CS229336B1 - Process for the production of sodium borohydride with isotope of boron - Google Patents

Abstract

The invention belongs to the field of synthesis of inorganic halides and solves a method of producing sodium tetrahydroborate containing the isotope ΙθΒ, which allows to obtain this hydride in a pure state and in high yield on the basis of the boron compound. The essence of the invention consists in reacting sodium tetraaluminium hydride and tria (2-methoxyethoxy) borane (3) in a molar ratio of 1.33 to 1.75:1 in a benzene or toluene environment. The product is used mainly for the synthesis of substituted boranes and the isotope 1°B, used in neutron treatment of malignant tumors.

Description

The present invention relates to a process for the preparation of sodium tetrahydroborate with isotopes

Sodium tetrahydroborate is one of the most widely produced and widespread hydrides. It is used as a reducing agent in organic chemistry, in the paper industry and in the removal and regeneration of mercury, copper, lead, silver and gold from industrial waste water · At the same time it is one of the basic raw materials for higher rams production Tumors using Substituted Higher Rams and isotope have resulted in the need to prepare these compounds from simple Isotope Compounds. However, only the method that yields high isotope yields is usable for this preparation *

The proposed processes for the preparation of sodium borohydride can be divided into four groups, namely the reactions of (a) sodium hydride with diborane or trialkylanine borane (3), (b) sodium hydride with boric acid esters, (c) sodium hydride with boron halides and ( (d) hydrides with boron oxides or borates.

Reaction of sodium hydride with diborane or trialkylamine-boranene (3) is demanding on starting materials, which adversely affects the loss of rta isotope yield, but as the only method provides tetrahydroborate without by-products.

NaCl + - »2 NaBH ₄

The reaction is carried out in diethylene glycol dimethyl ether (US Pat.

461,661 and 3,029,128). The reaction of sodium hydride with trilakylaminoborane (3) follows the equation

KaK * BHj Nijj -v NaliH * ♦ NRj and the production of sodium tetrahydroborate in this manner is the subject of German patents 1,034,596 and 1,035,109. 229 33S

The most widely used industrially is the preparation of sodium hydride and trimethoxyborane (3) (U.S. Pat. Nos. 2,461,661 and 2,534,533).

NaH + B (OCH3) _{3 4} + 3 NeBH NaOCH ₃

The product is isolated by extraction with isopropylanine or ammonia. The by-product of the reaction is sodium monohydrotrimethoxyborate, the formation of which reduces the yields of ¹⁰ B isotope to the present trimethoxyborane (3). '

Lower yields on boron provide reactions of sodium hydride with boron trichloride or boron trifluoride diethyl etherate. pat.ě. 944,546). In the reaction of boron trifluoride diethyl etherate, sodium fluoroborate is formed as a by-product of the reaction.

Sodium fluoroborate is used as the starting boron compound in the industrial production of sodium borohydride (German Pat. No. 958 646, U.S. Pat. No. 2,929,676 and U.S. Pat. No. 120,100). _χ

NaH + NaBF ₄ NaBH ₄ + 4 NaF

The reaction is carried out in paraffin oil and does not proceed quantitatively to the present sodium fluoroborate. Product isolation is complicated.

Hydride reactions with boron oxides or borates, for example, are also industrially useful

KaK + 2 B ₂ O ₃ NaBLI ₄ + 3 NaB0 ₂ according to US Pat. Or 2,715,058, or

NaBOg ♦ 2 CaHg — NaBK ₄ + 2 CaO according to it. pat.č. The most widespread of this group is the so-called silicate method according to brit. pat.č. 962 005 and German Pat.

10ε 670 and 1 061 301.

At ₂ B ₄ 0 _? + 16 Na + 8 Ii ₂ + 7 oi0 ₂ 4 NaBH ₄ + 7 Na ₂ SiO ₃

These methods are suitable for industrial production. The reaction is carried out without solvent and the product is isolated with ammonia. The waste is easy to process. However, the reaction yields are low.

Higher yields are achieved in the simultaneous production of sodium dihydridobis (2-methoxyethoxo) and sodium tetrahydroborate according to U.S. Pat. aut.osv. 186 046. However, the production passes over

228,338 boron into solution and this reduces the yields to the present boron.

A common disadvantage of these manufacturing processes is the isolation of the product from the slurry or solid reaction mixture. NaBH content. in 4 of this mixture is less than 20%. Isolation of sodium borohydride is carried out by filtration, evaporation of the solvent and further drying.

For the above production processes, the yield of sodium borohydride was assessed for hydride hydrogen recovery. To date, no method has been proposed to allow the preparation of pure sodium borohydride without loss of the starting boron compound.

The present invention is directed to a process for the preparation of sodium borohydride with isotope S by reacting sodium aluminum hydride with a boronic acid trialkyl ester with isotope SC in a inert organic solvent. The principle of the invention consists in reacting sodium borohydride stris (2-methoxyethoxy) borane (3) in a molar ratio of 1.33 to 1.75: 1 in benzene or toluene.

A preferred embodiment of the process of the present invention is the synthesis carried out in benzene under boiling such that tris (2-methoxyethoxy) borane (3) is added dropwise to the present sodium borohydride. it proceeds quantitatively. The resulting sodium borohydride, which is the only insoluble product in the reaction medium, is pure and readily separable by filtration. The process according to the invention guarantees the conversion of the boronic acid ester to sodium borohydride in an almost quantitative yield per boron.

The following are some examples of embodiments of the method of the invention.

Example 1

A 1.82 g of 97.6 D-KaAlH4 (0.0330 mol) and 35 ml of benzene were charged to a 100 ml ground-glass centrifuge tube. The cuvette was fitted with a dropping funnel and a reflux condenser, protected by a cap against air humidity. The resulting mixture was heated and 5.81 g of ¹⁰ 5 (OCH ₂ CH ₂ OCH 3) 3 (0.0247 mol) was added over 30 minutes while boiling benzene. The reaction mixture was then heated at reflux of benzene for 2 hours. The reaction mixture was then centrifuged, the clear solution was withdrawn and the solid decanted three times with 20 ml of benzene. After the last wash the benzene towing the solid was dried for 2 hours at 325 5θ Pa · K was obtained 0.9167 g of white powdery sodium borohydride analysis: 26.16% ¹⁰ 10.53 B and Fe-H, which corresponds to 96.85 Fe- him

NaBH4 and the reaction yield not presented at 97.1 fe.

Example 2

The apparatus of Example 1 was charged with 1.987 g

97.8 g of NaAlH4 (0.0360 mol) and 35 ml of benzene * 4.98 g of ^ (OCHgCH2OCH3) (0.021167 mol) was added to the mixture at boiling temperature over a period of 25 minutes. of the reaction mixture was carried out analogously to Example

1. 0.6082 g of white powdered sodium borohydride containing 26.18% and 10.55% H * was obtained, corresponding to

The yield of the reaction to the present boron was 99.96.

Example 3

To a 250 mL flask equipped with a dropping funnel and a water condenser protected by a seal against atmospheric moisture was added 5.87 g of 97.6 g of NaAlpha (0.1063 mol) and 100 µl of benzene. 16.64 g of ¹⁰ Β (ΟΟΗ ₂ ΟΗ ₂ ΟΟΚ ₃ ) ₃ (0.07073 mol) were added to the mixture at boiling temperature over a period of 25 minutes and the reaction mixture was heated at reflux for 2 hours under reflux. filtered through a glass frit (Z-3) and the white insoluble matter passed through the frit 3 times > 0 µl of benzene; analysis 26.15 fe ¹⁰ B and 1C, 54 fe H, corresponding to 96.8 fe NaBH 4 and a reaction yield of the present boron of 99.2 fe.

Claims (1)

SUBJECT OF THE INVENTION 229,338 is ^rH10 A method for producing sodium borohydride with izotopenk B reacting lithium sodium trialkyl boric acid then with izoťopenf ^(1O B in an inert organic solvent, indicate Nu that in the medium of benzene or toluene by reacting lithium, sodium with tris (2-methoxyethoxy) borane (3 ) in a molar ratio of 1.33 to 1.75: 1.