Preparation of substituted butenes

Details Preparation of substituted butenes Preparation of substituted butenes

1999-11-02

2001-12-11

Padmanabhan, Sreeni (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S449000, C568S450000, C568S487000, C568S647000, C568S697000, C568S904000

Reexamination Certificate

active

06329555

ABSTRACT:

The present invention relates to a process for preparing substituted butenes, especially alkyloxy-, aryloxy- or aralkyloxybutenes.
Substituted butenes of the formula I and/or II
where R is unsubstituted or mono- or di-C
1
-C
10
-alkoxy-substituted or mono- or dihydroxy-substituted C
2
-C
20
-alkyl or alkenyl or is C
6
-C
10
-aryl, C
7
-C
11
-aralkyl or methyl are important intermediates in the preparation, for example, of n-butyraldehyde and/or n-butanol. They are obtained by reacting 1,3-butadiene with an alcohol. DE 44 00 837 describes a process for preparing n-butyraldehyde and/or n-butanol, wherein the substituted butenes of the formula I and/or II are isomerized to the enol ether of the formula III
which is reacted with hydrogen and water or water in the presence of a transition metal catalyst to give n-butyraldehyde and/or n-butanol.
For reacting butadiene with the alcohol DE 44 00 837 recommends using solid Bronsted acids, especially organic ion exchangers, which are arranged in a fixed bed traversed in upflow or downflow by the liquid reaction mixture.
It has been found that in the process conceived in DE 44 00 837 there is an increase in the pressure drop along the catalyst bed as the period of operation increases. To manage the increasing pressure drop, therefore, the catalyst has to be replaced at intervals of a few weeks. Examination of the catalyst removed has indicated that the ion exchanger pellets swell in the presence of the reaction medium. Because of this, forces are exerted in the axial and radial directions of the reactor. The ion exchanger pellets in the lower section of the reactor, in particular, are unable to withstand these forces, and undergo deformation. In this way the catalyst bed is compacted and its interstitial volume falls. An increasingly higher pressure must be applied for further throughput of the reaction medium.
The examinations have also shown deposits of a rubberlike polymer covering large areas of the surface of the catalyst particles. Because of these deposits there is a considerable deactivation of the ion exchanger. The deposits are presumed to be polymerization products of the butadiene.
It is an object of the present invention to specify a process which prevents compaction of the catalyst bed and the deposition of polymer on the catalyst surface.
We have found that this object is achieved in accordance with the invention by a process for preparing substituted butenes of the formula I and/or II
where the radical R is unsubstituted or mono- or di-C
1
-C
10
-alkoxy-substituted or mono- or dihydroxy-substituted C
2
-C
20
-alkyl or alkenyl or is C
6
-C
10
-aryl, C
7
-C
11
-aralkyl or methyl by reacting 1,3-butadiene with an alcohol of the formula ROH where R is as defined in the presence of an acidic particulate catalyst insoluble in the reaction medium, which comprises contacting the butadiene, the alcohol and the catalyst in a fluidized bed reactor which is flow-approached from below and is operated at above the loosening point.
In the fluidized bed that is flow-approached from below, i.e., against the direction of gravity, the catalyst particles are able to swell without becoming compressed. Frictional contact between the catalyst particles is thought to prevent the formation of polymer deposits.
FIG. 1
shows the relative catalyst activity as a function of the amount of product produced in fixed bed operation and in the fluidized bed operation of the invention.
FIGS. 2 and 3
show scanning electron micrographs of ion exchanger pellets after having been deployed 35 days in fixed bed operation (
FIGS. 2
a
,
2
b
) or for 20 days in fluidized bed operation (
FIGS. 3
a
,
3
b
).
1,3-Butadiene is a basic chemical generated in large amounts in steam crackers and isolated by extraction using N-methylpyrrolidone, for example, from the C
4
cut of the steam cracker.
In the presence of a catalyst, 1,3-butadiene reacts with the alcohol ROH in accordance with equation (1)
to form the 1,4 adduct of the formula I and the 1,2 adduct of the formula II. Because of the position of the double bond, the 1,4 adduct I exists in both the cis and the trans forms. Depending on the reaction conditions and catalyst employed, the adduct I and II are generally formed in a molar ratio of from 1:1 to 1:3.
The nature of the alcohol ROH employed in the reaction is not generally critical for the process. Both primary and secondary alcohols can be used, although the former are preferred. The alcohols used can be aliphatic, cycloaliphatic, aromatic and araliphatic, preference being given to the use of aliphatic and araliphatic alcohols. In general, in the alcohols ROH used in the process of the invention, the radical R is a C
1
-C
20
-alkyl or C
2
-C
10
-alkenyl group, such as the 2-butenyl group, preferably a C
1
-C
4
-alkyl group, especially the n-butyl group, a C
6
-C
10
-aryl group, preferably the phenyl group, or a C
7
-C
11
-aralkyl group, preferably the benzyl group. The radicals R may if desired carry substituents such as C
1
-C
10
-alkoxy and/or hydroxyl groups. As a result, diols or triols or alkoxy alcohols may also be used as alcohols ROH. Since the substituents generally have no critical influence on the reaction, it is preferred to use alcohols ROH with unsubstituted radicals R. It is of course also possible to employ alcohols with a higher number of carbon atoms, but since they are generally more expensive than lower alcohols the latter are preferred on economic grounds.
The reaction takes place in the presence of an acidic particulate catalyst which is insoluble in the reaction medium. The use of organic cation exchangers is preferred.
By organic cation exchangers are meant pulverulent, gel-like or macroporous, polymeric polyelectrolytes which carry Brönsted acid functional groups, such as sulfonic, phosphonic or carboxylic acid groups, on a polymeric matrix, examples being sulfonated phenol-formaldehyde resins, sulfonated styrene-divinylbenzene copolymers, sulfonated polystyrene, poly(perfluoroalkylene)-sulfonic acids, and sulfonated carbons. In the process of the invention the cation exchangers are judiciously employed in their protonated form, known as the H
+
form. Examples of suitable commercial organic cation exchangers are Amberlite® 200, Amberlite® IR 120, Amberlite® IR 132 E, Lewatit® SC 102, Lewatit® SC 104, Lewatit® SC 108, Lewatit® SPC 108, Lewatit® SPC 112, Lewatit® SPC 118 and Amberlyst® 15, Amberlyst® 35 wet, Amberlyst® 38 wet, Amberlyst® CSP 2, Amberlyst® CSP 3, and Purolite® CT 175.
The acid group content of the ion exchangers is preferably from 4 to 6 and more preferably from 5 to 5.5 eq/kg.
In place of organic acid cation exchangers in the process of the invention it is possible to employ inorganic solids with a Brönsted acid action, examples being zeolites, such as &bgr;-zeolites or Y-zeolites in the H
+
form, bleaching earths, such as bentonites, montmorillonites and attapulgites, phosphate-based nonzeolite molecular sieves, as claimed, for example, by U.S. Pat. No. 4,440,871, U.S. Pat. No. 4,310,440, U.S. Pat. No. 4,567,029, U.S. Pat. No. 4,554,143, U.S. Pat. No. 4,500,651, EP-A 158 976, EP-A 158 349 and EP-A 159 624, and acidic or acid-impregnated metal oxides, whose preparation is described, for example, in U.S. Pat. No. 4,873,017. Preferred Brönsted acid inorganic solids are &bgr;-zeolites or Y-zeolites in the H
+
form, especially &bgr;-zeolites in the H
+
form. &bgr;-zeolites are obtainable, for example, by the process of U.S. Pat. No. 4,891,458.
The invention is based on the use of a vertical fluidized bed reactor for contacting the butadiene, the alcohol and the catalyst. The process of the invention is operated with a liquid reaction medium which preferably is essentially homogeneous. The fluid bed state prevails when the linear velocity of a fluid in a bed flow-approached from below is raised above the loosening velocity, so that the individual particles are held in suspension and are homogeneously suspended in the fluid. At the loosening point, the bed is in the state of incipient expansion.

Affiliated with

Also associated with

Rating

Preparation of substituted butenes does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Preparation of substituted butenes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of substituted butenes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2593777