Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
1999-04-30
2001-07-03
Bernhardt, Emily (Department: 1611)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C540S567000, C540S555000, C544S282000, C544S245000, C248S301000, C248S302000
Reexamination Certificate
active
06255488
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a novel process for the preparation of bicyclic amidines by reaction of lactones with primary amines. The invention also relates to novel bicyclic amidines having functional groups, especially amino, hydroxyl and/or mercapto groups, and to their use as catalysts for the preparation of polyurethanes.
2. Background Art
Bicyclic amidines are strong organic bases which, owing to their high basicity coupled with low nucleophilicity and their ready solubility in almost all solvents, have found numerous applications. Particularly well-known bicyclic amidine compounds are those commonly referred to by the abbreviations DBN and DBU, i.e., 1,5-diazabicyclo[4.3.0]non-5-ene (2,3,4,6,7,8-hexahydropyrrolo[1,2-a]pyrimidine) and 1,8-diazabicyclo[5.4.0] undec-7-ene(2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine), respectively.
A review of the uses of these compounds in chemical syntheses can be found, for example, in
Synthetica Merck
, Volume II, E. Merck, Darmstadt, (1974), pp. 118-119 and 124.
A known process for preparing bicyclic amidines starts from N-(&ohgr;-aminoalkyl)lactones which, when heated with acidic catalysts, undergo cyclization with elimination of water to form the amidines (German Patent No. C 1,545,855). The N-(&ohgr;-aminoalkyl)lactones are obtained, for example, from the corresponding cyano compounds by hydrogenation; in particular, for example, N-(&ggr;-aminopropyl)pyrrolidone is obtained from N-(&bgr;-cyanoethyl)-pyrrolidone [see, e.g., W. Reppe et al., Justus Liebigs Ann. Chem., 596, (1955), p.211]. It is also possible to prepare N-(&ohgr;-aminoalkyl)lactones from the corresponding lactones and &agr;,&ohgr;-diaminoalkanes (German Patent No. C 730,182). The known processes for the preparation of bicyclic amidines have the disadvantage that they include at least two synthesis steps with working up of the intermediates.
It is known that bicyclic amidines are highly suitable as catalysts for the preparation of polyurethanes (French Patent No. 1,542,058). A considerable disadvantage of this use, however, is that bicyclic amidines are not firmly bonded within the polyurethane formed and therefore, over time, diffuse out of or are extracted from the polyurethane. In each case there is unnecessary pollution of the environment.
BROAD DESCRIPTION OF THE INVENTION
The main object of the invention is to provide an improved and simplified process for the preparation of bicyclic amidines and, from this class of compounds, to provide new compounds which, when used as catalyst for the preparation of polyurethanes, are bonded so firmly to the polymer that they no longer have any notable tendency towards migration. Other objects and advantages of the invention are set out herein or obvious to one skilled in the art.
The objects and advantages of the invention are achieved by the preparation process of the invention, the novel compounds of the invention and the process of using the novel invention compounds.
The invention preparation process involves preparing bicyclic amidines of the general formula:
wherein A and B are defined below, in a one-pot process, without isolation or purification of intermediates, from the corresponding lactones of the general formula:
wherein A is defined below, and amines of the general formula:
H
2
N—B—NH
2
III
wherein B is defined below.
The group A in the lactone (II) and in the amidine (I) is in each case a 3-, 4- or 5-membered carbon chain of the formula —CR
1
R
2
—CR
3
R
4
—CR
5
R
6
—, —CR
1
R
2
—CR
3
R
4
—CR
5
R
6
—CR
7
R
8
— or —CR
1
R
2
—CR
3
R
4
—CR
5
R
6
—CR
7
R
8
—CR
9
R
10
—, where R
1
and R
2
are in each case attached to the carbon atom which is adjacent to the heteratom.
The group B in the amine (III) and in the amidine (I) is in each case a 2-, 3- or 4-membered carbon chain of the formula —CR
11
R
12
—CR
13
R
14
—, —CR
11
R
12
—CR
15
R
16
—CR
13
R
14
— or —CR
11
R
12
—CR
15
R
16
—CR
17
R
18
—CR
13
R
14
—.
The general formula I, therefore, encompasses bicyclic amidines having 5-, 6- or 7-membered rings; the two rings can have identical or different numbers of members. Correspondingly, the general formula II encompasses lactones having from 5 to 7 ring members, in other words, &ggr;-, &dgr;- and &egr;-lactones.
The substituents R
1
, R
2
, and R
11
to R
14
of the carbon chains A and B are, in each case independently of one another, hydrogen, C
1
-C
4
-alkyl or aryl or C
1
-C
4
-alkyl groups which are in turn substituted with hydroxyl, amino, C
1
-C
4
-alkylamino or mercapto. The substituents R
3
to R
10
and R
15
to R
18
can be either the groups mentioned for R
1
, R
2
and R
11
to R
14
or else hydroxyl, amino, C
1
-C
4
-alkylamino or mercapto groups.
C
1
-C
4
-alkyl here refers to all primary, secondary and tertiary, unbranched or branched alkyl groups having up to 4 carbon atoms, for example, methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl, and tert-butyl. Aryl refers in particular to phenyl or to alkyl-substituted phenyl, such as, o-, m- or p-tolyl or the various isomeric xylyl groups. Examples of suitable lactones are &ggr;-butyrolactone, &ggr;- and &dgr;-valero-lactone, &egr;-caprolactone or substituted lactones such as pantolactone (2-hydroxy-3,3-dimethyl-&ggr;-butyrolactone).
Functional groups as substituents, that is, hydroxyl, amino, alkylamino or mercapto, are preferably located on the groups B of the amine component (III).
Amines (III) which are suitable are therefore not only primary diamines but also compounds having additional primary or secondary amino groups. Examples of suitable amines are 1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane, 1,2,3-triaminopropane, 1,1,1-tris(aminomethyl)ethane or tetrakis (aminomethyl)-methane. If amines having non-equivalent amino groups are employed, then under some circumstances mixtures of products can be formed—as in the case, for example, with 1,2-diaminopropane or 1,2,3-triaminopropane.
When reacting the lactone (II) with the amine (III) it is advantageous to use a molar ratio of at least 1 mol of amine to 1 mol of lactone (i.e., 1 to 30 mols per mol). Preferably, from 2 to 20 mols of amine are employed per mole of lactone. The excess of amine can be recovered when working up the reaction mixture.
The reaction is advantageously carried out at a temperature of at least 150° C. The reaction temperature is preferably between 200° and 300° C. The addition of an inert solvent, such as, toluene or xylene, while possible, is not necessary. The reaction is preferably carried out without solvent. In order to attain the reaction temperature it is generally necessary to maintain the reaction mixture under elevated pressure, since the boiling points of many starting materials at atmospheric pressure are lower than the reaction temperature. In order to achieve this, customary autoclaves can be employed. In order to accelerate the reaction it is preferable to add an acidic catalyst. Suitable catalysts are Brnsted acids, such as, hydrochloric acid, sulfuric acid, phosphoric acid or ammonium chloride, or alternatively acidic aluminium silicates or acidic metal oxides, such as, tin (IV) oxide or antimony (III) oxide.
In accordance with the invention, the reaction mixture is distilled directly without isolating an intermediate. For practical reasons, this is typically carried out by transferring the reaction mixture from the autoclave to a distillation apparatus. If appropriately equipped apparatus suitable both for superatmospheric pressure and reduced pressure is available, the reaction of the lactone with the amine and the distillation can be carried out in one and the same apparatus. In the distillation, the initial fraction passing over is the water formed during cyclization and the excess amine, followed by the amidine. Depending on the boiling point of the product, the distillation is carried out at an appropriately reduced pressure.
Using the process according to the invention, the known bicyclic amidines mentioned in the back
Bregy Rachel
Daum Ulrich
Werbitzky Oleg
Bernhardt Emily
Fisher Christen & Sabol
Lonza AG
LandOfFree
Bicyclic amidines, process for their preparation, and their... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bicyclic amidines, process for their preparation, and their..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bicyclic amidines, process for their preparation, and their... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2522547