Title of Invention

PROCESS FOR PREPARING TRIALLYL ISOCYANURATE (TAIC)

Abstract The invention is directed to an improved, reliably performable process for preparing triallyl isocyanurate (TAIC) by Cu2+-catalysed rearrangement of triallyl cyanurate (TAC) at at least 90° C. According to the invention, TAC and, if required, also a Cu2+ catalyst and solvent are fed continuously to a start reaction mixture after onset of the in tially inhibited isomerization reaction, the isomerization is performed at from 90 to 160° C and an amount of reaction mixture equivalent to the amount of reactant is drawn off continuously and sent to the workup. Preference is giver to effecting the isomerization in TAIC as the reaction medium.
Full Text Process for preparing triallyl isocyanurate (TAIC)
Description
The invention is directed to an improved, reliably
performable process for preparing triallyl isocyanurate
(TAIC) by Cu2+-catalysed rearrangement of triallyl
cyanurate (TAC) at at least 90°C.
Triallyl isocyanuiate [triallyl-s-triazine-
2, 4, 6(1H,3H,5H)-trione; referred to as TAIC in
abbreviated form] is a trifunctional polymerizable
monomer which finds use as a crosslinking component for
high-value thermoplastics and synthetic rubber, and
also as a raw material for the production of flame
retardants. Moreover, TAIC also finds use as a copoly-
merization component in the polymerization of vinylic,
allylic and acrylic mononers.
TAIC can be prepared essentially by three methods:
In the process accord..ng to US patent 3,322,761,
triallyl isocyanurate (T'AIC) is obtained by reacting
cyanuric acid with allyl chloride and sodium hydroxide
in the presence of copper chloride as a catalyst. A
disadvantage in this piocess is the high excess of
allyl chloride (6 mol,mol o:: cyanuric acid), the
formation of allyl alcohol, and diallyl isocyanurate as
hydrolysis products, anc the complicated removal and
purification of the TAIC obtained.
An industrially more useiul route to the preparation of
TAIC is the trimerizatior of allyl isocyanate formed in
situ. In this case, as c escribed by way of example in
JP 52-109627 or DE-A 28 S 084, an alkali metal cyanate
is reacted with allyl chloride in a dipolar aprotic
solvent, preferably dimehylfornamide, at temperatures
around 130°C. Although the process affords good yields,
a disadvantage is the occurrence of large amounts of

organically contaminated sodium chloride, the use of
toxic solvents and tha quite expensive purification
steps which are neede 1 in crder to provide a TAIC
quality which satisfies market requirements.
A third method for the preparation of TAIC is the
Claisen rearrangement of tr:.allyl cyanurate (TAC) ,
which is itself obtained on the industrial scale by
reaction of cyanuric chloride with allyl alcohol, in
the presence of catalysts (cat.).

In the process accorcing to EP 0 078 567 Al, the
rearrangement of TAC to TAIC is performed in the
presence of quaternary ammorium compounds. Disad-
vantages in this proces.s are the long reaction times
and the risk of spontaneous polymerization of the
entire mixture. In the rsworking of the process by the
inventors of the presert application, polymerization
with temperatures of > 200 °C and vigorous evolution of
smoke occurred after a few minutes.
The isomerization of cyarurates to isocyanurates in the
presence of metallic copper is described by Balitskaya
et al. in Ukr. Khim. Zt . 40(8), 881, (1974). In the
presence of 20% copper, the rearrangement of TAC to
TAIC at 70°C is said to have ended within 5 h. Attempts
of the inventors of the present application and also of
EP 0 078 567 Al, in contrast, did not lead to any such
result.

SU patent 1121259 teaches a process for preparing TAIC
by isomerizing TAC in toluene in the presence of copper
and a reducing agent from the group of tin (II) chloride
and iron (II) chloride it temperatures of 95 to 130°C.
The molar ratios of th= components here are: TAC (1);
toluene (1.3-4.1); copper (0.39-0.8); reducing agent
(0.0013-0.0026). Depending on the temperature and the
catalyst concentration, the reaction times are 1 to
20 h. Disadvantages hero are the very high catalyst use
and the long reaction t.mes.
SU patent 1121260 claims the isomerization of TAC to
TAIC in toluene as a solvent using a Cu salt, such as
CuCl2 • 2H20 • CuAc2 • 2HzO, CJCI, CuS04 • 5H20, CuF2 •
2H20, Cu(N03)2 • 3H20 anc CuBr, as a catalyst. The molar
TAC:toluene:catalyst ratios are specified as 1:(1.3-
4) : (0.0015-0.0073) . The processes of SU 1121259 and
SU 1121260 are perforned batchwise, catalyst being
initially charged in a glass reactor and being admixed
with a portion of a solution of TAC in toluene. After
heating to about 100°C, the remaining amount of the
TAC/toluene mixture is added within 3 h and the
reaction is continued for 2 h; thereafter, the reaction
mixture is worked up by distillation.
In the reworking of the process of SU 1121260, it has
been found that the orocedure described cannot be
operated reliably and safely for a preparation of the
triallyl isocyanurate on the industrial scale. Even
though the SU document teaches the use of a minimum
amount of toluene in order to prevent an explosion-like
process, uncontrollable process states occurred in the
reworking of the process. This document does not give
any information as to how the process can be operated
on the industrial scale and continuously without any
safety risk.
A further disadvantage of the process described in

SU 1121260 is the formation of polymerization products:
since the TAIC remains in the reactor over a long
period, it is possible, as the inventors of the present
application have found for up to 20% by weight of
oligomers to form, which are not detectable in the gas
chromatogram but give rise to a precipitate with
methanol after the solvent has been distilled off. It
has also been found ;hat the use of the hydrate-
containing Cu salts taught in the SU document leads
either to an unsatis.factory conversion or to the
formation of a by-product. As experiments by the
Applicant have found, water eliminates allyl alcohol
from TAC under the catalytic action of the copper
salts, so that diallyl isocyanurate is formed as a by-
product.
It is accordingly an object of the invention to
indicate the provision of an improved and reliably
performable process foe preparing TAIC by Cu salt-
catalysed rearrangement of TAC. The process should be
simple to perform. In a further object, embodiments by
which the use of solver t can be minimized should also
be indicated. In a further object, TAIC should be
obtainable in high yiel i and high purity. In a further
object, the process should largely avoid the formation
of oligomeric and polymeric by-products.
The aforementioned objects and further objects as are
evident from the description are achieved by the
process according to the invention according to the
main claim and in particular embodiments according to
the subclaims. The process according to the invention
is a continuous process which overcomes the problems of
the batch process.
A process has been found for preparing triallyl
isocyanurate (TAIC), comprising rearrangement of
triallyl cyanurate (TACi in the presence of a Cu salt

at a temperature of at least 90°C, which is charac-
terized in that TAC end a Cu2+ salt are introduced
continuously in an amount of 0.01 to 1% by weight of
Cu2+, based on TAC, separately from one another or in
the form of a mixture Comprising these components, into
a TAIC-containing reaction mixture which has been
formed at at least 90°C by rearrangement of TAC in the
presence of a Cu2+ salt and has not been cooled below
90°C thereafter, the rearrangement is performed under
these conditions while maintaining a temperature in the
range of 90 to 160°C ard an amount of reaction mixture
corresponding to the addition is discharged
continuously and TAIC is isolated therefrom.
The isomerization of TAC to TAIC under Cu salt
catalysis is, as has beun found, very probably an auto-
catalytic process with an incubation time which depends
upon the type of catalyst used, upon the catalyst
concentration, upon the temperature and upon the
solvent used.
The isomerization proceeds with release of
700 kJoule/kg of TAC. Measurements in a Contraves
calorimeter additionally showed that more than 90% of
the total exothermicity is released within approx.
5 min. This behaviour led to the indicated problems of
the process known to da:e. These problems are solved by
the process according tc the invention.
In the process according to the invention, the start
phase and hence the composition of the start mixture of
the reaction are highly significant with regard to safe
performance of the overall reaction. It is important
that the start mixture originated from the Cu2+-
catalysed isomerization of TAC to TAIC and had not been
cooled to a temperature below 90°C before use. Cooling
of the start mixture comprising TAIC and Cu2+ to values
below 90°C deactivates the catalyst or catalyst

complex; simple heatinc of the mixture does not result
in reactivation; instead, another incubation time has
to be passed through after adding TAC. Use of an
inventive reaction mixture into which TAC is introduced
continuously prevents spontaneous reactions which may
occur before the incubation time has ended and may be
uncontrollable.
In a particular embodiment, the isomerization is
performed in the riesence of a polymerization
inhibitor; examples are hydroquinone, hydroquinone
monomethyl ether, tert-butylated phenols and alkyl-
phenols. Such inhibitors are often already present in
the TAC.
The dependence of the incubation time upon the catalyst
concentration in toluene as the solvent follows from
Table 1.

The measurements were effected in 100 ml flasks which
were present in a silicone bath at 120 ± 2°C. The
commencement of the isomerization is recognizable by a
sudden temperature rise which leads to vigorous boiling
of the entire flask contents. Gas chromatography
analyses show consistently that virtually no reaction
has taken place beforehand. The TAC:toluene volume
ratio was 1:2; the catalyst used was CuCl2 • 2H2O; the

amount in % is based on TAC.
Apart from aromatic hydrocarbons, there are, as has
been found, further solvent croups in which the iso-
merization can be performed. Apart from toluene,
suitable solvents are a orotic solvents which are stable
with respect to a combination of Cu2+ and TAC, such as
aliphatic, cycloalipha ,ic or aromatic hydrocarbons,
diesters of carbonic acid, aromatic and aliphatic
carboxylic acid esters and ethers. In a preferred
embodiment, TAIC itself serves as a solvent and means
of evaporative cooling. Table 2 shows some solvents and
the incubation times del ermined with them.

The selection of the so .vents is, when operation is not
to be effected under pressure, determined by the
boiling temperature, which should preferably be in the
range of 110 to 160°C. A reaction temperature of 110 to
140°C has been found to be favourable. Higher-boiling
solvents such as TAIC can be transferred into the
favourable working range by applying a vacuum.
Alcohols, ketones, acid anhydrides and many dipolar

aprotic solvents are less suitable or completely
unsuitable since they form by-products.
All of the problems which afflict the isomerization of
TAC are circumvented by the continuous process
according to the invention, since operation is effected
here with small operating volumes and very short
residence times. This irinimizes the risk potential of a
spontaneous polymerization and prevents polymerization
as a result of long thermal stress.
The basis of the prccess is the discovery that a
reaction, once it has set in :.n a Cu2+-containing start
reaction mixture, can be maintained by supplying TAC or
a mixture of TAC and solvent in which catalyst may
additionally be dissolved or be dispersed ultrafine,
when an amount equivalent to the amount supplied can
simultaneously be withdrawn from the reaction vessel,
specifically in the form of distilled-off TAIC or in
the form of a solution of TAIC and Cu2+ catalyst in the
particular solvent.
Copper(II) chloride exhibits the surprising property of
dissolving readily in nixtures of toluene and TAC with
a blue colour but onl^ poorly in the pure starting
components. This system is therefore particularly
preferred, also owing to th= ready availability of
CUCI2. Sparingly solubl 3 Cu2+ catalysts can be used for
the continuous process only when they have been ground
to microfine particles by suitable dispersion units
before or during the reaction.
In a preferred embodiment, the Cu2+ catalyst used is an
anhydrous salt, especially a salt from the group of
CuCl2, CuBr2, CUI2, Cu(HCOO)2 where R = alkyl or aryl.
Typically, the rearrangement is performed in the
presence of 0.01 to 1% by weicht of Cu2+, in particular
0.02 to 0.2% by weight of Cu2+, based on the TAIC

present in the start reaction mixture converted - TAC
has been converted virtually quantitatively a few
minutes after its addition. When catalyst-containing
reaction mixture is drawn off to the degree in which
TAC and solvent are supplied, the catalyst concen-
tration also has to be Maintained by supplying
catalyst.
In a preferred embodimeit, the reaction is performed in
the absence of an extraneous solvent, i.e. TAIC is the
reaction medium. In this case, TAC is introduced
continuously into a TAIC-containing start reaction
mixture which has beei formed at at least 90 °C by
rearrangement of TAC in the presence of a Cu2+ salt and
has not been cooled below 90°C thereafter, the
rearrangement is performed at 90 to 160°C, in
particular 110 to 14(i°C, and TAIC which forms is
distilled continuously out of the reaction mixture
under reduced pressure, the addition rate of TAC (g of
TAC/min) corresponding essentially to the distillation
rate of TAIC (g of TAIC/min). Advantages of this
embodiment are dispensing with an extraneous solvent,
the use of catalyst only once and the simple workup.
In a preferred embodimeit, the process according to the
invention can be impleoented by the following process
steps:
Start reaction: A mixture of TAC, solvent and catalyst
is introduced into a reaction vessel. The
TAC:solvent:Cu2+ ratio, in order to reliably capture the
exothermicity and allow a relatively rapid start, is
selected at about 250 M! of TAC: 750 ml of solvent: 3 g
of CuCl2 per litre of solution. The reactor is heated
to internal temperature 110 to 115°C and stirred. After
approx. 15 to 17 min, the rearrangement to TAIC sets
in, which is recognized by vigorous boiling of the
reactor contents.

Continuous method: Once the reaction has set in, a
mixture of TAC, sol/ent and catalyst is pumped
continuously into the ] eactor, specifically in such an
amount that the mean residence time of the TAC is not
less than approx. 10 md r. and not more than 60 min. The
amount of solvent in the solution supplied is variable
within wide limits, tut the content of solvent is
preferably reduced in order to reduce distillation
work.
It is in principle also possible to work without
solvent; in this case, the TAIC which forms serves as
the reaction medium, a;id the heat of isomerization is
removed here by evaporative cooling under reduced
pressure. The ratio of the reactants can vary in the
TAC: solvent volume ratio of about 1:4 to 1:0. The
catalyst concentration can, once the reaction has set
in (start reaction), b= lowered very greatly. Concen-
trations of 0.15 g cf Cu2+ per litre of reactant
solution are still effective.
Isolation of the TA.IC: The same amount of
TAIC/solvent/catalyst as synchronously pumped out of
the reactor as that in which reactants are added. When
CUCI2 and toluene or ciethyl carbonate are used, the
incoming TAC solution has a bLue colour, the withdrawn
TAIC solution a green colour. The reaction is monitored
by gas chromatography. Once the solvent has been
distilled off, the TAIC is purified by vacuum
distillation. The bottom effluent contains the Cu2+. In
a particular embodiment of the process, disposal of the
Cu2+ can be largely dispensed with: in this case, the
bottoms of the vacuum distillation, whose proportion is
set somewhat higher, are puuped directly and while
still hot to the reaction vessel, and ensure the
maintenance of the catalyst concentration here.
However, the activity is preserved only when the

temperature of the bottom is kept at at least 90 °C;
after cooling of the bottom to room temperature and
reheating, the reaction can no longer be maintained.
The process according to the invention can be performed
reliably and without r..sk of a spontaneous reaction. A
rapid reaction and continuous method largely avoid the
formation of by-products and oligomers.
The examples which follow are intended to illustrate
the process in detail:
Example 1
A solution of 25 ml of TAC, 0.3 g of CuCl2 (anhydrous)
in 75 ml of toluene was introduced into a jacketed
stirred vessel of capacity 500 ml, which was heated by
a thermostatted silicoie bath adjusted to 130°C. The
internal flask temperature was adjusted to 113 to
115°C. After 16 min, vigorous reflux set in; the
initially blue solution had been converted to a dark
olive green solution. After the reaction had abated,
10 ml/min of a mixture of 3000 ml of TAC, 3.0 g of
CuCl2 and 3000 ml of toluene were pumped in
continuously by means of a metering pump. At the same
time, 10 ml/min of the reaction solution were withdrawn
by means of a 2nd metering pump. The reaction
temperature rose to approx. 123 to 125°C.
When the system is operated with higher TAC
concentration (higher space-time yield), the reaction
temperature is limited to max. 140°C by applying an
appropriate vacuum.
The conversion rate was > 99.9%. The by-product formed
by residual water in TAC ard toluene was a little
diallyl isocyanurate. The process was operated without
any problem over a period of 10 h.

Example 2
Process according to Example 1, except that diethyl
carbonate was used as the solvent. The reaction mixture
for the start reaction was prepared by mixing TAC with
diethyl carbonate in a volume ratio of 1 to 3 and
adding 2.5 g of CuCl2 per litre of reactant solution,
and then ultrafine grinding in a wet mill. After
initially charging 200 nL of this solution, heating to
130°C and waiting for the stait reaction, 15 ml/min of
a homogeneous dispersion of TAC and diethyl carbonate
in a volume ratio of L to 1 and 0.4 g of CUCI2 per
litre of solution were pumped in and, in parallel,
15 ml/min of green THIC solution were withdrawn. The
conversion of the TAC was > 99.8%. This procedure was
maintained over a pericd of 8 h without disruption or
decline in the yield anc purity.
Example 3
Process according to Example 1, except that, after the
onset of the start reaction, a. homogeneous, ultrafine-
dispersed mixture of LO00 ml of TAC and 0.25 g of
anhydrous CUCI2 was metered in. The amount metered in
was 10 ml/min; at the same time, 10 ml/min of reaction
solution were pumped oul . Since the reaction vessel had
become low in toluene in the course of time as a result
of distilling-off toluene, the operating temperature in
the reactor rose continually. In order to prevent poly-
merization, a vacuum was applied at internal flask
temperature 140°C in order to maintain a constant
working temperature thr 3ugh evaporative cooling of the
TAIC formed. The vacuum necessary for this purpose was
2.0 to 3.0 hPa. This process afforded TAIC with a
purity of 98.5%; the isomerization rate of the TAIC was
> 99.8%.

Claims
1. Process for pieparinc triallyl isocyanurate
(TAIC), comprising rearrangement of triallyl
cyanurate (TAC) in the presence of a Cu salt at a
temperature of at least 90°C,
characterized in 1 hat
TAC and a Cu2+ salt are Lntroduced continuously in
an amount of 0.01 to 1% by weight of Cu2+, based on
TAC, separately from one another or in the form of
a mixture comprising these components, into a
TAIC-containing reaction mixture which has been
formed at at leas. 90 °C by rearrangement of TAC in
the presence of a Cu2+ salt and has not been cooled
below 90°C thereafter, the rearrangement is
performed under these conditions while maintaining
a temperature in the range of 90 to 160CC and an
amount of reaction mixture corresponding to the
addition is discharged continuously and TAIC is
isolated therefrom.
2. Process according to Claim 1,
characterized in that
the rearrangement of TAC to TAIC is performed in
the presence of an aprot.LC solvent which is stable
at 90 to 160°C with respect to a combination of
Cu2+ and TAC.
3. Process according to Claim 1 or 2,
characterized in that
TAC and, if required, additionally Cu2+ salt are
introduced into the reaction mixture in the form
of an aprotic solvent which is stable at 90 to
160°C with respect to a combination of Cu2+ and
TAC.
4. Process according to Claim 2 or 3,
characterized in that

TAC and a Cu2+ salt are introduced separately or in
a mixture, where the individual components or the
mixture may additionally comprise an aprotic
solvent which is stable at the reaction
temperature with respect to a combination of Cu2+
and TAC, into a TAIC-containing reaction mixture
which has been formed at 90 to 160CC by
rearrangement of TAC in the presence of a Cu2+ salt
and of an aprotic solvent which is stable at the
reaction temperature mentioned with respect to a
combination of Cu2" and TAC.
5. Process according to one of Claims 2 to 4,
characterized in that
the aprotic solvent used is an aliphatic, cyclo-
aliphatic or aromatic hydrocarbon, a diester of
carbonic acid, an ester of an aliphatic or
aromatic carboxylic acid or an ether.
6. Process according to one of Claims 1 to 5,
characterized in that
the rearrangement is performed at a temperature in
the range from 13 0 to 14 0°C.
7. Process according to one of Claims 1 to 6,
characterized in that
the Cu2+ salt used is an anhydrous salt, especially
a salt from tire group of CuCl2, CuBr2, Cul2,
Cu(RCOO)2 where P = alkyl or aryl.
8. Process according to Claim 7,
characterized in that
the catalyst fed continuously to the reaction
mixture is CUCI2 in an amount of 0.02 to 0.2% by
weight of Cu2+, based on TAC.
9. Process according to one of Claims 1 to 8,
characterized in that

the Cu2+ salt fed in continuously is a bottom
product which has been ootained by distilling TAIC
out of the reaction mixture drawn off con-
tinuously, the temperature of the bottom product
not having been cooled co a temperature of below
90°C before its reuse.
10. Process for preparing TAC, comprising
rearrangement of triallyl cyanurate (TAC) in the
presence of a Cu salt at a temperature of at least
90°C,
characterized in that
TAC is introduced continuously into a TAIC-
containing start reaction mixture which has been
formed at at least 90°C by rearrangement of TAC in
the presence of a Cu2+ salt and has not been cooled
below 90°C thereafter, the rearrangement is
performed under these conditions while maintaining
a temperature in the range of 90 to 160 °C, and
TAIC which forms Ls distilled continuously out of
the reaction mixture under reduced pressure, the
addition rate of TAC (g of TAC/min) corresponding
essentially to the distillation rate of TAIC (g of
TAIC/min).
11. Process according to Claim 10,
characterized in that
the rearrangement is performed in the presence of
0.01 to 1% by weight of Cu2+, based on the TAC used
to prepare the start reaction mixture.
12. Process according to Claim 10 or 11,
characterized in that
the rearrangement is performed at 110 to 140°C.
13. Process according to one of Claims 10 to 12,
characterized in that
TAC is added at such a rate that the TAIC

distilled off is virtually free of unconverted
TAC.
Dated this 17* day of DECEMBER 2008

OF L S DAVAR & CO.
APPLICANTS' AGENT

The invention is directed to an improved, reliably performable process for preparing triallyl isocyanurate (TAIC) by Cu2+-catalysed rearrangement of triallyl cyanurate (TAC) at at least 90° C. According to the invention, TAC and, if required, also a Cu2+ catalyst and solvent are fed continuously to a start reaction
mixture after onset of the in tially inhibited isomerization reaction, the isomerization is performed at from 90 to 160° C and an amount of reaction mixture equivalent to the amount of reactant is drawn off continuously and sent
to the workup. Preference is giver to effecting the isomerization in TAIC as the reaction medium.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=ACdcoQZJxF9LUbcrfgh0qQ==&loc=wDBSZCsAt7zoiVrqcFJsRw==


Patent Number 269291
Indian Patent Application Number 5145/KOLNP/2008
PG Journal Number 42/2015
Publication Date 16-Oct-2015
Grant Date 14-Oct-2015
Date of Filing 17-Dec-2008
Name of Patentee EVONIK DEGUSSA GMBH
Applicant Address RELLINGHAUSER STRASSE 1-11, 45128 ESSEN
Inventors:
# Inventor's Name Inventor's Address
1 DR. PETER WERLE IM BÖRNER 43 63571 GELNHAUSEN
2 DR. MANFRED SCHMIDT LANGGASSE 27 63571 GELNHAUSEN
3 KLAUS STADTMÜLLER HEMSBACHER STR. 3 63755 ALZENAU
4 MARTIN TRAGESER SCHULSTR. LA 63571 GELNHAUSEN-HÖCHST
5 DR. HANS-PETER KRIMMER WIESENSTRAβE 3 84558 KIRCHWELDACH
PCT International Classification Number C07D 251/34
PCT International Application Number PCT/EP2007/055879
PCT International Filing date 2007-06-14
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10 2006 032 167.7 2006-07-12 Germany