DE1119237B - Process for the production of alkali hypophosphites - Google Patents

Description

The invention relates to a process for the production of alkali hypophosphites. Alkali hypophosphites have been made from alkaline earth hypophosphites with relatively low yields, since Phosphorus is oxidized by alkaline earth bases and there are considerable amounts of hydrogen phosphide and phosphite form.

A method has now been found in which these disadvantages are avoided and in which the Alkali hypophosphites directly in the form of their aqueous, concentratable and salable through crystallization Products transferable solutions are obtained. This is achieved when you get the reason the conversion of phosphorus into hypophosphite ions increased. According to the invention is in the Process for the preparation of alkali hypophosphites by oxidation of phosphorus in the presence of Water with a mixture of alkali hydroxides and alkaline earth bases is the sum of the gram equivalents of the individual elements of the basic mixture used at most 1 and the ratio of the gram equivalents of alkali hydroxide to gram equivalents Alkaline earth hydroxide is between 1.7 and 2.2.

The process according to the invention can be used to prepare aqueous, saturated alkali metal hypophosphite solutions; however, the optimum yield will only be obtained at concentrations of less than 300 g of hypophosphite achieved per liter of solution. The yield is reduced at greatly increased concentrations. the The amount of water is preferably adjusted so that the solution after the reaction is less than Contains 100 g of phosphorus in the form of hypophosphite anions per liter. Since the reaction speed with the temperature increases, it is advantageous to use at temperatures above the melting point of phosphorus, but to work below the boiling point of the alkali hypophosphite solution. In the inventive Processes always form certain phosphite fractions, which in the process are again in the form of dissolved Alkali phosphite accumulate. With appropriate precautionary measures, especially when regulating the Ratio between alkali and alkaline earth metal hydroxides, these proportions are seldom less than 1%.

According to a further feature of the process according to the invention, to produce practically phosphite-free, crystalline hypophosphite in the fractional crystallization of the filtered hypophosphite solution, the mother liquors containing hypophosphite and phosphite from the crystallization are combined with another reaction mixture obtained by oxidation of phosphorus with aqueous alkali and alkaline earth bases, in of the predetermined ratio method of making
of alkali hypophosphites

Applicant:

Societe Anonyme, Omnium de Produits
Chimiques pour l'Industrie et! 'Agriculture

"OPCIA", Paris

Representative: Dr.-Ing. A. v. Kreisler,

Dr.-Ing. K. Schönwald and Dr.-Ing. Th. Meyer,

Patent attorneys, Cologne 1, Deichmannhaus

Claimed priority:

France of June 20th (No. 716 958)

and December 24, 1956 (No. 10 105)

Georges Peyruc and Rene Marquie, Paris,
have been named as inventors

is changed from alkaline earth to alkali hydroxide in that the sodium hydroxide content of the Mixture is reduced by the proportion that is introduced by the phosphite of the mother liquors, and that the amount of alkaline earth metal hydroxide required for the stoichiometric precipitation of this amount of phosphite is increased. A new fractional crystallization of the hypophosphite solution thus obtained is then carried out through and repeat this process as desired.

Expediently, one combines the returned mother liquors with the washing water with which one washed the residue of the filtration after the oxidation of the phosphorus in an aqueous solution.

The method according to the invention is particularly for the production of pure crystalline sodium hypophosphite suitable by oxidation of phosphorus with sodium hydroxide and alkaline earth metal hydroxide in aqueous solution.

According to the invention, by fractional crystallization of alkali hypophosphite solutions _{containing 1% phosphite, crystalline, very pure hypophosphite salts containing no more than 0.1% phosphite (Na 2} HPO _{3 -5H 2} O) are obtained. However, this result is not achieved if solutions with more than 5% phosphite are fractionally crystallized. In such a process, considerable amounts of 30 to 50% hypophosphite were formed.

109 749/496

holding mother liquors, which after crystallization The reaction continues at a temperature of the Restark contain phosphite (7 to 10% hypophosphite). aküonsasse of 47 ° C, which then by the Re-Such Mother liquors are to be returned to the heat of action being maintained. After completion of crystallization for the production of pure hypophosphere the formation of hydrogen phosphide is made by FiI-phit unsuitable, and the phosphite would have to separate the insoluble part and remove the phosphite by trimming special procedure to be removed. Magnesium phosphite residue washed.

It is also already known that phosphites are obtained from After the process has ended, 11500 ecm are obtained

Alkali hypophosphite solutions by adding earth and sodium hypophosphite solution with a content

alkali hydroxides, which dissolve the alkali phosphite in the form of 63.4 g of phosphorus in the form of hypophosphite

Liches alkaline earth phosphite and alkali hydroxide cerium phite anions per liter and 5400 ecm of washing water from

put, can be removed. So treated washing of the residue, the 8.15 g of phosphorus in

However, solutions must be filtered again as they contain the form of hypophosphite anions per liter. the

to remove the formed alkaline earth phosphite, and the yield is therefore 64.4%.

the filtered solutions are then as such.

alkaline, in order to obtain pure hypophosphate 15 Example /

to make phit from it. In the reaction vessel of Example 1,

It has now been found that the presence of one led:

determined 7000 ecm of water during the oxidation of phosphorus

in aqueous solution by alkali and alkaline earth 5000 ecm wash water from washing the

hydroxyde introduced amount of alkahophosphite the * o residue with a content of

Final content of the filtered solutions of acahphosphate _{g 15 phosphorus in the form of} hypo-

would like to change if you take certain precaution- whnsnWtiminnpn i? Titpr

complied with the predetermined intake 2000 g of phosphorus

ratio of alkaline earth to alkali hydroxide for one ^ gQ | Caustic soda

optimal conversion of phosphorus to alkali hypo- 25 ^ 45 _g calcium oxide
phosphite is affected. The change depends on

the amount of Na introduced by the phosphite.

trium hydroxide and the action mass of 47 ° C for the precipitation of the phosphite. The temperature is rising

required stoichiometric Erdalkah'hydroxyd- then quickly up to 90 ° C and is by cooling

amount from. The obtained alkali hypophosphite filtrate 30 is kept at this temperature. After filtering and

should contain less than 1% alkali phosphite. Washing of the calcium phosphite gives 10,900 ecm

such solution is for the fractional crystallization of a sodium hypophosphite solution containing

for the production of pure crystalline alkali hypo- of 102.05 g phosphorus in the form of hypophosphite

phosphite suitable, the less than 0.2% phosphite ions per liter and 7800 ecm of water from washing

and only very slight traces of heavy metals from the residue, the 11.25 g of phosphorus in the form of

holds. Such a hypophosphite also does not contain hypophosphite anions,

free alkaline groups. The yield is therefore 57.96%.

Thus, according to the invention, alkali hypophosphate is obtained. .

phite, which is still phosphite and pure hypophosphite in Example 3

in crystalline form. After the first return 40 The Na-

Leading the mother liquor to obtain a hypophosphite solution in vacuo

phite solution, the phosphite content of which is practically concentrated from a solution saturated at 80 ° C,

does not differ from the solution obtained first. After that, the solutions are slowly down to one

cooled in the mother liquors as well as in the subsequent temperature of 20 ° C. After suction

Hypophosphite obtained process stages can be obtained in 45:

can be recovered in their pure state without the use of Crystalline sodium hypophosphite

special cleaning treatments were required. NaH PO-HO 5555

The inventive method can with con mother liquor (d _o = l 33) 2380 ε

continuous or intermittent oxidation of the phos- ^{6 ffl} ' ^ö

phosphorus in aqueous solution in the same way. 50 The salt, the 99% sodium hypophosphite

be turned. The washing of the residue NaH PO -H _n O

from the filtration of the hypophosphite solution from the ^{2 2} ^

Wash water produced by oxidation processes and contains less than 0.05% sodium phosphite,

the preferably with the returned mother holds a maximum of 5% p. M. iron and 1%

lyes united. 55 p. M. lead. The content of magnesium and calcium

The invention is in the following enclosures below 0.001%.

play explained.

Example 4

In the reaction vessel described in Example 1 In a 20-1 reaction vessel equipped with a stirrer 60 are introduced:
plant, heating and cooling devices and devices _{10 nnn} "" __ _w " _opo .

is provided for gas evacuation, em- ^ 200 see phosphorus

^fills: 312 g caustic soda,

ηηηΛ w 2 055 g of barium oxide.

12 000 ecm of water, 65 & j

1200 g of phosphorus, The reaction that takes place at a temperature of 48 ° C

1 008 g of sodium hydroxide solution, begins, runs slowly, and the temperature of the

276 g of magnesium oxide. Reaction mass does not rise above 66 ° C. After loading

5 6

When the formation of phosphine has ended, the following mixture is poured in:

Trieren the sodium hypophosphite solution separated ₉ ^ j water

and washed the residue. As a result of this, 400 kg of phosphorus

Driving you get 11,800 ecm of sodium and 2'oi6kg of sodium hydroxide solution

Barium hypophosphite solution with a content of 5-120ke barium oxide '

46.1 g of phosphorus in the form of hypophosphite anions -> S.

and 4500 ecm of water from washing the back.

standes, with a content of 4.5 g of phosphorus in trier and washing of the residue is obtained

Form of hypophosphite anions per liter. The out 23 1 filtrate, consisting of a hypophosphite solution

loot is 47%. 10 containing 63.5 g of phosphorus in the form of

Before concentration, these solutions are hypophosphite anions per liter and 1.7 g of phosphorus in

with one of the amount of barium present in the form of phosphite anions per liter and 111 detergents

stoichiometrically corresponding amount of sodium carbonate of the residue with a content of 8 gPhos-

bonat treated. The barium carbonate precipitate in the form of hypophosphite anions per liter and

is separated by filtration and washing. The 15 0.25 g of phosphorus in the form of phosphite anions per liter,

Losses resulting from this process are due to concentration and fractionated crystalline

1% of the phosphorus used in the process. cation is obtained from the filtrate 3.340 kg of crystalline

Salt with a content of 99.5% NaH ₂ PO ₂ · H ₂ O

Example 5 and 0.15% Na ₂ HPO ₃ -5H ₂ O and 3.320 kg mother. The reaction vessel is filled with: 20 lye with a content of 50% NaH ₂ PO ₂ -H ₂ O

1 ο nnn xxr ^{and 7} > ⁷ ° / »Na ₂ HPO„ · 5 H ₂ O.

12,000 ecm of water, '232

1,200 g of phosphorus, second process stage

1400 g of potassium hydroxide solution, into the reaction vessel of the first process stage

716 g of strontium oxide. the following mixture is given:

The reaction starts at a temperature of Re- H> 51 water,

action mass of 47 ° C, which is then washed through the H.01 wash water of the residue

Heat of reaction is maintained. After the first stage of the process,

ended formation of hydrogen phosphide in a 3,200 kg mother liquor with sodium hypophosphere

The mass is nitrided at a temperature of 70 ° C. After 30 ^{hours of the first stage of the} process,

Washing of the residue gives Il 750 ecm 2.400 kg of phosphorus,

a potassium hypophosphite solution with a content of 1> ^{915 k} S sodium hydroxide solution,

of 63.3 g of phosphorus in the form of hypophos- 0.610 kg of magnesium oxide,

phitanionen per liter and 3850 ecm of wash water after completion of the reaction and after filtration and

A residue with a content of 9.5 g of phosphorus in 35 washing of the residue gives 23.3 l of one

Form of hypophosphite anions per liter. The out filtrate, consisting of a sodium hypophosphite

the yield of the procedure is 65%. solution with a content of 81.9 g of phosphorus inForm

of hypophosphite anions per liter and 1.6 g of phosphorus

Example 6 i _n p _{orm of} phosphite anions per liter and 15.41

In a 10-1 carboy, the 40 washing water of the residue with a stirrer with a content of

and a reflux condenser is provided, 10.3 g of phosphorus in the form of hypophosphite anions

filled: per liter and 0.15 g of phosphorus in the form of phosphite

£ (\ c \ i \ """, \\ j _n ^^ r anions per liter.

oOÜÜ ecm water, _, ^J _T _. ,. ,. . _T,. ,,.

600 s phosphorus by concentrating and fractionating crystal

ςη? ο -NTstrnnisii ^ 45 sation is obtained from the filtrate 3.975 kg of salt with

1090lBarkmhXtlauge ^{a content of 99 '6} ° ^{/ o} NaH ₂ PO ₂ -H ₂ O and

iuyu g banumnyarati eye. _{0 / β Ν3ίHpOjj} . 5 H ₂ O and 3.260 kg mother liquor

Due to the very lively implementation, the temperature increases with a content of 50% NaH ₂ PO ₂ -H ₂ O and

temperature of the mass quickly to 85 ° C and is replaced by 7.8% Na ₂ HPO -5 H ₂ O.

Keep cooling the balloon at this temperature. 50 _τ t ^^ t, ™ «,,,,, * ,,. ^

τλ t. T ^ -ii · j - ». Τ * · i_ 1. τ. · *! ·· j Last confusion
By filtering the sodium hypophosphite solution and

Washing of the barium phosphite residue is obtained in the reaction vessel of the preceding process

5900 ecm of a sodium hypophosphite solution with driving calls the following mixture is given:

a content of 78.5 g phosphorus in the form of 111 water,

Hypophosphite anions per liter and 2150 ecm washing 55 121 washing water of the residue

water of the residue with a content of 7.9 g the previous process steps

Phosphorus in the form of hypophosphite anions per liter. with a content of 10.1 g of phos-

The yield is 68%. phosphor in the form of hypophosphite

The sodium hypophosphite solution with free Ba- ions per liter and 0.13 g of phosphorus in

rium hydroxide is concentrated with gaseous 60 form of phosphite anions per liter,

carbon dioxide and filtered. The 3.3001 mother liquor with sodium hypophosphate

losses incurred in this cleaning process phit from the previous process

amount to 0.6% of the phosphorus used. grades with a salary of

Example? 50 · /. NaH ₂ PCVH ₂ O and 7.5%

^ 65 Na ₂ HPO ₃ -5H ₂ O,

First process stage 2,400 kg of phosphorus,

In a 45-1 reaction vessel, which is 1.921 kg of sodium hydroxide solution,

plant and a device for evacuating gases. 2.350 kg of barium oxide.

After the reaction has ended and after filtering and washing the residue, 23.41 liters of water are obtained. consisting of a sodium hypophosphite solution containing 85.1 g of phosphorus in the form of Hypophosphite anions per liter and 1.6 g of phosphorus in the form of phosphite anions per liter and 15.51 of washing water of the residue with a content of 10.4 g of phosphorus in the form of hypophosphite anions per liter and 0.14 g of phosphorus in the form of phosphite anions per liter.

Concentration and crystallization give 4.270 kg of salt with a content of 99.6% NaH ₂ PO ₂ -H ₂ O and 0.10% Na ₂ HPO ₃ -5H ₂ O and 3.250 kg of mother liquor with a content of 50% NaH ₂ PO ₂ -H ₂ O and 7.8% Na ₂ HPO ₃ -5H ₂ O.

Claims (5)

PATENT CLAIMS: 1. A process for the production of alkali hypophosphites by oxidation of phosphorus in the presence of water with a mixture of alkali hydroxides and alkaline earth bases, characterized in that the sum of the gram equivalents of the individual elements of the basic mixture used is at most 1 and the ratio of the gram equivalents of alkali hydroxide to gram equivalents of alkaline earth hydroxide between 1.7 and 2.2. 2. The method according to claim 1, characterized in that such an amount of water is used is that the solution formed in the reaction less than 100 g of phosphorus in the form of Contains hypophosphite anions per liter of solution. 3. Process according to Claims 1 and 2, characterized in that at temperatures above the melting point of phosphorus and below the boiling point of the alkali hypophosphite solution is working. 4. Process according to Claims 1 to 3, characterized in that one is used to obtain practically phosphite-free crystalline hypophosphite after the fractional crystallization of the Dissolve the mother liquors from the crystallization containing hypophosphite and phosphite in the reaction mixture from a new oxidation, wherein in this new reaction mixture the predetermined ratio of Alkali to alkaline earth hydroxide by reducing the amount of sodium hydroxide by the Phosphite content of the mother liquors introduced and by increasing the stoichiometric precipitation this phosphite required alkaline earth hydroxide amount is changed, a new fractionated Crystallization carried out and the process repeated as often as desired. 5. Process according to Claims 1 to 4, characterized in that the recycled Mother liquors with that obtained by washing the residue of the filtration of the oxidation product obtained washing water combined. Legacy Patents Considered:
German Patent No. 1029 809. © 109 749/496 12.61