EP0000043B1 - Bisphosphinic acid anhydrides and process for its preparation - Google Patents

Description

Alkanephosphinic anhydrides of the formula R'R "P (0) -OP (0) R'R", in which R 'and R "denote alkyl, aryl or aralkyl groups, are already known. They can be prepared, for example, by reacting alkanephosphinic acids or alkanephosphinic esters with phosgene can be obtained (DE-OS 2129583).

Bis-phosphinic acids are already known from DE-OS 2 328 343. However, these free bisphosphinic acids differ fundamentally in their reactivity from the anhydrides described below and cannot be reacted with compounds which contain hydroxyl groups because of this different reactivity, as is the case with the anhydrides. However, the end products of this reaction are valuable flame-retardant compounds, and these flame-retardant compounds can therefore not be obtained using the previously known free bisphosphinic acids, but only by way of the anhydrides according to the invention.

In an effort to extend this reaction to the production of other phosphinic anhydrides, it has now been found that bisphosphinic anhydrides can also be prepared in an excellent manner by reacting the free bisphosphinic acids, their salts and / or esters with inorganic acid chlorides, phosgene or oxalyl chloride.

worin R = gesättigter offenkettiger oder cyclischer Alkylrest, ein Arylen- oder Aralkylenrest, sowie R¹ und R², welche gleich oder verschieden sein können, gegebenenfalls halogensubstituierte Alkyl-, Aryl- oder Aralkylreste und
m ganze Zahlen ≧ 1, vorzugsweise ≧ 2, bedeutet,
das dadurch gekennzeichnet ist, daß man Bisphosphinsäurederivate der Formel

worin R, R¹ und R² die gleiche Bedeutung wie in Formel I haben, und R³ und R⁴, welche gleich oder verschieden sein können, Wasserstoff, einwertige Kationen, die Ammoniumgruppe oder gegebenenfalls halogensubstituierte Alkylgruppen bedeuten, mit anorganischen Säurechloriden und/oder mit Phosgen und/oder mit Oxalylchlorid und/oder mit den entsprechenden Bromverbindungen im Molverhältnis von 1 : 1 bei Temperaturen zwischen Raumtemperatur (ca. 20°C) und 250°C, vorzugsweise zwischen ca. 100 und 200°C, gegebenenfalls in Gegenwart inerter Lösungsmittel, umsetzt.The subject of the invention is thus a process for the preparation of bisphosphinic anhydrides of the formula

wherein R = saturated open-chain or cyclic alkyl radical, an arylene or aralkylene radical, and R ¹ and R ² , which may be the same or different, optionally halogen-substituted alkyl, aryl or aralkyl radicals and
m means integers ≧ 1, preferably ≧ 2,
which is characterized in that bisphosphinic acid derivatives of the formula

wherein R, R ¹ and R ^{2 have} the same meaning as in formula I, and R ³ and R ⁴ , which may be the same or different, denote hydrogen, monovalent cations, the ammonium group or optionally halogen-substituted alkyl groups, with inorganic acid chlorides and / or with phosgene and / or with oxalyl chloride and / or with the corresponding bromine compounds in a molar ratio of 1: 1 at temperatures between room temperature (approx. 20 ° C.) and 250 ° C., preferably between approx. 100 and 200 ° C., if appropriate in the presence of inert Solvent.

in Frage; bevorzugt sind gesättige offenkettige verzweigte oder unverzweigte Alkylenreste mit 1 -10, vorzugsweise mit 1 -6 C-Atomen, wovon die unverzweigten Alkylenreste wiederum besonders bevorzugt sind.Saturated open-chain or cyclic alkyl radicals R in formulas I and 11 include all possible branched and unbranched and cyclic alkylene radicals, for example

in question; preference is given to saturated open-chain, branched or unbranched alkylene radicals having 1-10, preferably 1-6, carbon atoms, of which the unbranched alkylene radicals are again particularly preferred.

The arylene radicals R are, for example, the phenylene and naphthylene radicals, of which the p-phenylene radical is preferred. Aralkylene radicals R are, for example, the tolylene radical, the xylylene radical etc., of which the p-xylylene radical is the preferred radical.

Of course, all radicals which can be considered as R can still carry reaction-inert substituents, for example halogen substituents.

bevorzugt sind (unsubstituierte) Alkylgruppen mit 1 bis 4, insbesondere 1-2 C-Atomen.Examples of optionally halogen-substituted alkyl radicals R ¹ and R ² , which can be the same or different, are:

(Unsubstituted) alkyl groups with 1 to 4, in particular 1-2, carbon atoms are preferred.

Suitable aryl and aralkyl radicals R ¹ and R ² are, for example, the phenyl, the naphthyl and the benzyl radical.

In compounds I and 11, the radicals R ¹ and R2 are preferably the same,
In the formula, m denotes integers of at least 1, preferably at least 2.

The monovalent cations for the radicals R ³ and R ⁴ in formula II are primarily the alkali ions, especially Na and K ions; if R ³ and R ^{4 are} optionally halogen-substituted alkyl groups, primarily alkyl groups with 1 -5 C atoms are possible, which can also be substituted by halogen, in particular by chlorine, preferably 1 -3 times. R ³ and R ⁴ are preferably the same.

• Methan-bis-methylphosphinsäuremethylester,
• Methan-bis-methyl-phosphinsäureäthylester,
• Methan-bis-methylphosphinsäureisopropylester,
• Äthan-1,2-bis-(methylphosphin-säurebutylester),
• Äthan-1,2-bis-(methylphosphinsäureamylester),
• Äthan-1,2-bis-(äthylphosphinsäureäthylester),
• Äthan-1,2-bis-(methylphosphinsäure-2-chloräthylester),
• Äthan-1,2-bis-(butylphosphinsäuremethylester),
• Butan-1,4-bis-(methylphosphinsäurebutylester),
• Hexan-1,6-bis-(methylphosphinsäurebutylester),
• Dekan-1,10-bis-(methylphosphinsäureisobutylester),
• Butan-1,4-bis-(methylphosphinsäure)-monobutylester,
• Methan-bis-(methylphosphinsäure), Äthan-1,2-bis-(methylphosphinsäure),
• Propan-1,3-bis-(methylphosphinsäure), Butan-1,4-bis-(äthylphosphinsäure),
• Hexan-1 ,6-bis-(methylphosphinsäure), Dekan-1,10-bis-(methylphosphinsäure),
• Cyclohexan-1,4-bis-(methylphosphinsäure), p-Phenylen-bis-(äthylphosphinsäure), p-Xylylen-bis-(chlormethylphosphinsäure),

die Natrium-, Kalium-, Ammoniumsalze der genannten Säuren.Examples of bisphosphinic acid derivatives of the formula 11 which are used as starting compounds for the process according to the invention are:

• Methyl methane-bis-methylphosphinate,
• Methyl methane-bis-methylphosphinate,
• Isopropyl methane-bis-methylphosphinate,
• Ethane-1,2-bis (methylphosphinic acid butyl ester),
• Ethane-1,2-bis (methylphosphinate),
• Ethane-1,2-bis- (ethylphosphinate),
• Ethane-1,2-bis (2-chloroethyl methylphosphinate),
• Ethane-1,2-bis (methyl butylphosphinate),
• Butane-1,4-bis (methylphosphinic acid butyl ester),
• Hexane-1,6-bis (methylphosphinic acid butyl ester),
• Dekan-1,10-bis- (isobutyl methylphosphinate),
• Butane-1,4-bis (methylphosphinic acid) monobutyl ester,
• Methane-bis- (methylphosphinic acid), ethane-1,2-bis- (methylphosphinic acid),
• Propane-1,3-bis (methylphosphinic acid), butane-1,4-bis (ethylphosphinic acid),
• Hexane-1, 6-bis (methylphosphinic acid), decane-1,10-bis (methylphosphinic acid),
• Cyclohexane-1,4-bis (methylphosphinic acid), p-phenylene-bis- (ethylphosphinic acid), p-xylylene-bis (chloromethylphosphinic acid),

the sodium, potassium, ammonium salts of the acids mentioned.

These compounds can be prepared by known methods; e.g. For example, the ethane-1,2-bis (alkylphosphinic acid alkyl esters) are technically easy to prepare by the process of DE-OS 2 302 523. The corresponding acids can be prepared from these and analogous esters, preferably by the process of DE-PS 2441783 and 2441878. The inorganic acid chlorides used as reaction components are preferably thionyl chloride and phosphorus pentachloride. These acid chlorides as well as the phosgene and the oxalyl chloride can be used both individually and in a mixture. Instead of the acid chlorides, it is also possible to use the corresponding bromine compounds - that is to say thionyl bromide, phosphorus pentabromide, COBr ₂ , oxalyl bromide. The preferred acid chloride is phosgene.

The reactants can be fed to the reaction in any order. As a rule, it is expedient to present the bisphosphinic acid derivatives II and to supply the acid chlorides or bromides. The reaction of the bisphosphinic acid salts must take place in the presence of inert solvents, of which chlorinated hydrocarbons such as chloroform, methylene chloride, chlorobenzene, dichlorobenzene are preferred.

The reaction of the free bisphosphinic acids and the bisphosphinic esters does not require any solvents per se. However, their use may be appropriate for technical reasons.

The reaction proceeds in such a way that bisphosphinic acid derivatives II and acid halide in a molar ratio of about 1: 1 are used, small excesses of acid halide being not critical since they contribute to a complete reaction.

Larger excesses are not expedient since the bisphosphinic anhydrides I formed react further with excess acid halide to form the bisphosphinic acid halides. If such halides are formed as by-products, they can be hydrolyzed again to the bisphosphinic anhydrides I by adding calculated amounts of water.

In principle, the reactions take place at room temperature; however, it is often advantageous to work at temperatures between approximately 50 and 250 ° C., preferably between approximately 100 and 200 ° C. When the alkyl biphosphinates are used at about room temperature, the corresponding alkyl halides are obtained as by-products. Short-chain alkyl halides escape in gaseous form and have no effect on the reaction material. Longer-chain alkyl halides, such as butyl chloride, can, however, precipitate the anhydrides formed, so that the course of the reaction disrupts the course of the reaction. In such a case, it is therefore advantageous to work at higher temperatures at which the higher alkyl halides formed distill off. If you do not work in solvents, a reaction temperature that is above the solidification point of the end product must be selected at the latest towards the end of the reaction.

When the reaction has ended, measures known per se for separating off any solvents and / or by-products which may have remained in the reaction material, such as by blowing with inert gas (for example nitrogen), and distilling, if appropriate distilling, in vacuo give the end products in largely pure form. The yields are practically quantitative. Since cleaning of the end products is difficult to carry out, pure starting products should be used.

• und R¹ und R²=gleiche oder verschiedene Alkylgruppen mit 1 -4, vorzugsweise mit 1 -2 C-Atomen sind neue und wertvolle Verbindungen, welche - ebenso wie die vorstehend beschriebene Herstellungsverfahren - Erfindungsgegenstand sind. Die bevorzugten Verbindungen sind diejenigen, bei welchen in Formel 1
• R = gesättigter unverzweigter Alkylenrest mit 1 - 10, vorzugsweise mit 1 - C-Atomen und
• R¹ = R².

The anhydrides obtained in this way are generally in the form of linear polymers, the degree of polymerization of which - denoted by m in formula I - is unknown. The end group of the polymer chain is probably closed by hydrogen or hydroxyl. In individual cases there may also be ring-shaped connections. In particular the bisphosphinic anhydrides of the formula I in which R = saturated, open-chain, branched or unbranched alkylene radical having 1 -10, preferably 1 -6 C atoms,

• and R ¹ and R ² = identical or different alkyl groups with 1 -4, preferably with 1 -2 C atoms are new and valuable compounds which - like the production processes described above - are the subject of the invention. The preferred compounds are those in which in Formula 1
• R = saturated unbranched alkylene radical with 1 - 10, preferably with 1 - C atoms and
• R ¹ = R ² .

The novel compounds according to the invention are used as comonomers in the production of plastics, for example polymers, polycondensates or polyaddition products; Particularly noteworthy are - in particular linear - polyesters such as those of terephthalic acid, to which they impart good flame-retardant properties but also improved dyeability (see DE-PS 2236037). In particular, the new compounds come into question as intermediates for the preparation of flame retardants for fiber material (see German patent application P 2 726 478.4; laid-open specification 2 726 478). These products are obtained according to DE-OS 2726478 by reacting compounds containing hydroxyl groups with an organic phosphoric anhydride. The resulting reaction products are then oxyalkylated. The end products obtained in this way are distinguished by the fact that they have favorable hydroxyl numbers. These low hydroxyl numbers mean that very little substance of a fixing agent is required to fix these organophosphorus flame retardants on the textile material, for example in the form of melamine resin precondensates. If one were to use such organophosphorus compounds which had high hydroxyl numbers, one would also need correspondingly higher amounts of such melamine resin precursors for fixation. However, the use of larger amounts of melamine resin negatively affects the feel of the textile material thus finished and also causes a decrease in the relative phosphorus content, which is associated with a deterioration in the flame retardant effect. In addition, as is known in the art, the melamine resins have a so-called scaffolding or wicking effect due to their structure, which in the event of a fire intensifies instead of diminishes the fire effect. All these disadvantages are avoided if one uses organophosphorus compounds which have only relatively low hydroxyl numbers, as is the case with these compounds of DE-OS 2 726 478.

The following examples are intended to further illustrate the invention without restricting it.

example 1

211 g of methane-bis- (methylphosphinic acid isopropyl ester) are heated to 100 ° C. Then about 100 g of phosgene are gassed in with vigorous stirring within 3 hours, the Internal temperature is increased to 190 ° C. At the same time, the isopropyl chloride formed is distilled off. After the reaction has ended, nitrogen is passed through the reaction mixture at 190 ° C. for 2 hours. Residual volatile constituents are then removed in a water jet vacuum at 190 ° C. for one hour.

127 g of methane bis (methylphosphinic acid) anhydride with a solidification point of about 150 ° C. are obtained. The product is insoluble in chloroform. The yield is 100% of theory. Th.

Example 2

300 g of ethane-1,2-bis (isobutyl methylphosphinate) are heated to 160 ° C. Phosgene is then passed through for 3 hours with vigorous stirring. Isobutyl chloride formed is distilled off in the course of the reaction. After the reaction has ended, nitrogen is bubbled through at 170 ° C. for 6 hours.

169 g of ethane-1,2-bis (methylphosphinic acid) anhydride with a solidification point of about 115 ° C.-120 ° C. are obtained. The product is soluble in chloroform. The yield is 100% of theory. Th.

• CH₃: 1,9 ppm (J_pH=15 Hz)
• CH₂: 1,5-3 ppm

The following signals were detected in the ¹ H-NMR spectrum, recorded with the Varian T60 spectrometer at a measuring frequency of 60 MHz in CDCI ₃ as a solvent with the reference substance tetramethylsilane (TMS) as an internal standard:

• CH ₃ : 1.9 ppm (J _pH = 15 Hz)
• CH ₂ : 1.5-3 ppm

Example 3a

580 g of n-butyl methanephosphonate are heated to 165 ° C. under nitrogen. A mixture of 175 g of 1,5-hexadiene and 3 _{g of} di-tert-butyl peroxide is then added dropwise with vigorous stirring and the mixture is stirred at this temperature for 1 hour. The mixture is then distilled at 5 torr up to an internal temperature of 170 ° C. There remain 655 g of hexane-1,6-bis (n-butyl methylphosphinate). This corresponds to a yield of 87% of theory. Th.

Example 3b

701 g of hexane-1,6-bis (n-butyl methylphosphinate) are heated to 130.degree. Now, with vigorous stirring, 220 g of phosgene are gassed in over 5 hours and then nitrogen is blown through for 2 hours. During this, n-butyl chloride distilled off. The mixture is then heated to 180 ° C. and kept at this temperature in a water jet vacuum for 4 hours.

There remain 442 g of hexane-1,6-bis (methylphosphinic acid) anhydride with a solidification point of about 55 ° -60 ° C. The product is soluble in chloroform. The yield is approximately 100% of theory. Th.

• CH₃: 1,9 ppm (J_pH=15 Hz)
• CH₂: 1-3 ppm

The following signals were detected in the ¹ H-NMR spectrum, recorded with the Varian T60 spectrometer at a wet frequency of 60 MHz in CDCI ₃ as solvent with the reference substance TMS as the internal standard:

• CH ₃ : 1.9 ppm (J _pH = 15 Hz)
• CH ₂ : 1-3 ppm

Example 4

394g of dean-1,10-bis (methylphosphinic acid) are heated to 130 ° C to 140 ° C. Now 150 g of phosgene are introduced within 4 hours. The mixture is then heated to 180 ° C. and a water jet vacuum is applied for 6 hours.

There remain 370 g of dean-1,10-bis (methylphosphinic acid) anhydride with a solidification point of about 20 ° -25 ° C. The product is soluble in chloroform. The yield is 100% of theory. Th.

• CH₃: nicht bestimmbar
• CH₂: 1-3 ppm

The following signals were detected in the ¹ H-NMR spectrum, recorded with the Varian T60 spectrometer at a measuring frequency of 60 MHz in CDCI ₃ as a solvent with the reference substance TMS as an internal standard:

• CH ₃ : not determinable
• CH ₂ : 1-3 ppm

Example 5

39 _{g of} p-phenylene-bis- (methylphosphinic acid ethyl ester) are heated to 180 ° C. and phosgene is slowly introduced with stirring. The temperature is raised to 230 ° C. over the course of 1.5 hours. Then nitrogen is passed through. There remain 29 g of p-phenylene-bis- (methylphosphinic acid) anhydride with a solidification point of about 190-200 ° C. The product is soluble in chloroform. The yield is 100% of theory. Th.

• CH₃: 1,85 ppm und 2,1 ppm (2J_pH: 14-14 Hz)
• arom.: 7,5-8,5 ppm

The following signals were detected in the ¹ H-NMR spectrum, recorded with the Varian T60 spectrometer at a measuring frequency of 60 MHz in CDCI ₃ as a solvent with the reference substance TNS as the internal standard:

• CH ₃ : 1.85 ppm and 2.1 ppm (2J _pH : 14-14 Hz)
• aroma: 7.5-8.5 ppm

Example 6

44 g of p-xylylene-bis- (methylphosphinic acid) are heated to 240 ° C. and phosgene is slowly introduced with stirring. The temperature is reduced to 210 ° C. over the course of 1.5 hours. Nitrogen is then passed through at this temperature. There remain 41 g of p-xylylene-bis (methylphosphinic acid) anhydride with a solidification point of about 165-175 ° C.

The product is soluble in chloroform. The yield is 100% of theory. Th.

The following signals were detected in the ¹ H-NMR spectrum, recorded with the Varian T60 spectrometer at a measuring frequency of 60 MHz in CDCI ₃ as a solvent with the reference substance TMS as an internal standard:

Example 7

200 g of propane-1,3-dimethylphosphinic acid are heated to 170 ° and the amounts of phosgene required for the reaction are slowly introduced with stirring. After the reaction has ended, the hydrogen chloride present in the reaction mixture is removed in a water jet vacuum at 140.degree. The residue is distilled. 175 g of propane-1,3-dimethylphosphonic anhydride of the formula given below, mp. 122-130 ° C, Kpo ₃ : 163 °. This corresponds to a yield of 96% of theory. Th.

Claims (5)

1. Bisphosphinic acid anhydrides of the formula

in which R is a saturated, open-chain, branched or unbranched alkylene radical having from 1 to 10, carbon atoms,

and R¹ and R² represent identical or different alkyl groups having from 1 to 4, carbon atoms and m is an integer of greater than or equal to 1.

2. Bisphosphinic acid anhydrides as claimed in claim 1, in which R is an alkylene radical having from 1 to 6 carbon atoms, and R¹ and R² are alkyl with 1 or 2 carbon atoms with the proviso that R¹ and R² are identical.

3. Process for the preparation of bisphosphinic acid anhydrides as claimed in claim 1 which comprises reacting bisphosphinic acid derivatives of the formula

in which R, R¹ and R² are defined as in formula I, and R³ and R⁴, which may be the same or different, represent hydrogen, a monovalent cation, the ammonium group, C₁-C₄-alkyl or C₁-C₄-chloroalkyl with inorganic acid chlorides and/or with phosgene and/or with oxalyl chloride or with the corresponding bromine compounds in a molar ratio of about 1 : 1 at temperatur in the range of from about room temperature to 250° C.

4. Process as claimed in claim 3, which comprises reacting the bisphosphinic acid derivatives of the formula with phosgene.

5. Process as claimed in claim 3, which comprises carrying out the reaction in an inert solvent.