Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2000-07-25
2002-07-02
Gitomer, Ralph (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S101000, C528S198000, C558S282000
Reexamination Certificate
active
06414178
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process and apparatus for the continuous preparation of mono and bis-chloroformate products of halogenated dihydroxy compounds by an interfacial process. The mono and bis-chloroformate products may optionally be converted to capped oligomers.
BACKGROUND OF THE INVENTION
Mono- and bis-chloroformates of halogenated diphenols are useful in the preparation of a wide variety of materials including additives that function as flame retardants and higher molecular weight products. For example, membranes made from high molecular weight tetrabromobisphenol A polycarbonate have shown high selectivity for oxygen
itrogen separation.
In making mono- and bis-chloroformates of halogenated diphenols, it is desirable to minimize production of by-product diarylcarbonates (DAC). This enables the mono- and bis-chloroformates of halogenated diphenols to be used in subsequent reactions to prepare oligomers or higher molecular weight product without first being purified by such methods as distillation.
Diarylcarbonates have a low melting point, compared with the glass transition temperature of polycarbonate or of capped oligomeric halogenated polycarbonate additives, and are therefore the last components to freeze during a polycarbonate molding operation. Therefore, halogenated polycarbonate with significant levels of DAC requires longer molding cycle times compared with polycarbonate that is substantially free of DAC. Further, because DAC can sublime, a polycarbonate containing diaryl carbonates can lead to undesirable effects, such as “plate out” in which the DAC from previous molding cycles condenses and deposits on the mold and leads to blemishes in subsequent moldings. Further, subliming DAC has a tendency to condense and plug in extruder vent lines, necessitating frequent maintenance and equipment outages. The term “DAC” as used herein is understood to include also di(alkylphenyl) carbonates and di(arylphenyl)carbonates.
U.S. Pat. No. 5,212,281, Munaj et al., discloses a process for the preparation of high molecular weight halogenated polycarbonate in a two stage continuous process. In the first stage, an oligomer mixture is formed and in the second stage, the oligomer mixture is polymerized in the presence of a coupling catalyst and an additional base. For the phosgenation step, the preferred amount of phosgene is 1.8-2.2 moles per mole of halogenated diphenol., according to Munaj et al.
It would be desirable to develop a process whereby the mono- and bis-chloroformates of halogenated diphenols may be produced directly, without the need for purification, and in a continuous manner. It would further be desirable to develop a process to produce the mono- and bis-chloroformates of halogenated diphenols that may be coupled with a process for oligomer synthesis, to produce a product having low DAC content and good quality.
It would further be desirable to develop a process to produce the mono- and bis-chloroformates of halogenated diphenols in a continuous reactor or reactor system in which the residence time is relatively low (<5 minutes). Finally, it would be desirable to develop a process to produce the mono- and bis-chloroformates of halogenated diphenols with efficient use of the carbonyl halide. The efficiency of carbonyl halide use is defined as: 100*(moles C═O incorporated into chloroformate product)/(mole COCl2 fed to process), where COCl2 (phosgene) is a typical carbonyl halide. The C═O incorporated into the chloroformate product represents both carbonate linkages and chloroformate groups.
BRIEF SUMMARY OF THE INVENTION
The present invention solves these problems, and provides further surprising properties. These and further objects of the invention will be more readily appreciated when considering the following disclosure and appended claims.
In a first aspect, the invention relates to a continuous process for the preparation of mono- and bis-chloroformates. In one embodiment, the invention relates to a continuous process for the preparation of mono- and bis-chloroformates from halogenated diphenols of structure (I)
X is selected from the group consisting of substituted or unsubstituted divalent C
1
-C
18
hydrocarbon radicals, —S—, —S—S—, —O—,
each Z is independently hydrogen, a linear or cyclic alkyl, alkoxy, aryl, alkaryl, aralkyl or aryloxy radical;
each Y is the same or different halo radical, selected from the groups consisting of fluoro, chloro, bromo and iodo; and a is an integer from 0 to 4; b is an integer from 0 to 4; with the proviso that both a and b are not equal to 0; and c=4-a and d=4-b; the process comprising the steps of:
a) introducing
1) an aqueous caustic solution;
2) a carbonyl halide;
3) at least one halogenated diphenol compound;
4) at least one inert organic solvent; and
5) a catalyst into a continuous reaction system;
b) effecting contact between 1), 2), 3) 4) and 5) for a time and at conditions sufficient to produce a chloroformate of the halogenated diphenol.
The invention further relates to chloroformates of halogenated diphenols prepared by the aforementioned methods, reaction systems utilizing the method coupled with polycarbonate polymerization systems, and polycarbonates produced by these systems.
In a second aspect, the invention relates to the preparation of capped oligomers of halogenated diphenols in a process coupled with the chloroformate synthesis reactor.
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 that follow, reference will be made to a number of terms that shall be defined to have the following meaning.
The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.
“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.
“Molar flow rate” is in moles per minute, unless otherwise stated.
“Mixture average temperature” is defined as the temperature that a mixture of two or more combined streams achieves at equilibrium under adiabatic conditions, i.e., with no input or loss of heat.
The term “polycarbonate” as used herein includes copolycarbonates, homopolycarbonates and (co)polyestercarbonates.
The terms “endcapping agent” and “chainstopping agent” are used interchangeably.
A “semi-batch” reactor receives an initial charge of materials, after which one or more reactants and optionally solvents are added to the reactor during the course of the reaction. Such reactors, however, are often referred to simply as “batch” reactors. The terms “batch” and “semi-batch” are used interchangeably throughout the rest of the specification.
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.
In one aspect, this invention concerns a continuous process for the production of mono or bis-chloroformates of halogenated diphenols useful in polymer synthesis, in particular in polycarbonate synthesis.
In another aspect, this invention concerns a process for the production of capped oligomeric polycarbonates of halogenated diphenols in which a process for producing mono- or bis-chloroformates of halogenated diphenols is coupled with a reaction system for producing capped oligomeric polycarbonate product.
I
Brunelle Daniel Joseph
Bui Pierre-Andre
Dardaris David Michel
Fyvie Thomas Joseph
Silva James Manio
Caruso Andrew J.
General Electric Company
Gitomer Ralph
Johnson Noreen C.
Khare Devesh
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