Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
2001-11-16
2003-07-01
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
C556S411000
Reexamination Certificate
active
06586612
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improved process of producing secondary and tertiary amino-functional silanes, and to the novel silyl imines, silyl imides, and secondary and tertiary amino-functional silanes produced therefrom.
BACKGROUND OF THE INVENTION
Amino silanes are commonly used as adhesion promoters in adhesives and sealants, and as coupling agents in compositions used in the plastics and glass-fibers industries and in foundries, in fabric treatment compositions, and in personal care products.
In particular, secondary and tertiary amino functionalized silanes are useful as coupling agents in the fiberglass and automotive glass industries. Currently the best technology for producing functionalized amino silanes is either through hydrosilation of a functionalized allyl amine, through reductive amination of a primary amino silane, or by nucleophilic substitution of gamma-chloropropyltrialkoxysilane. Unfortunately, functionalized allyl amines are not readily available, and are often quite expensive when they are available. Reductive aminations, on the other hand, are limited to symmetrical secondary amines, and often occur in such low yields that they are cost prohibitive, while nucleophilic substitution generates one equivalent of hydrochloride salt that must be recycled or disposed of.
Primary amines are one of the more reactive functional groups in organic chemistry and are known to react rapidly with a variety of carbonyl containing compounds. In the case of aldehydes and ketones, nucleophilic addition and dehydration results in an analogous imine structure that forms almost quantitatively at room temperature. Subsequent reduction of the imine functionality has been shown to provide an economical route to secondary amines. While the application of this methodology to amino silanes has already been reported in the patent literature, the direct reaction of silanes with aldehydes or ketones inevitably leads to the formation of siloxanes and lower yields.
SUMMARY OF THE INVENTION
The present invention overcomes the aforementioned problems by performing a water-producing condensation reaction between a carbonyl compound and a water-insensitive carrier amine, for instance butyl amine or aniline, to give an imine as the first intermediate adduct product; after removing water from the product and drying by conventional means, the carrier amine is then regenerated and recovered in an exchange reaction with a water sensitive aminoorganosilane to produce a second silyl imine intermediate adduct which is further reduced to either a secondary or tertiary amine depending on the nature of the aminoorganosilane.
The starting carbonyl compound may be a ketone, aldehyde, carboxylic acid or anhydride. In the case where the carbonyl compound is an aldehyde or ketone, the first and second intermediate adduct products are imines (i.e. aldimines and ketimines, respectively). Compounds which exist as aldehyde and ketone equivalents, e.g. ketals and acetals, may also be used to produce imine intermediates. In the case where the carbonyl compound is an anhydride or carboxylic acid, the resulting intermediate compounds are amides.
The use of secondary amino silanes as adhesion promoters is well known in urethanes and glass sizing agents. The conversion of silyl imines, produced by the process described above, to secondary amine can be accomplished under moderate hydrogen pressure and in the presence of a precious metal catalyst, i.e. Pd, Pt, Rh-containing catalysts, and the like. Other reduction methods for conversion of imines to secondary amines are also applicable and have been described in the prior art and are equally as applicable.
Using the method of the present invention, a whole new class of novel secondary amines, not possible using other methods, becomes available. In the case where an imine or imide of a volatilizable amine is already available, the first step of the process may be eliminated.
The second intermediate compounds, i.e. ketimino, aldimino and imido silanes, produced by the process of the invention have utility in their own right, as adhesion promoters, crosslinkers, as components of silicate clearcoats and the like. EP 976771, incorporated by reference herein in its entirety, describes a curable resin composition containing a curable resin and a ketimine structure-bearing organo-silicon compound that is useful as an adhesive. With respect to such compounds, therefore the final reduction step in the process described above may be eliminated.
The present invention herein also relates to the novel secondary and to novel second intermediate compounds, i.e. ketimino, aldimino and imido silanes, formed by the processes as described above.
DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS
The present invention provides a process whereby novel and valuable silyl imines or silyl imides having hydrolyzable groups bound to silicon can be produced and isolated. Silyl imines and imides produced by this method can be obtained in high yield and substantially siloxane-free. More particularly, the process of the invention provides product yields typically exceeding 90% and containing less than about 2 weight percent siloxanes. Moreover, subsequent reduction of the aforementioned imines provides a novel route to secondary and tertiary amines.
The steps of the invention are described in sequence, although as noted, the formation of the first intermediate may be eliminated if that product is available and the reduction to amine may be eliminated if the compound described herein as the second intermediate is the desired end product.
The process steps of the present invention can be practiced using either a batch mode process, or using a continuous process.
Step 1—Formation of First Intermediate Imine or Imide
The first step in the process of the invention involves a condensation reaction which forms an imine or imide from a water insensitive volatilizable primary amine (a “carrier” amine) and a carbonyl compound. The imine forming condensation reaction may be represented by the following general reaction (I):
In formula (I), R
1
is a hydrocarbon group, suitably one having from 1 to 30 carbon atoms, although in principle even larger hydrocarbon groups may be employed as R
1
groups, and may be an alkyl, aryl, alkaryl, aralkyl or alkarylalkyl group. Preferably, R
1
has from 1 to 20 carbon atoms. R
1
may also be an alkenyl or alkynyl group, although in such cases the final reduction step will likely hydrogenate some or all of the sites of aliphatic carbon—carbon unsaturation. R
2
is hydrogen or a hydrocarbon group having from 1 to 20 carbon atoms, more preferably from 1 to 4 carbon atoms, and may be suitably an alkyl, aryl, alkaryl, aralkyl or alkarylalkyl group, or R
1
and R
2
together form a cyclic hydrocarbon group containing up to 8 carbon atoms. R
3
is a hydrogen or a hydrocarbon group having from 1 to 10 carbon atoms, more preferably from 3 to 8 carbon atoms, and may be an alkyl, aryl, alkaryl, aralkyl or alkarylalkyl group, and n is 0 to 20, preferably 1 to 3.
In one specific embodiment of the reaction depicted above, R
1
is benzyl, R
2
is hydrogen and R
3
is phenyl.
The primary carrier amines, R
3
NH
2
, useful herein include but are not limited to, allyl amine, ammonia, aniline, butyl amine, ethyl amine, isopropyl amine, tert-octyl amine, and so forth. Preferred amines are relatively low boiling, or are amines which will form a readily volatilizable azeotrope with a non-aqueous solvent such as toluene. Butylamine, which has a boiling point of about 76° C., is an example of a preferred relatively low boiling amine. Aniline, which can be azeotropically distilled with toluene, is an example of an amine which is readily volatilizable with a non-aqueous solvent.
The condensation reaction (I) above may also be implemented starting with a compound which exists in equilibrium with an aldehyde or ketone, in particular an acetal, ketal, or an aldehyde-ammonia trimer.
Useful aldehydes include, but are not limited to, formaldehyde, acetaldehyde, butyraldehy
Gedon Steven C.
Trotto Andrea
Crompton Corporation
Dilworth Michael P.
Vollano Jean F.
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