Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
1999-08-06
2001-06-19
Dentz, Bernard (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S508000, C568S864000
Reexamination Certificate
active
06248906
ABSTRACT:
The present invention relates to a process for the production of tetrahydrofuran, gammabutyrolactone and butanediol starting from maleic anhydride esters, consisting of two subsequent hydrogenations.
It is known that tetrahydrofuran (THF), gammabutyrolactone (GBL) and butanediol (BDO) can be produced thanks to several methodologies. THF and GBL are chiefly produced starting from BDO. THF is produced starting from butanediol (BDO) by a dehydrogenation process.
THF and GBL production from BDO results to be expensive, because of the relatively high costs arising from the BDO production processes, inherently rather complex.
According to a technique employed in industry, BDO is produced by reaction of acetylene with formaldehyde, with ensuing formation of butanediol, which itself undergoes hydrogenation to BDO.
Mitsubishi Chemical Industries developed a process apt at producing BDO with Butadiene as starting material.
The process involves butadiene acetoxylation to 1,4-diacetoxy-2-butene, that is then hydrogenated and hydrolised to BDO.
General Electric Corp. patented a process for the production of BDO starting from propylene.
The process includes the conversion of propylene to allyl acetate, which is converted into 4-acetoxybutanol. This eventually hydrolyses to afford BDO.
A special attention has been devoted to the development of processes where butane is employed as starting material, via the formation of a maleic anhydride intermediate.
Several processes have been proposed for the production of THF, GBL and BDO starting from maleic anhydride, esters thereof, or homologous compounds such as succinic acid and/or fumaric acid esters.
In U.S. Pat. Nos. 4,584,419 and 4,751,334 in the name of Davy MeKee Ltd., processes are described for the production of BDO by hydrogenation of carboxylic acid esters containing 4 Carbon atoms, typically ethyl maleate.
In the above patents, claims refer to hydrogenations carried out within a field with pressures ranging between 25 and 75 bars, and temperatures between 150 and 240° C., in the presence of a stabilised copper chromite type catalyst.
An aim of the present invention is to provide a process whereby THF and GBL can be produced in variable proportions by hydrogenation at moderate pressures with maleic anhydride esters as starting materials, without going through BDO production.
BDO can be produced starting from GBL by subsequent hydrogenation carried out at a higher pressure.
It is another aim of the present invention that of proposing a more straightforward process with higher final product yields, without the need to resort to the extreme pressure and temperature conditions which are proper of the processes proposed in the prior art.
According to the invention the above aims are accomplished thanks to a process for the production of tetrahydrofuran, gamma butyrolactone and butanediol with maleic anhydride esters as starting materials, by two successive hydrogenations.
More particularly the process comprises:
a) A primary hydrogenation of maleic anhydride ester in the vapour phase, at a moderate pressure, in a reactor comprising three reaction stages connected in series.
In the first of the stages thereof a heterogeneous selective hydrogenation catalyst is employed to carry out a conversion of maleic anhydride ester into succinic anhydride ester.
In the second stage a selective hydrogenation catalyst is employed to carry out a conversion of succinic anhydride ester mainly into GBL.
In the third stage of dehydration catalyst is employed mainly to produce THF.
b) Separation of the effluent from the primary from THF and GBL products.
c) Feeding a fraction of the GBL produced to a secondary hydrogenation in the vapour phase and at a higher pressure, on a hydrogenation catalyst where GBL is mainly converted to BDO.
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Dentz Bernard
Stevens Davis Miller & Mosher LLP
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