Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1998-02-23
2001-07-24
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S454000, C568S840000, C568S880000, C562S512000, C560S129000
Reexamination Certificate
active
06265619
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for the manufacture of aldehydes, alcohols, acids, and esters, the use of the latter as synthetic lubricants, as plasticizers, to polymeric compositions plasticized by the esters, and to products made from the compositions.
BACKGROUND OF THE INVENTION
The esters of 2-ethylhexanol, especially the phthalate, are among the most commonly used plasticizers. The alcohol is obtainable by, for example, subjecting propene to hydroformylation, dimerizing the resulting butanal by the aldol reaction, a term which is used throughout this specification, including the claims, as including the subsequent dehydration to an unsaturated aldehyde, and hydrogenating the resulting aldehyde to form a saturated alcohol.
The propene, produced for example by a steam cracking plant, has to be purified before hydroformylation, and its cost as feedstock is increased as a result.
There accordingly remains a need for an alternative route to commercially useful organic molecules, and more especially one that is capable, if desired, of producing a single isomeric product or a preponderant proportion of one or two isomers.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a process for the manufacture of at least one higher aldehyde, higher alcohol, or a higher acid, from a lower hydrocarbon,
which comprises hydroformylating two different ethylenically unsaturated hydrocarbons to form a first aldehyde and a second aldehyde, the hydrocarbons being hydroformylated separately or in admixture and, if the latter, if desired or required at least partially separating the first aldehyde from the second aldehyde,
subjecting the first aldehyde, if desired in admixture with the second, to aldolization, hydrogenating at least a portion of the resulting unsaturated aldehyde or aldehydes to form a corresponding higher alcohol or alcohols, and, if only a portion is so hydrogenated, optionally selectively hydrogenating a further portion of the unsaturated aldehyde to form a corresponding saturated higher aldehyde, optionally oxidizing it to form a corresponding higher acid,
optionally dehydrating a portion of the higher alcohol or of the higher alcohols to form at least one ethylenically unsaturated hydrocarbon and returning it to hydroformylation, and
optionally recovering the second aldehyde as higher aldehyde, hydrogenating it to form a higher alcohol, or oxidizing it to form a higher acid.
Advantageously, the process includes returning unsaturated hydrocarbon produced by dehydration to oxonation. It is within the scope of the invention to return unsaturated aldehyde to aldolization, although this is not at present preferred.
More especially, in a first aspect, the present invention provides a process comprising
(a) subjecting a composition comprising two ethylenically unsaturated hydrocarbons having differing numbers of carbon atoms, carbon monoxide, and hydrogen to hydroformylation conditions to form a composition comprising at least a lower aldehyde and a higher aldehyde,
(b) at least partially separating the lower and higher aldehydes, to form a lower aldehyde-containing composition and a higher aldehyde-containing composition,
(c) subjecting the lower aldehyde-containing composition to aldol condensation, and, optionally,
(d) hydrogenating the unsaturated aldehyde resulting from the aldol condensation to form a first alcohol and, optionally, dehydrating at least a portion of the first alcohol to form an ethylenically unsaturated hydrocarbon, and optionally returning the resulting ethylenically unsaturated hydrocarbon to hydroformylation, and optionally hydrogenating the higher aldehyde-containing composition to form a second alcohol and optionally esterifying the first, the second, or both the first and second alcohols separately or together.
Advantageously the two unsaturated hydrocarbons subjected to hydroformylation are such that the resulting lower and higher aldehydes are readily separable by, for example, distillation.
Except where the context otherwise requires, the features of the first aspect said below to be advantageous are advantageous in all aspects of the invention, especially the specifically listed succeeding aspects.
Advantageously, return of the ethylenically unsaturated hydrocarbon resulting from dehydration to the hydroformylation step in the process takes place when it has the same number of carbon atoms as one of the feedstock hydrocarbons and preferably, when there are only two, the hydrocarbon having the higher number of carbon atoms. If it differs from both the feedstock hydrocarbons it is advantageously transferred to a parallel operation, carrying out a process on a hydrocarbon feed to which it is identical. It is, however, although not presently preferred, within the scope of the invention to carry out the process with unsaturated hydrocarbons having three or more different carbon numbers.
DETAILED DESCRIPTION OF THE INVENTION
As examples of unsaturated hydrocarbons to be treated by the process of the invention there may be mentioned, more especially, olefins, and advantageously olefins having from 2 to 20 carbon atoms.
The invention is especially applicable to treating a mixture of a lower, C
2
to C
4
, and a higher, C
5
to C
20
, olefin. As lower olefins there may be mentioned ethylene, propene, n-butene and 2-methylpropene. As higher olefins there may be especially be mentioned single isomeric olefin feeds, for example, pentene-1, hexene-1 and their higher homologues, or mixtures of linear and branched olefin isomers predominantly of the same carbon number. An example of the latter is a hexene feed, which may contain 2-methylpentene-1, 2-methylpentene-2-, cis- and trans-4-methylpentene-2, 4-methylpentene-1, cis- and trans-hexene-3, cis- and trans-hexene-2, 2,3-dimethylbutene-2, 2-ethylbutene-1 and trans-3-methylpentene-2. Usually olefin feeds of this nature also contain varying amounts of the corresponding alkanes.
The invention is more especially applicable to treating a mixture of ethylene and higher e.g., C
5
and above, alkenes, especially hexenes, especially 2-methylpentene-1.
On subjecting such a mixture to hydroformylation, a mixture of C
3
and C
7
saturated aldehydes results; on subjecting the C
3
aldehyde to aldolization an unsaturated C
6
aldehyde results. This may, if desired, be selectively hydrogenated to a C
6
saturated aldehyde, which may in turn be hydrogenated to a C
6
alcohol, or oxidized to form a C
6
acid. The alcohol, or a portion thereof, may be dehydrated to hexene, which will largely be 2-methylpentene-1 and -2, which may be recycled to the hydroformylation stage. Accordingly, from the C
6
and C
7
saturated aldehydes there may be produced the corresponding alcohols and their esters, or the corresponding acids and their esters.
The invention accordingly provides a means of obtaining C
6
and C
7
products from ethylene as the sole hydrocarbon starting material.
In an advantageous embodiment of the first aspect of the invention, there is accordingly provided a process comprising hydroformylating a composition comprising ethylene and a 2-methylpentene, separating the resulting C
3
aldehyde and C
7
aldehydes, aldolizing the C
3
aldehyde, hydrogenating the resulting C
6
unsaturated aldehyde to form an alcohol, dehydrating the alcohol to form a composition comprising a 2-methylpentene, returning the composition to the hydroformylation stage, and recovering a product comprising a C
7
aldehyde.
The 2-methylpentene may be a mixture of isomers, advantageously predominantly 2-methylpentene-1 and -2.
U.S. Pat. No. 4,426,542 discloses dimerizing propene, oxonating the resulting hexenes to heptanals, hydrogenating to heptanois, dehydrating to heptenes and oxonating the heptenes, the octanals resulting being aldolized in turn with hexanal and hydrogenated to form inter alia a C
14
alcohol.
U.S. Pat. No. 4,262,142 discloses the low pressure hydroformylation of mixtures of ethylene and an alpha-olefin having from 3 to 20 carbon atoms using a rhodium-based catalyst, while GB-A-1,120,277 disclos
Collins Douglas J
Exxon Chemical Patents Inc.
Padmanabhan Sreeni
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