Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-11-02
2001-07-31
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S198000
Reexamination Certificate
active
06268461
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for preparation of hydroxyaromatic chloroformate products by an interfacial process. The hydroxyaromatic chloroformates are suitable for use as an endcapping agent in polymer synthesis. In particular, it is desirable to use the hydroxyaromatic chloroformate products as an endcapping agent in polycarbonate synthesis.
BACKGROUND OF THE INVENTION
The use of hydroxyaromatic chloroformates as a chainstopping or endcapping agent in polycarbonate synthesis facilitates control of the molecular weight of the polycarbonate to be formed. In general, the greater the quantity of endcapping agent introduced into a polycarbonate synthesis, the lower the molecular weight of the polycarbonate product. Hydroxyaromatic chloroformates are particularly suitable as endcapping agents in interfacial polycarbonate synthesis because they produce a polycarbonate product in a single step phosgenation with a lower level of diarylcarbonate (DAC) than products produced using a hydroxyaromatic endcap, such as p-cumyl phenol. Diarylcarbonates have a low melting point, and a polycarbonate containing diaryl carbonates can lead to undesirable effects, such as “plate out” in which the DAC from previous molding cycles condenses on the mold and leads to blemishes in subsequent molding. The term “DAC” as used herein is understood to include also di(alkylphenyl carbonates) and di(arylphenyl)carbonates.
U.S. Pat. No. 5,399,657 (Van Hout et al) discloses a method of preparing hydroxyaromatic chloroformate compounds in which a solution of phosgene in a solvent is introduced into a reactor, to which phosgene and a phenol compound are then added while maintaining the temperature at the desired level by cooling, and maintaining the pH at desired levels by the addition of an aqueous caustic solution.
U.S. Pat. No. 5,274,164 (Wettling et al) discloses a method of preparing aryl chloroformates by the reaction of phenols with phosgene in the presence of organic phosphorous compounds. The addition of a catalyst, such as the organic phosphorous compounds, necessitates extra process steps to recover the catalyst from the product.
U.S. Pat. No. 4,864,011 (Bussink et al) discloses a method of preparing an aromatic polycarbonate with a phenolic chloroformate chain stopper.
It would be desirable to develop a process in which hydroxyaromatic chloroformates are produced in an interfacial process from one or more monofunctional hydroxyaromatic compounds, a carbonate precursor, an aqueous caustic solution and an organic solvent with a minimal amount of DAC contaminants and unreacted monofunctional hydroxyaromatic compound. Such a process would allow production of a polycarbonate product having superior properties.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a method of preparing an aryl chloroformate of the formula I:
wherein n is an integer from 1 to 5, and R
1
represents hydrogen, a branched or unbranched alkyl group having from 1-15 carbon atoms, an aryl group which may be substituted or unsubstituted, a cycloaliphatic group which may be substituted or unsubstituted, or an arylalkyl group which may be substituted or unsubstituted, comprising the steps of:
A) introducing an aqueous caustic solution to a reaction vessel comprising a precharge solution, the precharge solution comprising
1) from 0 to 100% of total input inert organic solvent;
2) from 0 to 100% of total input monofunctional hydroxyaromatic compound of formula II, wherein n and R
1
in formula II has the same meaning as n and R
1
in formula I;
and 3) from 0 to 100% of total input phosgene, said precharge solution not including added water; and
B) simultaneously introducing
1) a remaining portion of the total input monofunctional hydroxyaromatic compound; 2) a remaining portion of the total input phosgene; and 3) a remaining portion of total input inert organic solvent;
where a first overall molar ratio of phosgene to monofunctional hydroxyaromatic compound introduced into the reaction vessel is in a range of from about 1.25 to about 10 moles of phosgene per mole of monofunctional hydroxyaromatic compound introduced into the reaction vessel, and a second overall molar ratio of caustic to phosgene introduced in the reaction vessel is in a range of from about 0.6 to about 1.0 equivalents of caustic per mole of phosgene introduced into the reaction vessel,
steps A) and B) being conducted until a total monofunctional hydroxyaromatic compound level is reached or a desired ratio of phosgene to monofunctional hydroxyaromatic compound is reached,
and thereafter, maintaining the pH of the contents of the reaction vessel at a pH of from about 2 to about 5 for a period of time sufficient to stabilize the contents of the reaction vessel.
DETAILED DESCRIPTION OF THE INVENTION
The present invention may be understood more readily by reference to the following detailed description of the preferred embodiments of the invention and the examples included therein.
Before the present method and apparatus are disclosed and described, it is to be understood that this invention is not limited to specific systemic methods or to particular formulations, as such may, of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meaning.
The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.
The terms “aryl” and “hydroxyaromatic” are used interchangeably in the specification.
“Optional” or “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.
“Overall molar ratio” is defined as the molar ratio of the total amount of the identified components introduced into a reaction system to form the desired product.
“Total input”, as used herein, means the total amount, by weight, of the referenced component that is introduced into the reaction system.
A “remaining portion” as used herein, is the difference between the amount of a referenced component in the precharge solution and the total input of the referenced component.
Throughout this application, where publications are referenced, the disclosures of these publications are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.
The present invention relates to a semi-batch process for the interfacial preparation of endcapping agents useful in polymer synthesis, the endcapping agents having the formula (I):
where n varies from 1 to 5, and R
1
represents hydrogen, a branched or unbranched alkyl group having from 1-15 carbon atoms, an aryl group which may be substituted or unsubstituted, a cycloaliphatic group which may be substituted or unsubstituted, or an arylalkyl group which may be substituted or unsubstituted. It is preferred than n is equal to 1 and that R
1
is present in the para position.
In a semi-batch process, an initial charge of materials is added to a reactor, after which one or more reactants and optionally solvents are added to the reactor during the course of the reaction. “Reaction system” as used herein means the vessel or reactor in which the reaction of the components takes place to form the monofunctional hydroxyaromatic chloroformate.
Endcapping agents produced by the method of the present invention include, but are not limited to, phenyl chloroformate, t-butyl phenyl chloroformate, p-cumyl phenyl chloroformate, chroman chloroformate, octyl phenyl or nonyl phenyl chloroformate, or a mixture thereof; more preferably phenyl chloroformate, p-cumyl phenylchloroformate, or a mixture thereof; even more preferably p-cumyl phenylchloroformate.
In the process as described herein, the production of hydroxyaromatic chlor
Fyvie Thomas Joseph
Silva James Manio
Boykin Terressa M.
General Electric Company
Johnson Noreen C.
Stoner Douglas E.
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