3,793,321 United States Patent Office Patented Feb. 19, 1974 1. 2 the case with conventional commercially available triglyci 3,793,321 dyllisocyanurate. PROCESS FOR THE MANUFACTURE OF The epoxidation of olefinically unsaturated compounds TRGLYCDYL SOCYANURATE Juergen Habermeier, Pfeffingen, Hans Batzer, Arlesheim, with nitrile and hydrogen peroxide has already been de and Daniel Porret, Binningen, Switzerland, assignors to scribed in the literature (compare U.S.A. patent specifica Ciba-Geigy AG, Basel, Switzerland tion 3,053,856 and the investigations by Y. Ogata and Y. No Drawing. Filed June 29, 1971, Ser. No. 158,110 Sawaki, published in "Tetrahedron' 1964 (volume 20) Claims priority, application Switzerland, July 2, 1970, 2065-2068). However, this method has hitherto not been 10,043/70 proposed for the epoxidation of triallylisocyanurate. int, C. C07d 55/38 O It was entirely unexpected to an expert that according U.S. C. 260-248 NS 8 Claims to this method it is possible to manufacture triglycidyl isocyanurate which is free even of traces of undesired ABSTRACT OF THE DISCLOSURE decomposition products and has a substantially improved Manufacture of triglycidyllisocyanurate (TGIC) by storage stabiliy. epoxidation of triallylisocyanurate with HO--nitrile, 5 The subject of the present invention is hence a process such as benzonitrile. The TGIC manufactured according for the manufacture of triglycidyllisocyanurate, charac to the new process has the advantage over conventional terized in that triallylisocyanurate is epoxidized, at a pH TGIC, obtained by reaction of epichlorohydrin with of at least 4, with a mixture of hydrogen peroxide and a cyanuric acid, of substantially improved storage stability. nitrile of the formula R-CEN, or a peroxycarboximide Triglycidyllisocyanurate is a known compound. It can 20 acid of the formula be cured by means of the customary curing agents for epoxide resins, such as polycarboxylic anhydrides or poly amines to give mouldings which find diverse uses in com merce and industry. 25 wherein R denotes either an organic acyclic radical or an The industrial manufacture of triglycidyllisocyanurate organic cyclic radical which possesses no other unsatura has hitherto been effected by reaction of cyanuric acid tion than double bonds present in an aromatic ring. When with epichlorohydrin. Numerous variants of this process using a mixture of H2O and nitrile of the formula are described in the patent literature (compare, for exam 30 R-CsN, the peroxycarboximid-acid of the formula ple, U.S.A. patent specification 2,809,942, British patent NE specification 996,723 and French patent specification 1,570,826). By these processes, crystalline triglycidyliso R-C cyanurate with over 14% of epoxide oxygen (theory: 16.1% of epoxide oxygen) can be manufactured. The 35 storage stability of these commercially available conven is presumably formed in situ. tional types of crystalline triglycidyllisocyanurate is how The triallylisocyanurate used as the starting compound ever unsatisfactory; after prolonged storage, not only does is a known compound which can for example be manu an undesirable turbidity manifest itself, but the reactivity factured from cyanuric acid via trisodium cyanurate by of the resin increases so greatly that after mixing with the 40 reaction with allyl chloride. Another possible method of curing agent the pot-life becomes so short that process manufacture is the isomerization of triallylcyanurate ing, for example in casting, is no longer possible, or only which is manufactured from cyanuric chloride and ally possible with difficulties. alcohol. Investigations have shown that this relatively poor stor 45 As suitable nitriles for the process according to the in age stability, above all the rise in the reactivity and hence vention, there may, for example, be mentioned: acetoni the shortening of the pot-life, after prolonged storage, is trile, adiponitrile, 1,3-di(cyanoethyl)-5,5-dimethylhydan due to basic impurities (amines, amides and ureas), which toin, glycollic and nitrile or aromatic nitriles such as are produced during the dehydrohalogenation stage in the phthalonitrile or especially benzonitrile. manufacturing process. While part of these impurities 50 The preferred reaction conditions are as follows: the can be removed by washing, and the stability hence im temperature should lie in the range between 15 and 60' proved, complete removal is not possible without un C., and the pH (glass electrode) should be 8.5–10.0. Per economically high expenditure. mol of C=C double bond to be epoxidized, it is preferred It has also already been proposed to treat triallyliso to use 1.0-1.3 mols of nitrile and 1.1-1.4 mois of HO, cyanurate with per-acids, (compare British patent specifi 55 and, as the solvent, 300-1500 ml. of methanol. Further cation 941,507). Using this process, however, it is possi more, 0.5-5 g. of Na2HPO are preferably added as the ble to epoxidize at most two of the total of three allyl buffer per mol of S=C double bond. groups in the molecule of the triallylisocyanurate, so that The amide, formed from the nitrile, which is obtained mixtures of monoglycidyl and diglycidyl derivatives of can be removed by extraction or by filtration. The tri glycidyllisocyanurate obtained as a crystal slurry can be isocyanuric acid are produced which still contain allyl 60 purified by recrystallization. groups. In commercially available triglycidyllisocyanurate manu It has now been found that the epoxidation of triallyl factured from cyanuric acid and epichlorohydrin, two isocyanurate to give triglycidyllisocyanurate can be carried stereoisomers can be detected, a low melting ot-form (melt out in good yield and economically, if the epoxidation is ing point: 103-105 C.) and a higher-melting 6-form carried out with hydrogen peroxide and a nitrile. 65 (melting point: 156-158 C.), which occur in an approxi Surprisingly, the triglycidyllisocyanurate manufactured mately statistical ratio (compare M. Budnowski "Agnew. according to this process has a higher storage stability Chemie' 8 (1968), 851-852). than the commercially available triglycidyllisocyanurate These stereoisomers were also detectable in the trigly manufactured from epichlorohydrin and cyanuric acid. cidyllisocyanurate manufactured according to the inven In particular, the resin shows no undesirably pronounced 70 tion by epoxidation of triallylisocyanurate, but the weight increase in reactivity even after prolonged storage, as is ratio of a-form:f3-form is approximately 10:1 to 12:1. 3,793,321 3 4 The triglycidyllisocyanurate manufactured according to 20 g. of the crude product with 9.0 epoxide equivalents the process of the invention is particularly suitable for are warmed with 80 g. of methanol. The insoluble residue those applications where even after prolonged storage of is recrystallized from acetone. 1.2g. of the 8-form (6.0% the resin, a sufficiently long pot-life is demanded of the of the amount employed) of melting point=154-157 C. resin-curing agent mixture; this is above all the case in are thus obtained, having an epoxide content of 10.1 the casting resin field. equivalents/kg. (100% of theory). 14.8 g. of the c-form In the examples which follow, parts denote parts by (74% of the amount employed), of melting points:97 weight and percentages denote percentages by weight. 100° C., with an epoxide content of 9.62 equivalents/kg. EXAMPLE 1. (95.4% of theory) crystallize at room temperature from O the methanol solution. 312 g. (= 1.25 mols) of 1,3,5-triallylisocyanurate (boil A further 3 g. (15% of the amount employed) of a ing point0.2-0.3=120-125 C.), 2300 ml. of methanol, product having the following characteristics can addition 3.55 g. of disodium hydrogen phosphate, 485 g. of ben ally be crystallized from the mother liquor: melting zonitrile (4.7 mols) and 220 g. of a 35% strength aque point=55-60 C.; epoxide content=8.39 equivalents/kg. ous hydrogen peroxide solution are introduced into a flask (83% of theory). This fraction still contains allyl group equipped with a stirrer, thermometer, reflux condenser, IngS. dropping funnel and pH electrode. The dropping funnel EXAMPLE 2. is filled with 0.5 N aqueous sodium hydroxide solution. The reaction mixture is now brought to 50° C. while Analogously to Example 1 249 g. of triallylisocy stirring, and a pH of 9.5 is established, and maintained, anurate (1.0 mol) in 1.84 1. of methanol are epoxidized by means of the sodium hydroxide solution. The reaction at 50° C. and pH-9.5 with 154.4 g. of technical aceto is slightly exothermic, so that the heating bath can be nitrile (3.76 mols) and 176 g. of 35% strength hydro removed. After one hour, a further 110 g. of a 35% gen peroxide, with the aid of 2.84 g. of disodium hy strength aqueous hydrogen peroxide solution are added, drogen phosphate. The further hydrogen peroxide ad and the temperature is kept at 50° C. and the pH at 9.5. ditions (35% strength) consist of 88.0 g. added after After a further hour, a last portion of 35% strength hy 25 one hour, and 84.0 g. added after a further hour. In drogen peroxide solution (105 g.) is added, and the mix total, 3.58 mols of hydrogen peroxide are thus used. ture is allowed to react under the abovementioned con The reaction procedure, and the end point determina ditions until the conttent of active oxygen, calculated as tion, are carried out analogously to Example 1. 435 g. HO, has dropped to 0.85% (iodometric titration). The of 0.5 N NaOH are required to maintain the pH. A total reaction in total lasts 5% hours. The reaction mixture is 30 of 24 hours are required until the peroxide content of now treated with 2.3 litres of water and is extracted by the solution has dropped to 0.4%. shaking 3 times with 1 litre of chloroform at a time. The Working up takes place as described in Example 1. chloroform phase is concentrated to /3, mixed with 200 In the course thereof, however, the acetamide formed ml. of petroleum ether and cooled to 0°C. The benz remains dissolved in the aqueous phase. amide which precipitates is filtered off. Thereafter, the After concentration and drying, 197.2 g. of a sub clear solution is completely concentrated on a rotary evap stance which crystallizes (66.4% of theory) are obtained, orator at 70° C. under a Waterpump vacuum. Thereafter, having an epoxide content of 6.1 equivalents/kg (59.6% the product is dried to constant weight at 70° C./0.2 mm. of theory). Hg. 317 g. of a yellowish crystal mass (100% of theory) 40 The crude product is purified by stirring with 200 ml. are obtained. The epoxide content of the crude product of methanol at 50 C., and after cooling, the colorless is 7.12 epoxide equivalents/kg. To remove the last traces crystals are filtered off; after drying, they weigh 111 g. of nitrile and other impurities, the product is triturated The melting point is 59.1° C. (“Mettler FP 51' auto with 100 ml. of methanol. A crude triglycidyllisocyanurate matic apparatus). The epoxide content is 6.9 g, equiva with 9.0 epoxide equivalents/kg. (89% of theory) is ob lents/kg. (68.2% of theory). The proton-magnetic reso tained in about 70% yield. This crude product melts at 45 nance spectrum shows that 59% of N-glycidyl groups and 90-110° C. The proton-magnetic resonance spectrum 41% of N-allyl groups are present. Accordingly, the prod (60-mc. H-NMR, recorded in deuterochloroform at 37 uct is a mixture of triglycidyllisocyanurate, diglycidyl C., with tetramethylsilane as the internal standard) shows monoallylisocyanurate and diallylmonoglycidyllisocya that the crude product with 9.0 epoxide equivalents es lurate. sentially consists of 1,3,5-triglycidyllisocyanurate: 50 Comparison of the properties of triglycidyllisocyanurate manufactured from triallylisocyanurate according to the O invention (TGIC I) and a conventional triglycidyllisocya M. N. nurate manufactured by reaction of cyanuric acid and 8=2.48-2.89 (sextet): CH-CH epichlorohydrin (TGIC I): O 55 / N (A) Storage stability 8s3.10-3.36 (multiplet): CI-CH (a) Samples of the crude triglycidylisocyanurate manu 6=4.05-4.15 (quartet):N-CH-CH factured according to Example 1 (TGIC I), with an epoxide content of 9.0 epoxide equivalents/kg, are stored O 60 for 16 and 40 days at room temperature (25 C.), and / N in a first series of tests the influence of the storage time (H-CH-CH, on the Viscosity of a sample warmed to 120° C., as well as on the viscosity increase after 24 hours' heating to O OscC -N C=O O 120 C, is determined. 65 In a second test series, the influence of the storage cá SCH-N N-CH-cá SoH, time on the reactivity is investigated by producing a cast N / ing resin Sample by homogeneously mixing 1 epoxide O equivalent of TGIC I with 0.85 mol of hexahydrophthalic anhydride, and determining its pot-life at 120° C. The H-NMR spectrum further shows that the product still 70 (=time in minutes, by which the viscosity of the mixture possesses traces of N-allyl groups (weak CH=C signals at 120° C. reaches a value of 1,500 cp). at 8=5.2-5.7). (b) Analogously to (a), a triglycidyllisocyanurate The product can be purified by recrystallization from manufactured according to the process of French patent alcohols. A separation of the isomer mixture can also be Specification 1,570,825 (TGIC II), with an epoxide con achieved at the same time. 75 tent of 9.5 epoxide equivalents/kg, which has been 3,793,321 5 6 washed with 5% strength aqueous sulphuric acid in order For testing the aging resistance and the water resistance, to remove basic impurities, is stored, and the viscosity the mouldings obtained were subsequently stored for a change as well as the decrease in the pot-life of a casting further 7 days at 200° C. and thereafter still placed in resin sample, the composition of which is other analogous water (25 C.) for 72 hours. The mouldings aged in this to that under (a), is subsequently determined. way show the following mechanical and electrical proper The results are summarized in the table which follows: ties: TABLE (b) Com (a) Sarple with (b) Comparison parison TGIG sample with (a) Sample sample TGIC II with with 10 TGICI TGIC II Storage at room temperature (days)- 0 16 40 O 16 40 Flexural strength (VSM), kp.fmm.?------9.8 9.0

Viscosity at 120° C. in cp------50 35 35 60 60 55 Wiscosity increase after 24 hours at Deflection (VSM), mm.------4.8 3.8 120C., in percent.------O 0 ------41.7 36.4 Tracking resistance (VDE), level.------KA3e KA3e Pot-life of the mixture of TGIC plus Glass transition temperature, measured be- 249 242 hexahydrophthalic anhydride at fore the storage in water (C.) 120° C., up to 1,500 cp., in minutes. 305 273 238 217 98 68 15 Decrease in pot-life, in percent------1. 22 ------55 69 What is claimed is: 1. A process for the preparation of a sterioisomeric (B) Gelling times of casting resin mixtures mixture of triglycidylisocyanurate, said mixture contain (a) 3.0 g. of a homogeneous mixture of crude trigly ing by weight the ox and 3-form in the ratio of from 10:1 cidyllisocyanurate manufactured according to Example 1 20 to 12:1 which process is characterized in that triallyliso (TGIC I) with an epoxide content of 9.0 equivalents per cyanurate is epoxidized at a pH of at least 4 with a mix kg., and hexahydrophthalic anhydride (0.85 mol per ture of hydrogen peroxide and a nitrile selected from the epoxide group) as the curing agent, are introduced into group consisting of acetonitrile, adiponitrile, 1,3-di(cy a glass vessel in a thermostatic heating bath at 80' C., anoethyl)-5,5-dimethylhydantoin, phthalonitrile or benzo and the gel time was determined. Gelling did not yet oc 25 nitrile. cur over the course of 1440 minutes at 80° C.; the bath 2. Process according to claim 1, characterized in that temperture was therefore raised to 120° C.; gelling then benzonitrile is used as the nitrile. occurred within 180 minutes. 3. Process according to claim 1, characterized in that (b) Analogously to the description under (a), the the epoxidation is carried out in the temperature range of gelling time of a homogeneous mixture of hexahydro 30 5-60 C, phthalic anhydride and a triglycidyllisocyanurate (TGIC 4. Process according to claim 1, characterized in that II) manufactured according to the process of French the epoxidation is carried out in the pH range of 8.5 to patent specification 1,570,826, reaction of cyanuric acid 10.0. with epichlorohydrin, is determined in a comparison ex 5. Process according to claim 1, characterized in that periment. 35 1.0-1.3 mols of nitrile and 1.1 to 1.4 mols of hydrogen The sample had gelled after 70 minutes at 80° C. The peroxide are employed per mol of C=C double bond of triglycidylisocyanurate manufactured according to the in the triallylisocyanurate. vention hence has a much longer pot-life. 6. Process according to claim 1, characterized in that TGIC I (according to the invention): gelling time with 300-1500 ml. of methanol are employed as the solvent hexahydrophthalic anhydride is 1440 minutes/80 40 per mol of C=C double bond of the triallylisocyanurate. C.--180 minutes/120° C. 7. Process according to claim 1, characterized in that TGIC II (commercially available): gelling time with Na2HPO4 is added as a buffer substance. hexahydrophthalic anhydride is 70 minutes/80 C. 8. Process according to claim 7, characterized in that 0.5 to 5.0 g. of Na2HPO are used permol of C=C double (C) Properties of mouldings 45 bond of the triallylisocyanurate. The following casting resin mixtures (a) and (b) were manufactured by homogeneous mixing of the components References Cited at 80 C, cast into aluminium moulds of 4 mm. wall UNITED STATES PATENTS thickness and then uniformly cured for 3 hours at 80 50 3,053,856 9/1962 Payne et al. ------260-348.5 C.--16 hours at 140 C: (a) 380 parts of the triglycidyllisocyanurate manu FOREIGN PATENTS factured according to Example 1 (TGIC I) with 9.0 epoxide equivalents/kg, --513 parts of hexahydrophthalic 941,507 11/1963 Great Britain ------260-248 anhydride. (b) 100 parts of a triglycidyllisocyanurate manufac 55 OTHER REFERENCES tured according to French patent specification 1570,826, Ogata et al.: Tetrahedron, 1964, vol. 20, pp. 206.5-8. with 9.3 epoxide equivalents per kg, -128 parts of hexahydrophthalic anhydride, JOHN FORD, Primary Examiner