AU2007276289A1 - Process for preparing triallyl cyanurate - Google Patents

Description

WO 2008/009540 PCT/EP2007/056316 Process for preparing triallyl cyanurate Description 5 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. 10 Triallyl cyanurate (TAC) is a trifunctional monomer which is especially versatile in polymer chemistry and has three reactive allyl double bonds - see Kirk Othmer, Vol. 2, p. 123-127. Uses of TAC include as a 15 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. Moreover, TAC serves as a curing medium for a wide 20 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. 25 For many of the possible uses mentioned, 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 30 10. It is known that TAC is obtained by reacting cyanuric chloride with allyl alcohol in the presence of an acid acceptor, preferably of an alkali metal hydroxide. The 35 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 WO 2008/009540 PCT/EP2007/056316 2 process technology for the preparation and isolation of the TAC. US patent 2,510,564 describes a process for obtaining 5 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 400C, with subsequent heating up to 800C). In one modification of this method, powdered sodium hydroxide is used as the acid 10 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 15 yields reported in the examples (85% and 76%) are likewise unsatisfactory. In the processes of US patents 2,631,148 and 3,644,410, the reaction is performed in the presence of toluene at 20 below 100C and from 50 to 800C respectively. Even though both processes provide acceptable results with regard to product yield and purity, the performance of the process is complicated. The use of an organic solvent is not unproblematic, and makes the process 25 more expensive through the equipment required and the energy input for the complete removal of the solvent from the aqueous and TAC-containing phase. US patent 3,635,969 teaches a process by which the 30 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 35 sodium hydroxide concentration 40 ± 0.5% by weight. The reactants are added to 70% aqueous allyl alcohol while maintaining a reaction temperature of 15 ± 30C and a weakly alkaline pH. Disadvantages of this process, WO 2008/009540 PCT/EP2007/056316 3 which permits the preparation of TAC with an APHA number around 10 in about 90% yield, are: long addition and post-reaction times - for example 5 around/above 10 hours overall - lead to low space-time yields; the phase separation is time-consuming and the formation of emulsions formed entails additional 10 technical measures, for instance those of coalescers; after the distillative dealcoholization of the TAC containing phase, a purification/filtration step, if appropriate with use of activated carbon, is required 15 to remove flocculations. In the reworking of the process of US patent 3,635,969, the applicant of the present application also found that, in the workup of the aqueous reaction phase and 20 wash phases for the purpose of recovering the allyl alcohol excess, there is contamination of the allyl alcohol with ammonia. Reuse of such a contaminated allyl alcohol in the TAC preparation results in the formation of triazine compounds which cannot be washed 25 out and hence to an increase in the APHA colour number and corresponding reduction in the TAC quality. It is an object of the present invention to improve the process known from US patent 3,635,969, in order to at 30 least partly remedy the disadvantages indicated. 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 35 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 WO 2008/009540 PCT/EP2007/056316 4 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 5 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 10 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 15 temperature in the range of -5'C to +500C. Surprisingly, it has been found that a reduction in the amount of acid acceptor in the molar use ratio of the reactants compared to the processes known to date 20 allows the reaction to be performed in a shorter time and without the tightly restricted temperature control required to date, and additionally allows TAC to be obtained with a relatively low APHA colour number, i.e. below 10. This allowed the space-time yield to be 25 increased and TAC to be obtained in over 99% purity in yields over 90%. Surprisingly, the TAC-containing organic phase and the aqueous phase can additionally be separated from one another rapidly and without any problem after the reaction and the scrubbing, and 30 recovered allyl alcohol can be reused without reducing the quality of the TAC. The process according to the invention is technically simple to perform and requires a lower level of 35 technical complexity compared to the process known to date, since phase separation problems and a filtration step do not occur.

WO 2008/009540 PCT/EP2007/056316 5 In the process according to the invention, 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 5 preferred as an acid acceptor. In principle, the acid acceptor can be introduced into the reaction mixture in pulverulent form or in the form of an aqueous solution or suspension. 10 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 15 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 20 reaction mixture can be kept at a low level in this way. According to the invention, 3.9 to 6.0 mol of allyl alcohol and 3.0 to 3.2 equivalents of acid acceptor are 25 used per mole of cyanuric chloride. However, 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. In the case of use of sodium hydroxide solution as the acid acceptor, the numerical values 30 specified correspond directly to the molar use ratio of the reactants. The temperature range selected for the reaction is between -5'C and +500C, preferably between 0 and 40C; 35 in a one-stage version, particular preference is given to a temperature range of +50C to +300C. The reaction can be performed either isothermically at low temperature or semi-adiabatically with single-stage or multistage raising of the temperature. Preference is WO 2008/009540 PCT/EP2007/056316 6 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 +150C and preferably +5 to +100C; in the second stage, the 5 reaction is continued up to a conversion of essentially 100% at elevated temperature, preferably at +30 to +400C. The reactants cyanuric chloride and acid acceptor, 10 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. 15 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. Alternatively, it is also possible to introduce cyanuric chloride and the acid 20 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. In a further but less preferred 25 alternative, cyanuric chloride is introduced into a mixture of allyl alcohol and aqueous acid acceptor solution. In a particularly preferred embodiment of the process, sodium hydroxide solution, with and without simultaneous addition of cyanuric chloride, is 30 introduced into a mixture of cyanuric chloride and allyl alcohol and optionally a little water. To suppress hydrolytic side reactions which therefore reduce the yield, the reactants are combined 35 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 WO 2008/009540 PCT/EP2007/056316 7 than 3 hours and preferably less than 2 hours, in particular 1 to 1.5 hours. In view of the high reaction enthalpy, in order to 5 achieve the short reaction times, intensive cooling, for instance cooling using cooling brine, is required. On the industrial scale, the heat is removed particularly efficiently through an external cooling circuit with a suitable heat exchanger as well as a 10 circulation pump. As already detailed, the excess of acid acceptor is restricted to minimal values in the process according to the invention. In principle, the excess can be 15 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 20 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 25 no contamination thereof with ammonia as a result of hydrolytic cleavage of triazine compounds present in the aqueous phases. After the reaction has ended, just sufficient water is 30 added to the reaction mixture that the precipitated chloride goes back into solution. After the stirrer has been switched off, 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 35 salt. Typically, 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. After removal of the aqueous phase, the organic phase is washed at least once, preferably two to three WO 2008/009540 PCT/EP2007/056316 8 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 300C, which can be established easily under the 5 process conditions. If appropriate, preheated water can also find use for the maintenance of the washing temperature of about 300C. The washing of the organic phase can be performed batchwise or else continuously in a customary extraction apparatus. After the wash, 10 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 15 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 20 to or greater than 270C. 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. 25 The examples which follow illustrate the process of the invention without restricting it. In a series of comparative experiments, the influence of the size of the sodium hydroxide excess, the reaction temperature 30 and the post-reaction time on the cleavage caused by hydrolysis and the associated decomposition of the TAC formed was examined: it follows from this that, in the case of the inventive, very small excess of acid acceptor, the degradation rate of TAC is significantly 35 lower than when using the excess mentioned of acid acceptor (sodium hydroxide solution) in the process known to date. In view of this finding, it is surprising that the significance of a very low excess of acid acceptor has not already been recognised WO 2008/009540 PCT/EP2007/056316 9 before. The APHA number was messured according to EN ISO 6271-1:2004 (D). Example 1 5 A coolable reaction vessel was initially charged with 354 g (5.0 mol) of 82% by weight allyl alcohol and cooled to 100C. Thereafter, 184.5 g (1 mol) of cyanuric chloride were added, and 3.09 mol of 50% by weight 10 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 100C until 75% of the sodium hydroxide solution had been consumed. Thereafter, the cooling medium was 15 removed and the remaining alkali was added rapidly, so that the temperature rose to 400C. The mixture was stirred at 400C for another 15 minutes, in the course of which complete conversion was achieved according to analytical monitoring. Subsequently, 335 ml of water 20 were added and the precipitated sodium chloride was brought into solution by adding water. After the stirrer had been switched off, two phases with a sharp separation line formed immediately. The upper organic phase was washed twice with 200 ml each time of water, 25 which reversed the phases, and the TAC-containing phase was removed as the lower phase. The TAC-containing phase was stabilized with 100 ppm of hydroquinone monomethyl ether and, after being transferred into a rotary evaporator, dealcoholized at 90'C in a water-jet 30 vacuum. This gave 231.7 g of triallyl cyanurate of melting point 270C, corresponding to a yield of 93.0%. The APHA number was determined to be 5, the purity to be 99.9%. 35 Example 2 The procedure was as in Example 1, except that the proportion of the sodium hydroxide solution metered in at 100C was increased to 80 1 and the metering time WO 2008/009540 PCT/EP2007/056316 10 correspondingly to 65 minutes. The remaining alkali was added rapidly and without cooling, in the course of which the temperature rose to 300C. After 15 minutes of post-reaction time and the workup specified in 5 Example 1, 235.5 g of triallyl cyanurate (= 94.5% yield) were obtained in a purity above 99.9% and with an APHA colour number of zero. 164.0 g of 70% allyl alcohol, which contained less than 50 ppm of ammonia, was distilled off from the combined aqueous phases 10 under virtually azeotropic conditions and used again (see Example 3). Examples 3 to 6 15 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, 20 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. 25 Example 7 A brine-cooled reaction vessel was initially charged with 290.4 g of pure allyl alcohol which were cooled to -50C. Thereafter, 184.5 g of cyanuric chloride were 30 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 0C. Subsequently, the mixture was allowed to continue 35 to react without cooling for another approx. 30 minutes until complete conversion had been achieved. Thereafter, the mixture was warmed to 300C; to dissolve the precipitated sodium chloride, 409 ml of water preheated to 300C were added and, after the stirrer had WO 2008/009540 PCT/EP2007/056316 11 been switched off, the phases which form within a few minutes were separated. The organic phase was removed, washed twice with 200 ml each time of water and, after stabilization with 100 ppm of hydroquinone monomethyl 5 ether, freed of the volatile constituents on a rotary evaporator under reduced pressure. This gave 240.5 g (corresponding to a yield of 96.5%) of pure triallyl cyanurate with an APHA number of 0. 10 Example 8 A jacketed stirred reactor with an external heat exchange circuit consisting of cooler and circulation pump was initially charged with 119.0 kg (2049 mol) of 15 allyl alcohol and 26.5 kg of water; 75.0 kg of cyanuric chloride were then added with stirring. Thereafter, the cooling circuit charged with brine was put into operation and the circulating mixture was cooled to 80C. The addition of a total of 101.0 kg = 66.2 1 20 (1262 mol) of 50% by weight NaOH solution was then commenced, in the course of which the reaction temperature was kept at 9 to 140C until 54 1 had been consumed. 25 Subsequently, the cooling circuit was shut down and the remaining sodium hydroxide solution was allowed to flow in within the shortest possible time. In the course of this, the internal temperature of the reactor rose to 350C. The total introduction time was about 70 minutes. 30 To complete the conversion, stirring was continued for another 20 minutes; 140 1 of water were then added to the solution of the precipitated sodium chloride. After the stirrer had been switched off, two clear phases formed within a few minutes, which were separated by 35 means of a separating vessel. The organic phase was recycled into the reactor and washed twice with 80 1 each time of water. After the second extraction, the washed TAC still contained 2.1% water and 6.5% allyl alcohol. To remove the volatile fractions, the product, WO 2008/009540 PCT/EP2007/056316 12 after stabilization with 100 ppm of hydroquinone monomethyl ether, was fed through a falling-film evaporator, which distilled off the low boilers at 50 mbar and 1000C. This gave 95.1 kg of triallyl 5 cyanurate, corresponding to a yield of 93.9%; purity of the TAC 99.9%, APHA number 0 to 5. Example 9 10 The reaction apparatus described in the preceding example, which had additionally been equipped with a metering unit suitable for pulverulent bulk material, was initially charged with 145.5 kg of 81.8% by weight allyl alcohol (2049 mol) together with 15 kg (81.3 mol) 15 of cyanuric chloride, and the mixture was cooled to 80C. Cyanuric chloride and the sodium hydroxide solution present in a small excess (50% strength by weight) were then metered in simultaneously under quantitative control continuously via the external heat 20 exchanger circuit with intensive stirring and cooling, in the course of which the reaction temperature was kept at 9 to 100C. Once the further addition of 60.0 kg (325.5 mol) of cyanuric chloride and 56 1 (85.4 kg; 1061.7 mol) of 50% by weight sodium hydroxide solution 25 was complete, the cooling was shut down and the remaining alkali of 10.2 1 (15.6 kg; 194.5 mol) was allowed to flow in as rapidly as possible. Thereafter, the temperature rose to 300C. The mixture was stirred at this temperature for a further 15 minutes; 30 subsequently, workup was effected in the manner described in Example 8. This gave 95.8 kg of pure triallyl cyanurate, corresponding to a yield of 94.6%. The product had an APHA number of below 10. 35 Example 10 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 WO 2008/009540 PCT/EP2007/056316 13 to 80C, 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 5 9 to 100C. Just before the end of the parallel metered addition, the reaction temperature was allowed to rise to 15 to 170C by appropriate regulation of the cooling. Once all of the cyanuric chloride had been added, the cooling was removed and the remaining sodium hydroxide 10 solution was allowed to flow in rapidly, while the temperature rose further to 30 to 320C. 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 15 above. Yield and product quality do not differ from the preceding example. Example 11 20 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 80C. After the end of the parallel addition, the reaction temperature was initially maintained further at 100C; only after 25 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 350C had been attained was 75 minutes. The yield of triallyl cyanurate was 94.1%, the purity 99.9% and the APHA 30 colour number 0 to 5. Example 12 The procedure was according to Example 9, except that, 35 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%.

WO 2008/009540 PCT/EP2007/056316 14 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. 5 Example 13 To illustrate the improvement of the process according to the invention over the prior art process, the influence of the sodium hydroxide excess, the post 10 reaction temperature and the post-reaction time on the cleavage, caused by hydrolysis, of the TAC formed and its degradation rate as a function of the parameters mentioned were determined in a series of comparative experiments. 15 In each case, a model mixture of TAC, allyl alcohol, water and NaCl prepared according to Example 2 was used, with the proviso that the reaction was performed without sodium hydroxide excess (3.0 mol of 50% by 20 weight NaOH per mole of cyanuric chloride), and that, after the reaction had ended, no dilution water was added. The TAC content in the mixture was in each case 64.0 to 64.2%. After the desired post-reaction temperature had been set, these model mixtures were 25 admixed with a certain amount (corresponding to the desired excess) of 50% by weight sodium hydroxide solution, and stirred at constant temperature for several hours. Samples were taken at certain time intervals, and their TAC content was compared with the 30 TAC content of the starting sample (zero sample) of the model mixture. The post-reaction temperature, the added NaOH excess (mol per mole of cyanuric chloride) and the TAC degradation rate (%) after 30, 60, 120 and 180 minutes of the experiments follow from the table. The 35 results demonstrate the harmful influence of relatively high NaOH excesses on the decomposition of the TAC formed.

WO 2008/009540 PCT/EP2007/056316 15 c) Lfl -i co co H C) (n ND G -d ~ ~ G CDHl-d N C)) (D 0C D > D E-H C) GD-i GD 1 -~ CP ,-n C) C ) 'l ) a)Y ) GD CD (D D CD (1) 4-4a aY) C)l 4-) GD GD Gn D GDn ~ G GD~~ C) C D C) 0 u -H 0 (a) 0) LH u~ rz o 0 Ea a) ~C)4n F-a0

Claims (7)

1. Process for preparing triallyl cyanurate (TAC) having an APHA number of less than or equal to 10 5 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, 10 extractively washing the organic phase with water and distillatively removing water and allyl alcohol from the TAC-containing organic phase, characterized in that

3.9 to 5.0 mol of allyl alcohol and 3.0 to 15 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 20 one or more stages at a temperature in the range of -50C to +500C. 2. Process according to Claim 1, characterized in that 25 the acid acceptor used is an alkali metal hydroxide, preferably sodium hydroxide, and is preferably used in the form of a concentrated aqueous solution. 30 3. Process according to Claim 1 or 2, characterized in that

4.9 to 5.2 mol of allyl alcohol and 3.0 to 3.15 equivalents, preferably 3.05 to 3.10 equivalents of acid acceptor are used per 35 mole of cyanuric chloride. 4. Process according to one or more of Claims 1 to 3, characterized in that the reaction is performed at 0 to 400C. WO 2008/009540 PCT/EP2007/056316 17

5. Process according to one or more of Claims 1 to 4, characterized in that the reaction is performed in two stages, a temperature of 0 to +150C, preferably +5 to +100C, being maintained in the 5 first stage up to a conversion of 65 to 90%, and a temperature of 30 to 400C being maintained in the second stage up to a conversion of essentially 100%. 10 6. Process according to one or more of Claims 1 to 5, characterized in that aqueous allyl alcohol with an allyl alcohol content of 75 to 90% by weight is used. 15

7. Process according to one or more of Claims 1 to 6, characterized in that the entire reaction time, i.e. the time for the addition of the reactants to allyl alcohol and the continued reaction, is 20 limited to not more than 3 hours, preferably less than 2 hours.

8. Process according to one or more of Claims 1 to 7, characterized in that, for the purpose of removing 25 the salt and depleting the excess allyl alcohol, the organic phase is washed at least once, preferably two to three times, with water at temperatures around 300C. 30 9. Process according to one or more of Claims 1 to 8, characterized in that allyl alcohol present in the combined aqueous phases is distilled off therefrom, preferably as an azeotrope with water, and sent to a subsequent 35 batch.

10. Process according to one or more of Claims 1 to 9, characterized in that WO 2008/009540 PCT/EP2007/056316 18 cyanuric chloride is added in the initial feed relative to the acid acceptor to initially charged, anhydrous or aqueous allyl alcohol or to a mixture of allyl alcohol and at least some of 5 the cyanuric chloride.