Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C211/00—Compounds containing amino groups bound to a carbon skeleton
  • C07C211/43—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton
  • C07C211/54—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to two or three six-membered aromatic rings
  • C07C211/55—Diphenylamines
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/48—Separation; Purification; Stabilisation; Use of additives
  • C07C67/62—Use of additives, e.g. for stabilisation

Definitions

• the subject of the present invention is a composition which can be used as an inhibitor of the radical polymerization of ethylenically unsaturated aliphatic monomers and a process intended to prevent the radical polymerization of such unsaturated monomers during their industrial preparation. It relates more particularly to vinyl aliphatic monomers.
• Inhibitors have now been found exhibiting improved properties compared to those conventionally used such as in particular, hydroquinone.
• the invention relates to a composition intended to prevent the radical polymerization of ethylenically unsaturated aliphatic monomers, characterized in that it comprises at least one diphenylamine derivative corresponding to the general formula (I):
• R 1 and R2 identical or different, represent a hydrogen atom or one or more substituents
• n and m representing the number of substituents on the cycle. It has been found according to the invention that the inhibitory action of the diphenylamine derivative as defined, is reinforced when said derivative which carries at least one hydroxyl group on one of the rings, comprises at least one other substituent on the one of the rings which can be a substituent such as R-
• a first class of inhibitors according to the invention are of the hydroxydiphenylamine type comprising at least one substituent other than a hydroxyl group.
• inhibitors according to the invention are of the dihydroxydiphenylamine type optionally comprising other substituents on the rings.
• a variant of the invention consists in combining the diphenylamine derivative of the invention with another polymerization inhibitor.
• diphenylamine derivative according to the invention corresponds to the general formula (I) in which A and B represent one of the following cycles:
• a and B are identical and represent a benzene ring.
• One of the rings A and B carry at least one substituent other than the hydroxyl group. It should be noted that if n is equal to 0, m is at least greater than or equal to 1 or if m is equal to 0, n is at least greater than or equal to 1.
• the number of substituents on rings A and B can vary. Thus, n is less than or equal to 3, preferably equal to 0 or 1. For m, m is less than or equal to 4, preferably equal to 1 or
• the remainder A and B may optionally carry one or more substituents which are represented in formula (I), by the symbol Ri and R2 and whose preferred meanings are defined below:. a hydrogen atom,
• an alkyl radical linear or branched, having from 1 to 12 carbon atoms, preferably from 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl,.
• a linear or branched alkenyl radical having from 2 to 6 carbon atoms, preferably from 2 to 4 carbon atoms, such as vinyl, allyl, .
• a linear or branched aikoxy or thioether radical having from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms such as the methoxy, ethoxy, propoxy, isopropoxy, butoxy radicals, an alkenyloxy radical, preferably an allyloxy radical or a phenoxy radical,.
• R3 represents a valence bond or a divalent, linear or branched, saturated or unsaturated hydrocarbon radical, having from 1 to 6 carbon atoms such as, for example, methylene, ethylene, propylene, isopropylene, isopropylidene; the identical or different R4 radicals represent a hydrogen atom or a linear or branched alkyl radical having from 1 to 6 carbon atoms.
• R ⁇ represents a hydrogen atom, an alkyl or aikoxy group having from 1 to 4 carbon atoms and R 2 represents a hydrogen atom, an alkyl or aikoxy group having from 1 to 4 carbon atoms.
• n is equal to 0 and m is equal to 1.
• diphenylamine derivatives preferably used. They are more particularly chosen from: - 2-hydroxy-5-methyldiphenylamine, - 2-hydroxy-4-methyldiphenylamine, - 2-hydroxy-4 ', 5-dimethyldiphenylamine,
• diphenylamine derivatives are of the dihydroxydiphenylamine type and mention may more particularly be made of 4,4'-dihydroxydiphenyiamine, 2,2'-dihydroxydiphenylamine, 2-hydroxy-4'-hydroxydiphenylamine
• compositions of the invention comprising at least one diphenylamine derivative of formula (la) constitute a particularly preferred embodiment of the invention.
• compositions of the invention are suitable for the stabilization of aliphatic monomers having at least one ethylenic unsaturation.
• the ethylenically unsaturated monomers more specifically comprise olefinic monomers comprising one or two unsaturations such as isoprene and butadiene; halogenated unsaturated monomers of the type of vinyl chloride, chloroprene, vinylidene chloride, vinylidene fluoride and vinyl fluoride; unsaturated acids such as acrylic acid, methacrylic acid and crotonic acid; unsaturated esters in particular the unsaturated esters of acrylic acid of the methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate; unsaturated esters of methacrylic acid such as methyl methacrylate, butyl methacrylate, lauryl methacrylate, dimethylaminoethyl methacrylate, stearyl methacrylate; vinyl acetate; unsaturated resins such as, for example
• compositions of the invention are particularly effective in the case of the stabilization of ethylenically unsaturated aliphatic monomers such as the esters of acrylic acid and of methacrylic acid.
• compositions of the invention form either true solutions, that is to say that they consist of perfectly miscible ingredients, or emulsions, or else suspensions. According to a preferred embodiment, however, the compositions are in the form of true solutions in the monomer itself.
• the compositions of the invention may contain other polymerization inhibitors such as hydroquinone; p-methoxyphenol; phenothiazines; nitroxide compounds such as tetramethylpiperidine-N-oxyl (TEMPO), 4-hydroxytetramethylpiperidine-N-oxyl, 4-oxotetramethylpiperidine-N-oxyl; imidalines / imidazolines-N-oxyl as described in FR 97/04230, preferably 2,2,3,4,5,5-hexamethylimidazolidine-1-oxyl or any other inhibitor known in the art provided that these these are compatible with the other ingredients of the composition under the operating conditions to which the monomer to be stabilized is subjected.
• other polymerization inhibitors such as hydroquinone; p-methoxyphenol; phenothiazines; nitroxide compounds such as tetramethylpiperidine-N-oxyl (TEMPO), 4-hydroxytetramethylpiperidine-N-oxyl, 4-oxot
• the invention further relates to a method for preventing the radical polymerization of an ethylenically unsaturated aliphatic monomer, preferably a vinyl aliphatic monomer.
• This method comprises, for example, adding to said monomer, an effective amount of a composition of the invention as defined above.
• the amount of diphenylamine derivative to be added to achieve effective inhibition of polymerization varies widely. It is a function of the monomer to be stabilized and of the operating conditions to which this monomer is subjected. It is clear that at high temperatures, the amount of inhibitor will be greater.
• the process of the invention is in fact applicable for the stabilization of the monomer, during manufacture and purification. However, it is not uncommon for the purification to be carried out by distillation of the monomer, the temperature at the reboiler being able to exceed 120 ° C.
• the ideal amount of inhibitor should be assessed on a case-by-case basis.
• a total quantity of diphenylamine derivative of between 1 and 2000 ppm, preferably between 5 and 1000 ppm is generally sufficient, this quantity being expressed relative to the total weight of the monomer to be stabilized.
• the proportion of the polymerization inhibitor (s) is preferably such that the ratio of the total mass of components of the diphenylamine type of formula (I) to the total mass of all the components is between 90/10 and 10/90, better still between 80/20 and 20/80.
• the diphenylamine derivative according to the invention optionally combined with other conventional polymerization inhibitors can be added to the monomer in a completely conventional manner.
• the point of introduction in the case of a distillation, is very variable: one can consider adding each of these compounds at the level of heat exchangers, pipes, pumps, reboilers, compressors or more generally distillation columns. It should be understood that the addition can be carried out continuously or else repeated over time at one or different particular sites.
• the invention also includes the use of the diphenylamine derivatives according to the invention for the stabilization of the monomer during storage by adding an amount equivalent to that previously mentioned.
• the invention also contemplates mixing with other inhibitors.
• the process of the invention is particularly advantageous in terms of effectiveness in inhibiting the radical polymerization of vinyl aliphatic monomers, in particular the esters of acrylic acid and methacrylic acid.
• composition of the invention is advantageously used as an emergency inhibitor during the synthesis of polymers from aliphatic monomers containing ethylenic unsaturation.
• the effectiveness of an inhibitor according to the invention is determined by measuring the induction time which represents the time to end of which the monomer begins to polymerize when it is heated in a temperature-controlled bath and in the presence of an initiator. This time is determined by a slight exothermicity of the sample studied.
• the measurements are carried out in a laboratory calorimeter, the time and temperature parameters are recorded and converted on a microcomputer.
• MMA methyl methacrylate
• MMA restored with 20 ppm of inhibitor to be tested are then introduced into a test tube and then 100 ppm of azobisisobutyronitrile initiator (AIBN).
• AIBN azobisisobutyronitrile initiator
• the tube is immersed in a bath thermostatically controlled at 80 ° C. and the temperature difference between this sample and a reference tube containing silicone oil is recorded continuously.
• the induction time Ti corresponds to the visible exotherm which indicates the start of the polymerization of MMA.
• the curve T as a function of time is recorded continuously. The longer the induction time, the more effective the inhibitor tested at constant weight concentration.
• the induction time values are better or equivalent to hydroquinone which is currently one of the best industrial inhibitors for the (meth) acrylates industry.
• Example 8 The same remark applies when comparing Example 8 with the two comparative examples 10 and 11.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Polymerisation Methods In General (AREA)

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• 1998
  • 1998-12-22 FR FR9816223A patent/FR2787444B1/fr not_active Expired - Fee Related
• 1999
  • 1999-12-21 CN CN99814961A patent/CN1331669A/zh active Pending
  • 1999-12-21 EP EP99959507A patent/EP1140772A1/de not_active Withdrawn
  • 1999-12-21 KR KR1020017007801A patent/KR20010103717A/ko not_active Application Discontinuation
  • 1999-12-21 AU AU16656/00A patent/AU1665600A/en not_active Abandoned
  • 1999-12-21 BR BR9916403-5A patent/BR9916403A/pt not_active Application Discontinuation
  • 1999-12-21 JP JP2000589484A patent/JP2002533309A/ja not_active Withdrawn
  • 1999-12-21 WO PCT/FR1999/003229 patent/WO2000037412A1/fr not_active Application Discontinuation

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