DD214610A1 - PROCESS FOR THE SIMULTANEOUS PREPARATION OF DIALKOXYMETHANOPHOSPHONSAEUREDIALKYLESTER, METHANE-BIS- (PHOSPHONSAEUREDIALKYLESTER) AND TRIALKYL PHOSPHATE - Google Patents

Abstract

The invention relates to a one-step process for the preparation of the above compounds, in which no non- or poorly recoverable by-products are obtained and which is characterized by a high environmental friendliness. The object of the invention is to use as starting materials cheap and technically well available compounds. It was found that Dialkoxymethanphosphonsaeure, methane bis (phosphonates and Triakylphosphat by reaction of white elemental phosphorus (Ptief 4), alcohol and carbon tetrachloride with metal alkoxide in the known Mohlenverhaeltnissen P deep 4; Alcohol: Tetrachloromethane = 1: 6: 6 to 1: 100: 20 in the temperature range of 0-100Grad C can be prepared in a solvent mixture, according to the invention the elemental phosphorus with the metal alcoholate in the molar ratio P deep 4: metal alcoholate = 1:10 to 1:30 is reacted in a solvent mixture, the amount of elementary phosphorus to be reacted per mole of 1 mole to 4 moles of an aprotic or low-polar solvent component.

Description

for the simultaneous preparation of Dialkoxymethanphosphonsäuredialkylesterj methane «Tbis» (phosphon acid dialkyl ester) and trialkyl phosphate

Field of application of the invention ;

The invention relates to a one-step process for the simultaneous preparation of Dialkoxymethanphosphonsäuredialkylester (MPA), methane bis (phosphonates) (MbPA) and trialkyl phosphate (TAP). ^ä MPA, MBPA and TAP compounds are versatile. MbPA and MPA are suitable as plastic and oil additives as well as flame retardants. TAP, especially the tributyl phosphate, is used on an industrial scale as extractant.

Characteristic of the known technical solutions

TAP is obtained from the reaction of phosphorus oxytrichloride with alcohol and sodium alcoholate or dialkyl phosphite with sodium alcoholate and carbon tetrachloride or directly from elementary phosphorus according to WP 127.188 by reacting elemental phosphorus (P ₄ ) * alcohol, metal alcoholate and polyhalohydrocarbon (eg tetrachloroethane) in the preferred range of P _4: alcohol: metal alkoxide: tetrachloromethane β 1: 10:> 8: 10 to 1: 100: 10: at temperatures of 0 to 100 ⁰ C, preferably 44 - 60 ⁰ C, MBPA is currently on a laboratory scale from methylene dibromide and triisopropyl phosphite or from methylene dibromide or chlorobromoethane and Natriumdialkylphosphiten under

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MPA is prepared according to WP 77.712 or WP 99.168 by reaction of dialkyl phosphite, dialkyl chlorophosphite, anhydrous phosphorous acid, phosphorus trichloride or phosphorus trioxide P ₄ O ₆ and orthoformic acid alkyl ester. This synthetic route is associated with multi-step processes for the preparation of the starting compounds and their isolation, where u »a. the preparation of the ortho-formate alkyl ester requires, in addition to sodium alcoholate, the use of the chloroform component, which is more expensive than tetrachloromethane. In the previously practiced on an industrial scale syntheses of trivalent P compounds over phosphorus trichloride occur in addition to losses of the P-component stronger harassment of the environment by hydrogen chloride and alkyl chlorides, and there are extensive equipment costs required to bind those compounds or to remove the exhaust stream. In the preparation of trialkyl phosphate (for example tributyl phosphate) as well as of dialkyl phosphites, when the chlorine-containing starting compounds POCl ₃ or PCl _{3 are used,} very exact reaction conditions must be maintained in order to obtain chlorine-free end products.

Object of the invention

The aim of the invention is a technologically and economically advantageous synthesis route for the production of MPA, MbPA and TAP, wherein practically the accumulation of not or poorly usable by-products is avoided and a high environmental friendliness is given.

Explanation of the essence of the invention

The object of the invention is to develop a method that starts from cheap and technically readily available starting compounds.

It has been found that in the reaction of elemental phosphorus with metal alkoxide in the presence of alcohol and tetrachloromethane at the molar ratios known per se P .: alcohol: tetrachloromethane = 1: 6: 6 to 1: 100; 20 in the temperature range from 0 to 100 ⁰ C _1, preferably from 44 to 60 ⁰ C surprisingly next Trialkylphosphat, Dialkoxymethanphosphonsäuredia ^ kyl ester and HQth9n- ^ is "- (PhoßphQPsäLirQdialkylö8ter) al $ main products arise when the starting ratio P ₄ : Metallalkoholat = 1 :> 10 to 1: 30, preferably 1: 15 to 1: 20 and the reaction is carried out in a solvent mixture, which 'in addition to the excess components alcohol and tetrachloroethane at least 1 mole, preferably 4 moles of an apolar aprotic or slightly polar aprotic Solvent component per mole of elemental phosphorus amount to be reacted (P.) contains.

The colorless (yellow) modification of the elementary phosphorus (P ₄ ) is used for the process according to the invention. The alcohols to be used represent monohydric aliphatic alcohols having a chain length of preferably C ₁ to Cg atoms. In the addition of the longer-chain alcohols, a distillative separation of the P-organic reaction products is associated with difficulties, so that in this case other separation methods must be used , Alcoholates used are alkali metal or alkaline earth metal compounds, in particular those of Na, K and Ca.

The formation of MPA, MbPA and TAP takes place in one reaction stage. The amount of phosphorus to be reacted is placed in a temperature-controlled reaction vessel with reflux condenser together with a solvent or solvent mixture. As solvents, the components involved in the reaction, such as carbon tetrachloride and the corresponding alcohol (e.g., butanol), as well as apolar aprotic or less polar aprotic substances such as e.g. Dialkyl ethers, dioxane, toluene, alkyl halo

aide. Tetrahydrofuran and the resulting end products used individually or in Geraisch. While stirring, the alkoxide component and tetrachloromethane are added separately at temperatures of 0-100 ⁰ C, preferably 44-65 C added. The released heat of reaction is removed by suitable cooling devices and / or by the boiling heat of the solvent or the solvent mixture. An immediate reaction takes place between the components blementary phosphorus, carbon tetrachloride, alcohol and metal alcoholate, which can be recognized by the deposition of the metal chloride. The rate of addition of the alcoholate component is adjusted to ensure adequate heat removal and dissolution rate of the phosphorus in the solvent phase. When adding tetrachloromethane, the rate of addition of this substance is adjusted so that no phosphine can form in the phosphorus reaction. After complete conversion of the phosphorus, the metal chloride is filtered off or centrifuged and the solution is worked up by distillation. Primary here are the solvents and halogenated hydrocarbons and, when using short-chain aliphatic alcohols, secondary trialkyl phosphate (eg tributyl phosphate), MPA (eg Dibutoxymethanphosphonsäuredibutylester and methane bis (phosphonsäuredialkylester) (MbPÄ), eg methane-bis (phosphonsäuredibutylester) distilled off in vacuo is readily convertible by a simple hydrolysis into the methanediphosphonic acid, a pharmaceutically useful drug The process has the advantage that, despite the high use of metal alcoholate (= 10 moles per mole of P.), the reaction can be conducted in such a way that a high proportion The expected further conversion of intermediately formed P (III) intermediates to trialkyl phosphate can be suppressed or greatly restricted in favor of the formation of MPA and MbPA.

th yields directly accessible from elemental phosphorus, while the previously known synthetic routes make the isolation of various partially difficult to reach intermediates necessary. It is achieved a virtually complete implementation of the phosphorus used, as another main reaction product is the technically sought trialkyl phosphate (tributyl) formed. The latter also comes in a very clean form (chloride-free),

The process according to the invention will be explained in the following examples.

AusführuQgsbeispiele Example 1

1 mol (124 g) of white phosphorus (P ₄ ) is introduced into a mixture of 6 moles (924 g) of anhydrous tetrachloromethane and 4 mol (520 g) of anhydrous dibutyl ether, which is in a reaction vessel with stirrer, dropping funnel, reflux condenser and gas inlet tube located. Subsequently, oxygen-free, dried nitrogen is passed through the apparatus. The gas is discharged via the reflux condenser with a downstream cold trap and a drying tower with calcium chloride. After the air has been displaced from the apparatus, the reaction mixture is heated with vigorous stirring to about 45 ⁰ C, wherein the phosphorus melts and partially dissolves. Thereafter, the heating is removed and slowly added dropwise with vigorous stirring and maintaining a low nitrogen overpressure slowly a solution of 16 moles (368 g) of sodium butoxide in 4800 g of anhydrous butanol in the reaction mixture. The temperature rises slightly and sodium chloride precipitates. The rate of dripping is regulated so that the reaction temperature is between 48 and 50 ^° C. After 4 hours, the reaction is complete. The failed sodium

Chloride is filtered off and distilled from the filtrate, the solvent mixture at 60 - 143 ⁰ C under atmospheric pressure over a Vigreux column · left behind a mixture consisting of 1.8 moles MPA, 0.2 mol MbPA and 2 moles of tributyl phosphate, which by vacuum distillation over a Column is disconnected,

Example 2

Colorless phosphorus is' butoxide and butanol in the same proportion and in the same way as ira Example 1 in the temperature range of 55 to Tet ^ chlormethgm, sodium · - 60 ⁰ C implemented. In place of the dibutyl ether, 1 mole (478 g) of trichloromethane is used as the solvent. The reaction is complete after 3.5 hours. There are obtained 0.08 mol MbPA and 1.2 mol MPA. The rest is tributyl phosphate.

Claims (3)

Erf indunc] san saying 1. A process for the simultaneous preparation of Dialkoxymethanphosphonsäuredialkylesterj methane-bis (phosphonate) and trialkyl phosphate by reaction of white elementary phosphorus (P ₄ ). Alcohol j and carbon tetrachloride with metal alkoxide at the molar ratios known per se P .: Alcohol 1 carbon tetrachloride = »! 56: 6 bir» 1: 100; 20 in the temperature range from 0 to 100 ° C. in a solvent mixture, characterized in that the reaction of the elemental phosphorus with the metal alcoholate in the molar ratio P ₄ : metal alcoholate = 1: 10 to 1: 30, in a solvent mixture, the per mole elemental phosphorus amount to be reacted contains at least 1 mole, preferably 4 moles, of an aprotic or low-polarity aprotic solvent component. 2. A process for the simultaneous preparation of Dialkoxymethanphosphonsauredialkylester, methane-bis (phosphonate and trialkyl phosphate according to item 1, characterized in that the Alkoholatkomponente and carbon tetrachloride are added separately but simultaneously to the rest of the reaction mixture. 3. A process for the simultaneous preparation of Dialkoxymethanphosphonsauredialkylester, methane-bis (phosphonates and Trialkylphosphat according to item 1, characterized in that are used as aprotic or slightly polar aprotic solvents dialkyl ethers, dioxane, toluene, alkyl halides, tetrahydrofuran and the resulting end products.