CS238919B1 - A method for preparing bis (triphenylphosphenoxyl) trichloro ferric complex - Google Patents

Abstract

The invention relates to a method for preparing a bis-/triphenylphosphine oxide/trichloroferric complex of the formula FeCl,/Ph,PO/-, where Ph denotes phenyl. The essence of the method according to the invention consists in reacting compounds selected from the group comprising an elemental metal and salts of strong inorganic acids with alkali metal chlorides and triphenylphosphine in a molar ratio of 1:3:2 in acetonitrile in the presence of dioxygen at temperatures of 20 to 80 °C.

Description

The invention relates to a method for preparing a bis(triphenylphosphane oxide) trichloroferric complex of the formula FeCl2/Ph2PO2, where Ph here and hereinafter denotes phenyl.

This compound can be used as a catalyst in the oxidation of triphenylphosphine PhjP with dioxygen according to AO No. 205 483 and is also a potential catalyst for the oxidation of various substrates such as tertiary phosphanes and arsanes, olefins, styrene, alkylbenzenes.

The complex of composition FeCl ₃ /Ph ₃ PO/ ₂ is prepared according to J. Chem. SOc. /A/ 1971, 859 by direct reaction of an ethanolic solution of FeCl ₃ with triphenylphosphine oxide PhjPO or according to Chem.

Zvesti 30, 86 /1976/ by the reaction of FeClj and Ph-jP with O ₂ in acetonitrile.

The disadvantage of both preparation methods is the use of anhydrous FeCl ₃ and in the first method the necessity of preparing Ph ₃ PO by oxidizing Ph ₃ r. The above disadvantages can be eliminated by the method of preparing the bis/triphenylphosphine oxide/trichloroferric complex according to the invention, the essence of which lies in the fact that iron compounds selected from the group comprising an elemental metal and salts of strong inorganic acids are reacted with alkali metal chlorides and triphenylphosphine in a molar ratio of 1 : 3 : 2 in acetonitrile in the presence of dioxygen at temperatures of 20 to 80 °C.

If the molar ratio of the above substances is not maintained, then in addition to the FeCl ₃ /Ph ₃ PO/ ₂ complex, unreacted starting substances are present in the reaction mixture after oxidation, except for triphenylphosphine, which is catalytically oxidized to triphenylphosphine oxide.

In the case of ferrous chloride, in the absence of chloride ions, ferric oxide is formed as a by-product. In the case of starting materials of ferric or ferrous sulfate hydrates, the by-product is always potassium sulfate.

After the reaction is complete, the reaction mixture is filtered and from the filtrate, after cooling, fine crystals of the composition FeCl ₃ /Ph ₃ PO/ ₂ slowly crystallize, which are recrystallized. At a concentration of iron in oxidation state XXI, IX or O equal to approximately 0.1 M in 30 cm ³ in the reaction mixture, while maintaining the above-mentioned molar ratio, the complex FeCl ₃ /Ph ₃ PO/ ₂ is obtained upon intensive contact with dioxygen in 3-4 days.

By lowering the temperature below 50 °C, the reaction time is extended. At higher temperatures, there are losses due to evaporation of acetonitrile. The subject of the invention is described in the following examples.

Example 1 ΐ o “ 4

Into a temperature-controlled reaction vessel (50 C) flushed with oxygen were placed 2.5.10 - 3 - 3 moles of Fe ₂ /SO^/ _3< 9 HjO; 1.5.10 mols of KC1 and 10 mols of PhjP and after connecting to the apparatus for measuring O ₂ consumption, 10 cm ³ of acetonitrile was dosed.

By monitoring the dependence of O ₂ consumption on time, it was found that the oxidation of PhjP to PhjPO lasted 4 days. After filtering off KjSO^ as a by-product from the solution, the compound FeCl ₃ /Ph ₃ PO/ ₂ - bis/triphenylphosphanoxide/trichloroferric complex crystallized.

The obtained crystals were rinsed with acetonitrile after filtration, recrystallized and dried at room temperature. The purity of the complex was determined by elemental analysis. Results of the analyses:

Fe - off. 7.77 Cl - off.14.79 C - off.60.16 H - off. 4.21 Yield 80 exp. 7.83 % exp.14.85 % exp.59.97 % exp. 4.05 %

Example 2

0.5 g of JIC1; 1.0 g of PhjP and 0.6 g of Fe ₂ /SO ₄ / ₃ · 9 f^O were weighed into the reaction flask. After adding about 30 cm^ of acetonitrile, the mixture was heated at 55 °C with the addition of O ₂ and stirred for 3.5 days.

After filtering off the solids from the reaction mixture, a white powder was obtained from the filtrate after evaporation of the acetonitrile, which was recrystallized from acetonitrile. The obtained crystals were dried and subjected to analysis.

Analysis results:

Fe - off. 7.77% exp. 7.82% Cl - off. 14.79% exp. 14.82% C - off 60.16% exp. 60.05% H - off 4.21% exp. 4.08%

Yield 80%.

Example 3

0.09 to 0.1 g of iron powder was placed in a temperature-controlled reaction vessel /60 °C/,

3

0.8 Ph^P and 0.40 cm 36% HCl in 30 cm acetonitrile. With continuous addition of 0 ₂ and stirring, the reaction lasted for 4 days.

After filtering off the by-products from the filtrate, fine crystals of the composition FeCl ₃ /Ph ₃ PO/ ₂ gradually crystallized. The dried crystals were analyzed as in Example

1.

Analysis results:

Fe - off. 7.77% exp. 7.80% Cl - off. 14.79% exp. 14.75% C - off 60.16% exp. 60.10% h - off 4.21% exp. 4.18 The yield was 60%.

Example 4

In a reaction vessel heated to 70 °C, 0.556 g of FeSO.7 H.0 (iron (II) sulfate heptahydrate, 3% by weight), 1.05 g of PhjP and 0.45 g of KC1 and 30 cm of acetonitrile were placed and 0 _{2 was added with constant stirring.}

The oxidation of Fe^ to Fe ¹¹¹ and Ph ₃ P to PhjPO lasted 4 days. The reaction can be accelerated by adding a few drops of concentrated HCl. After filtering off the by-product from the filtrate, the FeCl ₃ /Ph ₃ PO/ ₂ complex crystallized, which was subjected to analysis after rinsing with acetonitrile and drying (similar to example 1).

Analysis results:

Fe - off. 7.77% Cl - off. 14.79% C - off. 60.16% H - off. 4.21% The yield was 40%.

exp. 7.79 % exp. 14.78 % exp. 60.20 % exp. 4.15 %

Example

0.26 g of anhydrous ferrous chloride was placed in a temperature-controlled reaction vessel (50 °C)238919

3 g FeCl 3 , 1.05 g Ph 3 P and 0.17 cm 36% HCl in 30 cm acetonitrile. With constant addition of oxygen and stirring, the oxidation lasted 4 days. After filtering off the by-product from the solution, the compound FeCl ₃ /Ph ₃ PO/ ₂ crystallized. Analogously to example 1, the dried sample

underwent analysis. Analysis results: Fe - calc. 7.77 % exp. 7.82 % Cl - off 14.79 % exp. 14.86 % C - off, 60.16 % exp. 59.98 % H - off 4.21 % exp. 4.08 % The yield was 60%.

Example 6

Oxygen was introduced into a reaction flask containing 0.25 g of anhydrous FeCl2, 1.1 g of triphenylphosphine Ph2P (1.1 g) and 25 ^cm3 of acetonitrile at 40 °C with stirring for 4 days. The reaction of the starting materials produced the FeCl2/Ph2PO2 complex, uncoordinated Ph2PO2 and iron oxide.

The isolated Fe ₂ O ₃ was contaminated with a small amount of the complex FeCl ₃ /Ph ₃ PO/ ₂ . After isolation, recrystallization and drying, the complex was subjected to elemental analysis.

Analysis results

Fe - off. 7.77 Cl - off. 14.79 C - off. 60.16 H - off. 4.21 Yield 38%.

FeCl ₃ /Ph ₃ PO/ ₂ i % exp. 7.84 % exp. 14.85 % exp. 59.92 % exp. 4.19

Results of analyses of ^p ®2°3 contaminated with FeCl ₃ /Ph ₃ PO/ ₂ :

Fe - exp. 56.6%

C - exp. 4.70% H - exp. 4.21%

One m<5l of Fe ₂ O ₃ is contaminated with about 0.03 moles of FeClj/PhjPO/j.

Identification of the preparations prepared according to Examples 1 to 6 was carried out by measuring the electron and infrared spectra. The end of the oxidation of Ph ₃ P was determined by comparing the electron spectrum of the product with the spectrum of pure triphenylphosphine oxide Ph 3 PO , which has four absorption bands with absorption maxima in the region of 254, 260, 265 and 272 nm in acetonitrile.

The presence of coordinated Ph ₃ PO in the sample was proven by measuring infrared spectra /^p_0 ^{= 1} 149 cm ^-1 /. For uncoordinated PhjPO, _ρ _θ “ 1 190 cm ^-1 .

The oxidation of PhjP to PhjPO was monitored by measuring the O ₂ consumption at constant temperature and atmospheric pressure. After oxidation, the amount of O ₂ consumed stabilized at a constant value identical to the calculated amount of O ₂ .

Claims (1)

OBJECT OF THE INVENTION A process for the preparation of a bis (triphenylphosphine oxide) trichloroferrate complex of the formula FeCl ₃ / Ph ₃ PO 4, wherein Ph is phenyl, characterized in that iron compounds selected from elemental metal and strong inorganic acid salts are reacted with alkali metal chlorides and triphenylphosphate in a molar ratio of 1: 3: 2 in acetonitrile in the presence of oxygenation at temperatures of 20 to 80 ° C.