Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
  • C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
  • C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
  • C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
  • C07D251/30—Only oxygen atoms
  • C07D251/34—Cyanuric or isocyanuric esters

Definitions

• the present invention relates to a process for preparing triallyl cyanurate (2, 4, 6-tris (allyloxy) -s- triazine) , referred to hereinafter as TAC for short, in high yield and high purity, including an APHA number of less than or equal to 10.
• TAC Triallyl cyanurate
• a crosslinking component in the preparation of alkyd resins, polyurethanes, polyesters, and as a comonomer in vulcanization processes, and also as an adhesion promoter in rubber-latex mixtures for tyre cord.
• TAC serves as a curing medium for a wide variety of different polymers; for example, copolymers of TAC with methacrylates give rise to glass-like substances with excellent optical and mechanical properties, as required for the production of high- quality optical glasses.
• TAC very pure TAC is required, which also features a very low degree of discolouration, expressed as the APHA colour number, which should as far as possible not exceed the value of 10.
• TAC is obtained by reacting cyanuric chloride with allyl alcohol in the presence of an acid acceptor, preferably of an alkali metal hydroxide.
• the reaction can be performed in the presence or absence of an organic solvent.
• the processes known to date are afflicted by various deficiencies, for instance too low a yield, inadequate purity or excessively complicated process technology for the preparation and isolation of the TAC.
• US patent 2,510,564 describes a process for obtaining TAC by adding cyanuric chloride to a suspension of sodium carbonate in 90% allyl alcohol (molar ratio 1 : 3.0 : 13.51 at temperatures up to 40 0 C, with subsequent heating up to 80 0 C) .
• powdered sodium hydroxide is used as the acid acceptor and the reaction is performed at room temperature. In both cases, it is necessary to filter off sodium chloride formed. What are obtained are opalescent to cloudy reaction products whose purity, at below 90%, leaves a great deal to be desired. The yields reported in the examples (85% and 76%) are likewise unsatisfactory.
• US patent 3, 635, 969 teaches a process by which the reaction of cyanuric chloride with allyl alcohol and sodium hydroxide solution is effected in the absence of another organic solvent apart from the allyl alcohol reactant.
• the molar use ratio of cyanuric chloride to allyl alcohol to sodium hydroxide is 1 : 4.5 : 3.3, the sodium hydroxide concentration 40 ⁇ 0.5% by weight.
• the reactants are added to 70% aqueous allyl alcohol while maintaining a reaction temperature of 15 ⁇ 3°C and a weakly alkaline pH. Disadvantages of this process, which permits the preparation of TAC with an APHA number around 10 in about 90% yield, are:
• phase separation is time-consuming and the formation of emulsions formed entails additional technical measures, for instance those of coalescers;
• the process should also permit TAC to be prepared on the industrial scale with a yield of over 90%, based on cyanuric chloride, and an APHA colour number of below 10 as far as possible, and allow recovered allyl alcohol to be reused without reducing the quality of the TAC.
• a process has been found for preparing triallyl cyanurate (TAC) having an APHA number of less than or equal to 10 by reacting cyanuric chloride with allyl alcohol in the presence of an alkali metal acid acceptor and in the absence of an organic solvent other than allyl alcohol, removing the salt formed by adding water and subsequent phase separation, extractively washing the organic phase with water and distillatively removing water and allyl alcohol from the TAC- containing organic phase, which is characterized in that 3.9 to 6.0 mol of allyl alcohol and 3.0 to 3.2 equivalents of acid acceptor are used per mole of cyanuric chloride, cyanuric chloride and acid acceptor are added simultaneously or successively to anhydrous or at least 50% by weight aqueous allyl alcohol, and the reaction is performed in one or more stages at a temperature in the range of -5°C to +50 0 C.
• TAC triallyl cyanurate
• alkali metal compounds which are suitable as acid acceptors can be used. Essentially, they are thus oxides, hydroxides of alkali metals. Sodium hydroxide is particularly preferred as an acid acceptor.
• the acid acceptor can be introduced into the reaction mixture in pulverulent form or in the form of an aqueous solution or suspension.
• the acid acceptor is preferably used in the form of an aqueous solution, especially sodium hydroxide solution. While the concentration of the sodium hydroxide solution used in the process known to date had to be very tightly restricted, the concentration in the process according to the invention is less critical; typically, the concentration will be between 30 and 50% by weight of NaOH, preference being given to a maximum concentration, i.e. in particular one around 50% by weight, since the amount of aqueous phase in the reaction mixture can be kept at a low level in this way.
• 3.9 to 6.0 mol of allyl alcohol and 3.0 to 3.2 equivalents of acid acceptor are used per mole of cyanuric chloride.
• preferably 4.9 to 5.2 and in particular 3.05 to 3.10 equivalents of acid acceptor are used per mole of cyanuric chloride.
• the numerical values specified correspond directly to the molar use ratio of the reactants.
• the temperature range selected for the reaction is between -5°C and +50 0 C, preferably between 0 and 40 0 C; in a one-stage version, particular preference is given to a temperature range of +5°C to +30 0 C.
• the reaction can be performed either isothermically at low temperature or semi-adiabatically with single-stage or multistage raising of the temperature. Preference is given to a two-stage process: here, the reaction in the first stage is performed up to a conversion of 65 to 80% at low temperature, for example at 0 to +15°C and preferably +5 to +10 0 C; in the second stage, the reaction is continued up to a conversion of essentially 100% at elevated temperature, preferably at +30 to +40 0 C.
• the reactants cyanuric chloride and acid acceptor, especially sodium hydroxide solution, are introduced in any way into the allyl alcohol initially charged in excess, which may contain up to 59% by weight of water. Preference is given to using aqueous allyl alcohol having an allyl alcohol content of 75 to 90% by weight.
• the acid acceptor which is preferably used in the form of an aqueous solution, can be added to a mixture of allyl alcohol or aqueous allyl alcohol and the total amount of cyanuric chloride.
• cyanuric chloride and the acid acceptor simultaneously or with a certain initial feed of the cyanuric chloride into the initially charged, anhydrous or aqueous allyl alcohol, or a mixture comprising allyl alcohol and at least some of the cyanuric chloride.
• cyanuric chloride is introduced into a mixture of allyl alcohol and aqueous acid acceptor solution.
• sodium hydroxide solution with and without simultaneous addition of cyanuric chloride, is introduced into a mixture of cyanuric chloride and allyl alcohol and optionally a little water.
• the reactants are combined sufficiently rapidly that the addition time, which corresponds to the greatest part of the overall reaction time, is kept to a minimum.
• the entire reaction time i.e. that for the combination of the reactants and the post-reaction, is preferably not more than 3 hours and preferably less than 2 hours, in particular 1 to 1.5 hours.
• the heat is removed particularly efficiently through an external cooling circuit with a suitable heat exchanger as well as a circulation pump.
• the excess of acid acceptor is restricted to minimal values in the process according to the invention.
• the excess can be reduced to zero, but a minimal excess is useful with regard to the minimization of the post-reaction time.
• Only a very small excess of acid acceptor is found to be advantageous in two ways in the process according to the invention: firstly, the decomposition of the hydrolysis-sensitive TAC is suppressed, so that only insignificant yield losses, if any, occur; secondly, owing to the low alkalinity of the aqueous reaction phase and of the washing solutions in the distillative recovery of the excess of allyl alcohol used, there is no contamination thereof with ammonia as a result of hydrolytic cleavage of triazine compounds present in the aqueous phases.
• the reaction After the reaction has ended, just sufficient water is added to the reaction mixture that the precipitated chloride goes back into solution.
• two phases form within a very short time: an upper organic phase which comprises virtually all of the TAC and a lower phase which comprises the salt.
• the phases are separated virtually instantaneously or within a few minutes, and give rise to a sharp separation line without formation of a crud layer.
• the organic phase is washed at least once, preferably two to three times, with water, in order to deplete the content of allyl alcohol and to wash out salt residues.
• the washing-out is effected preferably at temperatures around 30 0 C, which can be established easily under the process conditions.
• preheated water can also find use for the maintenance of the washing temperature of about 30 0 C.
• the washing of the organic phase can be performed batchwise or else continuously in a customary extraction apparatus. After the wash, the organic phase generally still contains about 2 to 7% allyl alcohol and 1 to 3% water.
• the volatile constituents mentioned are, after addition of a suitable polymerization inhibitor, typically a hydroquinone derivative, distilled off gently at elevated temperature and under reduced pressure.
• the TAC obtained as the bottom product in yields of significantly above 90% is a water-clear liquid having a purity of at least 99.5%, an APHA number of 0 to 10, preferably 0 to 5, and a solidification point of equal to or greater than 27°C. Allyl alcohol present in the combined aqueous phases of the reaction and the wash is preferably recovered therefrom as a 60 to 73% azeotrope with water, supplemented with 100% allyl alcohol and fed to a subsequent batch.
• a coolable reaction vessel was initially charged with 354 g (5.0 mol) of 82% by weight allyl alcohol and cooled to 10 0 C. Thereafter, 184.5 g (1 mol) of cyanuric chloride were added, and 3.09 mol of 50% by weight sodium hydroxide solution were added dropwise with intensive stirring and cooling within 60 minutes, in the course of which the temperature was kept at 9 to 10°C until 75% of the sodium hydroxide solution had been consumed. Thereafter, the cooling medium was removed and the remaining alkali was added rapidly, so that the temperature rose to 40 0 C. The mixture was stirred at 40 0 C for another 15 minutes, in the course of which complete conversion was achieved according to analytical monitoring.
• Example 2 was repeated, except that the 60 to 70% by weight aqueous allyl alcohol which had been recovered essentially as an azeotrope from the preceding example in each case was supplemented to 5.0 mol with 100% by weight allyl alcohol and initially charged. Yield, purity and APHA number were virtually identical in Examples 3 to 6 and corresponded essentially to the values of Example 2; the APHA number was always significantly below 10.
• a brine-cooled reaction vessel was initially charged with 290.4 g of pure allyl alcohol which were cooled to -5°C. Thereafter, 184.5 g of cyanuric chloride were stirred in and the addition of 50% sodium hydroxide solution was commenced. Within 60 minutes, a total of 248.1 g (3.10 mol) of sodium hydroxide solution were metered in such that the temperature did not rise above 0 0 C. Subsequently, the mixture was allowed to continue to react without cooling for another approx. 30 minutes until complete conversion had been achieved.
• Example 9 The procedure was as in Example 9, except that only 10% of the 75.0 kg of cyanuric chloride used were initially charged together with the allyl alcohol. After cooling to 8 0 C, the simultaneous addition of cyanuric chloride and 50% by weight sodium hydroxide solution in a molar ratio of 1 : 3.10 was commenced, in the course of which the internal temperature of the tank was kept at 9 to 10 0 C. Just before the end of the parallel metered addition, the reaction temperature was allowed to rise to 15 to 17°C by appropriate regulation of the cooling. Once all of the cyanuric chloride had been added, the cooling was removed and the remaining sodium hydroxide solution was allowed to flow in rapidly, while the temperature rose further to 30 to 32°C. The total reaction time until the end temperature was attained was approx. 80 minutes. After a further 15 minutes of post-reaction time, workup was effected as described above. Yield and product quality do not differ from the preceding example.
• Example 9 The procedure was as in Example 9, except that 50% of the cyanuric chloride was initially charged with the 81.8% by weight allyl alcohol at 8 0 C. After the end of the parallel addition, the reaction temperature was initially maintained further at 10 0 C; only after addition of approx. 80 1 of the total amount of sodium hydroxide solution was the cooling shut down. The total reaction time until the end temperature of 30 to 35°C had been attained was 75 minutes. The yield of triallyl cyanurate was 94.1%, the purity 99.9% and the APHA colour number 0 to 5.
• Example 9 The procedure was according to Example 9, except that, for this purpose, the allyl alcohol recovered as a 60% solution from this example was reused and supplemented to the total amount of 5.0 mol/mol of cyanuric chloride with fresh allyl alcohol. This lowered the concentration of the allyl alcohol used to 78.9%. 95.0 kg were obtained, corresponding to a yield of 93.8% of triallyl cyanurate . The content was 99.7%; the APHA number was measured at 10.
• Examples 12.1 to 12.3 have an inventive NaOH excess; the NaOH excess of Example 12.4 corresponds to that of US patent 3,635,969.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38788845

Family Applications (1)

Country Status (13)

Families Citing this family (3)

Family Cites Families (4)

• 2006
  • 2006-07-21 DE DE102006034257.7A patent/DE102006034257B4/de active Active
• 2007
  • 2007-06-25 WO PCT/EP2007/056316 patent/WO2008009540A1/en not_active Ceased
  • 2007-06-25 CN CNA2007800272305A patent/CN101490020A/zh active Pending
  • 2007-06-25 EP EP07786835A patent/EP2044039A1/de not_active Withdrawn
  • 2007-06-25 JP JP2009521181A patent/JP2009544642A/ja active Pending
  • 2007-06-25 RU RU2009105820/04A patent/RU2009105820A/ru not_active Application Discontinuation
  • 2007-06-25 BR BRPI0714504-7A patent/BRPI0714504A2/pt not_active IP Right Cessation
  • 2007-06-25 MX MX2008015260A patent/MX2008015260A/es not_active Application Discontinuation
  • 2007-06-25 KR KR1020097001221A patent/KR20090031583A/ko not_active Withdrawn
  • 2007-06-25 AU AU2007276289A patent/AU2007276289A1/en not_active Abandoned
  • 2007-06-25 CA CA002657173A patent/CA2657173A1/en not_active Abandoned
• 2008
  • 2008-10-22 IL IL194803A patent/IL194803A0/en unknown
• 2009
  • 2009-01-20 ZA ZA200900459A patent/ZA200900459B/xx unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events