DE1793203B2 - Process for the preparation of dialkylphosphine oxides - Google Patents

Description

R ₁

R.,

P-H

in which R ₁ and R are alkyl groups with 1 to 6 carbon atoms, by hydrolysis of dialkyl halophosphines, characterized in that dialkyl halophosphines of the general formula

in which R ₁ and R _{2 are} alkyl groups having 1 to 6 carbon atoms, by hydrolysis of dialkylhalosephosphines, characterized in that dialkylhalophosphines of the general formula

P-X

in which R ₁ and R _{2 have} the abovementioned meaning and X is a halogen atom, or their hydrogen halide adducts are hydrolyzed by aqueous, non-oxidizing mineral acids.

2. Use of dimethylphosphine oxide as a flame-retardant additive in polyurethanes.

R "

The hydrolysis of secondary monohalophosphines generally does not lead to the corresponding phosphine oxides. but rather with disproportionation to phosphinic acids and phosphines:
2 R ₂ PCI -f 2 H ₂ O * R ₂ P (O) OH - R ₂ PH + 2 HCI

(K ο s ο I a ρ ο f f, "Organophosphorus Compounds" [1950], p. 52, and Van Wazer, “Phosphorus and its Compounds "I [1964], pp. 354 and 355). The only exception are the diarylchlorophosphines, which can be hydrolyzed to the corresponding diarylphosphine oxides. When making the Diphenylphosphine oxide is less resistant to the multiply substituted diphenylphosphine oxides you have to do the hydrolysis in organic diluents in a hydrogen or Nitrogen atmosphere with pure water or in the presence of tertiary amines as acid-binding amines Carry out means (Houben - Weyl, "Methods of Organic Chemistry", ΧΙΓ, 1, pp. 193 and 194).

Of the dialkylphosphine oxides, only dioctylphosphine oxide has so far been able to do this by hydrolysis of dioctylbiomophosphine with molar amounts of water and triethylamine in benzene under nitrogen. The dioctylphosphine oxide is obtained in one Yield of about 72% (J. Org. Chem. 24 (1959), S. 2013).

It has also been reported that dimethylphosphine oxide to form in the hydrolysis of dimethylfluorophosphine or dimethylchlorophosphine with water (F. Se e I et al., Angew. Chemie 79, p. 686 [1967]).

In contrast, the invention relates to a process for the preparation of dialkylphosphine oxides all my formula

in which R ₁ and R _{2 have} the abovementioned meaning and X is a halose atom, or their hydrogen halide adducts are hydrolyzed by aqueous, non-oxidizing mineral acids.

The invention further relates to the use, as flame-retardant Dimethylphosphinoxyd _n / isatz to polyurethanes.
The main starting compounds are

Dialkylchlorphosphine and Dialkylbromphosphirc in Consideration, the dialkylchlorophosphines of their Generally preferred for ease of access. Instead of the dialkyl haloce -: - Phosphines can also contain their halocene hydrogen .-. Γί-

adducts, which can also be present in the form of phosphoranes, can be used. examples for Dialkylhalophosphines, which in the case of the erfindu.K: -, - according to Process used as an initial connection are dimethylchlorophosphine, dimethylfluorophosphine, diethylchlorophosphine. Diethylbromophosphine. Methylethylchlorophosphine. Dipropylchlorophosphine, di-n-butylchlorophosphine and Di-n-hexylchlorophosphine and their hydrogen halide, especially hydrogen chloride adducts.

The non-oxidizing mineral acids are above all aqueous hydrochloric acid. Hydrobromic acid. sulfuric acid and phosphoric acid. The acid concentration to be used in the hydrolysis is mainly on the acid used in each case, the reaction temperature and the d «m to be hydrolyzed Dialkylhalophosphine determined. Hydrochloric and hydrobromic acids are useful at a concentration between about 10 percent by weight and the saturation concentration and preferably used between about 30 percent by weight and the saturation concentration at the reaction temperature. Sulfuric and phosphoric acid come expediently in a concentration between 20 and 80 percent by weight, preferably between 30 and 50 percent by weight, for use. In the manufacture of higher dialkylphosphine oxides is generally a lower acid concentration than when making the lower limbs, especially of dimethylphosphine oxide, sufficient. In general, concentrated hydrochloric acid is used as the hydrolysis medium preferred.

The hydrolysis is expedient at temperatures

between -30 and + 5O ⁰ C, preferably between -20 and + 2O ⁰ C, made. The hydrolysis is preferably carried out with the exclusion of air. Examples of suitable inert gases are argon. Hydrogen chloride, hydrogen bromide and especially nitrogen. The aqueous mineral acid is at least in one

3 4

used in such an amount that the n. '. ch addition of the hishcr known process is not obtained in substance

Dialkylhalophosphine obtained conversion could be produced, and the soiuir

is mixable stirrable. The upper limit is only in almost quantitative terms,

determined by practical considerations. It was very surprising that hot the drol \ ie

The hydrolysis is expediently carried out in the manner no oc "er according to the process according to the invention

by that the dialkylhalophosphines or practically no disproportionation r.u Fhcsphin-

their hydrogen halide addition products take place in the acids and phosphines. This is un. so iiter-

aqueous mineral acid is allowed to flow in with stirring. more surprising than the tendency to disproportionate

As already mentioned, one works here preferably with a decreasing number of carbon atoms in the

in the absence of air. After the reaction has ended, organic residues rise sharply (Am. Soc. 77,

one works up the reaction mixture, what on [1955], p. 3412, and Houben-Weyl. "Me-

can be done in different ways. methods of organic chemistry ”, XII, 1. p. 193).

The work-up can, for example, it is allowed for example dimethylchlorophosphine perform unier that the water under reduced nitrogen in excess water at 0 to 10 to ^c largely distilled off C pressure, incorporate the mineral acids 15 and then neutralized with Natronneutralisiert and the inorganic salts formed liquor in compliance a temperature of about filtered off. The filtrate containing the crude dialkyl 0 ^c C, it is observed phosphine oxide at the end of neutralization. Here you can also proceed in such a way, a spontaneous ignition, which leads to the release, that neutralization of the inorganic acids and self-ignition of the by disproportionation is carried out before the water is distilled off. The 20 formed dimethylphosphine is due. Neutralization is expedient at temperatures. In addition, red polymeric phosphorus below 50 ^; C made. compounds deposited. When working up

For neutralization, alkali or alkaline earth could only be the sodium salt of the dimer> lphosphine

Throw oxides, hydroxides, carbonates or bicarbonates acid in isolation.

be used. Preference is given to using sodium with a view to the fact that secondary phosphine oxides

hydroxyd, potassium hydroxide, or barium hydroxide have a strong tendency when heated in one

Calcium oxide used. Also ammonia or intermolecular redox reaction to secondary phos-

organic nurses such as dimethylamine. Diethylamine to disproportionate phinen and phosphinic acids

or triethylamine, can be used. Die (Houben - Weyl, op. Cit. P. 64). was it on-

Aniines should, however, be selected in such a way that it is surprising that the lower dialkyl

the salts formed not in de; Dialkylphosphine phosphine oxides, especially dimethyl phosphine oxide.

dissolve oxides. Basic ion exchangers can also be distilled without decomposition,

can be applied. According to the method of the present invention

If volatile acids are used as mineral acids, available dialkylphosphine oxides are valuable

It is also possible to represent a large part of the intermediate products. As a result of their high purity

to remove the acid by being able to use them especially as reactant components for

The mixture to be worked up is a stream of inert gas, suitable for those reactions caused by radical formers

Nitrogen. be catalyzed.

In the work-up methods given above, the lowest member in the series of dialkylphosphorus

It is often advantageous in the presence of an inert phinoxide, which also possesses dimethylphosphine oxide

Diluents, such as benzene, methylene chloride, bacteriostatic and bactericidal properties,

or a lower alcohol, which after it can continue to work as oil and water soluble

the filtering off of the inorganic salts again corrosion inhibitor can be used and is in

is distilled off. of interest in this context as lubricating oil

The products of the process can also be added by Ex- 45.

traction that can be done before or after neutralizing the polyester, epoxy resins or polyurethanes Reaction mixture can be carried out, flame-recovered by adding dimethylphosphine oxide will. As an extractant come before test can be made. The dimethylphosphine oxide all diethyl ether, benzene or methylene chloride can be used during the preparation of the polymers Question. After the organic layer 50 has been separated off, the following are added: the polymers can, however, also becomes the extractant, if necessary after its preparation with dimethylphosphine oxide Neutralization and drying, distilled off. Which are treated.

Obtaining the process products by extraction with the addition of dimethylphosphine oxide in general only with the higher posed polyurethane foam is already with one Divided, from dipropylphosphine oxide to 55 phosphorus content of about 1.5 percent by weight upwards, as the lower links, especially the flammable one. Dimethylphosphine oxide catalyzes au-dimethylphosphine oxide, are very soluble in water. Furthermore, the onset of the polyol-isocyanate reaction

The crude dialkylphosphine oxides obtained in this way are so effective that they are used in polyurethane production

can then be reduced by distillation with the addition of other activators such. B. amines,

Pressure or recrystallization can be cleaned. 60 can be dispensed with.

The advantage of the method according to the invention. 11th

compared to the previously known method for B e 1 s ρ 1 e i l

Production of dialkylphosphine oxides consists in 185 g of dimethylchlorophosphine being evenly

that technically easily accessible starting compounds in 165 g of concentrated hydrochloric acid at -5 ⁰ C below

gen used, the dialkylphosphine oxides in a nitrogen atmosphere within about

not yet yields up to receive l '/ ₂ hours left flow. After completion

and that according to the method of the present the reaction is the reaction mixture with

Invention also dimethylphosphine oxide, which after the concentrated sodium hydroxide solution to a pH of

I 793 203

6.5 breaks, the temperature being 20 to. .10 C not so top !! The shark tip of the water will then under reduced pressure at a nuiximalcn fiine-uemperaiur of about fiO C ahdistilled. Afterward 300 ml of benzal are added and the rest of the water is removed by azenirope distillation. The sodium chloride is then filtered off with suction and rinsed with 30 ml of benzene. The benzene will then distilled off at a maximum internal temperature of about 6D to 70C under reduced pressure. 146 g of crude dimethylphosphine oxide are obtained, which corresponds to a yield of 97.5%, according to theory. The purification is carried out by distillation with the aid of a column, with a cooling water temperature Oiäihylphosphinoxyd, according to one distributed 00 '' .. the theory.

ι in

example
121 ü dimethylchlorophosphine

50 ^{n 'is} ₀ sulfuric acid at - 20

are in j00 ml of C under a

Stoffaimosphere evenly dripped in within about 1 hour. After completion of the reaction, the reaction mixture by adding 5O ° / _O ijier sodium hydroxide to a pH-value is taken from. 7 A temperature of 20 to 30 ° C is maintained here. The sodium sulfate which has separated out is then filtered off with suction and washed with a little methanol. Methanol and water are then

40 C is maintained. The thus obtained 15 was distilled off under reduced pressure. The residue

Pure Dimethyiphosphinoxyd has a boiling point of 1 Torr of 54 "C, a freezing point of 34 to 36 C and has a refractive index; / i "-!, 4450.

Example 2

Under a hydrogen chloride atmosphere, dripped evenly 255 dimethylchlorophosphine-hydrogen chloride adduct g in 165 g of concentrated hydrochloric acid at a temperature of -1O ⁰ C within I ¹ Z ₂ hours. When the reaction has ended, the water is distilled off under reduced pressure, whereupon the residue is taken up in 300 ml of methylene chloride. Gaseous ammonia is passed into this solution with cooling until it is neutralized, whereupon traces of water still present are removed by azeotropic distillation. It is then filtered off with suction and rinsed with 30 ml of methylene chloride. After Abdestilüuren the methylene chloride 146 g of crude is obtained Dimethyiphosphinoxyd, corresponding to a yield of 97.5 ° "corresponds to the theory. The purification of the product that is described in Example 1 is mixed with VIethanoi, whereupon the remaining sodium sulfate is suctioned off and washed with a little methanol. After distilling off the methanol under reduced pressure, 89 g of dimethylphosphinox ^ d are obtained as residue, which corresponds to a yield of 90 ° _o of theory. The crude product is purified in the manner described in Example 1.

B e i s ρ i e 1 6

181 g of di-n-butylchlorophosphine are allowed to flow in under a nitrogen atmosphere into 200 ml of 20% hydrochloric acid at 4-10 ° C. over the course of about 1 hour. After completion of the reaction, the mixture obtained by adding 50 ° / ₀ sodium hydroxide solution to a pH value is brought from the 7th The oil that separates out is extracted with ether. After the ether has been distilled off, the di-n-butylphosphine oxide thus obtained is purified by distillation under reduced pressure. 149 g of di-n-butylphosphine oxide are obtained, which corresponds to a yield of 92% of theory; Kp. _{] S} : 153 ⁰ C.

If in the above example, instead of di-n-butylchlorophosphine, the equivalent amount of di-

Product is identical, is carried out in Example 1 40 n-biitylbromophosphine and the rest of the procedure is the same described way. described above, the same connection is obtained

Example 3

in approximately the same yield. Example 7

108 g of diethylchlorophosphine are under a

Nitrogen atmosphere in 80 g of concentrated hydrochloric acid 300 ml of concentrated hydrochloric acid are in an open

at -10 ⁰ C within 80 minutes evenly filled a 1-liter beaker and a dropping funnel was added dropwise in this way. ^C is then at a 30 to 40 carbon attached to that one Auslaiifrohr / ₀ leads strength sodium hydroxide solution of hydrochloric acid under the surface temperature not exceeding 50 °. Now the dropping funnel is neutralized with caustic up to a pH of 7. Flushed nitrogen in such a way that the nitrogen flow at. Thereafter, the water is distilled off through the outlet pipe of the dropper under reduced pressure with the tap open, whereupon 200 ml of benzene is added and the funnel escapes. After flushing with nitrogen, the last traces of water are azeotropically distilled off 74 g of dimethylchlorophosphine under nitrogen at now. After suctioning off, the benzene is poured into the dropping funnel under a closed tap and distilled off at reduced pressure. That as residue 55 and the dropping funnel until the reaction has ended

connected to a gasometer filled with nitrogen. Now, the hydrochloric acid is cooled to about -5 ⁰ C and added dropwise to the dimethylchlorophosphine with vigorous stirring using a magnetic stirrer for 1 hour and 15 minutes. With this arrangement, the self-igniting ^ dimethylchlorophosphine remains until it is thoroughly mixed

The crude diethylchlorophosphine obtained is then distilled in a high vacuum.

86 g of diethylphosphine oxide, b.p. _02m m: 47 to 48 ° C. (yield 93.5% of theory) are obtained.

Example 4

101 g Diäthylbroinphosphin is allowed under a nitrogen atmosphere within I hour in 100 g of 48 ° / _o hydrobromic acid at -1O ⁰ C incorporated uniformly. After the reaction has ended, the reaction mixture is worked up in the manner described in Example 3. This gives 57 g of hydrochloric acid under nitrogen; the reaction itself takes place in the presence of atmospheric oxygen. After the reaction has ended, work-up is carried out as in Example 1. 52 g of crude dimethylphosphine oxide are obtained. This corresponds to a yield of 87% of theory.

Claims (1)

i 793 203 claims: 1. Process for the preparation of dialkylphosphine oxides of the general formula P-H R.,