Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-09-19
2003-08-26
Gerstl, Robert (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C564S373000, C564S463000
Reexamination Certificate
active
06610859
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to polymerization initiators, and more particularly to anionic polymerization initiators having protected amine functionality, as well as processes for making and using the same and polymers prepared using the initiators.
BACKGROUND OF THE INVENTION
Olefinic containing monomers can be polymerized using organo-alkali metal initiators, such as butyllithium. The resultant intermediate polymer contains an active alkali metal end group, which can be subsequently reacted with a suitable protonating, functionalizing, or coupling or linking agent to replace the alkali metal with a more stable end group. In many applications, it can be useful to react the polymer living end with a functionalizing agent, such as ethylene oxide, to provide a polymer having a terminal functional group, such as a hydroxyl, carboxyl, or amine group.
Telechelic polymers contain two functional groups per molecule at the termini of the polymer and are useful in a variety of applications. For example, telechelic polymers have been employed as rocket fuel binders, in coatings and sealants, and in adhesives. One approach that has been used to prepare telechelic polymers is the generation and subsequent functionalization of a “dilithium initiator.” A dilithium initiator can be prepared by the addition of two equivalents of secondary butyllithium to meta-diisopropenylbenzene. The dilithium initiator is then reacted with suitable monomers, such as butadiene, to form a polymer chain with two anionic sites. The resultant polymer chain is then reacted with two equivalents of a functionalizing agent such as ethylene oxide.
While useful, gelation is frequently observed during the functionalization step. This leads to lower capping efficiencies (see, for example, U.S. Pat. No. 5,393,843, Example 1, wherein the capping efficiency was only 82%). Additional details of this gelation phenomena are described in U.S. Pat. No. 5,478,899. Further, this dilithium approach can only afford telechelic polymers with the same functional group on each end of the polymer chain.
Progress has been made in the synthesis of dihydroxy terminated polymers. For example, monofunctional silyl ether initiators containing alkali metal end groups are disclosed in GB 2,241,239. These monofunctional silyl ether initiators were demonstrated to be useful in producing polybutadienes having an alpha protected hydroxyl functional group. The living polymer can be reacted with suitable functionalizing agent such as ethylene oxide, and the silyl protecting group removed to provide a dihydroxy telechelic polymer.
Monofunctional ether initiators of the formula M—Z—O—C(R
1
R
2
R
3
) wherein M is an alkali metal, Z is a branched or straight chain hydrocarbon tether group, and R
1
, R
2
and R
3
are independently defined as hydrogen, alkyl, substituted alkyl, aryl or substituted aryl, have also been proposed as anionic polymerization initiators to introduce a protected hydroxyl functionality into a polymer. See U.S. Pat. No. 5,621,149. The hydrocarbon solubility of such initiators can be increased by chain extension of the initiator with a conjugated diene. See U.S. Pat. No. 5,565,526.
Anionic initiators containing a tertiary amine functionality have also been proposed for use in hydrocarbon solvent polymerizations. Such initiators have the general formula
M—Z—N—(C—R
1
R
2
R
3
)
2
wherein M is defined as an alkali metal selected from lithium, sodium and potassium; Z is defined as a branched or straight chain hydrocarbon connecting group which contains 3-25 carbon atoms; and R
1
, R
2
and R
3
are independently defined as hydrogen, alkyl, substituted alkyl groups, aryl or substituted aryl groups. See M. J. Stewart, N. Shepherd, and D. M. Service,
Brit. Polym. J
., 22, 319-325 (1990).
However, these amine functional initiators possess low solubility in hydrocarbon solvents (typically less than 0.3 Molar in aliphatic or cycloaliphatic solvents like hexane or cyclohexane). The addition of an ethereal co-solvent does increase the solubility of these initiators; however, this also increases the amount of 1,2-microstructure in the resultant polymer. See H. L. Hsieh and R. P. Quirk,
Anizionic Polymerization Principles and Practical Applications
, pp. 397-400. Various other techniques have been employed to increase the solubility of these initiators in hydrocarbon solvent. For example, chain extension of the initiator with a conjugated diene increased the solubility several fold. See U.S. Pat. No. 5,527,753.
The synthesis of diamino terminated polymers remains relatively unexplored. Nakahama reports the preparation of amino terminated polystyrene by trapping the dianion with an electrophile that contained a protected amine group. A high degree of functionality was achieved by this technique. See K. Ueda, A. Hirao, and S. Nakahama,
Macromolecules
, 23, 939-945 (1990). However, the reaction conditions (−78° C., THF solvent) were not practical for commercial production of these functionalized polymers.
El-Aasser et al. recently reported the preparation of amino terminated telechelic polybutadiene by a free radical approach. See J. Xu, V. L. Dimonie, E. D. Sudol, and M. S. El-Aasser,
Journal of Polymer Science. Part A: Polymer Chemistry
, 33, 1353-1359 (1995). Since this is a free radical synthesis, little control of molecular weight, molecular weight distribution, and position of the amine functional group was obtained.
SUMMARY OF THE INVENTION
The present invention relates to protected amine functionalized initiators and processes for making and using the same to prepare amine functionalized polymers. The initiators of the invention include a tertiary amine functionality. The amine functionality includes two protecting groups, which may be the same or different. When the protecting groups are different, the groups are selected so as to have differential stability under specified deprotection conditions. Accordingly one of the protecting groups can be selectively removed without removing the other protecting group. In this manner, secondary amine functionalized polymers can be readily prepared.
Specifically the initiators of the invention include compounds of the formula:
wherein:
M is an alkali metal selected from the group consisting of lithium, sodium and potassium,
Z is a branched or straight chain hydrocarbon connecting group which contains 3-25 carbon atoms, optionally substituted with aryl or substituted aryl;
Q is a saturated or unsaturated hydrocarbyl group derived by the incorporation of one or more unsaturated organic compounds, such as one or more compounds selected from the group consisting of conjugated diene hydrocarbons, alkenyl substituted aromatic compounds, and mixtures thereof, into the M—Z linkage;
n is from 0 to 5;
R
1
is a protecting group selected from the group consisting of aralkyl, allyl, tertiary alkyl, and methyl; and
R
2
can be the same as R
1
, with the proviso that when R
1
is methyl, R
2
is not C1-C4 alkyl, or R
2
can be different from R
1
, in which case R
2
is selected from the group consisting of alkyl, substituted alkyl, alkoxy, substituted alkoxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, cycloalkyl, substituted cycloalkyl, heterocycloalkyl, and substituted heterocycloalkyl, with the proviso that when R
2
is not the same as R
1
, then R
2
is more stable under conditions used to remove R
1
,
or R
1
and R
2
together with the nitrogen atom to which they are attached form
wherein y is from 1 to 4 and each R
11
is independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, cycloalkyl, substituted cycloalkyl, alkoxy, substituted alkoxy, heteroaryl, substituted heteroaryl, heterocycloalkyl, and substituted heterocycloalkyl.
In especially advantageous embodiments of the invention, the protecting group R
1
is aralkyl, preferably benzyl or a benzyl derivative; allyl; or tertiary alkyl, preferably tertiary butyl. In this aspect of the invention, advantageously R
2
is the same as R
1
. Alternatively, in
Brockmann Thorsten Werner
Hall Randy W.
FMC Corporation
Gerstl Robert
Myers Bigel & Sibley Sajovec, PA
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