Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
1999-06-04
2001-08-07
Padmanabhan, Sreeni (Department: 1621)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C568S388000, C568S390000
Reexamination Certificate
active
06271171
ABSTRACT:
1. BACKGROUND OF THE INVENTION
1.1 Technical Field
The present invention relates to a new process for obtaining &bgr;-hydroxy carbonyl compounds and/or &agr;,&bgr;-unsaturated carbonyl compounds. More particularly its subject-matter is a process for aldolization and/or aldolization-crotonization of an aldehyde and/or of a ketone.
1.2 Description of Related Art
Industrial processes based on the reaction of aldol condensation of aldehydes and of ketones utilize a basic catalyst such as dilute solutions of potassium hydroxide and sodium hydroxide. The separation of these catalysts at the end of the reaction is not, however, easy and requires the addition of acidic solutions, especially sulfuric acid, to convert the catalysts into the corresponding salts. In addition, the removal of salts thus formed, which is necessary for the protection of the environment, is costly for industry.
To overcome the above-mentioned disadvantages the use of solid catalysts has been proposed. Thus, copper oxide supported on a &ggr;-alumina has been described in U.S. Pat. No. 4,739,122 for catalyzing the reaction of mixed aldol condensation between acetone and butanal.
U.S. Pat. No. 5,144,089 discloses a process for liquid-phase aldol condensation, especially the conversion of butanal to 2-ethyl-2-hexenal in the presence of a solid catalyst. The catalyst is a solid solution of magnesium oxide and aluminum oxide, derived from a hydrotalcite and has a specific surface area greater than 250 m
2
/g.
Titanium dioxide has also been described as catalyst for the aldol condensation reaction in the process for obtaining &agr;,&bgr;-unsaturated aldehydes (U.S. Pat. No. 4,316,990).
Catalysis on an ion exchange resin has also been used but without great success, because the resin cannot withstand a temperature higher than 90° C. In addition, once the resin is deactivated, it can no longer be regenerated.
2. SUMMARY OF THE INVENTION
It has now been found that the above-mentioned disadvantages can be overcome by employing a catalyst of the general formula (I):
[(Mg
2+
)
1−x
(Al
3+
)
x
(OH
−
)
2
]
x+
[(OH
−
)
x
]
x−
(H
2
O)
n
(I)
with 0.20≦x≦0.33 and n<1.
The subject-matter of the invention is therefore a process for obtaining &bgr;-hydroxy carbonyl compounds and/or &agr;,&bgr;-unsaturated carbonyl compounds. This process is characterized in that at least one aldehyde or one ketone is brought into contact with a solid catalyst of general formula (I):
[(Mg
2+
)
1−x
(Al
3+
)
x
(OH
−
)
2
]
x+
[(OH
−
)
x
]
x−
(H
2
O)
n
(I)
with 0.20≦x≦0.33 and n<1.
In most cases an aldehyde or a ketone which has at least one hydrogen atom on the carbon a to the carbonyl functional group is employed.
3. DESCRIPTION OF THE INVENTION
The process according to the present invention preferably consists of reacting, in the presence of a catalyst of the general formula (I), an aldehyde of general formula R
1
—CHO, in which R
1
denotes a linear or branched alkyl radical containing from 1 to 10 carbon atoms with, optionally, at least one compound chosen from another aldehyde of general formula R
2
—CHO in which R
2
denotes a hydrogen atom or a linear or branched alkyl or cyclic radical containing from 1 to 10 carbon atoms or a phenyl radical or a benzyl radical or an aralkyl radical and/or a ketone of general formula R
5
—CO—R
6
in which each of R
5
and R
6
, which are identical or different, denotes a linear or branched alkyl radical containing from 1 to 10 carbon atoms and capable of being joined to each other to form a ring. As used herein, aralkyl is understood to include arylalkyl.
It is also preferred to react A ketone of general formula R
3
—CO—R
4
in which each of R
3
and R
4
, which are identical or different, denotes a linear or branched alkyl. radical containing from 1 to 10 carbon atoms, with optionally at least one compound chosen from an aldehyde of general formula R
2
—CHO in which R
2
denotes a hydrogen atom or a linear or branched alkyl or cyclic radical containing from 1 to 10 carbon atoms or a phenyl radical or a benzyl radical or an aralkyl radical, and/or another ketone of formula R
5
—CO—R
6
, in which each of R
5
and R
6
, which are identical or different, denotes a linear or branched alkyl radical containing from 1 to 10 carbon atoms and capable of being joined to each other to form a ring, in the presence of a catalyst of general formula (I).
The subject-matter of the present invention is very particularly a process of aldolization and/or aldolization-crotonization of at least one aldehyde or one ketone (with the exclusion of the process of selective aldolization of acetone to diacetone alcohol) in the presence of a catalyst of formula (I).
The process according to the present invention advantageously includes bringing a ketone of general formula R
3
—CO—R
4
and an aldehyde of general formula R
2
—CHO into contact with a catalyst of formula (I).
The ketone is preferably chosen from those in which R
3
or R
4
denotes a methyl radical, such as in particular acetone, ethyl methyl ketone or methyl propyl ketone. Acetone is particularly preferred.
The aldehyde is advantageously chosen from methanal, ethanal, propanal, butanal, isobutanal and benzaldehyde. Butanal or isobutanal is preferably employed.
The process advantageously also includes bringing an aldehyde R
1
—CHO and optionally another aldehyde R
2
—CHO into contact with the catalyst whose formula (I) is given above.
The aldehyde R
1
—CHO is advantageously chosen from ethanal, propanal, butanal, isobutanal, pentanal, hexenal and heptenal.
The aldehyde R
2
—CHO is advantageously chosen from methanal, ethanal, propanal, butanal, isobutanal and benzaldehyde. Methanal, butanal and isobutanal are preferably employed.
Ethanal, butanal or isobutanal is advantageously employed for the process of aldolization and/or aldolization-crotonization of an aldehyde. Butanal is particularly preferred.
The &bgr;-hydroxy and &agr;,&bgr;-unsaturated carbonyl compounds which are advantageously manufactured according to the process of the present invention are those such as, especially, mesityl oxide, 2-ethyl-2-hexenal, 5-methyl-3-hexen-2-one, 3-hepten-2-one and 2,2′,4-trimethyl-3-hydroxypentanal.
The &agr;,&bgr;-unsaturated carbonyl compounds obtained in accordance with the process of the present invention can be subjected either to a selective hydrogenation, using known catalysts, to give corresponding saturated carbonyl compounds like aldehydes or ketones which have a higher molecular weight than that or those which are used, or to a total hydrogenation, to give the corresponding saturated alcohols. These aldehydes or ketones or alcohols are employed industrially as synthesis intermediates or as solvents or in the perfumery industry.
The process for obtaining &bgr;-hydroxy carbonyl compounds and/or &agr;,&bgr;-unsaturated carbonyl compounds according to the present invention can be conducted at a temperature within limits that are also far apart, ranging approximately from 0° C. to approximately 200° C.
In most cases the operation is preferably carried out at a temperature of between approximately 0° C., and approximately 140° C.
A temperature of between approximately 0° C. and approximately 100° C. is more preferably employed.
The pressure at which the operation is carried out is such that the reactants (aldehydes and/or ketones) are in the liquid state at the aldolization or aldolization-crotonization temperature. Although it may be possible to work at a pressure higher than the atmospheric pressure, in most cases it is preferred to operate at atmospheric pressure.
The process according to the invention can be conducted equally well continuously and noncontinuously. The continuous process is preferred industrially.
When operating continuously, the process consists of introducing at least one aldehyde and/or one ketone through a stationary bed or stirred bed of solid catalyst of general formula (I).
The reactants ma
Fournier Maurice
Teissier Remy
Elf Atochem S.A.
Padmanabhan Sreeni
Pennie & Edmonds LLP
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