DD216465A1 - PROCESS FOR PRODUCING SUBSTITUTED ALKANPHOSPHONIC ACIDS - Google Patents

Abstract

The invention relates to a process for the preparation of 1-0- and 1-N-containing alkane-1,1-diphosphonsaeuren, which can be used as a complexing agent for many industrial purposes. The aim and object of the invention is to produce these substituted alkanediphosphonic acids in high yields and without chloride. This is carried out according to the invention from P deep 4 O deep x (X = 6-9 preferably 6) or a mixture of P deep 4 O deep x and optionally H deep 3 PO deep 3 with an alkanoic acid and an N-compound in the molar ratio P deep 4th O deep x: Alkanoic acid: N-compound = 1: 4: 0.1 to 1: 20: 3 at temperatures up to 150 degrees C, wherein any impurities present are to be separated after a maximum of 30 minutes. As alkanoic acid is preferably acetic acid and as N-compounds are preferably urea or urea derivatives used.

Description

Process for the preparation of substituted alkanophosphonic acids

Field of application of the invention

The invention relates to a process for preparing 1-0- and 1-H-containing alkane-1,1-diphosphonic acids. Certain 1-0 and 1-containing alkane-1,1-diphosphonic acids, e.g. 1-U-dimethylaminomethane-1,1-diphosphonic acid and 1-hydroxyethane, 1-diphosphonic acid for χ OH

0.CH ₃ 0

^H0 ^ -p - C - P - ^

X ».

find application as a complexing agent for many commercial purposes.

Purely numerous derivatives of Aminoalkandiphosphonsäure, in particular the Aminoethandiphosphonsäure for χ β ΪΓΗ2 (II) are given to the unsubstituted body numerous improved application properties.

a _eg known techniaohgn solutions

The Syn'fchesewege to such derivatives are complex ( ^T üehrstufenstufen) and / or require the use of expensive chemicals and thereby lead to bad üjid / or not usable waste products · In DE 2 _e 519 »264 (1975) Bind ζ _β β _β the better application properties of H-acetylaminoethanediphosphonic acid

X s N ^ _ / (III) compared to (II) and the

The latter is complicated since the primary amino-amino diphosphonic acid is first converted into its sodium salt, then dried and subsequently treated with excess acetic anhydride, with some of the anhydride changing to acetic acid. This complex route entails a technical use. for water treatment ·

According to DE 2,446,749, unsubstituted 1-ureidoalkane-1,1'-diphosphonic acids are formed

X β im - CTH ₂ (IV) in the reaction of acyl urea (acetylurea) with a mixture of phosphorous acid and PCI, at temperatures up to 120 ⁰ C in the presence of inert solvents. IY will continue in accordance with DE however arise 2,446,749 by reacting II with urea at temperatures from 130 to 190 ⁰ C · According to the review in DE 2,838,437 from the same company are both methods for production on an industrial scale disadvantages and larger amounts of the phosphonic acids can be difficult to produce. Therefore, according to this patent specification, syntheses of HH-dialkylureidodiphosphonic acids are more advantageous from a technological and economical point of view.

Substituted urea derivatives, formic acid and _{3 are} considered. The better Anwendungseigenschafttsn these substituted üreidomethandiphosphonsäuren (irr <compared to the unsubstituted acid) are based ^una * using relatively expensive starting Verbindunger. ¹ as formic acid and the urea derivatives reached; An additional separation of the end products from the chlorine-containing reaction mixture is required, so that this method can not be evaluated as technically advanced. Complex is also the synthesis of another derivative of I of Acetoxyethandiphosphonsäure for

X = OC ¹ CH ₃ (V). PRENTICE et al., Isolated this compound in the form of the disodium salt by reacting I with acetic anhydride in glacial acetic acid, whereby also the condensate

O O

⁰ I! ! ^Θ

op-0 -po

0 · j O

CH ₃ - C - 0-C-CH ₃ CH ₃ - COC CH ₃

\ i

0-P -0-PrO

θ, j! Ι) Θ

0 0

is formed, which in aqueous solution then passes into V, which can be isolated after the addition of NaOH in the form of the disodium salt (eg PRENTICE, 0.Ti QUIMBY, B.α. Grabenstatter and DA NICHJ-SON, 3. Amer, Chetr Soc., 94 (17), 6119-24 (1972).) The same procedure as described in DAS 1,248,654 is likewise not utilizable for the practice of crystallizing out of a still chlorine-containing phosphoric acid by-product from PCI, + acetic acid by recrystallization in glacial acetic acid V, Data on the yield will not

gemacht®

Object of the invention

The aim of the invention is to develop an economically and technologically favorable way of producing 1-0- and 1-N-substituted alkane-1,1-diphosphonic acid.

Statement of the essence of the invention

The object of the invention is to produce these substituted alkanediphosphonic acids in high yields and chlorine-free from technically readily available starting compounds,

It has been found that 1-0- and 1-H-substituted alkane-1,1-diphosphonic acids, and in a mixture with one another, in very high yields (up to 95 % and more, based on the P (III) component used) , optionally in the form of salts and in admixture with pentavalent P compounds, when P ^ O _x (xe 6 - 9, preferably χ β 6) optionally in admixture with H ^ PO ^, wherein the molar ratio P ^ O _x s H3PO3 _Ä 1 · max.3 is with an alkanoic acid (acetic acid) and an N-type compound

X · I!

for X »= 0, HH,

R 's * radicals such as alkyl * aryl, ITitril, acyl

Υ «a alkyl, NH ₂ , NHR '

as well as ammonia or ammonium compounds of organic anions, which are easily reversible with water-binding agents (even during the reaction with P ^ O _x ) in the above compounds (ZeBe ammonium acetate) in the molar ratio Ρ-0 _χ t alkanoic acid: N-compound 1: 4: 0 , 1 to 1 s 20 % 3, preferably 1ϊ6-1Οι1 »2,

if necessary, in an inert solvent, at temperatures <50 ⁰ C, preferably at temperatures around 20 ⁰ C with stirring in the course of 10 min to 3 h, preferably 30 min to 1 h, reacted, optionally present impurities such as phosphorus suboxides and yellow phosphor as quickly as possible are filtered off, the clear solution formed in the course of 0.5 to 30 h, preferably 1 - 5 hours, 90 to temperatures of max x 150 ⁰ C, preferably from - 130 ° C heated, and the resultant, if appropriate, solvents and / or alkanoic acid-containing reaction product

^ a) by distilling off volatile constituents

isolated as a solid,

b) with water and / or alkalis, preferably alkali metal hydroxide solutions in acidic to weakly basic, preferably neutral aqueous solutions, from which optionally after filtration of wasserschwerlöslieher components such as acetylurea. can be precipitated by addition of organic solvent salts or

c) is subjected to hydrolysis in an acid medium and water-sparingly soluble components are subsequently removed.

/ to be disconnected ·

Compounds prepared according to the invention correspond to the type

_ππ 0 OH, 0 _n "

· ^H0 \ ll I ³ Il ^ ^0H

P-C-P VI

0 0 0

X - O-CH-OH, HH ₂ , NHCCH ₃ , HH-C-UHZ

O HO O CH, OH

Il \ ΪΙ -.1? W /

ZH, C-CH ₃ PCP, alkyl aryl

y / I \ y

OR "and at Y. · .Y

R »β H, alkali such as Ha, K, H-containing cations M s OH, Y

Urea compounds and derivatives derived therefrom are preferably used. When acetic acid and urea are used, it is possible, in particular, to use derivatives of the acids II, III, V, VII, VIII in the reaction with PzO _x for χ = 6 and when von ^ 0 _χ for χ m 7 - 9 derivatives of the acid IX are also mixed with each other,

-C-

HO. Il I ^J / OH

I "OH

HH

C = 0

CH ₃

III

0 HO ^ O CHO O /OH HO. Il I ³ Il P -Ο P ^ OH Ι O I - C CH ₃

O CH ₃ OO CH ₃ O

HO Il 'I' / OH HOv Il I II / OH

^ - c - ρ. ) p - c - P ^

I ^X OH HO ^X I ^ OH

HH HH

I i

C = O C = O

I i

HH __ O HH O _ "

I HO. π ι H / OH

C = O ^N p - c - P

I ^V 0H

VII VIII

jf I ³ Il ^HO _N II I ³ Ii / ^OH

HO-P-C-P-OH P-C-P

Il

OH 0

0 - CH, - ^HO _N II I ³ P C HO ⁷ " C I σ I '\ I IF CH CH O

IX X

As by-products, condensates of EHDP with preferably POC bonds can be formed from I and V as well. The entire P (III) portion can be almost completely converted into diphosphonic acids, their proportions can vary depending on the conditions of presentation, especially the ratio Ρ * Ο _χ : acetic acid: urea. The purification of individual phosphonic acids is also given. With small amounts of urea (for example, 0.5 mol per mol P / O) ^{1 : 6} ^ ⁶¹¹¹ ^ sP 6 ^: acetic acid ratio 1: 10, almost exclusively V is formed, which, for example, by hydrolysis in its own acid Medium is easily transferable to I. II can be obtained in practically pure form in yields ^ 95 % , when P ₄ Og with acetic acid and urea in the molar ratio 1: 6: 2 reacted and then hydrolyzed.

The reaction of the reaction components is advantageously carried out in a temperature-controlled return tank with reflux condenser. To the presented alkanoic acid, optionally in admixture with an inert solvent and the U-compound, P ^ O _x optionally in admixture with impurities such as phosphorus suboxides and white phosphorus with stirring and cooling at temperatures <50 ⁰ C, preferably around 20 ⁰ C. to. The stirring time depends primarily on the dissolution and conversion rate.

-S

(Acetylability) of the H component used. Subsequently, white phosphorus and phosphorus suboxides are filtered off. This procedure is not mandatory · The reacted! Component can also only after the primary reaction of P _A 0_ and the alkanoic acid (acetic acid) and the subsequent filtering off of the impurities are added,

however, to the rearrangement reaction of the primarily formed acetyl phosphites to the ethane hydroxy diphosphonic acid group. suppress or exclude, the rapid filtration of the impurities after a maximum of 30 min at the lowest possible temperatures (<20 ⁰ C), the resulting acetyl phosphites as well as acetic anhydride (from the reaction acetyl phosphites + acetic acid) act on the urea acetylating. From the resulting solution acetylurea and diacetylurea could be isolated.

At temperatures> 80 ⁰ C, preferably 90-130 ⁰ C, he »follows a thermally well controllable Ümagerungsreaktion to derivatives of I to IX, even at high P ^ Og t acetic acid ratios (1: 6), a reaction of P-Og with acetic acid in this ffiolverhältnis without an additional solvent is not known to be practicable. The temperature of 90-130 ⁰ C can under reflux conditions as well as with the constant removal of volatile components (excess and liberated acetic acid, inert organic Lbsungsmittelkomponenten) take place. Conveniently, the reaction is conducted primarily under reflux conditions and after the P (III) <value has dropped to a sufficiently low value to complete the rearrangement to PC-bound phosphorus and to remove excess organic components while distilling off the same

 The formation of the aminoalkane (ethane) diphosphonic acids takes place

by reaction of the P (III) component with the carbonyl group from the acyl (acetyl) radical with elimination of water. The formation of III is mainly explained by the reaction of the ureido moiety with excess or re-released acetic acid (with liberation of CG ₂ ).

The obtained Rohphosphonsäuregemisch is at room temperature an easy to crush solid mass with high water solubility (>, 50 %). To ensure adequate storage stability of aqueous solutions, the conversion into salts is recommended. Optionally resulting or precipitating water-sparingly soluble acylated N compounds, such as, for example, acetyl-hindered material, can easily be filtered off. ,

The separation of compounds which are sparingly soluble in water, such as aminoethanethiphosphonic acid, can be carried out in a simple manner by hydrolysis in an autohydric solution and subsequent filtration.

The advantage of the method is i.a. in the use and use of a very reactive chlorine-free P (III) component and other very inexpensive and readily available reaction components. There are no non-recyclable waste products formed, so this process is classified as environmentally friendly.

The reaction products of the reaction P ₄ O + alkanoic acid (acetic acid) + IT compound are obtained in a directly usable form. Special purification stages, as they are usually necessary when using PCl ^ omitted due to the given freedom from chlorine.

The invention will be explained in more detail in the following exemplary embodiments.

Example 1 ,

In a temperature-controlled Ruhr vessel with reflux condenser, thermometer and dropping funnel are added to 20 moles of acetic acid and 0.8 moles of urea under an atmosphere of Eg 1 at room temperature 1 mol P / Og. With stirring and a temperature increase to about 50 ⁰ C, a clear solution. It was heated at 90-95 ⁰ C for 2 h. Ea formed two phases, with the lower phase containing all urea. Uach removing the excess acid by vacuum distillation at temperatures <100 ⁰ C. Produktge "could miseh be isolated with the following analytical values? P (III) j "0.1 ^, P (V) = 0.4 %, P _ges = 21.3%,> _gea = The ^ P-NMR spectrum recorded in water showed 15 j 9 at d ~ ^s ppm in the proton-decoupled spectrum a strong resonance signal (94 % of the total P amounts, corresponds to compound V). There were small amounts of impurities in I and phosphate as impurities. "The recorded paper chromatogram also confirmed the formation of V.

Example 2

100 g of the reaction product obtained according to Example 1 were dissolved in about the same amount of water and in the course of an hour to temperatures of'vioo ⁰ C er-

• 5-1

warms · The subsequently recorded P-HMR spectrum indicated the ethane hydroxy diphosphonic acid in a yield of about 97 % .

Example 3

Analogously to Example 1, 10 mol of acetic acid and 1 mol of dicyandiamide were metered in with stirring and Kg flow 1 mol of P ^ Og. The resulting reaction solution was treated for 2 h under refluxing conditions (^ 120 ⁰ C). It formed

two phases. The lower one was separated off and acetic acid dissolved in a water-jet pump vacuum was removed. The resulting reaction product had the following composition: P (III) 0.3 %, P (V) 0.9%, "« «, ^β 19.5 % U U" _e _> = 8,85 % · Based on the in water

ges oi S ^ea j

The ^ 'P-HMR spectrum was measured at Q ».15» 9 ppm as the main component O-acetylethanediphosphonic acid (V), partially in salt form, in a yield of 95%, based on the total PC-bound phosphorus. '

Example 4

The reaction of acetic acid, dicyandiamide and P.Og in a molar ratio of 10: 2: 1 was carried out analogously to Example 3. The solution was refluxed for 2.5 h at reflux conditions. The resulting reaction mixture was isolated from the lower phase and from excess acetic acid by means of vacuum distillation <100 ⁰ C free · This in water -5-1

The resulting P-IJMR spectrum gives the following distribution of the phosphorus in / u 60 mol % of O-acetylethanediphosphonic acid (V), present in part in the form of N-containing cations and -30. Mol % of a phosphonic acid which is identical in the 31P UMR spectrum _m ^ _V in.

Example 5

Analogously to Example 1, 10 mol of acetic acid and 2 mol of acetamide 1 mol IV), - added dropwise. 80 ⁰ C was performed in an exothermic reaction, the formation of a yellow-orange Reaktiönspröduktes · heated under reflux was continued for 2 hours and then peeled off excess acetic acid in vacuo · In one - upon heating to temperatures of 50 ⁰ C a clear solution at temperatures of 70 · arose P 22.6 % and IT _o β 4.1 % resulted in the

g, tiö Οή get) · ·.

Water - "P-NMR spectrum showed a proportion of PC bound phosphorus of 75 mol % (30 % III, 40 % V

and 3 % X) of phosphate of. 23 mole % and phosphite of 2 mole % _m

Example 6

Analogously to the previously described example, to 100 g of acetic acid and 25 g of ammonium acetate were added with stirring and at room temperature 36.6 g of P 2 O 3. After 2 hours of refluxing (»v 120 ⁰ C) gave a colorless reaction product · Excess acetic acid was separated by vacuum distillation. The P and U total determination gave 30.6 % P and 6.4 % N with a molar ratio P: H = 2.1: 1.

The evaluation of the ^ ¹ P-HMR spectrum resulted in a proportion of 55 mol % I and 35 mol % II (balance phosphite + phosphate) for the hydrolyzed in water reaction product.

Example 7

In a stirred vessel with internal thermometer, Hg gas supply and filler neck 600 g (10 mol) of acetic acid were placed. With vigorous stirring, nitrogen purge and cooling by means of a water bath, a total of 250 g of phosphorus (III, V) oxide having the composition Ϊ / 0 (x »7.3) (about 1 mol) were added in portions. After cooling below 20 C, the suspension was filtered to remove undissolved constituents (phosphorus suboxide, elemental white phosphorus). 750 g of the filtrate were added to a second stirred vessel with internal thermometer, Ng gas supply and reflux condenser and mixed with 50 g of urea (0.83 mol). The mixture was heated to boiling with stirring by means of an oil bath and refluxed for 2 hours. The P (III) value in the solution was then 0.4%. Subsequently, excess and liberated acetic acid was distilled off from the reaction mixture with stirring and atmospheric pressure. During the distillation occurred

at about 130 ⁰ C internal temperature increasingly COg release, which still increased with a temperature increase to 145 ⁰ C. The reaction mixture solidified to a bloated porous brownish mass, which was easily removed after cooling to room temperature. The amount of product obtained was 400 g with a 'P'. = 25.1 % and

ges o ^

^N " _ö o ^e 5»? % (Molar ratio P: N e 2.0: 1. After ·> ¹ P-HMR-ges

spectroscopic analysis (in aqueous solution) results for the distribution of the phosphorus: 19 mol% III, 6 mol % VII, 1 mol % II, 3 mol % I, 14 mol% V, 17 mol % phosphoric acid, 35 mol % IX, 5 mol % diphosphoric acid *

Example 8

As in Example 7, 250 g of P (III, V) oxide of the corresponding composition were reacted primarily with 600 g of acetic acid. After filtration, 750 g of the filtrate were mixed with 100 g of urea (1.67 mol). The mixture was refluxed with stirring for 5 h by means of an oil bath. The P (III) value was then 5.0% at a P " _öe value."

ges

12.0 % in the solution, at atmospheric pressure was then distilled off excess acetic acid. At an internal temperature of 130 ⁰ C ^ stepped stronger COG development · laughing cooling, the reaction product was in the form of a yellow porous solid (435 g) having a P _"is ^s 23.5% and 10.6% N ₀₁₀₀ s = ( P: Έ = 1.0: 1). The phosphorus was distributed as follows by ^J P-NMR analysis of an aqueous solution of the product as follows: 14 mol % III, 22 mol % VII, 6 mol % II, 4 mol % VIII, 4 mol% I, 28 mol% phosphoric acid, 13 Mol % IX, 5 mol % diphosphoric acid, 4 mol % phosphorous acid ·

Example 9

As in Example 1, acetic acid, urea and P.Og were reacted in a molar ratio of 10: 2: 1. After heating for 2 1/2 hours under reflux, excess acetic acid was added.

distilled off acid. The result was a yellow porous product with a P * 24.2 % and N " _M = 10.4 58 (P: H"

ges gee ^ ₁

1.0: 1) · The phosphorus was distributed as follows by "P-NMR analysis of an aqueous solution of the product as follows: 31 mol % VII, 30 mol % II, 15 mol % III, 7 mol % I, 5 mol% VIII . after the one-hour heating an intrinsically acidic solution at temperatures of 100 ⁰ C settled II in a yield of> 80%, after cooling, isolating preparatively. Including the still remaining in the solution share the yield of II ^ j 90%, of 17%, based on the phosphorus used.

Example 10

Acetic acid, acetylurea and P.Og were reacted in a molar ratio of 6: 1.5: 1 in the same way as in Example 9. At 50 ⁰ C, a clear reaction solution was formed, which was transferred to a rotary evaporator. In the apparatus, the reaction was carried out at reflux conditions for 2 hours. Subsequently, under atmospheric pressure at an internal temperature of about 140 ^° C., excess acetic acid was removed with slight addition. The result was a porous product which was added with simultaneous addition of UaOH and cooling with simultaneous stirring in water. The neutral aqueous solution of the resulting phosphonic acid mixture of derivatives of I and II, including portions thereof, was separated from excreted quantities of acetylurea. The at least 50% solution had one

P ^ a = 14.0 and an N " _ea = 4.4 % · The molar fraction of the gea tot

CK-containing diphosphonic acid to the proportion of CO-containing diphosphonic acids was Consistent on the basis of classical chemical analysis and the evaluation of the * P-NMR spectra -v? : 1, The yield of phosphonic acids was 95 % based on the P (III) proportion used.

Example 11

Analogously to Example 1 mol of acetic acid, 1.5 moles of urea and 2 moles ELPO- with stirring under N ₂ stream 1 mole P.Og were metered to 6 · The resulting reaction solution was 5 -8H under reflux (~ 130 ⁰ C) treated. Subsequently, from the reaction product by means of a water jet pump vacuum <100 ⁰ C, the excess acetic acid

31 removed. The P NMR spectrum recorded in water gives the following distribution of the phosphorus in * v 65 mol % aminoethanediphosphonic acid (II), * v 20 mol % N-acetylaminoethane diphosphonic acid (III) and * / 10% hydroxyethanediphosphonic acid (I). The remainders are phosphite and phosphate. ,

Example 12

Analogously to Example 1, 6 moles of acetic acid, 1.5 moles of urea and 2 moles of dioxane were reacted with 1 mol of P, 0 ^ under Np atmosphere in a stirred vessel. In <v70 ⁰ C a homogeneous reaction solution after 2 stUndigem treatment under reflux at * v 115 ⁰ C was further reacted to a 2-phase reaction product · After separating off the upper phase and after removal of excess acetic acid and the aprotic solvent (dioxane ) by vacuum distillation at temperatures <100 ⁰ C from the lower phase, a product mixture was isolated with the following analytical values:

P (III): 1.5 % P (V); 5.3 %; P_ _eg : 27.4%; H "_: 8,7

οι 6 ^it ges

The recorded in water ^J P-NMR spectrum showed a proportion of PC bound. Phosphorus of -v 65 mol % (30 20 % III, 10 % II, 5% I) of phosphate -v 33 mol % and phoaphitv 2 mol %,

Claims (9)

Erfindungaanspruch 1 · Process for the preparation of substituted alkanediphosphonic acids, preferably diphosphonic acid of the type 0 CH, 0 HO Il | /. H.OH > - o - P _x Y Y 0 0 0 H Il Il χ * -0-C-CH _3, -OH, Mg, ^ MC-CH _3, MC-MZ 0 CH ₃ 0 Z is H, O = C-CH-, ^HO "P-C- ^P'H , alkyl, aryl * Y 'T XX Y a OR and Y Y = P "- M 0 Rs H, alkali, such as Na, K, N-containing cations M β OH, Y characterized in that P ^ O (χ = 6-9 »preferably 6) or a mixture of P ^ O and optionally with a phosphorous acid, alkanoic acid and an H-compound in the molar ratio P ₄ O ₃ -: .Alkansäure s K ~ Compound = 1: 4: 0.1 to 1: 20: 3 is reacted at temperatures up to 150 ⁰ C, wherein optionally present impurities are separated after a maximum of 30 minutes. 2. A process for preparing substituted alkanediphosphonic acids according to item 1, characterized in that the reaction components PO, or P4O in admixture with H ₃ PO, alkanoic acid and N-compound, optionally in an inert solvent, at temperatures <50 ⁰ C, preferably at temperatures of about 20 ^° C. with stirring over the course of 10 minutes to 3 hours, preferably 30 minutes to 1 hour, and any impurities present, such as phosphorus suboxides and elemental white phosphorus, are filtered off, the resulting clear solution in the course of 0.5 up to 30 h, to temperatures of max. 150 ⁰ C vprzugsweise 90-130 ⁰ C heated, and the resulting optionally still solvent and / or alkanoic acid-containing reaction product a) isolated by distilling off volatile constituents as a solid, b) with water and / or alkalis, preferably alkali metal hydroxide solutions-converted into acidic to weakly basic, preferably neutral aqueous solutions, from which optionally after removal of water-sparingly soluble components such as acetylurea by addition of organic solvents salts can be precipitated, or c) is subjected to hydrolysis in acidic medium and water-sparingly soluble components are then separated. 3. A process for the preparation of substituted alkane diphosphonic according to item 1 and 2, characterized in that the molar ratio Ρ., 0 _ν : Η, ΡΟ, = 1: a maximum of 3, preferably 1: 2 · 4. A process for the preparation of substituted alkane diphosphonic according to item 1 and 2, characterized in that is used as the alkanoic acid acetic acid. 5. A process for the preparation of substituted alkane diphosphonic according to item 1 and 2, characterized in that N-type compounds X Y ¹ - & - NH " -is for X «. = O ₁ M, NR ' R 's org _e radicals such as alkyl, aryl _s citrile, acyl Υ »β alkyl, UH ₂ , UHR · as well as ammonia or ammonium compounds org _e Aßionen which are easily reversible with water binding agents (also during the reaction with PO) in obi »ge compounds are used (ζ _β Β _β ammonium acetate). 6. Process for the preparation of substituted alkanediphosphonic acid according to items 1 to 4, characterized in that urea and urea derivatives are used as preferred U-compounds » 7. A process for the preparation of substituted alkane diphosphonic acid according to item 2, characterized in that aprotic apolar solvents are used as the inert solvent. 8. A process for the preparation of substituted alkanediphosphonic acid according to P. punkt 1, characterized in that the separation of the impurities can also take place before the addition of! Compounds · 9. A process for the preparation of substituted alkanediphosphonic according to <item 1 and 2, characterized in that the reaction product is transferred to complete the reaction and separation of the volatile components in a rotating aggregate.