Chemistry of carbon compounds – Miscellaneous organic carbon compounds – C-metal
Reexamination Certificate
1998-02-05
2003-12-09
Shaver, Paul F. (Department: 1621)
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
C-metal
Reexamination Certificate
active
06660191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to novel 1,5-diethenylnaphthalene compounds, to a process for the preparation thereof, and to the conversion of same via reaction with an organic alkali metal compound into bifunctional primers for anionic polymerization mechanisms.
2. Description of the Prior Art
Organic alkali metal compounds, such as organodilithium compounds, are known to this art as especially advantageous bifunctional primers for anionic polymerization reactions, since the three-step procedure required to prepare ABA sequenced copolymers by monofunctional priming is reduced by one step through the use of bifunctional primers. These latter are also important in copolymerization reactions, when the second monomer cannot re-initiate polymerization of the first.
Numerous sequenced copolymers have been prepared using alkali metal naphthalides as bifunctional primers. These bifunctional primers are efficacious only in polar reaction media, such a tetrahydrofuran, in particular for the polymerization of diene monomers. However, they cannot provide a polydiene microstructure having a high degree of 1,4-configuration (cis- or trans-).
In the event that a special microstructure, in general a 1,4-cis addition for polydienes, is desired, the anionic polymerization must be carried out in a nonpolar solvent utilizing the alkali metal, e.g., lithium, as the counter-ion. Unfortunately, and probably because of associated reagents, organic alkali metal compounds, such as organodilithium compounds, exhibit a low level of solubility in hydrocarbonaceous solvents. Tests for increased solubility using very small amounts of ether or amines indicated that these additives affect the microstructure of the diene block. The disadvantage presented by the seeding technique is a high dispersion index for the central sequence.
To date, many compounds have been described for their possible use as bifunctional lithium-containing primers which are soluble in nonpolar solvents.
For example, U.S. Pat. No. 4,200,718, at column 14, describes the compound corresponding to the formula:
which is reacted with secondary butyllithium to prepare [2,7-naphthalenediylbis(3-methyl-1-phenylpentylidene]-bis(lithium), a primer used for the anionic polymerization of butadiene.
Turgut Nugay and Savas Kucukyavuz, in
Polym. International
, 29, 195 (1992), describe the preparation of 1,5-diethenylnaphthalene and reaction thereof with secondary butyllithium in n-heptane, in the absence of any polar additive, thereby producing 1,5-bis(1-lithio-3-methylpentyl)naphthalene. This compound was easily isolated and the soluble monofunctional compounds removed. When dissolved in benzene (solubility: 3.2×10
−2
mole/liter), it was used a primer for the sequenced copolymeriztion of isoprene and styrene.
Nonetheless, need continues to exist to provide even better solubility in nonpolar solvents and enhanced control over the bifunctionality of such 1,5-bisubstituted naphthalene-containing primers.
SUMMARY OF THE INVENTION
Accordingly, a major object of the present invention is the provision of novel 1,5-diethenylnaphthalene compounds that avoid or conspicuously ameliorate the above disadvantages and drawbacks to date characterizing the state of this art.
Briefly, the present invention features compounds having the formula (I):
in which R
1
is a linear, branched, or cyclic alkyl radical having from 1 to 12 carbon atoms, or a substituted or unsubstituted aryl radical.
The alkyl radicals R
1
are preferably methyl radicals; the aryl radicals R
1
are preferably phenyl radicals.
The present invention also features a process for preparing the compounds (1), comprising, in a first step, reacting a compound having the formula (II):
with a compound having the formula (III):
R
1
—M (III)
in which R
1
is as defined above; and M is an alkali metal or M′Hal (M′ representing an alkaline earth metal, and Hal, a halogen), thereafter hydrolyzing the derivative thus formed to provide a compound having the formula (IV):
and, in a second step, dehydrating the compound having formula (IV), thereby providing the desired final product.
DETAILED DESCRIPTION OF BEST MODE AND PREFERRED EMBODIMENTS OF THE INVENTION
More particularly according to the present invention, in the first step of the process aspect thereof, to add the organometallic compound (III) to the compound (II), the respective reagents are employed in amounts of at least two moles of compound (III) per 1 mole of compound (II), preferably using an amount of compound (III) slightly in excess of the stoichiometric amount, such addition being carried out in an aprotic solvent medium (e.g., tetrahydrofuran, toluene, ethyl ether, benzene, ethylbenzene, cyclohexane, and mixtures thereof), the temperature being regulated depending on the reagents used, and the reaction time being approximately 6 to 24 hours. This reaction is followed by hydrolysis carried out under conditions resulting in the deactivation of the reaction product, whether by means of methanol acidified with acetic acid or via the use of a water/ice/hydrochloric acid mixture.
The second step entailing dehydration can be carried out, for example, in an acetic acid/sulfuric acid medium concentrated under reflux, the proportion of sulfuric acid in comparison with the acetic acid being 0.1% to 5% by weight; or in a toluene/paratoluene sulfonic acid medium.
The present invention also features a bifunctional primer, namely, of the product of the reaction of the compound of formula (I), as indicated above, with a compound having the formula (V):
R
2
—M″ (V)
in which M″ is an alkali metal, notably lithium or sodium; and R
2
is a C
1
-C
6
alkyl radical, a C
5
-C
12
cycloalkyl radical or an aromatic radical, with the proviso that the compound (V) can be an anionic polymer comprising a terminal carbanion R
2
and the counter-ion M″, said bifunctional primer being represented by the following formula (IV):
in which R
2
preferably is a secondary butyl group.
When M″ represents Li and when the organolithium compound (V) is an anionic polymer, thus affording a bifunctional primer providing star-shaped polymers, the polymeric carbanion R
2
may be a vinylaromatic polymer carbanion, such as polystyrene and poly(alpha-methylstyrene), or a diene-containing polymer carbanion such as polybutadiene and polyisoprene.
The bifunctional primer is synthesized by reacting compounds (I) and (V) in amounts of at least 2 moles of compound (V) per 1 mole of compound (I), in particular utilizing a slight excess of compound (V) as compared with the stoichiometric amount in a purified aprotic solvent medium (examples of solvents are provided above with reference to the addition of the organometallic compound (III) to compound (II)), with the subsequent polymerization being carried out by the direct addition of monomers to the reaction medium. A slight excess of compound (V) gives rise to deactivation of the residual protic impurities in the reaction medium.
Too, the present invention features a process for anionic polymerization of at least one polymerizable monomer with an alkali metal compound employed as the primer, this process being characterized in that the primer used is a bifunctional primer, as indicated above.
By “polymerizable monomers” are intended diene-containing, vinylaromatic, and (meth)acrylic monomers.
By the expression “diene-containing monomer” is intended a diene selected from among conjugated linear or cyclic dienes having from 1 to 20 atoms of carbon. Exemplary thereof are butadiene, isoprene, 1,3-pentadiene, cyclopentadiene, and 6,7,8,9-tetrahydroindene. The preferred monomers are butadiene and isoprene.
By the term “vinylaromatic” monomers are intended ethylenically-unsaturated aromatic monomers. Exemplary thereof are styrene, vinyltoluene, alpha-methylstyrene, 4-methylstyrene, 3-methylstyrene, 4-ethylstyrene, 3,4-dimethylstyrene, 3-tert-butylstyrene, and 2-vinylnaphthalene. Hydroxylated styrene derivatives can a
Nugay Turgut
Riess Gerard
Elf Atochem S.A.
Shaver Paul F.
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