CS263979B1 - Double-cyclophosphate nikeijnato-loronate 'and the way to prepare them - Google Patents

Abstract

The solution concerns new compounds of the type of double nickel-magnesium cyclotetraphosphates of the formula c-Ni2-xMgxP40i2, where x is in the range from values approaching zero to values approaching two. They are prepared by crystallization in a dry atmosphere from a melt with a temperature above 1100 °C, containing nickel and magnesium cations in a mutual molar ratio Ni/Mg corresponding to the relationship (2—x)/x and further containing phosphate anions in an amount corresponding to the ratio P2Os/(Nl -j- Mg) equal to 0.97 to 1.08, upon solidification.

Description

BACKGROUND OF THE INVENTION The present invention relates to novel nickel magnesium magnesium double cyclotetaphosphates.

Of the compounds of the condensed phosphate type with one cation of divalent metal and with a molar ratio of phosphorus pentoxide (P2O5) to the corresponding metal equal to one, cyclo-tetraphosphates (formulas c-Me ”P40i2) and higher linear phosphates (formulas Μβη / 2 ^Π) Η2Ρηθ3η + ι).

This is also the case in the case of nickel condensed phosphates, where there is both dicotassium cyclotetrophosphate (c-N12P4O12) and higher linear hicelic phosphates (Nin ^ PúPnChn + i), and ^{in the} case of magnesium compounds where higher linear phosphates (Mgn ^ H) PnChn + i) product with cyclic tetrafosphate anions (c-Mg 2 P 4 O 12). Double cyclo-tetraphosphates containing magnesium cations in addition to other divalent metal cations are of increasing importance.

These products have not been known so far and, if the existence of condensed phosphates with pairs of these cations was considered, only as higher linear phosphates. However, these higher linear divalent metal phosphates, whether single-cation or double-cationic, have some properties that are less suitable for their use. They are substances of amorphous, non-crystalline, glassy character, which are fragile. They are also relatively easily soluble and some even tend to be moisturized. Their thermal stability is limited by recrystallization temperatures (600 to 850 ° C).

Due to the existence of simple higher linear phosphates (single cation) and simple cyclo-tetraphosphates with the corresponding cation, and especially from the comparison of their properties, it can be expected that double compounds of the cyclo-tetraphosphate type, where one of the cations is magnesium, will have properties entirely other. They can be expected to be far more suitable than the higher linear phosphates for all the contemplated uses of condensed phosphates to date - both as special inorganic pigments and also for agrochemical purposes.

SUMMARY OF THE INVENTION The present invention is directed to nickel magnesium magnesium double cyclotetraphosphates as novel compounds of the formula c-Ni _{2 x} Mg _x P ₄ O 12, where 0 <x <2.

The lower and upper limits for x result from the fact that the values zero and two cannot be used because they would no longer be a double product, but a pure, simple C-N12P4O12 or C-N12P4O12 cyclo-tetraphosphate. o simple magnesium di-cyclotetrophosphate c-Mg2P40i2.

Nickel-magnesium magnesium double cyclophosphates are pale to deep yellow-green substances (according to Ni content), the densities are in the range of 2.87 to 3.48 g / cm ³ according to the Ni / Mg ratio. / c. Its lattice parameters, according to the Ni / Mg ratio, range from:

1.164 to 1.175 nm for α,

0.824 to 0.828 nm for b,

0.981 to 0.991 nm for c,

118.5 to 118.9 ° for β and elementary cell volume ranging from 0.827 to 0.843 nm ³ ·

Nickel-magnesium double cyclo-tetraphosphates are chemically and thermally very stable substances. Ions insoluble in water, organic solvents and dilute mineral acids, only slowly dissolve in lye solutions. It melts only at high temperatures according to the Ni / Mg ratio in the range 1100 to 1250 ° C, the latent heats of melting being in the range of 50 to 85 kj / mol. In a completely dry atmosphere or in vacuum, they melt congruently, in an atmosphere containing at least traces of water vapor they melt inecongruently.

The present invention further provides that nickel-magnesium magnesium double cyclo-tetraphosphates are prepared in such a way that the melt at a temperature above 1100, preferably above 1,250 ° C, contains nickel and magnesium cations in a Ni / Mg molar ratio corresponding to ( 2-x) / x and further comprising phosphate anions in an amount corresponding to a molar ratio of P2O5 / (Ni-J-Mg) of 0.97 to 1.08, preferably of 1 to 1.005, is allowed to solidify in a completely dry atmosphere by cooling; preferably at a rate of less than 5 ° C / min to form a microcrystalline product.

The melt temperature must be selected above the melting point, respectively. solidification of the products, which has a Ni / Mg ratio of 1100 to 1,250 · ° C. The ratio of the nickel and magnesium cations in the melt is chosen according to the requirement for their content in the product, and the amount of magnesium cations can be in the range of _B from near zero to close to two. The meltphosphoric anion content of the melt must correspond to a molar ratio of P2O5 / / (Ni + Mg) equal to one, or values differing only slightly from one, corresponding to the c-Ni ₂ × xMg _x P ₄ 0 ₁₂ total formula. by-products in the form of other types of condensed phosphates and the proportion of the main product would decrease significantly. Solidification crystallization of the product from cooling melt should be conducted in a completely dry atmosphere (or under vacuum) since the presence of even trace amounts of water vapor would again lead to the formation of condensed phosphates with other anions and not with cyclotetrafosphate anions. It is advantageous to conduct the cooling of the melt at a rate of less than 5 [ ^deg .] C./min. reduces the possibility of other undesirable condensation products.

If desired, the products can be further purified by curing with hydrochloric, sulfuric, nitric or phosphoric acid, since the double cyclo-tetraphosphates resist this leaching, while the other products which have formed are dissolved. The preferred acid concentration for leaching is 0.05 to 5 wt. %, where by-product separation is sufficiently effective and the risk of attack of the main product is negligible.

The advantages of the invention are that it indicates the existence of new compounds which have not been known so far. These compounds accumulate advantageous physicochemical and application properties having simple divalent metal cyclotetrophosphates. Special pigment properties are emphasized and long-term solubility is influenced, which in turn is important for their agrochemical use.

Example 1

The melt prepared by melting 100 g of higher linear nickel phosphates and 84.1 g of higher linear magnesium phosphates at 1280 ° C was cooled in a dry atmosphere at a rate of 5 ° C / min. 184.1 g of a microcrystalline product were obtained which contained 99.2 wt. % of nickel magnesium magnesium double cyclo-tetraphosphate of the formula NiMgP40i2. Yellow-green microcrystals are in a monoclinic system, spatial rubber C 2 / c, whose lattice parameters are:

a = 1.169 nm, b = 0.826 nm, c = 0.985 nm, β = 118.7 °, and a unit cell volume of 0.835 nm ³ .

Their density: 3.18 g / cm ^3, melting point 1130 ^'Q C and the melting heat of 64.5 kJ / mol.

Example 2 of higher linear phosphates nickel and 42.1 g of higher linear magnesium phosphates at 1300 ° C is cooled in vacuo at 20 ^C, C''mín. It was obtained

192.1 g of a microcrystalline product containing 98.1 wt. % of double nickel magnesium magnesium cyclo-tetraphosphate of the formula:

c-Nii, ₅ Mgn, ₅ P40: 3.

Yellow-green microcrystals are in a monoclinic system, spatial group C 2 / c, whose lattice parameters are:

a = 1.167 nm, b = 0.825 nm, c = 0.984 nm, β = 118.6 °, and a unit cell volume of 0.831 nm ³ .

Their density is: 3.33 g / cm ³ , melting point: 1 210 · ° C and latent heat of fusion: 57.8 kj / mol.

Example 3

Melt prepared by melting 50 g of higher linear nickel phosphates; and

126.2 g of higher linear magnesium phosphates at 1250 ° C were cooled in a dry atmosphere at a rate of 2 ° C / min. 176.2 g of a microcrystalline product were obtained which contained 99.6 wt. % of double nickel magnesium magnesium cyclo-tetraphosphate of the formula:

C-Ni _0,;, MGI ₅ P4Oi2.

Light yellow-green microcrystals are in a monoclinic system, spatial group C 2 / c, whose lattice parameters are:

a = 1.172 nm, b = 0.827 nm, c = 0.986 nm, β = 118.8 °, and a unit cell volume of 0.838 nm ³ .

Their density is: 3.03 g / cm ³ , melting point: 1110 ° C and latent heat of melting: 72.1 kj / mol.

Melt prepared by melting 150 g

Claims (2)

Double nickel-magnesium magnesium cyclo-tetraphosphates of the formula c-Ni ₂ x xM g gxP ₄₀ 12, where 0 x x 2 2. 2. A process according to claim 1, characterized in that the melt at a temperature above 1100, preferably above 1,250 [deg.] C., comprises nickel and magnesium cations in a Ni / Mg molar ratio corresponding to (2-x) /. xa) OF THE INVENTION 1e comprising phosphate anionics in an amount corresponding to a molar ratio of P2O5 / (Ni + Mg) of 0.97 to 1.08, preferably of 1 to 1.005, is allowed to solidify in a completely dry atmosphere by cooling, preferably at a rate of less than 5 ° C / min. to give double cyclotetraphosphates of nickel magnesium magnesium microcrystalline nature, which are optionally purified by leaching with hydrochloric, sulfuric, nitric or phosphoric acid, preferably a concentration of 0.05 to 5% by weight.