Process for preparing polysubstituted piperazinones

Abstract: A particular branched chain polyalkylenepolyamine ("PAPA") having plural amine groups including a secondary amine group intermediate terminal free primary amine groups (that is, neither one is hindered), and having at least two C atoms between each group, may be selectively cyclized with a ketoform reaction to form a polysubstit­ uted piperazinone ("PSP"), with specific directivity. Such PSPs are linked to a triazine nucleus to yield pip­ erazinone-triazine ("PIP-T") compounds which are excel­ lent stabilizers for polyolefins and other light-degrad­ able polymers. Certain acyclic polyalkylenepolyamines may have a PIP-T substituent at each N atom forming pend­ ant PIP-Ts ("P[PIP-T]" for brevity) which are also excel­ lent stabilizers, and like some of the PIP-Ts, some P[PIP-T]s provide photostabilization without noticeably interfering with the color of films and fibers provided by even pastel-colored pigments and dyes.

Description: BACKGROUND OF THE INVENTION This invention is related to a process for preparing branched bridge polysubstituted piperazinone ("PSP") compounds which are useful in the manufacture of 2-oxo-piperazinyl-triazine ("PIP-T" for brevity) compounds in which the polysubstituted piperazinone ("PSP") substituent is linked to the triazine ring through a single N (nitrogen) atom and at least two C (carbon) atoms, hence termed "distally linked". The term "polysubstituted" refers specifically to a piperazinone ring in which at least the N⁴-adjacent C atoms (at the 3 and 5 positions) are each dialkylsubstituted, or one of the 3 or 5 C atoms is shared by a spiro cycloalkylene substituent, and the other is dialkylsubstituted. More particularly, the PSP compounds are metal for the preparation of PIP-T compounds in which the PSP is connected to the triazine ring with a branched bridge, so termed because the bridge includes at least three serially linked atoms, the first, a N atom bound to the triazine ring, then two C atoms, and the N-adjacent C atom is always disubstituted. PIP-T compounds including bis compounds and oligomers thereof having a polymethylene bridge (unbranched) are disclosed in our U.S.-A-4,480,092 ("the '092 patent") for use as ultraviolet ("UV") light stabilizers in organic materials, whether natural or synthetic, which are to be protected against degradation by UV light by incorporating a UV light stabilizer in the material. Many classes of compounds are known to be useful UV light stabilizers, some being more effective than others. Particularly effective 2-keto-diazacycloalkanes which provide stabilized compositions resistant to degradation by UV light, include the 2-keto-1,4-diazacycloalkanes disclosed in U.S.-A-4,190,571; and, the 2-keto-1,5-diazacycloalkanes disclosed in U.S.-A-4,207,228. Other 2-keto-diazacycloalkanes useful as UV light stabilizers are disclosed in U.S.-A-3,919,234; 3,920,-659; and 3,928,330 which teach substituted piperazinediones. Cycloalkanes useful as UV light stabilizers, are disclosed in DE-A-2,315,042; Japanese Patents JP-A-. 7,453,571 and 7,453,572. The PIP-T compounds belong to a well-recognized chemical class of UV light stabilizers known as multi-ringed triazine derivatives. Though most such derivatives disclosed as UV light stabilizers have a significant level of UV-stabilization ("UV-S") activity, each has one or more serious drawbacks which makes the one less desirable from a practical, utilitarian point of view, than another having a less serious drawback. This reality dictates the unending search, even in the narrow field of multi-ringed triazine derivatives, for compounds with better UV-S activity, and results in discarding numerous multi-ringed triazine derivatives which have no appreciable UV-S activity, if at all. Prior art multi-ringed triazine derivatives with UV-S activity are also disclosed in U.S.-A-4,086,204; 4,051,137; 4,108,829; French Patent No. 2181 059; and, Japanese Patent JP-A-51-4247; inter alia. In particular regard to our '092 patent, we found that a distally linked PSP was unexpectedly effective not only for its UV-S activity, but also for its antioxidant ("AO") activity, particularly in combination with certain hindered phenols, as disclosed in US-A-4 722 806. We disclosed in our '092 patent how to provide a bridge of plural atoms for the critical distally linked rings. We started with a particular class of alkylated polyalkylenepolyamine ("PAPA"), namely a N-(alkyl)-N'-(aminoalkyl/aryl/aralkyl/cycloalkyl)-1,p-alkanediamine, wherein "p" is the number of methylene C atoms (hereafter "2AAD" for brevity), and one primary amine group was free, the other was substituted and hindered. The process comprises reductively alkylating a particular class of PAPA, such as a N'-(aminoalkyl/aryl/aralkyl/cycloalkyl)-1,p-alkanediamine (hereafter "2AD" for brevity) with a ketone in the presence of a Group VIII metal hydrogenation catalyst and a solvent for the reactants, by carrying out the reaction under elevated temperature and pressure to produce the 2AAD compound; separating the solvent from the reaction mass; adding chloroform and a ketone, preferably in the presence of a phase transfer catalyst; and, carrying out the reaction to produce a PSP which is recovered. The PSP is then reacted with cyanuric chloride or other reactive triazine compound. In a particular preferred embodiment of the invention, a PSP is produced from 2AD using a ketone as a reactant to produce 2AAD; and then, again using a ketone as a reactant, to cyclize the 2AAD. The PSP is then coupled with a triazine ring-containing compound to provide at least one distally linked PSP substituent on the triazine ring. The phase transfer catalyzed reaction referred to hereinabove is known as the "ketoform reaction" disclosed in greater detail in U.S.-A-4,167,512, also in an article titled "Hindered Amines. Novel Synthesis of 1,3,3,5,5-Pentasubstituted 2-Piperazinones" by John T. Lai in J. Org. Chem. 45 , 754 (1980), and in our '092 patent, relevant parts of all of which are incorporated by reference thereto as if fully set forth herein. The ketoform reaction may also be carried out without a phase transfer catalyst as disclosed in U.S.-A-4,466,915. The "2AAD" compound, for example, N-(2-butyl)-N'-(2-amino-2-methylpropyl)-1,2-ethanediamine (identified as 1A herebelow), provided a hindered primary amine group by introducing a substituent at the N-position, which is precisely where it was needed to allow us to use the subsequent ketoform reaction to close the ring and form the PSP by connecting the unhindered primary amine group and the intermediate secondary amine group. It was this blocking of the N-position which so effectively allowed cyclization of the unhindered primary amine group and the next adjacent secondary amine group with such regioselective specificity, as was noted in the Lai article, supra. Thus, it became evident, and it was our belief at that time, that the desired reaction required that one unhindered primary amine group only be left on a 2AAD if it was to be cyclized effectively. It was obvious that if two unhindered primary amine groups were present on a 2AAD, each would be equivalent to, and as active as, the other, and, in a ketoform reaction, both would react with the chloroform generating a trichloromethide ion, in turn resulting in an array of unwanted compounds, few, if any, of which would be cyclized so as to have formed the piperazinone ring. This invention documents the error of that belief. We accidentally found that the desired reaction proceeded with unhindered or "free" terminal primary amine groups. In other words, blocking the N-position, by converting the primary amine group to a secondary amine group, could be avoided if we disubstituted the C atom adjacent the N-position, thus making both terminal primary amine groups equivalent and equally unhindered. After the ketoform reaction, after the PSP is formed, we are left with a terminal free primary amine group - a fortuitous discovery which leaves the free primary amine to react directly with a reactive triazine compound. From an economic point of view, this is highly fortunate. Typically, PIP-T compounds are used as photostabilizers ("PS") in conjunction with a hindered phenol antioxidant ("AO") This appears to be a peculiarity of PIP-T compounds since it has been found that there is generally a strong antagonistic effect between many a hindered amine light stabilizer ("HALS") and a hindered phenol AO used in combination for the stabilization of polymers (see "Photostabilizing Performance of a Hindered Piperidine Compound in Polypropylene Film: Antioxidant/Light Stabilizer Effects" by N.S. Allen Polym. Degrad. Stabil. 2 , 129 (1980) and "Catalytic Thermal Oxidation of Phenolic Antioxidants by Hindered Piperidine Compounds" by N.S. Allen Polym. Degrad. Stabil. , 3 , 73 (1980-81). It was also known that a particular hindered phenol AO, namely tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate commercially available as Good-rite R 3114, and a bis-(hindered piperidine) PS commercially available as Tinuvin R 770, showed an unexpectedly beneficial coaction, as disclosed in "Interaction Between Antioxidants and Hindered Piperidine Compounds in the Photostabilization of Polypropylene: Influence of Processing History" by N.S. Allen et al, Polym. Photochem. 1 , 11 (1981). It was further known that bis-1-(piperazin-2-one) provided not only excellent photostabilization properties as disclosed in U.S.-A-4,190,571 but also excellent AO properties, as disclosed in U.S.-A-4,309,336. Moreover, the bis-1-(piperazin-2-one), like many other hindered piperazin-2-one PS compounds, in combination with hindered phenol AOs, were more effective as both PSs and AOs than the sum of their individual effectiveness as PSs and AOs, as disclosed in "Hindered Diazacycloalkanones as UV Stabilizers and Antioxidants" by J.T. Lai et al Polym. Preprints , 25 (1), 1984. Yet, quite surprising is the disclosure that commercially available Chimassorb® 944 when used in combination with BHT, Good-rite® 3114 and Irganox® 1010 is indeed less effective as determined by Weather-O-Meter® tests (see brochure entitled "Light Stabilization of Polypropylene Multifilaments and Monofilaments" published by Chimosa S.P.A. (1978), Fig 3. From the foregoing unpredictable behavior of particular HALS in combination with hindered phenol AOs generally, it is evident that the effectiveness of any HALS which is structurally dissimilar from the foregoing HALS, can be no more predictable. Certainly, there was no reason to expect that a compound from the particular class of HALS containing linked piperazinone and triazine rings, when combined with one of specific hindered phenols, would exhibit a higher degree of PS and AO activity than that obtained by summing the activity of the individual HALS and hindered phenol when used separately. This unique synergistic behavior of a PIP-T compound is now attributable to its being less basic, because of the 2-one group, than compounds containing linked triazine and pyridine, piperidine, or piperazine rings. SUMMARY OF THE INVENTION It has been discovered that a particular branched chain polyalkylenepolyamine ("PAPA") having plural amine groups including a secondary amine group intermediate terminal free primary amine groups (that is, neither one is hindered), and having at least two C atoms between each group (referred to herein as a "TFPA" compound because it has "terminal free primary amine" groups), may be selectively cyclized with a ketoform reaction to form a PSP, with quite unexpected specific directivity, in the same manner as with the ketoform reaction disclosed in our '092 patent. It is therefore a general object of this invention to provide a process for cyclizing a TFPA compound comprising contacting the TFPA compound with a saturated cyclic or acyclic monoketone and a haloform, in the presence of (i) an organic solvent, (ii) solid or aqueous alkali, and optionally, (iii) a phase transfer catalyst. The phase transfer catalyst, if used, is selected from the group consisting of a tertiary or quaternary compound of an element selected from Groups VA and VIA of the Periodic Table, and a polyether. It has further been discovered that when a PSP is distally linked to a triazine ring through at least a three-atom chain of serially linked 1 (one) N and 2 (two) C atoms, and the N-adjacent C atom in the chain is disubstituted, the novel compounds so formed are found to be exceptionally well-suited for use as stabilizers in synthetic resinous materials subject to degradation by uv light. The PSP-compounds obtainable by the process of the present invention are useful for the provision of a novel class of hindered amine-triazine derivatives useful as uv light stabilizers for polyolefins and other light-degradable polymers, which derivatives are characterized by (a) having at least one PSP distally linked to a triazine ring through a chain of serially linked N (adjacent the triazine ring) and at least two C atoms, the N-adjacent one of which is disubstituted, and (b) improved resistance to extraction from such polymers in prolonged contact with an aqueous solution. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In detail the present invention relates to a process for preparing a branched bridge polysubstituted piperazinone ("PSP") having the structure wherein, R₂, R₃, R₄ and R₅ independently represent C₁-C₂₄ alkyl and polymethylene having from 4 to 7 C atoms which are cyclizable forming a spiro cycloalkylene substituent with the C atom of the piperazinone ring, R₁ represents hydrogen; R₈ and R₉ independently represent C₁-C₂₄ alkyl, and polymethylene having from 4 to 7 C atoms which are cyclizable; R₁₀ represents H; comprising, contacting a polyalkyleneamine having terminal free primary amine groups, represented by the structure wherein, R₄, R₅, R₈, R₉ and R₁₀ have the same connotation as that set forth above; with a saturated cyclic or acyclic monoketone and a haloform, in the presence of (i) an organic solvent, (ii) solid or aqueous alkali, and optionally, (iii) a phase transfer catalyst, at a temperature in the range from -10°C to 30°C by ketoform reaction. The basic structure of the stabilizer compounds prepared by the synthesis described herein, is a substituted triazine ring to at least one C atom of which is attached a PSP by means of a branched bridge containing at least three atoms serially linked, the first, an N atom bound to a H atom, the N atom linked to the triazine ring, then at least two C atoms, and the N-adjacent C atom of the bridge is always disubstituted or branched (hence "branched bridge"). The manner of disubstitution is not narrowly critical provided both available bonds on the C atom are used, that is, both H atoms on the N-adjacent C atom are substituted. Though dialkyl-substituents are preferred, and most preferred are lower alkyl having from 1 to 6 C atoms ("C₁-C₆ alkyl"), disubstitution may also be effected with a cyclized polymethylene group having from 5 to 6 C atoms which forms a spiro cycloalkylene substituent. Since a disubstituted N-adjacent C atom was previously thought to negate the formation of cyclized PSP, there was every reason not to disubstitute this C atom of the bridge. The relative ease of formation of the branched bridge PIP-T from conveniently available PAPA, and the concomitant economic benefit of a simpler and more effective process, was never a consideration because the reaction was not believed to be "doable". Neither was there any consideration, for the same reason, that the branched bridge compounds may have better resistance to extraction than otherwise analogous unbranched bridge PIP-T compounds. PAPA which provide the branched bridge upon cyclization in the ketoform reaction, and a method for making such PAPA, are disclosed in U.S.-A-4,293,682. The PIP-T stabilizers which may be prepared using the PSP-compounds may be represented by the following structural formula (I): wherein, n is an integer in the range from 1 to 10, said compound having functional end groups selected from H, OH and Cl when n is greater than 1; X is the PSP-substituent having the following formula (II): wherein, R₂, R₃, R₄ R₅, R₈, R₉ and R₁₀ and as defined above; Y may be the same as X or M; M may be Z or Z', wherein Z represents a radical selected from the group consisting of R₆, R₇ represent alkyl having from 2 to 24 carbon atoms; and C₄-C₇ cycloalkyl; Ar represents aryl; Z' represents a radical selected from the group consisting of p represents an integer in the range from 2 to 20; X represents an integer in the range from 1 to 50; m represents an integer in the range from 2 to 4 and, when n = 1, Y and M may be the same as X. Preparation of polysubstituted piperazinone ("PSP"): In a typical preparation, the PSP is prepared by the ketoform synthesis, with or without a phase transfer catalyst. This synthesis is generally carried out with 1,2-diamines having TFPA groups. These diamines are reacted with a saturated or unsaturated monoketone and certain aromatic aldehydes such as benzaldehyde, along with a haloform reactant, in an organic solvent for the reactants, in the presence of aqueous or solid alkali. Though a phase transfer catalyst accelerates the reaction, it is found to proceed quite well even without it, provided the carbonyl reactant is a ketone and it is present in large excess. By large excess we refer to an amount in the range from 2 to 20 times the theoretical amount required. The reaction with a ketone proceeds at room temperature or below, though it may also be carried out at elevated temperatures, depending upon the particular other reactants present. A preferred temperature range is from -10°C to 30°C. Preferred ketones are aliphatic monoketones having from 3 to 12 carbon atoms, and cyclic monoketones having from 5 to 8 carbon atoms. Most preferred are the lower aliphatic ketones such as acetone including those having up to 12 carbon atoms, and the cycloaliphatic ketones such as cyclohexanone which may be substituted. A particular PSP is conveniently synthesized from N¹-(2-amino-2-methylpropyl)-2-methyl-1,2-propanediamine (identified herein as TFPA(1)" for brevity), as described hereinbelow. The PSP formed is 1-(2-amino-2-methylpropyl)-3,3,5,5-tetramethylpiperazinone having the following structure: In a 5 liter three-necked flask were placed 1137.1 g (19.6 moles) of acetone, 269.5 g (2.26 moles) of CHCl₃, and 267.8 g (1.5 moles) of 89% pure TFPA(1). To this cooled and stirred mixture was added at intervals, aliquots of NaOH until 295.2 g (7.38 moles) were added over a period of 3 hr while maintaining the temperature of the flask in the range from -3° to 6°C. After reacting overnight at -4°C, the resulting white slurry was filtered. The filtrate and an acetone wash of the white cake were stripped to obtain 383.3 g of straw-colored liquid (75.1% yield). The crude product was distilled in a 10.16cm (4") diam column in the presence of NaOH. The desired product boils at 110-2°C/66.6 Pa(0.5 mm Hg), and 240.2 g of 96% pure PSP was isolated. It is important to note that the TFPA(1) used in the foregoing preparation has terminal free primary amine groups, but a disubstituted ("branched") C atom next to each terminal free primary amine group, as seen in the following structure: which is one preferred embodiment of the general structure: In the '092 patent, though the general structure for a reactive PAPA showed terminal free primary amine groups, such an amine with one unbranched C atom adjacent a terminal free primary amine group, fails to produce the desired cyclized product with any directivity. Therefore, one TFPA in the '092 preparation was substituted, so as to negate its reactivity. The amine with the substituted amine group is N-(2-butyl)-N'-(2-amino-2-methylpropyl)-1,2-ethanediamine which has the structure:

Claims: A process for preparing a branched bridge polysubstituted piperazinone ("PSP") having the structure wherein, R₂, R₃, R₄ and R₅ independently represent C₁-C₂₄ alkyl and polymethylene having from 4 to 7 C atoms which are cyclizable forming a spiro cycloalkylene substituent with the C atom of the piperazinone ring, R₁ represents hydrogen; R₈ and R₉ independently represent C₁-C₂₄ alkyl, and polymethylene having from 4 to 7 C atoms which are cyclizable; R₁₀ represents H; comprising, contacting a polyalkyleneamine having terminal free primary amine groups, represented by the structure wherein, R₄, R₅, R₈, R₉ and R₁₀ have the same connotation as that set forth above; with a saturated cyclic or acyclic monoketone and a haloform, in the presence of (i) an organic solvent, (ii) solid or aqueous alkali, and optionally, (iii) a phase transfer catalyst, at a temperature in the range from -10°C to 30°C by ketoform reaction.

Inventors: LAI JOHN TA-YUAN, LAYER ROBERT WESLEY, SON PYONG NAE, LAI, JOHN TA-YUAN, LAYER, ROBERT WESLEY, SON, PYONG NAE
Applicants: GOODRICH CO B F, THE B.F. GOODRICH COMPANY
Application year: 1986
Main classification: C07D241
IPC codes: C08K5, C07D403