxide comprising at least s an extraction step with water and at least one separation step implemented on the aqueous phase, obtained following the extraction step, in order to recover an aqueous solution rich in alkyl hydroperoxide.
• alkyl hydroperoxide preferably tert-butyl hydroperoxide or tert-amyl hydroperoxide
• dialkyl peroxide comprising at least s an extraction step with water and at least one separation step implemented on the aqueous phase, obtained following the extraction step, in order to recover an aqueous solution rich in alkyl hydroperoxide.
• the invention also relates to an aqueous composition rich in alkyl hydroperoxide containing less than 0.1% by weight of dialkyl peroxide relative to the total weight of the composition.
• Alkyl hydroperoxides are commonly used as raw materials to produce crosslinking agents, intended to be mixed with polymers, such as polyesters, copolymers of ethylene and vinyl acetate (EVA) and terpolymers of 'ethylene-propylene-diene-monomer (EPDM), or initiators of radical polymerization, such as peroxyesters or peresters, peroxyacetals or peracetals, as well as monoperoxypercarbonates or percarbonates, involved in the preparation of polymers, such as p olystyrene or polyethylene.
• EVA ethylene and vinyl acetate
• EPDM terpolymers of 'ethylene-propylene-diene-monomer
• initiators of radical polymerization such as peroxyesters or peresters, peroxyacetals or peracetals, as well as monoperoxypercarbonates or percarbonates, involved in the preparation of polymers, such as p olystyrene or polyethylene.
• the alkyl hydroperoxides available on the market generally contain impurities, mainly consisting of alkyl peroxides, in particular di-alkyl peroxides, which originate from the preparation of the alkyl hydroperoxides in question.
• the alkyl hydroperoxides, in particular the tertioalkyl hydroperoxides are conventionally obtained by acid catalysis, causing the formation of the associated dialkyl peroxides, generally present between 3 and 30% by weight relative to the total weight of the composition of alkyl hydroperoxides.
• tert-butyl hydroperoxide can be carried out by reaction of tertiary butanol with hydrogen peroxide in the presence of sulfuric acid which will have the effect of catalyzing the undesired formation of peroxide di-tertio-butyl.
• dialkyl peroxides are not desired in association with their respective alkyl hydroperoxides and prove to be the main source. harmful contamination in the synthesis of crosslinking agents and polymerization initiators.
• these impurities obtained in alkyl hydroperoxide raw materials are used in the production of crosslinking agents for polymers and polymerization initiators. This has the direct consequence of lowering the degree of purity of the products obtained.
• LDPE low density polyethylene
• dialkyl peroxide in the initiators can be a source of bad thermal reaction profiles, affecting the implementation of the polymerization.
• the purification can be carried out by adding potassium hydroxide (KOH) or sodium hydroxide (NaOH) so as to form a water soluble tertiary butyl hydroperoxide salt.
• KOH potassium hydroxide
• NaOH sodium hydroxide
• alkyl hydroperoxide salt in order to obtain separation from the corresponding dialkyl peroxide can lead to numerous disadvantages on an industrial scale. Indeed, when the use of alkyl hydroperoxide and not that of its salt is required in the subsequent synthesis of a polymerization initiator or crosslinking agent, as for example in the case of peroxyacetals, such as 1, 1 - (di-tert-amyl) peroxy cyclohexane, l, l - (di-tert-butyl) peroxy 3, 3, 5 trimethyl cyclohexane, 2,2- (di-tert-butyl peroxy) -butane, 2,2- (di-tert-amyl peroxy) -butane, ethyl- 3,3 - di-tert-amyl peroxy butyrate , ethyl-3, 3 - di-tert-butyl peroxy butyrate, n-butyl
• the alkyl hydroperoxide is thus recovered by phase shift or by extraction with a solvent, for example a hydrocarbon.
• a solvent for example a hydrocarbon.
• the major drawbacks of this technique come on the one hand from its low productivity if we consider that the same reactor has the different stages (salt formation / decantation, re-acidification / extraction), on the other hand large quantities of saline aqueous effluents.
• the aqueous effluents formed during acidification, such as potassium sulphate for example, must be treated.
• the use of base and acid increases production costs.
• a base when using a mixture containing alkyl hydroperoxide and dialkyl peroxide can induce parasitic reactions with the crosslinking agents and / or the initiators of polymerization.
• KOH potassium hydroxide
• NaOH sodium hydroxide
• the use of potassium hydroxide (KOH) or sodium hydroxide (NaOH) at the same time as the mixture based on alkyl hydroperoxide and dialkyl peroxide can in particular lead to the saponification of peroxyesters.
• document FR 2455036 describes a process for the direct purification of alkyl hydroperoxides, in particular tert-amyl hydroxide (TAHP).
• TAHP tert-amyl hydroxide
• the distillation of TAHP containing di-tert-peroxide amyl (DTA) is carried out in the presence of water under reduced pressure and at a temperature below 45 ° C, allowing the TAHP to be recovered at the bottom of the column. Distillation provides a TAHP composition with a residue of 0.8% (8000 ppm) of DTA.
• organic peroxides are of a chemical nature to decompose thermally, with in particular the formation of flammable vapors.
• one of the objectives of the present invention is to provide a process which makes it possible to effectively separate an alkyl hydroperoxide from the corresponding dialkyl peroxide in order to reduce the costs associated with the preparation of crosslinking agents and / or polymerization initiators obtained from said alkyl hydroxyperoxide.
• one of the aims of the present invention is to purify alkyl hydroperoxides, from mixtures containing dialkyl peroxides, without degrading their physicochemical properties so as to be able to prepare crosslinking agents and / or initiators good quality polymerization.
• the present invention therefore in particular has for object and a method for purifying a mixture containing at least one alkyl hydroperoxide, as defined below, and at least one dialkyl peroxide, said mixture preferably being obtained after of the preparation of the alkyl hydroperoxide in question, comprising successively:
• step b) at least one step of concentrating the alkyl hydroperoxide content in the first phase obtained in step a) so as to obtain two new phases, called third and fourth phases,
• step d) optionally, a recovery step from the fifth phase obtained in step c).
• the method according to the invention makes it possible to recover a solution containing at least 60% by weight of alkyl hydroperoxide and less than 0.1% by weight of dialkyl peroxide; the proportion s being calculated relative to the total weight of the solution.
• the process according to the invention is therefore a process for the separation of an alkyl hydroperoxide from a dialkyl peroxide.
• step a) consists of at least one extraction step carried out with water from the mixture.
• step b) consists of at least one step of concentrating the content of alkyl hydroperoxide in the first phase (rich in alkyl hydroperoxide) obtained in step a).
• the invention relates to a process for the purification of a mixture containing at least one alkyl hydroperoxide, as defined below, and at least one dialkyl peroxide, said mixture preferably being obtained following the preparation of the alkyl hydroperoxide in question, comprising successively:
• step a) at least one step of extraction carried out with water from the mixture, and b) at least one step of concentrating the content of alkyl hydroperoxide in the first phase rich in alkyl hydroperoxide obtained in step a ),
• step b) optionally a step of decanting the third phase rich in alkyl hydroperoxide obtained in step b),
• step c) optionally, a step for recovering the fifth phase rich in alkyl hydroperoxide obtained in step c).
• the extraction step a) makes it possible to entrain the alkyl hydroperoxide in a first phase, while the dialkyl peroxide as well as the possible by-products, resulting from the method of preparation of the alkyl hydroperoxide , remain in the second phase.
• step a) the appearance of two phases:
• the concentration step b) aims in particular to operate a separation step, from the first phase obtained in step a), between two new phases:
• step b) consists of at least one step of concentrating the content of alkyl hydroperoxide in the first phase obtained in step a).
• step b) the appearance of two phases from the first phase obtained in step a): - a third upper phase (rich in alkyl hydroperoxide);
• the third phase spontaneously settles into two new phases:
• Concentration step b) consists in concentrating the content of the alkyl hydroperoxide in the first phase, extracted in step a), to obtain a fifth phase containing at least 60% by weight of hydroperoxide. alkyl and less than 0.1% by weight of dialkyl peroxide.
• the process according to the invention is a process for the separation of an alkyl hydroperoxide, as defined below, and a dialkyl peroxide comprising:
• step b) at least one step of separation of the lower phase obtained in step a), so as to obtain two new phases, called third and fourth phases,
• step d) optionally, a recovery step from the fifth phase obtained in step c).
• the fifth phase is the upper phase obtained in step c), which is rich in alkyl hydroperoxide.
• the method according to the invention therefore makes it possible to lead to an aqueous composition rich in alkyl hydroperoxide in which the amounts of impurities, such as dialkyl peroxides, are minimized.
• the process according to the invention makes it possible to prepare a good quality alkyl hydroperoxide, that is to say without its physicochemical properties being degraded, so as to be able to efficiently prepare crosslinking agents and / or polymerization initiators.
• the method according to the invention makes it possible to reduce the amounts of dialkyl peroxides in an aqueous solution rich in alkyl hydroperoxide and, consequently, to minimize the risks of hindering the preparation of the crosslinking agents and / or polymerization initiators obtained from alkyl hydroperoxide.
• the method according to the invention also has the advantage of rationalizing the costs of preparation of crosslinking agents and / or polymerization initiators and of reducing the environmental risks.
• the process according to the invention makes it possible, by eliminating the peroxide dialkyl, to reduce the safety problems linked to the storage and / or transport of an aqueous composition based on alkyl hydroperoxide.
• the process makes it easy to recycle the water that contributed to the purification.
• the process according to the invention can be carried out in batch or continuously.
• the invention also relates to an aqueous composition containing at least 60% by weight of alkyl hydroperoxide and less than 0.1% by weight of dialkyl peroxide, the proportions being calculated by weight relative to the total weight of the composition .
• the aqueous composition obtained with the process according to the invention has the advantage of dispersing a small amount of impurities, which ensures effective preparation of crosslinking agents and / or polymerization initiators.
• the present invention also relates to the use of the composition as defined above for the preparation of crosslinking agents or polymerization initiators, preferably chosen from the group consisting of organic peroxides, in particular peroxyesters and peroxyacetals.
• FIG. l Figure 1 shows schematically the method according to the invention.
• the process according to the invention relates to the purification of a mixture comprising at least one alkyl hydroperoxide and at least one dialkyl peroxide.
• said mixture is obtained following the preparation of the alkyl hydroperoxide in question.
• the process according to the invention aims to purify an alkyl hydroperoxide obtained by synthesis.
• the alkyl hydroperoxide can be prepared in an acid medium.
• the process according to the invention can comprise a step a ’), prior to step a), of synthesis of said alkyl hydroperoxide in an acid medium.
• the method for preparing the alkyl hydroperoxide notably consists in reacting hydrogen peroxide (hydrogen peroxide) in the presence of at least one alcohol or at least one alkene in an acid medium. .
• the method for preparing the alkyl hydroperoxide notably consists in reacting hydrogen peroxide (hydrogen peroxide) in the presence of at least one alcohol or a compound saturated in an acid medium.
• the reaction can be carried out at a temperature ranging from 10 ° C to 80 ° C, preferably from 20 ° C to 40 ° C.
• the reaction is carried out in the presence of one or more mineral or organic acids, in particular one or more mineral acids.
• the mineral acid is sulfuric acid.
• the mixture may thus include at least one alkyl hydroperoxide, at least one corresponding dialkyl peroxide and at least one alcohol.
• said at least one dialkyl peroxide is a dialkyl peroxide corresponding to the alkyl hydroperoxide to be purified.
• dialkyl peroxide is meant in the sense of the present invention the alkyl peroxide which comes from the synthesis of alkyl hydroperoxide.
• dialkyl peroxide refers to the compound that forms during the synthesis of alkyl hydroperoxide.
• the mixture can comprise at least one alkyl hydroperoxide in a content of at least 40% by weight, preferably 50% by weight, preferably 60% by weight, and more preferably 68% relative to the total weight. of the mixture.
• the mixture may comprise at least 1% by weight, preferably at least 2% by weight, more preferably at least 3% by weight of dialkyl peroxide relative to the total weight of the mixture.
• the mixture can comprise less than 25%, preferably less than 10% by weight, preferably less than 8% by weight of dialkyl peroxide relative to the total weight of the mixture.
• the alkyl hydroperoxide can also be obtained by oxidation of at least one alkane or at least one corresponding alkene.
• the mixture may thus comprise at least one alkyl hydroperoxide, at least one corresponding dialkyl peroxide, at least one alkane or at least one alkene in the presence of one or more oxidizing agents.
• the method according to the invention comprises at least one step a) of extraction carried out with water of the mixture as defined above.
• Step a) of water extraction can be carried out one or more times according to the conventional liquid extraction processes as described for example in the work entitled "Chemicals Engineer 's Handbook", 5 th 1973 edition of Perry et al.
• step a) of extraction is carried out by using water in contact with the mixture, as defined above, preferably obtained after the preparation of the alkyl hydroperoxide.
• step a) of extraction is carried out with an excess of amount of water relative to the total weight of the mixture as defined above.
• step a) of extraction is carried out with a water content which is 5 times greater, in particular 10 times greater, more particularly 15 times greater, than the content by weight of the mixture defined above.
• the extraction step a) is carried out with a water content which is 10 times greater than the content by weight of the mixture defined above.
• Step a) of extraction is carried out so as to obtain two phases.
• step a) of extraction is carried out so as to obtain: a first phase (rich in alkyl hydroperoxide); a second phase (rich in dialkyl peroxide).
• the first phase contains the alkyl hydroperoxide and a weight fraction of the corresponding dialkyl peroxide.
• the alkyl hydroperoxide is soluble in water.
• rich in alkyl hydroperoxide is meant that this phase contains more than 70%, preferably more than 80%, more preferably more than 90% by weight of the hydroperoxide present in the mixture before step a).
• soluble in water is meant in the sense of the present invention that the alkyl hydroperoxide has a temperature of 25 ° C. and at atmospheric pressure (760 mm of Hg, ie 1.03. 10 5 Pa) a water solubility of at least 4% by weight.
• the second phase contains a major fraction by weight of dialkyl peroxide, in particular the additional major fraction by weight of dialkyl peroxide found in the first phase.
• the second phase can also contain, for example, at least alcohol and possibly one or more by-products, apart from the method for preparing alkyl hydroperoxide, which are soluble in the second phase.
• step a) of extraction takes place in particular at the time of decantation of the composition from the mixture, as defined above, and water. Once decanted, the second phase is located above the first phase.
• Step a) can be carried out in batch or continuously.
• the first phase is recovered following step a) of extraction with water.
• Concentration step b) consists in particular in separating from the first phase, obtained in step a), a third phase rich in alkyl hydroperoxide and a fourth phase depleted in alkyl hydroperoxide.
• Step b) can be carried out using a process using at least one semi-permeable membrane or a distillation process.
• semi-permeable membrane in the sense of the present invention a selective organic or synthetic membrane capable of letting through a large quantity of water and not the substances in solution.
• a process using at least one semi-permeable membrane makes it possible to recover a water-rich solution, i.e. an aqueous phase depleted in alkyl hydroperoxide, and an aqueous solution enriched in alkyl hydroperoxide.
• the process using at least one semi-permeable membrane can be a reverse osmosis process or a pervaporation process.
• step b) is carried out using a distillation process.
• the distillation process has the advantage of leading to efficient and rapid separation.
• the distillation is carried out at a temperature between 25 ° C and 60 ° C, preferably between 30 ° C and 45 ° C.
• the distillation is carried out at a pressure of between 5 and 300 mbar (millibars), preferably between 30 and 200 mbar, preferably between 40 and 180 mbar, and more preferably between 50 and 160 mbar.
• the fourth phase depleted in alkyl hydroperoxide is preferably a solution containing less than 6%, preferably less than 5%, preferably less than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1% by weight of alkyl hydroperoxide relative to the total weight of the solution.
• the fourth phase depleted in alkyl hydroperoxide is advantageously recycled to the extraction step a) so as to conserve the amount of water necessary to carry out step a).
• Recycling can be done continuously or discontinuously.
• step b) spontaneously settles into two new phases:
• the fifth phase rich in alkyl hydroperoxide is a solution containing at least 60% by weight of alkyl hydroperoxide and less than 0.1% by weight of dialkyl peroxide.
• the fifth phase contains at least 60% by weight, preferably at least 68% by weight of alkyl hydroperoxide relative to the total weight of the solution.
• Step c) makes it possible to separate the solution containing at least 60% by weight of alkyl hydroperoxide and less than 0.1% by weight of dialkyl peroxide and a solution containing less than 20% by weight of hydroperoxide d 'alkyl, preferably less than 15%, the proportions being calculated relative to the total weight of the solution.
• the method according to the invention relates to the purification of a mixture comprising at least one alkyl hydroperoxide and at least one dialkyl peroxide.
• the alkyl hydroperoxide preferably corresponds to the following general formula R '-OO-H in which R 1 represents:
• a linear or branched alkyl group optionally substituted by one or more hydroxy groups, of C 4 -C 10 , preferably of C 4 -C 8 , more preferably of C4-C6, or
• cyclic group comprising from 5 to 8 carbon atoms, optionally aromatic, optionally substituted by one or more C 1 -C 3 alkyl groups.
• R 1 can represent a cyclic group comprising from 5 to 8 carbon atoms, optionally aromatic, optionally substituted by one or more C 1 -C 3 alkyl groups, in particular by a group in Ci.
• R 1 may represent a non-aromatic cyclic group containing from 5 to 8 carbon atoms, optionally substituted by a group in Ci.
• the alkyl hydroperoxide is a tert-alkyl hydroperoxide.
• R 1 represents a branched C 4 -C 10 , preferably C 4 -C 8 , more preferably C 4 -C 6 , even more preferably C 4 -C 5, alkyl group.
• the alkyl hydroperoxide is chosen from the group consisting of tert-butyl hydroperoxide, tert-amyl hydroperoxide, hexylene glycol hydroperoxide, tert-octyl hydroperoxide, hydroperoxide tert-hexyl, methylcyclopentyl hydroperoxide and methylcyclohexyl hydroxide.
• the alkyl hydroperoxide is chosen from the group consisting of tert-butyl hydroperoxide (TBHP) and tert-amyl hydroperoxide (TAHP), even more preferably tert-amyl hydroperoxide (TAHP ).
• dialkyl peroxide corresponds to the following general formula R 2 -00-R 3 in which R 2 and R 3 , identical or different, in particular identical, represent:
• C 4 -C 10 a linear or branched C 4 -C 10 , preferably C4-C8, more preferably C4-C6, alkyl group, optionally substituted by one or more hydroxide groups, or
• cyclic group comprising from 5 to 8 carbon atoms, optionally aromatic, optionally substituted by one or more C 1 -C 3 alkyl groups, in particular Ci.
• R 2 and R 3 may represent a cyclic group comprising from 5 to 8 carbon atoms, optionally aromatic, and optionally substituted by one or more C 1 -C 3 alkyl groups, in particular Ci.
• R 2 and R 3 may represent a non-aromatic cyclic group comprising from 5 to 8 carbon atoms, optionally substituted by a group in Ci.
• the dialkyl peroxide is a di-tert-alkyl peroxide.
• R 2 and R 3 identical or different, represent a branched alkyl group C 4 -C 10, preferably C 4 -C 8, more preferably C 4 - C è, optionally substituted by one or more groups hydroxides.
• R 2 and R 3 which may be identical or different, represent a branched C 4 -C 10 , preferably C 4 -C 8 , more preferably C 4 -C 6 alkyl group.
• the dialkyl peroxide is symmetrical, that is to say that the groups framing the group 0-0 are identical.
• R 2 and R 3 are more preferably identical and represent a branched C 4 -C 10 , preferably C 4 -C 8 , more preferably C 4 - alkyl group.
• the dialkyl peroxide is chosen from the group consisting of di-tertio-butyl, di-tertio-amyl peroxide, di-3-hydroxy-1,1-dimethylbutyl peroxide, di- tert-octyl, di-tert-hexyl peroxide, di (methylcyclopentyl) peroxide, di (methylcyclohexyl) peroxide.
• dialkyl peroxide is chosen from the group consisting of di-tertio-butyl and di-tertio-amyl peroxide.
• dialkyl peroxide is di-tertio-amyl peroxide.
• the alkyl hydroperoxide and the dialkyl peroxide have identical groups R 1 , R 2 and R 3 .
• the alkyl hydroperoxide is tert-amyl hydroperoxide (TAHP) and the dialkyl peroxide is di-tertio-amyl peroxide (DTA).
• the alkyl hydroperoxide is preferably tert-butyl hydroperoxide (TBHP) and the dialkyl peroxide is di-tert-butyl peroxide (DTBP).
• the alkyl hydroperoxide is hexylene glycol hydroperoxide and dialkyl peroxide and di-3-hydroxy-1,1-dimethylbutyl peroxide.
• the alkyl hydroperoxide is tert-octyl hydroperoxide and the dialkyl peroxide is di-tert-octyl peroxide.
• the alkyl hydroperoxide is tert-hexyl hydroperoxide and the dialkyl peroxide is di-tert-hexyl peroxide.
• the invention relates to a process for purifying a mixture containing at least one alkyl hydroperoxide selected from the group consisting of tert-amyl hydroperoxide, tert-butyl hydroperoxide, hexylene glycol hydroperoxide, tert-octyl hydroperoxide and is tert-hexyl hydroperoxide, and at least one dialkyl peroxide selected from the group consisting of di-tertio-amyl peroxide, di-tert-butyl, di-3-hydroxy-1,1-dimethylbutyl peroxide, di-tert-octyl peroxide and di-tert-hexyl peroxide, said mixture preferably being obtained as a result of preparation of the alkyl hydroperoxide in question, successively comprising:
• step b) at least one distillation step of the first phase, obtained in step a),
• the mixture is obtained in particular following the preparation of the alkyl hydroperoxide in an acid medium.
• 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 by weight relative to the total weight of the composition.
• the aqueous composition contains at least 68% by weight of alkyl hydroperoxide, as defined above, more preferably at least 80% by weight.
• R 1 represents a branched alkyl group, optionally substituted, at C4-C10, preferably at C5-C10, preferably at C5-C8, more preferably at C5-C6, even more preferably at C 5.
• the alkyl hydroperoxide is preferably chosen from the group consisting of tert-amyl hydroperoxide, hexylene glycol hydroperoxide, tert-octyl hydroperoxide and tert-hexyl hydroperoxide.
• the alkyl hydroperoxide is tert-amyl hydroperoxide (TAHP).
• 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. weight of dialkyl peroxide, more preferably less than 0.01% by weight of dialkyl peroxide relative to the total weight of the composition.
• dialkyl peroxide chosen from the group consisting of di-tertio-amyl peroxide, di-3-hydroxy-1,1-dimethylbutyl peroxide, di-tert-octyl peroxide and di peroxide -tert-hexyle.
• dialkyl peroxide is di-tertio-amyl peroxide.
• the aqueous composition contains at least 60% by weight of tert-amyl hydroperoxide (TAHP) and less than 0.1% by weight of di-tertio-amyl peroxide (DTA), the proportions being calculated by weight by relative to the total weight of the composition.
• TAHP tert-amyl hydroperoxide
• DTA di-tertio-amyl peroxide
• the present invention also relates to an aqueous composition rich in alkyl hydroperoxide which can be obtained by the process according to the invention.
• compositions as defined above for the preparation of crosslinking agent (s) or of polymerization initiator (s).
• the initiator or initiators is or are initiators for radical polymerization, in particular ethylene under high pressure.
• high pressure is meant in the sense of the present invention, a pressure greater than 50 MPa.
• the pressure varies from 500 bar (50 MPa) to 3000 bar (300 MPa), preferably from 1200 bar (120 MPa) to 3000 bar (300 MPa), better from 1200 bar (120 MPa) to 2600 bar (260 MPa).
• the crosslinking agents or the polymerization initiators are chosen from the group consisting of organic peroxides, in particular peroxyesters, hemi-peroxyacetals and peroxyacetals.
• hemi-peroxyacetal means a compound of general formula (R3) (R4) C (-ORI) (- OOR2), in which:
• Ri represents a linear or branched alkyl group, preferably in C1-C1 2, preferably in C1-C 4 , more preferably in C1 , or a cyclo alkyl group with R2 ,
• R 2 represents a linear or branched alkyl group, preferably C 1 -C 12, preferably C 4 -C 12 , more preferably C 5, or a cyclo alkyl group with R 1,
• R 3 represents a hydrogen or an alkyl group, linear or branched, preferably C 1 -C 12, more preferably C 4 -C 12 , or a cyclo alkyl group with R 4,
• R 4 represents a hydrogen or an alkyl group, linear or branched, preferably C 1 -C 12, more preferably C 4 -C 12 , or a cyclo alkyl group with R 3.
• R 3 forms a cycloalkyl group with R 4.
• R 4 is an alkyl group, linear or branched, preferably C 1 -C 12, more preferably C 4 -C 12 .
• the treated mixture is a solution of tert-amyl hydroperoxide (TAHP) containing 84.6% of tert-amyl hydroperoxide, 4% of di-tert-amyl peroxide (DTA), 0 , 8% acetone, 0.8% tert-amyl alcohol and 0.9% by weight of 2,2-di (tert-amylperoxy) propane peroxide.
• TAHP tert-amyl hydroperoxide
• the whole is mixed for 30 minutes using a magnetic stir bar and then left to settle for a period of 30 minutes at room temperature.
• the lower phase is introduced into a rotary evaporator flask.
• the distillation takes place under 100 mbar absolute pressure at a bath temperature of 50 ° C.
• One fifth of the aqueous phase is distilled.
• the distillate separates into an upper phase of 19 grams containing 89.2% tert-amyl hydroperoxide (TAHP) and only 0.06% di-tert-amyl peroxide (DTA) and a lower phase containing 5.5% tert-amyl hydroperoxide.
• TAHP tert-amyl hydroperoxide
• DTA di-tert-amyl peroxide
• the distillation residue represents 405 g containing 0.35% of TAHP.
• the treated mixture is a solution of tert-amyl hydroperoxide (TAHP) containing 84.6% of tert-amyl hydroperoxide, 4% of di-tert-amyl peroxide (DTA), 0 , 8% acetone, 0.8% tert-amyl alcohol and 0.9% by weight of 2,2-di (tert-amylperoxy) propane peroxide.
• TAHP tert-amyl hydroperoxide
• the starting mixture is identical to that of Example 1.
• the whole is mixed for 30 minutes using a magnetic stir bar and then left to settle for a period of 60 hours at room temperature.
• a quantity of 428 g of lower phase is introduced into a rotary evaporator flask.
• the distillation takes place under 100 mbar absolute pressure at a bath temperature of 50 ° C. Half of the lower phase is distilled.
• the distillate separates into an upper phase of 11.5 grams containing 89% tert-amyl hydroperoxide (TAHP) and only 0.005% di-tert-amyl peroxide (DTA) and a lower phase containing 4 , 7% tert-amyl hydroperoxide.
• TAHP tert-amyl hydroperoxide
• DTA di-tert-amyl peroxide
• the distillation residue represents 205 g containing 0.02% of TAHP.

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