Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2003-02-06
2004-03-02
Trinh, Ba K. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S530000, C568S815000
Reexamination Certificate
active
06700005
ABSTRACT:
The present invention relates to a process for preparing alkylaryl hydroperoxide containing product. Such product is suitable for use in various processes, such as in the preparation of oxirane compounds and in the preparation of alkenyl aryl.
BACKGROUND OF THE INVENTION
Processes for preparing propylene oxide employing alkylaryl hydroperoxide compounds, are well known in the art. As described in U.S. Pat. No. 5,883,268, such processes conventionally comprise peroxidation of ethylbenzene, followed by contacting the peroxidation reaction product with aqueous base in amount sufficient to neutralize acidic components thereof and separating the resulting mixture into an aqueous stream and a deacidified organic stream. The base contaminated, deacidified hydroperoxide stream is washed with water and the resulting mixture separated into an organics contaminated water phase and an organic phase having a reduced alkali metal content.
It has now been found that the peroxidation reaction product does not need to be washed with aqueous base. Surprisingly, the peroxidation reaction product can be washed with water only. An important advantage of the absence of a wash with aqueous base is that a larger amount of aqueous phase is allowable in the organic phase. The larger amount of aqueous phase is acceptable in the process according to the present invention as such aqueous phase will not contain aqueous base residue such as sodium salts. The presence of such compounds generally causes the problems in subsequent process steps. Water does not need to be rigorously removed in the process of the present invention and this makes that the separation of water and organic phase can be carried out in a more simple way. Furthermore, upsets in the plant leading to less efficient water removal are more acceptable in the present invention than they are in a conventional process.
It was found that alkylaryl hydroperoxide containing reaction product which was washed with water only, gave similar catalyst deactivation in a subsequent reaction as product washed with both aqueous base and water, while a higher yield of alkylaryl hydrogen peroxide was observed when the reaction product had been washed with water only. The latter is attributed to reduced decomposition of alkylaryl hydrogen peroxide. Such decomposition is thought to be catalysed by the presence of aqueous base at basic conditions. The similar deactivation is very surprising as a water wash removes very little contaminants such as benzoic acid, which are known to be present in the crude reaction product. Furthermore, less emulsion was observed to be formed when the alkylaryl hydroperoxide containing product was washed with water only.
WO 00/12470 describes a process for purifying a cyclohexyl hydroperoxide containing reaction mixture in order to make it suitable for decomposition or hydrogenation into cyclohexanol and cyclohexanone. This document contains no information on purification of an akylaryl hydroperoxide containing reaction mixture to be reacted with olefin in the presence of an epoxidation catalyst.
SUMMARY OF THE INVENTION
Surprisingly, a process has now been found which gives an improved alkylaryl hydroperoxide containing product.
The process for preparing organic hydroperoxide containing product according to the present invention comprises:
(a) oxidation of an alkylaryl compound to obtain reaction product containing organic hydroperoxide,
(b) contacting with water at least part of the alkylaryl hydroperoxide reaction product obtained in step (a) which reaction product contains less than 0.05% wt of sodium,
(c) separating the product of step (b) into a hydrocarbonaceous phase containing the alkylaryl hydroperoxide and an aqueous phase,
(d) optionally repeating process steps (b) and (c) one or more times,
(e) contacting at least part of the hydrocarbonaceous phase containing alkylaryl hydroperoxide obtained in step (c) or (d) with olefin and catalyst to obtain alkylaryl hydroxide and oxirane compounds, and
(f) separating at least part of the oxirane compound from the alkylaryl hydroxide.
The product subjected to step (b) is considered to be the product in total. If any aqueous phase is present in the reaction product to be subjected to the water wash, the sodium content of this aqueous phase is taken into account as well. A conventional alkylaryl hydroperoxide containing product which has been neutralised with aqueous base, will generally contain of from 0.10 to 0.15% wt of sodium, based on total amount of both organic and aqueous phase, before it is subjected to a water wash.
It is preferred that water is removed from the hydrocarbonaceous phase containing alkylaryl hydroperoxide obtained in step (c) or (d) before this hydrocarbonaceous phase is subjected to step (e). A convenient and preferred method for removing water from this hydrocarbonaceous phase is distillation.
The alkylaryl hydroxide obtained in step (f) can be used in a wide range of processes. Such process is preparing an alkenyl aryl by dehydrating the alkylaryl hydroxide. Another process is hydrogenating the alkylaryl hydroxide to obtain an alkyl aryl. Therefore, the process according to the present invention suitably comprises further:
(g) converting at least part of the alkylaryl hydroxide obtained in step (f). Generally, the conversion produces reaction product and water.
Preferably, step (g) comprises either dehydration or hydrogenolysis of the reaction product. Hydrogenolysis is the reaction of the alkylaryl hydroxide with hydrogen, preferably in the presence of catalyst. Dehydration will generally produce an alkenyl aryl and water, while hydrogenolysis will generally produce alkylaryl. Preferably, the hydrogenolysis will produce the alkylaryl used as starting compound.
DETAILED DESCRIPTION OF THE INVENTION
Alkylaryl compounds which are most preferably used in the process of the present invention are benzene compounds containing at least 1 alkyl substituent which alkyl substituent contains of from 1 to 10 carbon atoms, preferably of from 2 to 8 carbon atoms. Preferably, the benzene compound contains on average of from 1 to 2 constituents. The alkylaryl compounds most frequently encountered are ethylbenzene, cumene and di(isopropyl)benzene.
The oxidation of the alkylaryl compound can be carried out by any suitable process known in the art. The oxidation can be carried out in the liquid phase in the presence of a diluent. This diluent is preferably a compound which is liquid under the reaction conditions and does not react with the starting materials and product obtained. However, the diluent can also be a compound necessarily present during the reaction. For example, if the alkylaryl is ethylbenzene the diluent can be ethylbenzene as well and if the alkylaryl is cumene the diluent can be cumene as well.
Besides the desired alkylaryl hydroperoxide, a range of contaminants are created during the oxidation of organic compounds. Although most of these are present in small amounts, it has been found that the presence of compounds such as organic acids can cause problems in further use of the alkylaryl hydroperoxides. As described in U.S. Pat. No. 5,883,268, the conventional method of reducing the amount of contaminants is by contacting the reaction product containing alkylaryl hydroperoxide with an aqueous alkali solution. However, contact with the aqueous alkali solution introduces alkali metal into the hydroperoxide containing reaction product. Although the amount of organic acids present in the hydroperoxide containing product can be decreased by the alkali wash, the amount of alkali metal contaminants is increased.
It has now been found that a simple water wash is more efficient in purifying reaction product containing hydroperoxide than a treatment with aqueous base followed by a water wash. According to the present invention, the hydroperoxide containing product preferably is not contacted with aqueous base, more specifically sodium hydroxide, between the time at which it is produced by oxidation of organic compound and the time at which it is reacted further.
Aq
Kremers Antoon Paul Michael
Schouten Eduardus Petrus Simon
Schram Cornelis Willem Adriaan
Shell Oil Company
Trinh Ba K.
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