Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1999-05-03
2000-10-24
Shippen, Michael L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C07C 2726
Patent
active
061370169
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the production of butane-1,4-diol.
Butane-1,4-diol is used as a monomer in the production of plastics, such as polybutylene terephthalate. It is also used as an intermediate for the manufacture of .gamma.-butyrolactone and of the important solvent,tetrahydrofuran.
One route to butane-1,4-diol involves reaction of acetylene with formaldehyde by the Reppe reaction to yield butyne-1,4-diol which is then hydrogenated to produce butane-1,4-diol.
Another process for production of butane-1,4-diol uses maleic anhydride as a starting material. This is esterified with an alkanol, usually a C.sub.1 to C.sub.4 alkanol such as methanol or ethanol, to yield the corresponding dialkyl maleate which is then subjected to hydrogenolysis to yield butane-1,4-diol and the alkanol which can be recycled to produce further dialkyl maleate. Processes and plant for the production of dialkyl maleates from maleic anhydride are described, for example, in U.S. application. Ser. No. 4795824 and in WO-A-90/08127. The hydrogenation of dialkyl maleates to yield butane-1,4-diol is discussed further in U.S. patent application Ser. No. 4584419, U.S. patent application Ser. No. 4751334, and WO-A-88/00937, the disclosures of all of which are herein incorporated by reference.
In the hydrogenolysis of a dialkyl maleate, such as dimethyl maleate or diethyl maleate, there may also be produced amounts of the valuable by-products, .gamma.-butyrolactone and tetrahydrofuran. Since there is a ready market for these by-products, their co-production with butane-1,4-diol is not disadvantageous. In addition the hydrogenolysis product mixture will normally contain minor amounts of the corresponding dialkyl succinate, n-butanol, the corresponding dialkyl alkoxysuccinate, e.g. diethyl ethoxysuccinate, and water.
Another minor by-product has been identified as a cyclic acetal, i.e. 2-(4'-hydroxybutoxy)-tetrahydrofuran of the formula: ##STR1##
This is presumably formed by reaction of butane-1,4-diol with 4-hydroxybutyraldehyde which is a potential intermediate in the sequence of hydrogenolysis reactions or can be formed by dehydrogenation of butane-1,4-diol itself. The mechanisms for formation of all these products and by-products have not been fully elucidated. However, their production is consistent with the following reaction scheme: ##STR2##
The cyclic acetal by-product, i.e. 2-(4'-hydroxybutoxy)-tetrahydrofuran, is troublesome because its boiling point lies very close to that of butane-1,4-diol and because it forms an azeotrope therewith. Hence it is difficult, if not impossible, to produce using conventional distillation techniques a butane-1,4-diol product which is essentially free from this cyclic acetal. Hence butane-1,4-diol produced by this hydrogenolysis route typically contains from about 0.15% by weight to about 0.20% by weight of the cyclic acetal with other impurities in total comprising no more than about 0.02% by weight. The presence of even minor traces of the cyclic acetal, 2-(4'-hydroxybutoxy)-tetrahydrofuran, in butane-1,4-diol is disadvantageous because it is a colour forming material and hence gives rise to colour formation in the butane-1,4-diol.
It has been proposed in U.S. patent application Ser. No. 4383895 to remove colour-forming materials present in crude butane-1,4-diol produced by hydrogenation of butyne-1,4-diol by subjecting the crude butane-1,4-diol to distillation under conditions wherein subjecting all of the water present in the crude butane-1,4-diol is first removed and then the butane-1,4-diol with reduced water content is further distilled to remove the colour-forming materials sufficiently to provide a product for use in the preparation of polyesters.
In JP-A-61/197534 there is taught a method of purifying crude butane-1,4-diol in which crude butane-1,4-diol containing at least one of the compounds, 2-(4'-hydroxy-butoxy)-tetrahydrofuran, 2-(4'-oxobutoxy)-tetrahydrofuran and 1,4-di-(2'-tetrahydrofuroxy)-butane, is hydrogenated in the presence of a hydrogenation catalyst, such as a supported plati
REFERENCES:
patent: 2768214 (1956-10-01), McKinley
patent: 4383895 (1983-05-01), Ernst et al.
patent: 4584419 (1986-04-01), Sharif et al.
patent: 4751334 (1998-06-01), Turner et al.
patent: 4795824 (1989-01-01), Kippax et al.
patent: 5008408 (1991-04-01), Fischer et al.
patent: 5397439 (1995-03-01), Kandori
International Search Report, PCT/GB 97/00879, Oct. 7, 1997 (3 pages).
Colley Stephen William
Shariff Mohammad
Willett Paul
Wood Michael Anthony
Kvaerner Process Technology Limited
Shippen Michael L.
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