GB1559883A

GB1559883A - Process for the preparation of alkylphosphonic acid esters and the corresponding alkyl phosphonic acids

Info

Publication number: GB1559883A
Application number: GB4790976A
Authority: GB
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1975-11-18
Filing date: 1976-11-17
Publication date: 1980-01-30
Also published as: NL7612608A; FR2332283A1; DE2551598B1; DK516876A; BE848498A; IT1063803B; LU76203A1; FR2332283B1; CH622524A5

Abstract

Monoalkyl alkanephosphonates are prepared by reacting monoalkyl phosphites with sulphur-free, or virtually sulphur-free, alpha -olefins. The reaction is carried out in the presence of free-radical initiators at 150 to 200 DEG C. The resulting ester can be converted hydrolytically into alkanephosphonic acid, without isolation.

Description

(54) PROCESS FOR THE PREPARATION OF ALKYLPHOSPHONIC ACID ESTERS AND THE CORRESPONDING ALKYL PHOSPHONIC ACTDS (71) We, HOECHST AKTIEN GESELLSCHAFT, a body corporate organised according to the laws of the Federal Republic of Germany, of 6230 Frankfurt/Main 80, Postfach 80 03 20, Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a process for the preparation of alkylphosphonic acids and their esters.

Previously proposed processes for the preparation of alkylphosphonic acids and esters thereof, by the addition of alpha olefins to phosphorous acid or phosphonate esters have suffered from low yields and long reaction times. The process disclosed in U.S. Specification No. 2,957,931 for example, which is conducted at temperature of from about 100 to 1500C, has a yield of about 25% alkylphosphonic acid (where phosphorous acid is used) and about 70 to 75% of the reactants are converted to hydrocarbons.

These processes generally have too low a yield for technical applications, and there are also separation problems.

The present invention provides a process for the preparation of a compound of the general formula I

in which R1 represents an alkyl group having from 4 to 22 carbon atoms and R2 represents an alkyl group having from 1 to 22 carbon atoms or a mixture of such compounds which comprises reacting an alkyl hydrogen phosphonate of the general formula II

in which R2 is as defined above, with one or more alpha olefins having from 4 to 22, preferably from 4 to 12 carbon atoms and containing not more than 0.002 percent by weight of sulphur, under the influence of ultraviolet light and/or a radical-forming catalyst and at a temperature in the range of from 150 to 2000C, preferably from 160 to 1800C.

It is surprising feature of the invention that it is possible to conduct the reaction at such temperatures. Although it has been proposed in German Offenlegungsschrift No. 1,963,014, to react dialkyl phosphonates with alpha olefins at temperature above 1500C, it would have been expected that alkyl hydrogen phosphonates and phosphorous acid would disproportionate or decompose at such temperatures, for example, with formation of alkyl ethers and hydrocarbon mixtures, (see for example German Offenlegungsschrift No. 2,121,832, U.S. Patent Specification No. 2,834,797, L.

Hackspill et al., Chim. Ind. 27 (1932), 453 473, and D. E. Pearson, J. Chem. Soc., Chem. Commun. 1974, 397).

It is also surprising that it is possible to use radical forming catalysts such as peroxides as these are usually rapidly destroyed at temperatures above 1500C in acidic media and in the presence of reducing agents such as phosphorous acid.

(see Houben Weyl, Method yen der org.

Chemie, Vol VIII (1952), 66-67 and 7374).

In the process of the invention, the addition of the alphaolefins generally produces l-isomers at a yield in excess of 95% while the 2-isomers are usually only formed in insignificant quantities. Also the telomers which are often formed in large amounts in other reactions are usually obtained in quantities less than I to 2% by weight in the present process.

Phosphorous acid and/or a dialkyl phosphonate of the general formula III

may also be present in the reaction mixture.

The alkyl hydrogen phosphonates often occur at the reaction temperature, and even at room temperature, in equilibrium with phosphorous acid and/or the corresponding dialkyl phosphonates.

The alkyl hydrogen phosphonates may therefore be introduced as such or they may be formed in situ, for example, by reaction of phosphorous acid and the dialkyl phosphonate, the acid and the diester preferably having been added in substantially equimolar quantities. The alkyl hydrogen phosphonates may be obtained in known manner by esterification of phosphorous acid with a corresponding alcohol, preferably in a solvent suitable as an entrainer for the elimination of the water formed by distillation, for example benzene, toluene, or xylene.

It is not necessary to conduct the process of the invention using "pure" alkyl hydrogen phosphonates as starting materials, that is, using compounds of the formula (II) in which exactly one ester group is present per molecule. The reaction mixture may contain more phosphorous acid or more dialkyl phosphonate than is necessary to form an alkyl hydrogen phosphonate solution. However, since it is more difficult to convert phosphorous acid under the reaction conditions, it is preferred to use a reaction mixture having an initial composition such that the ratio of the concentration of alkyl groups R2 to the total concentration of phosphorous acid and esters thereof is in the range of from 0.9:1 to 1.5:1, especially from 1:1 to 1.3:1 by mole.

As alkyl hydrogen phosphonates, there may be mentioned: methyl-, ethyl-, npropyl-, isobutyl-, n-butyl-, n-hexyl-, ndodecyl-, or n-eicosyl hydrogen phosphonate. Lower alkyl hydrogen phosphonates having from 1 to 4 carbon atoms are preferred. Not only linear alphamono-olefins may be employed, but also branched isomeric alpha-mono-olefins. As olefins, there may be mentioned 1-butene, 1-hexene, l-octene, l-dodecene, 1tetradecene, l-hexadecene, l-octadecene, l-heneicosene, I-docosene, 2-methylpent- 1- ene or 2-ethylhex-l-ene. The olefin may be employed alone or as mixtures, preferably in substantially stoichiometric amounts or in a slight excess, for example of up to 1.1 times the stoichiometric quantity for the reaction by weight.

Of course, it is also possible to employ an excess of one of the reactants; however, this does not bring about any advantage when radical-forming agents are used.

It is an important factor in the success of the process of the invention that the alphaolefin is sulphur-free or nearly sulphur free, and accordingly, the alpha olefin should contain not more than 0.002 percent by weight of bound sulphur. It has been observed that a content of about 0.02 percent of bound sulphur causes a serious decrease of yields.

It is advantageous to use for the process of the invention alpha olefins which are free from sulphur by reason of their manufacture, for example alpha olefins obtained from the so-called Ziegler or Muhlheim process, in which ethylene is dimerized or oligomerized in the presence of catalysts, especially aluminium triethyl, to form linear alpha-olefins. According to the same method, branched alpha-olefins, for example 2-methyl pent-l-ene or 2ethylhex-l-ene may also be prepared by dimerizing olefins such as propene or isobutylene (see F. Asinger, Chemie and Technologie der Monoolefin, 1957, especially pp. 179-180). The dimerization may however be carried out in a different manner, for example by catalysis with the aid of alkali metals. Of course, alpha-olefins obtained from other processes, for example by cracking of petroleum distillate or waxes, by splitting-off of hydrogen chloride from paraffins having terminal chlorine atoms, or by dehydration of terminal alcohols may also be employed, the only qualification being that they have sulphur contents within the specified limits. Where olefins containing sulphur are to be used, the sulphur has to be eliminated, preferably completely, or at least nearly completely, but suitable means, for example by catalytic desulphurization.

For the process of the present invention, all generally used radical forming agents may be used as the catalyst for example, ditert. butyl peroxide, tert. butylperoxybenzoate, 2,5-dimethyl-bis-2,5 (peroxybenzoate), tert.-butylhydroperoxide, dicumyl peroxide or benzoyl peroxide.

The radical-forming agents may be applied by dissolving them in those reactants which are introduced into the reactor. It may be necessary to use an inert solvent as solubilizer in addition.

The radical-forming agent may be soluble in the phosphonate ester rather than in the olefin, in which case, part of the total alkyl hydrogen phosphonate in which the agent is dissolved may be introduced separately with the olefin. It is also possible to use the alkyl hydrogen phosphonate as a solubilizer for the radical-forming agent in the olefin.

The radical-forming agents are used in catalytic amounts. The concentration of the catalyst used is preferably in the range of from 0.1 to 5%, preferably from 0.5 to 3% of the concentration of alpha olefin by mole.

Di-tert. butyl-peroxide is the preferred catalyst.

When ultraviolet light is used for starting the reaction, the reaction solution must be subjected to the direct radiation of an ultraviolet lamp.

Advantageously, the process of the invention is carried out by slowly adding the olefin, optionally mixed with catalytic amounts of the catalyst, to the alkyl hydrogen phosphonate. Low-boiling olefins are advantageously added by means of a dropping funnel of which the outlet tube is immersed below the alkyl hydrogen phosphonate level.

The reaction may proceed in the presence of inert solvent, for example alcohols, esters, or hydrocarbons, such as benzene, although it is preferred to conduct the process without solvents.

The reaction proceeds preferably under an inert gas atmosphere; suitable inert gases being for example argon or nitrogen.

As a result of the possible decomposition reactions mentioned above, decomposition products. such as ethers, alcohols, or olefins, for example, dimethyl ether, methanol, or l-butene, may be formed in small amounts during the reaction. When operating under an inert gas atmosphere, these decomposition products may be carried off the reaction zone by means of the inert gas and, can, if desired, be condensed in a cooling trap. However, they may also be eliminated from the reaction mixture by distillation after the reaction is complete.

The reaction time of the process of the invention is generally considerably shorter than that of the previously proposed processes. The reaction time is usually up to about 6 hours, and can often be as little as from 3 to 5 hours. Only when ultraviolet radiation is applied, is it advantageous to prolong the reaction time to about 7 hours in order to obtain a high yield.

The process of the invention is preferably conducted in a continuous manner, which may cause the amount of telomers in the reaction product to increase slightly.

The mixture of alkylphosphonic acids and the mono- and diesters thereof generally obtained in the process of the invention is an interesting intermediate product per se.

The mixture can be used as preliminary product for the manufacture of alkylphosphonic acids which have important applications as mercerization or flotation agents.

The corresponding alkylphosphonic acids may be prepared from the product mixture by subjecting it to acidolysis in known manner. However, hydrolysis as described in German Offenlegungsschriften Nos.

2,441,783 and 2,441,878 is preferred. In this hydrolysis, the product mixture which consists substantially of alkylphosphonic acid and its mono- and diester, is reacted with at least a stoichiometric quantity of water, at temperatures of 160 to 3000C, and the alcohol formed is then distilled off.

Where the alkyl hydrogen phosphonate has been formed in situ from phosphorous acid and a dialkyl phosphonate, the resulting mixture may yield a mixture of the alkyl hydrogen alkylphosphonate, the dialkyl alkylphosphonate and/or the alkylphosphonic acid. This mixture may be separated in known manner, for example by distillation or chromatography, the main component thereof being the intended alkyl hydrogen alkylphosphonate. Such mixture may also and especially be worked up by first neutralizing the reaction mixture with alkali while cooling. The neutralized mixture consists substantially of alkali metal salts of the alkylphosphonic acids and the alkyl hydrogen phosphonates and the dialkyl alkylphosphonates. The diesters may be separated in principle by extraction with an organic solvent. Subsequently, because of their different solubility in alcohols, the alkali metal salts of alkanephosphonic acids and the alkanephosphonic adid monoester may be isolated by using an alcohol, preferably methanol.

The process of the invention provides an economically advantageous process for the manufacture of technically important alkylphosphonic acids, which involves partial esterification of phosphorous acid.

Phosphorous acid suitable for use in the present process can be ebtained without difficulty in numerous known processes and has hitherto been a by-product of these processes having almost no use.

The following Examples illustrate the invention.

EXAMPLE 1 200 g (2.47 mols) of phosphorous acid and 268 g (2.47 mols) of dimethyl phosphonate are mixed and heated to 17e1750C under a nitrogen atmosphere. Subsequently, a mixture of 545 g (4.87 mols) of l-octene and 6 g of di-tert. butyl peroxide is added dropwise over 2.25 hours and with thorough agitation. Agitation is continued at this temperature for I hour. In a cooling trap connected to the reactor, 12 g of dimethyl ether, 5.5 g of methanol and 1.5 g of 1octene are collected. 1000 g of octylphosphonic acid derivatives are obtained which, according to a gas chromatographic analysis, consist of 13 by weight of dimethyl octylphosphonate, 55% by weight of methyl hydrogen octylphosphonate and 29% by weight of octylphosphonic acid, and which contain only 0.5 fO by weight of telomers. Therefore, the yield is nearly 100% of the theoretical yield of octylphosphonic acid derivatives.

EXAMPLE 2 250 g (3.05 mols) of phosphorous acid, 450 g of n-butanol and 345 g of toluene are refluxed with agitation, during which 65 ml (3.62 mols) of water are eliminated within 4 hours with the aid of a water trap.

Subsequently, distillation is carried out at 100--120 mm Hg and up to an inner temperature of 1500C. The residue is crude n-butyl hydrogen phosphonate, which is heated to 1800C under a nitrogen atmosphere. Subsequently, a mixture of 342 g (3.05 mols) of l-octene and 3.5 g of di-tert.

butyl peroxide is added dropwise over 3 hours and with thorough agitation, which is then continued for a further hour at the same temperature. In a cooling trap connected to the reactor, about 5 g of 1butene are collected.

Subsequently, the reaction product is reacted with water at 2000C according to the process of German Offenlegungsschrift No. 2,441,783. 592 g of octylphosphonic acid are obtained which contain only 2% by weight of telomers. This corresponds to a yield of 100% of alkylphosphonic acid derivatives.

EXAMPLE 3 120 g (0.618 mol) of di-n-butyl phosphonate and 50.6 g (0.618 mol) of phosphorous acid are blended and heated to 180"C under a nitrogen atmosphere.

Subsequently, a mixture of 139 g (1.24 mols of l-octene and 1.4 g di-tert, butyl peroxide is added dropwise over 2.5 hours and with thorough agitation, which is then continued for 1 hour at the same temperature.

Subsequently distillation is carried out at 1 mm Hg and up to an inner temperature of 1500 C. 295 g of a mixture of dibutyl octylphosphonate, butyl hydrogen octylphosphonate and octylphosphonic acid are obtained as residue in a ratio approximately as in Example 1.

EXAMPLE 4 162 g (1.957 mols) of phosphorous acid and 217 g (1.975 mols) of dimethyl phosphonate are blended and heated to 155--160"C. Subsequently, a mixture of 775 g (3.95 mols) of l-tetradecene and 8 g of ditert. butyl peroxide is added dropwise over 3 hours under a nitrogen atmosphere and with thorough agitation, which is continued for a further hour at this temperature. In a subsequent cooling trap, 19 g of dimethyl ether and methanol are collected. The reaction mixture solidifies on cooling the product obtained has a solidification temperature of 35"C.

Subsequently, the reaction product is reacted with water at 1750C according to German Offenlegungsschrift No. 2,441,878.

1080 g of tetradecylphosphonic acid having a solidification temperature of 74"C are obtained, which corresponds to a yield of 98.5% of the theoretical yield of tetradecylphosphonic acid.

EXAMPLE 5 200 g (2.44 mols) of phosphorous acid and 268 g (2.44 mols) of dimethyl phosphonate are blended and heated to l55-l600C.

Subsequently, a mixture of 545 g (4.87 g mols) of l-octene and 6 g of di-tert. butyl peroxide is added dropwise within 2 hours under nitrogen atmosphere and with thorough agitation which is continued for a further hour at the same temperature. 8 g of dimethyl ether and 1.5 g of methanol are then collected in a cooling trap.

The reaction product is then reacted with water at 1700C according to the process of German Offenlegungsschrift No. 2,441,878, 941 g of octylphosphonic acid having a solidification point of 80.6"C are obtained, which corresponds to a yield of 99% of the theoretical yield of octylphosphonic acid.

WHAT WE CLAIM IS: 1. A process for the preparation of a compound of the general formula I

in which Rl represents an alkyl group having from 4 to 22 carbon atoms, and R2 represents an alkyl group having from 1 to 22 carbon atoms; or a mixture of such compounds, which comprises reacting an alkyl hydrogen phosphonate of the general formula II

in which R2 is as defined above, with one or more alpha olefins having from 4 to 22 carbon atoms and containing not more than

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

ether, 5.5 g of methanol and 1.5 g of 1octene are collected. 1000 g of octylphosphonic acid derivatives are obtained which, according to a gas chromatographic analysis, consist of 13 by weight of dimethyl octylphosphonate, 55% by weight of methyl hydrogen octylphosphonate and 29% by weight of octylphosphonic acid, and which contain only 0.5 fO by weight of telomers. Therefore, the yield is nearly 100% of the theoretical yield of octylphosphonic acid derivatives.

EXAMPLE 2

250 g (3.05 mols) of phosphorous acid, 450 g of n-butanol and 345 g of toluene are refluxed with agitation, during which 65 ml (3.62 mols) of water are eliminated within 4 hours with the aid of a water trap.

Subsequently, distillation is carried out at 100--120 mm Hg and up to an inner temperature of 1500C. The residue is crude n-butyl hydrogen phosphonate, which is heated to 1800C under a nitrogen atmosphere. Subsequently, a mixture of 342 g (3.05 mols) of l-octene and 3.5 g of di-tert.

butyl peroxide is added dropwise over 3 hours and with thorough agitation, which is then continued for a further hour at the same temperature. In a cooling trap connected to the reactor, about 5 g of 1butene are collected.

Subsequently, the reaction product is reacted with water at 2000C according to the process of German Offenlegungsschrift No. 2,441,783. 592 g of octylphosphonic acid are obtained which contain only 2% by weight of telomers. This corresponds to a yield of 100% of alkylphosphonic acid derivatives.

EXAMPLE 3

120 g (0.618 mol) of di-n-butyl phosphonate and 50.6 g (0.618 mol) of phosphorous acid are blended and heated to 180"C under a nitrogen atmosphere.

Subsequently, a mixture of 139 g (1.24 mols of l-octene and 1.4 g di-tert, butyl peroxide is added dropwise over 2.5 hours and with thorough agitation, which is then continued for 1 hour at the same temperature.

Subsequently distillation is carried out at 1 mm Hg and up to an inner temperature of 1500 C. 295 g of a mixture of dibutyl octylphosphonate, butyl hydrogen octylphosphonate and octylphosphonic acid are obtained as residue in a ratio approximately as in Example 1.

EXAMPLE 4

162 g (1.957 mols) of phosphorous acid and 217 g (1.975 mols) of dimethyl phosphonate are blended and heated to 155--160"C. Subsequently, a mixture of 775 g (3.95 mols) of l-tetradecene and 8 g of ditert. butyl peroxide is added dropwise over 3 hours under a nitrogen atmosphere and with thorough agitation, which is continued for a further hour at this temperature. In a subsequent cooling trap, 19 g of dimethyl ether and methanol are collected. The reaction mixture solidifies on cooling the product obtained has a solidification temperature of 35"C.

Subsequently, the reaction product is reacted with water at 1750C according to German Offenlegungsschrift No. 2,441,878.

1080 g of tetradecylphosphonic acid having a solidification temperature of 74"C are obtained, which corresponds to a yield of 98.5% of the theoretical yield of tetradecylphosphonic acid.

EXAMPLE 5

200 g (2.44 mols) of phosphorous acid and 268 g (2.44 mols) of dimethyl phosphonate are blended and heated to l55-l600C.

Subsequently, a mixture of 545 g (4.87 g mols) of l-octene and 6 g of di-tert. butyl peroxide is added dropwise within 2 hours under nitrogen atmosphere and with thorough agitation which is continued for a further hour at the same temperature. 8 g of dimethyl ether and 1.5 g of methanol are then collected in a cooling trap.

The reaction product is then reacted with water at 1700C according to the process of German Offenlegungsschrift No. 2,441,878, 941 g of octylphosphonic acid having a solidification point of 80.6"C are obtained, which corresponds to a yield of 99% of the theoretical yield of octylphosphonic acid.

WHAT WE CLAIM IS: 1. A process for the preparation of a compound of the general formula I

in which Rl represents an alkyl group having from 4 to 22 carbon atoms, and R2 represents an alkyl group having from 1 to 22 carbon atoms; or a mixture of such compounds, which comprises reacting an alkyl hydrogen phosphonate of the general formula II

in which R2 is as defined above, with one or more alpha olefins having from 4 to 22 carbon atoms and containing not more than

0.002 percent by weight of sulphur, under the influence of ultraviolet light and/or a radical-forming catalyst and at a temperature in the range of from 150 to 200"C.
2. A process as claimed in Claim 1 wherein the reaction mixture includes phosphorous acid and/or a dialkyl phosphonate of the general formula III

in which R2 is the same as in the compound of formula II.
3. A process as claimed in Claim 1 or Claim 2, wherein at least some of the alkyl hydrogen phosphonate of formula II is formed in situ.
4. A process as claimed in Claim 3, wherein substantially all of the compound of formula II is formed in situ.
5. A process as claimed in Claim 3 or Claim 4, wherein the compound is formed in situ from phosphorous acid and the corresponding dialkyl phosphonate of the general formula III as defined in Claim 2.
6. A process as claimed in any one of Claims 2 to 5 wherein the initial composition of the reaction mixture is such that the ratio of the concentratiom of alkyl groups R2 to the total concentration of phosphorous acid and esters thereof is in the range of from 0.9:1 to 1.5:1 by mole.
7. A process as claimed in Claim 6, wherein the said ratio is in the range of from 1:1 to 1.3:1 by mole.
8. A process as claimed in any one of Claims 1 to 7, wherein R2 represents an alkyl group having from 1 to 4 carbon atoms.
9. A process as claimed in any one of Claims 1 to 8 wherein the alkyl hydrogen phosphonate of the general formula II is any one of those specifically mentioned herein
10. A process as claimed in any one of Claims 1 to 9, wherein the or each alpha olefin has from 4 to 12 carbon atoms.
11. A process as claimed in any one of Claims 1 to 10, wherein the or each alpha olefin is any one of those specifically mentioned herein.
12. A process as claimed in any one of Claims 1 to 11, wherein the total quantity of the alpha olefin or olefins in the reaction mixture is in the range of from 1 to 1.1 times the stoichiometric quantity for the reaction by weight.
13. A process as claimed in any one of Claims I to 12, wherein the quantity of alkyl hydrogen phosphonate and alpha olefin or olefins in the reaction mixture are substantially equimolar.
14. A process as claimed in any one of Claims 1 to 13. wherein the alpha olefin or olefins have been prepared by the Ziegler or Mulhleim process.
15. A process as claimed in any one of Claims 1 to 14, wherein the alkyl phosphonate of the general formula II is reacted with one alpha olefin.
16. A process as claimed in any one of Claims 1 to 15, conducted in the presence of a radical forming catalyst.
17. A process as claimed in Claim 16, wherein the catalyst is any one of those specifically mentioned herein.
18. A process as claimed in Claim 15, wherein the catalyst is di-tert. butyl peroxide.
19. A process as claimed in any one of Claims 16 to 18, wherein the concentration of the catalyst in the reaction mixture is in the range of from 0.1 to 5 percent of the alpha olefin concentration by mole.
20. A process as claimed in Claim 19, wherein the concentration of the catalyst is in the range of from 0.5 to 3 percent of the alpha olefin concentration by mole.
21. A process as claimed in any one of Claims 1 to 20, conducted in an inert solvent.
22. A process as claimed in Claim 21, wherein the inert solvent comprises an alcohol, an ester or a hydrocarbon.
23. A process as claimed in any one of Claims 1 to 22, conducted under an inert gas atmosphere.
24. A process as claimed in Claim 23, which comprises removing any decomposition products formed during the reaction in a current of the inert gas.
25. A process as claimed in Claim 23 or 24, wherein the inert gas comprises argon or nitrogen.
26. A process as claimed in any one of Claims I to 25, conducted at a temperature in the range of from 160 to 180"C.
27. A process as claimed in any one of Claims 1 to 26, conducted in a continuous manner.
28. A process as claimed in any one of Claims 1 to 27, wherein the compound of general formula I is isolated from the product mixture.
29. A process for the preparation of an alkyl hydrogen alkylphosphonate, substantially as hereinbefore described in Example 1 or Example 3.
30. A process for the preparation of an alkylphosphonic acid which comprises a process as claimed in any one of Claims 1 to 29, and the step of hydrolysing the compound of the general formula I formed, to form an alkylphosphonic acid.
31. A process as claimed in Claim 30, wherein the hydrolysis is acid hydrolysis.
32. A process for the preparation of an alkylphosphonic acid substantially as hereinbefore described in any one of Examples 2, 4 or 5.
33. An alkyl hydrogen alkylphosphonate, whenever prepared by a process as claimed in any one of Claims 1 to 29.
34. A mixture comprising an alkyl hydrogen alkylphosphonate, whenever prepared by a process as claimed in any one of Claims 1 to 27 or 29.
35. An alkylphosphonic acid whenever prepared by a process as claimed in any one of Claims 30 to 32.