Organic compounds -- part of the class 532-570 series – Organic compounds – Four or more ring nitrogens in the bicyclo ring system
Reexamination Certificate
2000-06-15
2003-10-21
Ford, John M. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Four or more ring nitrogens in the bicyclo ring system
C544S107000, C544S193000, C548S335100, C548S358100, C558S017000
Reexamination Certificate
active
06635761
ABSTRACT:
The invention relates to a catalyst used for the catalytic cyclotrimerization of monomeric isocyanates to (poly)isocyanurate polyisocyanates and to a method of preparing (poly)isocyanurate polyisocyanates by catalytic cyclotrimerization of monomeric isocyanates.
It is known to prepare isocyanate trimers by catalytic trimerization of an isocyanate using a catalyst based on a quaternary ammonium hydroxide.
Thus, EP-003 765 describes the partial cyclo-trimerization of isophorone diisocyanate (IPDI or 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane) using a quaternary hydroxyalkylammonium hydroxide as catalyst.
Generally speaking, catalysts based on a quaternary ammonium hydroxide have a very high reactivity, which makes it difficult to control the trimerization reaction, especially when the initial isocyanate is an aliphatic or cycloaliphatic isocyanate.
In addition, control of the reaction is made still more difficult owing to the possible variations in the hydrolysable chlorine content of the initial isocyanate, which is a result of the phosgenation process used to synthesize these isocyanates.
It is also known that the effectiveness of the catalyst is reduced when the content of hydrolysable chlorine in the IPDI increases.
The content of hydrolysable chlorine also effects the coloration of the crude reaction product, which goes up as the amount of chlorine increases.
U.S. Pat. No. 4,040,992 describes, moreover, catalysts for the catalytic trimerization of isocyanates, the said catalysts being quaternary ammonium salts whose anion is represented by OH
−
or by the formula
−
OOC—(O)
a
—Y in which Y is selected from:
a hydrogen atom,
an alkyl group having 1 to 20 carbon atoms,
an alkenyl group having 2 to 15 carbon atoms,
a cycloalkyl group having 3 to 6 carbon atoms,
a phenyl group,
an alkylphenyl group having 1 to 9 carbon atoms in the alkyl radical or in the groups attached to the phenyl ring,
a benzyl group,
a carbamate group,
an alkylbenzyl group having 1 to 9 carbon atoms in the alkyl radical or in the groups attached to the benzyl ring, and
a group CH
(3−b)
Z
(b)
in which b is an integer from 1 to 3 and Z is OH, CN, Cl, an alkoxy group of 1 to 5 carbon atoms or a phenyl or methoxyphenyl group, or
Z is (CH
2
)
d
COOR in which d is an integer from 0 to 4 and R is a hydrogen atom or an alkyl group having up to 20 carbon atoms;
and a is zero or 1.
However, the anions illustrated in this patent are all anions derived from an alkylcarboxylic acid. Generally speaking, the catalysts described in this document do not allow the desired objective to be attained.
The objective of the invention is to provide a catalyst for cyclotrimerizing isocyanates, especially diisocyanates, which allows the reaction to be controlled while giving an acceptable degree of conversion, which should not substantially be dependent on the content of hydrolysable chlorine of the initial isocyanate, and which makes it possible to obtain a product whose coloration is not particularly marked.
The objective of the invention is also to provide a method of the catalytic trimerization of isocyanates, in particular for the partial cyclotrimerization of diisocyanates, which should be easy to control, which has little or no dependence on the content of hydrolysable chlorine in the monomeric isocyanate, and which as far as possible reduces the coloration of the crude reaction product.
It has now surprisingly been found that the catalysts of ionic type whose counteranion is the hydrogencarbonate anion allow the desired objective to be attained.
These catalysts are formed by a bulky monoatomic or polyatomic cation either as such or in the form of a complex formed with a complexing agent, in particular of the cryptand type.
The invention therefore relates to the use as catalyst for the cyclotrimerization reaction of isocyanates of a hydrogencarbonate of a cation which either as it is or in the form complexed with a complexing agent has an average molecular or ionic radius of more than 1 Å, preferably greater than 1.5 Å, as defined in the tables of Shannon and Prewitt in Acta Cris., 1969, vol. B25, page 925, and which is at least partially soluble in the reaction medium.
Advantageously, the cation is selected from the cations of bulky alkali metals, especially rubidium and caesium.
The cation may also consist of a light alkali metal cation in complexed form. Mention may be made in particular of sodium and potassium cations complexed by crown ethers.
The cation may likewise consist of a molecular species in which all of the atoms are linked by covalent bonds.
In this respect mention may be made of the onium-type cations, of which representative species are phosphoniums, sulphoniums and quaternary ammoniums.
Particular preference is given to the hydrogencarbonates of cations of the following formula I:
in which
Q is a nitrogen, phosphorus or sulphur atom; and
R
1
, R
2
, R
3
and R
4
are identical or different and are unsubstituted or hydroxylated alkyl groups having 1 to 20 carbon atoms, cycloalkyl radicals having 4 to 15 carbon atoms which are unsubstituted or substituted by hydroxyl groups, aralkyl radicals having 7 to 15 carbon atoms which are unsubstituted or substituted by hydroxyl groups, or aryl radicals having 6 to 15 carbon atoms which are unsubstituted or substituted by hydroxyl groups, or else, when Q is N, two of the radicals R
1
, R
2
, R
3
or R
4
may also form, together with the nitrogen atom and, if appropriate, with a heteroatom, especially oxygen or nitrogen, a heterocyclic ring having 4 to 6 carbon atoms, or else, when Q is N, the radicals R
1
, R
2
and R
3
are each ethylene radicals which form, in combination with the quaternary nitrogen atom and another, tertiary nitrogen atom, a bicyclic triethylenediamine skeleton, or one of R
1
to R
4
is a group
in which R
5
, R
6
and R
7
are identical or different and are hydrogen, an OH group, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, an alkynyl group having 3 to 6 carbon atoms, a hydroxyalkyl group having 1 to 9 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a group R
8
—O—(CH
2
)
n
in which R
8
is hydrogen, an alkyl radical having 1 to 12 carbon atoms, a cycloalkyl radical having 4 to 10 carbon atoms, an aralkyl radical having 7 to 10 carbon atoms or an aryl radical having 6 to 10 carbon atoms; and n is an integer ranging from 1 to 6; R
7
can also be a group OCOR
9
in which R
g
is a C
1
-C
6
alkyl group, preferably a C
1
-C
4
alkyl group and, more particularly, the methyl group.
The cation is represented more particularly by the following general formula II:
R
1
, R
2
and R
3
are identical or different radicals and are unsubstituted or hydroxylated alkyl groups having 1 to 20 carbon atoms, cycloalkyl radicals having 4 to 15 carbon atoms which are unsubstituted or substituted by hydroxyl groups, aralkyl radicals having 7 to 15 carbon atoms which are unsubstituted or substituted by hydroxyl groups, or aryl radicals having 6 to 15 carbon atoms which are unsubstituted or substituted by hydroxyl groups, it also being possible for two of the radicals R
1
, R
2
or R
3
to form, together with the nitrogen atom and, if appropriate, with an oxygen heteroatom or another nitrogen heteroatom, a heterocyclic ring having 4 to 6 carbon atoms, or else the radicals R
1
, R
2
and R
3
are each ethylene radicals which form, in combination with the quaternary nitrogen atom and another, tertiary nitrogen atom, a bicyclic triethylenediamine skeleton, R
5
, R
6
and R7 are identical or different and are hydrogen, an OH group, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, an alkynyl group having 3 to 6 carbon atoms, a hydroxyalkyl group having 1 to 9 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or a group R
8
—O—(CH
2
)
n
in
Bernard Jean-Marie
Revelant Denis
Balasubramanian Venkataraman
Burns Doane Swecker & Mathis L.L.P.
Ford John M.
Rhodia Chimie
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