Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-09-11
2001-10-16
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S727000, C568S728000
Reexamination Certificate
active
06303835
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the processing of bisphenol tars which are formed as by-products when phenols are reacted with ketones under acidic conditions, and more particularly to the recovery of useful chemical values from therefrom.
Among bisphenols prepared by the reaction of phenols with ketones under acidic conditions, bisphenol A is predominant in terms of the scale of its manufacture, its relatively low cost and the multitude of suitable applications for its use. The manufacture of bisphenol A (BPA) from acetone and phenol is practiced on a large scale with hundreds of millions of pounds of BPA produced annually. Although current processes used for its manufacture represent the fruits of years of research efforts and are highly efficient a small percentage of the starting materials are lost as a tarry by-product referred to as BPA tar. Given the scale of BPA manufacture the formation of even a small percentage of BPA tar by-product is significant and amounts to millions of pounds of tar produced annually. The tars are composed of a complex mixture of compounds which renders the separation and purification of individual components costly and inefficient. Currently employed recycle strategies for recovery of material values from BPA tars have focused on tar “cracking” in which the BPA tar is heated in the presence of an acidic or basic catalyst at atmospheric pressure. The combined action of the heat and catalyst results in bond cleavage of BPA tar components resulting in generation of phenol. The liberated phenol is distilled from the reaction vessel. The recovered phenol is then further purified and recycled into applications requiring the use of phenol.
In some instances the BPA tar has been heated in the presence of a catalyst under vacuum to afford a mixture of phenol and isopropenylphenol in the distillate. Isopropenylphenol is a valuable synthetic intermediate and its recovery from BPA tar represents an attractive means for its preparation. The recovery of both phenol and isopropenylphenol when BPA tar cracking is carried out under vacuum stands in sharp contrast to BPA tar cracking at atmospheric pressure in which little or no isopropenylphenol is obtained in the distillate. The requirement that vacuum conditions be employed for the cracking of BPA tar in order to produce a distillate containing isopropenylphenol reflects the chemical instability of isopropenylphenol and is a condition which adds cost and limits the economic viability of recovering phenol-isopropenylphenol mixtures from BPA tar.
It is of interest, therefore, to develop methods for the recovery of material values from BPA tar which do not require the use of vacuum equipment but which furnish phenol-isopropenylphenol mixtures from BPA tar under atmospheric pressure, and which will be applicable to the recovery of material values from bisphenol tars other than BPA tar.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to methods for the recovery of material values from BPA tar and other bisphenol tars under conditions of atmospheric pressure and focuses on the recovery of phenol-isopropenylphenol mixtures which may be transformed into other valuable products. Because BPA tar represents the most significant bisphenol tar produced worldwide and because the chemical behavior of other bisphenol tars is analogous to the behavior BPA tar, the present invention describes the recovery of material values from BPA tar as a preferred embodiment of the invention. It should be noted that the method of the invention extends to bisphenol tars generally, and is not limited to BPA tar alone. One aspect of the invention, therefore, is a method for the recovery of material values from bisphenol tars comprising the following steps:
a. contacting the bisphenol tar with a basic catalyst in an amount in the range between about 10 and about 10,000 parts catalyst per million parts bisphenol tar,
b. heating the bisphenol tar catalyst mixture at a temperature in the range between about 180° C. and about 300° C. while sparging the bisphenol tar catalyst mixture with an inert gas, and
c. collecting the distillate from said bisphenol tar catalyst mixture.
Still another aspect of the present invention is the conversion of the phenol-isopropenylphenol mixture to a phenol bisphenol A mixture by effecting reaction of the isopropenylphenol, contained in the collected phenol-isopropenylphenol mixture, with phenol in the presence of an acidic catalyst.
DETAILED DESCRIPTION OF THE INVENTION
The present invention may be understood more readily by reference to the following description of preferred embodiments of the invention and the Examples included therein. 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 meanings:
The singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that description includes instances where the event or circumstance occurs and instances where it does not.
“BPA” is herein defined as bisphenol A or 2,2-bis(4-hydroxyphenyl)propane or 4,4′-isopropylidenediphenol.
“p,p-BPA” is herein defined as bisphenol A or 2,2-bis(4-hydroxyphenyl)propane or 4,4′-isopropylidenediphenol.
“o,p-BPA” is herein defined as bisphenol A or 2-(2-hydroxyphenyl)-2-(4-hydroxyphenyl)propane or 2,4′-isopropylidenediphenol.
“IPP” is herein defined as isopropenyiphenol or p-isopropenylphenol or 4-(propen-2-yl)phenol.
“IPP linear dimer 1” refers to a BPA tar component having structure I.
“IPP linear dimer 2” refers to a BPA tar component having structure II.
“IPP cyclic dimer 1” refers to a BPA tar component having structure III.
“IPP cyclic dimer 2” refers to a BPA tar component having structure IV.
“Chroman 1” refers to a BPA tar component having structure V.
“Chroman 2” refers to a BPA tar component having structure VI.
“DMX” refers to a BPA tar component having structure VII.
“BPX” refers to a BPA tar component having structure VIII.
“Inert gas” is herein defined as a gas which is not reactive under the conditions used to convert BPA tar to mixtures comprising phenol and EPP and is exemplified by nitrogen, argon and steam.
“Material value” as used herein refers to the value inherent in a chemical derived from a given bisphenol tar, such as phenol at a given state of purity. The material value of phenol contained in the distillate obtained from heat treatment of BPA tar in the presence of a catalyst using the method of the present invention may at times be increased by its further purification. The material value of IPP is a result of its versatility as a chemical intermediate. IPP is a known intermediate in the preparation of the IPP linear and cyclic dimers, I-IV, and is a putative intermediate in the formation of BPA from acetone and phenol. If desired, the IPP can be reacted directly with phenol in the distillate in the presence of an added acidic catalyst to afford BPA.
The term “sparging” as used herein refers to the passage of a gas through a liquid which occurs when a gas is forced through the liquid.
“BPA tar” as used herein is defined as a by-product mixture produced during the manufacture of BPA from phenol and acetone. BPA tar varies in its composition but typically comprises the following constituents: BPA, o,p-BPA, phenol, IPP, IPP linear dimer 1, IPP linear dimer 2, IPP cyclic dimer 1, IPP cyclic dimer 2, chroman, DMX, and further condensation products of BPA with acetone or IPP such as BPX. Additionally, BPA tar includes materials of unknown structure. BPA and o,p-BPA are frequently among the chief components of the BPA tar and these two components represent most of the latent phenol and IPP contained within the BPA tar.
“Bisphenol tar” as used herein is defined as a by-product mixture produced during the manufacture of a bisphenol from a phenol and a ketone. “BPA tar” represents a particular bisphenol tar f
Lee Julia Lam
Pressman Eric James
Shafer Sheldon Jay
Caruso Andrew C.
General Electric Company
Johnson Noreen C.
Shippen Michael L.
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