Hydroxyphenyl Phosphine Oxide Mixtures and their use as Flame Retardants for Epoxy Resins
A hydroxyphenyl or alkoxyphenyl phosphine oxide composition comprises (i) a first mixture of mono-(hydroxyphenyl) or (alkoxyphenyl) phosphine oxide isomers each having the formula (I): (ii) a second mixture of bis-(hydroxyaryl) or (alkoxyphenyl) phosphine oxide isomers each having the formula (II): and (iii) a third mixture of tris-(hydroxyaryl) or (alkoxyphenyl) phosphine oxide isomers each having the formula (III): wherein R is hydrogen or an alkyl group containing from 1 to 6 carbon atoms, R 1 and R 2 are the same or different and each is an alkyl group containing from 1 to 6 carbon atoms, and each of x and y is an integer between 0 and 4. Each OR group is in the ortho or para position with respect to the bond between the P atom and the associated phenyl group such that, for each mixture (i), (ii) and (iii), the ratio of the number of OR groups in the ortho-position with respect to the bond between the P atom and the associated phenyl group to the number of OR groups in the para-position with respect to the bond between the P atom and the associated phenyl group is between about 50:50 and about 0.1:99.9.
1 . A hydroxyphenyl or alkoxyphenyl phosphine oxide composition comprising:
(i) a first mixture of mono-(hydroxyphenyl) or (alkoxyphenyl) phosphine oxide isomers each having the formula (I):
(ii) a second mixture of bis-(hydroxyaryl) or (alkoxyphenyl) phosphine oxide isomers each having the formula (II):
(iii) a third mixture of tris-(hydroxyaryl) or (alkoxyphenyl) phosphine oxide isomers each having the formula (III):
wherein R is hydrogen or an alkyl group containing from 1 to 6 carbon atoms, R 1 and R 2 are the same or different and each is an alkyl group containing from 1 to 6 carbon atoms, each of x and y is an integer between 0 and 4, and each OR group is in the ortho or para position with respect to the bond between the P atom and the associated phenyl group such that, for each mixture (i), (ii) and (iii), the ratio of the number of OR groups in the ortho-position with respect to the bond between the P atom and the associated phenyl group to the number of OR groups in the para-position with respect to the bond between the P atom and the associated phenyl group is between about the bond between the P atom and the associated phenyl group is between about 50:50 and about 0.1:99.9.
2 . The composition of claim 1 , wherein, for each mixture (i), (ii) and (iii), the ratio of the number of OR groups in the ortho-position with respect to the bond between the P atom and the associated phenyl group to the number of OR groups in the para-position with respect to the bond between the P atom and the associated phenyl group is between about 20:80 and about 1:99.
3 . The composition of claim 1 , wherein each of x and y is zero.
4 . The composition of claim 1 , wherein R is hydrogen.
5 . The composition of claim 1 and comprising about 10 to about 50 mole % of the first mixture (i), about 30 to about 60 mole % of the second mixture (ii) and about 10 to about 50 mole % of the third mixture (iii).
6 . The composition of claim 5 and comprising up 10 wt % of triphenyl phosphine oxides of the formula IV:
7 . A method of producing the composition of claim 3 , the method comprising:
(a) reacting phenol with an alkyl halide having 1 to 6 carbon atoms in the presence of an alkali metal base to produce a first product mixture comprising an alkoxybenzene and an alkali metal halide;
(b) contacting said first product mixture with an oxidizing agent under conditions such that the alkali metal halide reacts with the alkoxybenzene to produce a first mixture of meta and para-haloalkoxybenzenes;
(c) combining said first mixture with a benzene halide to produce a second mixture; and
(d) reacting said second mixture with magnesium and with phosphorus oxychloride to produce said alkoxyphenyl phosphine oxide composition wherein R in each of formulas (I), (II) and (III) is an alkyl group containing from 1 to 6 carbon atoms.
8 . The method of claim 7 , wherein the alkyl halide comprises methyl bromide.
9 . The method of claim 7 , wherein the benzene halide comprises chlorobenzene or bromobenzene.
10 . The method of claim 7 , wherein said oxidizing agent comprises hydrogen peroxide.
11 . The method of claim 7 and further comprising reacting the product of (d) with an acid to produce said hydroxyphenyl phosphine oxide composition wherein R in each of formulas (I), (II) and (III) is hydrogen.
12 . An epoxy resin composition comprising the reaction product of the composition of claim 4 and an epihalohydrin.
13 . A curable epoxy resin composition comprising (a) an epoxy resin and (b) a cross-linking system comprising the composition of claim 4 .