Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-02-05
2002-07-09
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
06417318
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a process for the removal of dissolved oxygen from phenol by admixing water into the phenol, which is then passed over metals of the platinum group applied to supports in order to catalyze the reaction of hydrogen and oxygen to give water in accordance with the equation: 2H
2
+O
2
→2H
2
O. The invention further relates to polycarbonate and bisphenol A that are prepared from oxygen-free phenol prepared by admixing water and subsequently passing the mixture over ion exchangers doped with platinum metal.
Phenol is an important unit in the preparation of the plastic polycarbonate. Phenol is first reacted with acetone under acid conditions to give bisphenol A. The molar ratio of the reactants phenol: acetone here is in the range of 8:1 to 14:1, preferably in the region of 12:1. Bisphenol A is then reacted with either phosgene or diphenyl carbonate to give polycarbonate in the following step.
This plastic is employed in a very wide-ranging spectrum of uses, inter alia in very demanding fields, such as in the preparation of high-quality optical materials and of compact discs and in the electronics field.
However, discoloration of the plastics often prevent their use in these applications, even when a very great effort is made to keep the quality of the starting substances at a high level.
It has now been found, surprisingly, that discoloration can be virtually completely avoided if hydrogen is added to the phenol and the mixture is then passed over a support, preferably an ion exchanger, doped with at least one metal of the platinum group.
How the discoloration arises has not yet been clarified in detail. At the moment, however, it is assumed that discoloration is caused by the nonselective action of oxygen present in the starting substances.
The invention relates to a process for the removal of dissolved oxygen from phenol by admixing hydrogen into the phenol, which is then passed over metals of the platinum group applied to supports in order to catalyze the reaction of hydrogen and oxygen to give water in accordance with the equation: 2H
2
+O
2
→2H
2
O. The invention further relates to polycarbonate and bisphenol A that are prepared from oxygen-free phenol prepared by admixing hydrogen and subsequently passing the mixture over ion exchangers doped with platinum metal.
SUMMARY OF THE INVENTION
The present invention relates to a process for the catalytic removal of dissolved oxygen from phenol comprising
(a) admixing hydrogen with phenol and
(b) passing the phenol stream over ion exchangers doped with platinum group metals to catalyze the reaction 2H
2
+O
2
→2H
2
O.
DETAILED DESCRIPTION OF THE INVENTION
The platinum metals to be used according to the invention are the elements of the series ruthenium, rhodium, palladium, osmium, iridium, and platinum. Palladium and platinum are preferred for the process according to the invention.
The ion exchangers to be used according to the invention are preferably anion exchangers and can contain weakly and/or strongly basic groups. Strongly basic exchangers in the C
1
form or weakly basic anion exchangers in the free base form are particularly preferred. A crosslinked polymer of ethylenically unsaturated monomers is used as the base polymer. Examples of ethylenically monounsaturated monomers are, for example, styrene, vinyltoluene, ethylstyrene, &agr;-methylstyrene, and derivatives thereof halogenated in the nucleus (such as chlorostyrene), vinylbenzyl chloride, acrylic acid and its salts and esters (particularly the methyl and ethyl esters), methacrylic acid and its salts and esters (particularly the methyl ester), and the nitriles and amides of acrylic and methacrylic acid.
The polymers are crosslinked, preferably by copolymerization with crosslinking monomers having more than one (preferably 2 or 3) copolymerizable C═C double bonds per molecule. Such crosslinking monomers include, for example, poly-functional vinylaromatics, such as di or trivinylbenzenes, divinylethylbenzene, divinyltoluene, divinylxylene, divinylethylbenzene, or divinylnaphthalene; poly-functional allylaromatics, such as di- or triallylbenzenes; polyfunctional vinyl or allyl-heterocyclic compounds, such as trivinyl or triallyl cyanurate or trivinyl or triallyl isocyanurate; N,N′-C
1
-C
6
alkylenediacrylamides or dimethacrylamides, such as N,N′-methylenediacrylamide or -dimethacrylamide or N,N′-ethylenediacrylamide or -dimethacrylamide; polyvinyl or polyallyl ethers of saturated C
2
-C
20
-polyols having 2 to 4 OH groups per molecule, such as, for example, ethylene glycol divinyl or diallyl ether or diethylene glycol divinyl or diallyl ethers; esters of unsaturated C
3
-C
12
-alcohols or saturated C
2
-C
20
-polyols having 2 to 4 OH groups per molecule, such as allyl methacrylate, ethylene glycol di(meth)acrylate, glycerol tri(meth)acrylate, or pentaerythritol tetra(meth)acrylate; divinylethyleneurea, divinylpro-pyleneurea or divinyl adipate; or aliphatic or cycloaliphatic olefins having 2 or 3isolated C═C double bonds, such as hexa1,5-diene, 2,5-dimethylhexa1,5-diene, octa1,7-diene, or 1,2,4-trivinylcyclohexane. Divinylbenzene (as an isomer mixture) and mixtures of divinylbenzene and aliphatic C
6
-C
12
-hydrocarbons having 2 or 3 C═C double bonds have proved to be particularly suitable crosslinking monomers.
The crosslinking monomers are in general employed in amounts of 2 to 20% by weight, preferably 2 to 12% by weight, based on the total amount of polymerizable monomers employed.
The crosslinking monomers do not have to be employed in pure form but can also be employed in the form of their technical grade mixtures of lower purity (such as, for example, divinylbenzene mixed with ethylstyrene).
The crosslinked polymers can be further processed to give anion exchangers in a known manner. The anion exchangers can be prepared on the one hand by chloromethylation (cf. U.S. Pat. Nos. 2,642,417, 2,960,480, 2,597,492, 2,597,493, 3,311,602, and 2,616,877), preferably with chloromethyl ether, and subsequent amination (cf. U.S. Pat. Nos. 2,632,000, 2,616,877, 2,642,417, 2,632,001, and 2,992,544) with ammonia, a primary amine, such as methyl or ethylamine, a secondary amine, such as dimethylamine, or a tertiary amine, such as trimethylamine or dimethylisopropanolamine, at a temperature of as a rule 25 to 150° C.
On the other hand, the anion exchangers can be prepared by the aminomethylation process, in which (a) the crosslinked polymers are reacted with phthalimide derivatives and (b) the resulting imides are hydrated. The amidomethylation (a) can be carried out by reaction of the crosslinked polymers with N-chloromethyl-phthalimide in the presence of swelling agents for crosslinked polymers and Friedel-Crafts catalysts (DE-A 1,054,715), the phthalimide derivative being employed in amounts suitable for the desired level of substitution (0.3 to 2.0 substitutions per aromatic nucleus) of the aromatic nuclei present in the crosslinked polymer (or in an excess of up to 20%, preferably up to 10%).
Suitable swelling agents include halogenated hydrocarbons, preferably chlorinated C
1
-C
4
-hydrocarbons. The most preferred swelling agent is 1,2-dichloroethane.
Preferred Friedel-Crafts catalysts include, for example, A1C1
3
, BF
3
, FeC1
3
, ZnC1
2
,TiC1
4
, ZrC1
4
, SnC4, H
3
PO
4
, HF, and HBF
4
. The catalysts can be employe amounts of 0.01 to 0.1 mol per mole of N-chloromethylphthalimide.
The reaction can be carried out, for example, by a procedure in which the crosslinked polymer is introduced into a solution of N-chloromethylphthalimide in a swelling agent and the reactants are allowed to act in the presence of the catalyst at elevated temperature, as a rule at 50 to 100° C., preferably 50 to 75° C., until the evolution of hydrogen chloride has substantially ended. This is in general the case after 2 to 20 hours. After separation of the substituted polymer and liquid reaction medium and inorganic products, it is advisable to take up the polymer in aqueous sodium chloride
Bödiger Michael
Heydenreich Frieder
Wagner Rudolf
Boykin Terressa M.
Gil Joseph C.
Henderson Richard E.L.
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