Phosphorus compounds

Details Phosphorus compounds Phosphorus compounds

2002-10-09

2004-07-27

Vollano, Jean F. (Department: 1621)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From phosphorus-containing reactant

C562S020000

Reexamination Certificate

active

06767989

ABSTRACT:

The present invention concerns novel phosphorus compounds which may be obtained by a process comprising reacting an acetylenic compound with hypophosphorous acid, or its salts.
The reaction of acetylene with hypophosphorous acid in the presence of perbenzoic acid or tertiary butyl peroxide to give 1,2-diphosphino ethane was described by Nifantev et al in Zh Obstich Khim Vol 56 Pp 773-781 (1986). The Authors state that the reaction product with two organic groups attached to the phosphorus was not obtained. This clearly implies that no polymeric material could be obtained by the method described.
Kneller et al (U.S. Pat. No. 5,647,995) describe the preparation of homologues and substituted analogues of 1,2-diphosphino ethane by reacting hypophosphorous acid with higher alkynes and substituted alkynes. The preparation of mono and diphosphinates is described but no copolymers of acetylene with hypophosphorous acid containing more than 2 phosphorus atoms per molecule were prepared or described. Kneller et al also describe reacting the mono or diphosphinates with unsaturated carboxylic acids such as acrylic acid to make telomers which are useful in water treatment as scale inhibitors of calcium carbonate scale.
We have now discovered that contrary to the teaching of Nifantev et al, the reaction between hypophosphorous acid and alkynes can be used to prepare polymers with more than two alkylene groups and more than two phosphorus atoms. Such polymers are particularly useful as corrosion inhibitors and/or as intermediates, for the synthesis of a variety of water treatment agents, fire retardants, tanning agents and biocides. The reaction with acetylene proceeds with difficulty and requires relatively extreme conditions to obtain a high degree of polymerisation, however higher alkynes and substituted alkynes, containing 3 to 25 carbon atoms, react more readily.
In a first embodiment, the present invention provides a compound of the formula (1):
wherein:
R and R′ are each independently selected from hydrogen, a hydroxyl group, a carboxyl group, an alkyl, aryl or alkaryl group or a hydroxy- or carboxy-substituted alkyl, aryl or alkaryl group, provided that R and R′ together have a total of less than 23 carbon atoms;
R″ is hydrogen, or CHR═CR′ or selected from the same categories as R′″;
R′″ is a group, or a polymeric chain comprising from 1 to 100,000 groups, each said group being derived from at least one ethylenically unsaturated compound wherein the double bond is activated by an adjacent electron-withdrawing group;
X is hydrogen or a cation or an alkyl group; and n is greater than 1.
According lo another embodiment our invention provides a method of producing a compound of the type described in the immediately-preceding paragraph, said method comprising the copolymerisation of hypophosphorous acid or a salt or ester of said acid with an acetylenic compound of formula RC≡CR′, where R and R′ (which may be the same or different) are each selected from hydrogen, a hydroxy group, a carboxy group, an alkyl, aryl or alkaryl group or a hydroxy- or carboxy-substituted alkyl, aryl or alkaryl group having from 1 to 22 carbon atoms, so that R and R′ together have from 0 to 25 carbon atoms, whereby in said formula (I) R″ and R′″ are each hydrogen and the average value of n is greater than one.
According to a further embodiment the invention provides the use of said polymer as a corrosion inhibitor and/or scale inhibitor in the treatment of a water system.
According to a fourth embodiment the invention provides a method of preparing a telomer which comprises reacting said polymer with an ethylenically unsaturated compound wherein the double bond is activated by an adjacent electron withdrawing group.
According to a fifth embodiment the invention provides a method of treating potentially corrosive and/or scale forming water systems which comprises adding a corrosion or scale inhibiting proportion of said polymer and/or said telomer to said system.
Preferably the reaction is carried out in a solvent capable of dissolving both reagents. Depending on the acetylenic compound, the solvent may be water or a polar organic solvent, typically in admixture, with aqueous hypophosphorous acid, eg: ethanol, dioxan, a water miscible glycol or glycol ether such as ethylene glycol or ethylene glycol monomethyl ether, ketones such as acetone or methyl isobutyl ketone, or diethyl formamide. The reaction also requires an initiator, which may preferably be a source of free radicals such as hydrogen peroxide, sodium persulphate, azo compounds such as azoisobutyronitrile, organic peroxides or a source of ultraviolet or ionising radiation.
The acetylenic compound may be acetylene itself, which may, for example, be bubbled through a solution of hypophosphorous acid or its salts. However good yields of higher polymers are not readily obtainable from acetylene itself due to its volatility, which may require conditions such as high pressure which are inconvenient or potentially hazardous. We therefore prefer to use less volatile acetylenic compounds, and especially alkynes and hydroxy or carboxy alkynes with 3 to 25 carbon atoms, such as propargyl alcohol, acetylene dicarboxylic acid or an alkyne having, preferably 3 to 20 carbon atoms such as 1-butyne, 2-butyne or a C
12-14
alkyne. It is also within the scope of the invention to use cyclic alkynes, eg: in which R and R1 in the foregoing formula together with the acetylenic group form a cycloalkyne ring.
The reaction may be carried out at an elevated temperature, eg: 40 to 100° C. preferably 50 to 70° C.
The proportions may be substantially equal or may comprise a small, eg: up to 20%, stoichiometric excess of either reagent but preferably of the hypophosphite. The reaction may be carried out under elevated, atmospheric or, preferably, reduced pressure.
The hypophosphorous reagent may be the acid or a soluble salt such as sodium, potassium or ammonium or an ester such as the methyl, ethyl or isopropyl ester.
The present invention further provides a polymer, of the formula (II):
where X is hydrogen or a cation or alkyl group, n is from 1.05 to 100, e.g.: 1.2 to 50, preferably 1.5 to 25 especially 2 to 20 more especially 3 to 15.
It is also possible to obtain polymers containing, e.g.:
units, especially when R is a bulky group e.g.: a phenyl group.
According to a further embodiment, the invention provides a compound comprising a telomer of the formula (III):
where X, R, R′ have the same significance as before, at least one R
v
, in each monomer unit is a hydroxy, carboxy, sulpho, phosphono, amido, aceto, or aryl group or halogen, and each other R
v
is independently selected from hydrogen, and C
1-4
alkyl, carboxyl, sulpho, phosphono, hydroxyl groups, and carboxy, sulpho, phosphono or hydroxy substituted C
1-4
alkyl groups, (a+b) is from 5 to 200 and n is greater than 1.
The novel telomers may be prepared by co-polymerising said polymers with at least one monomer of formula R
2
v
═CR
2
v
where R
v
has the same significance as before, in the presence of a free radical initiator.
Preferred monomers include acrylic acid, fumaric acid, maleic acid, vinylsulphonic acid, vinyl phosphonic acid, vinylidene diphosphonic acid, methacrylic acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, crotonic acid, isocrotonic acid, angelic acid, tiglic acid and the water soluble salts of the aforesaid acids.
The telomers may additionally comprise proportions, usually minor proportions, of styrene, styrene-p-sulphonic acid, 2-acrylamido-2-methylpropane sulphonic acid, vinyl alcohol, vinyl acetate, vinyl chloride and/or acrylamide. The relative proportions of oligomer or polymer and the monomer may range from 1:1 to 1:1000, preferably from 1:5 to 1:500 especially 1:10 to 1:100, eg: 1:15 to 1:50. The reaction is preferably carried out in aqueous solution and most preferably using water soluble salts of the monomers, eg: at a pH greater than 5 especially 6 to 8. T

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