DE2025052C - - Google Patents

Description

of ammonium ions, which you can completely through Passing the lactic acid, to which 300 g of water has been added, is removed via a cation exchange resin.

The catalyst used during the hydrogenation was prepared by adding activated carbon successively with a 1N sodium bicarbonate solution and then with a palladium (II) chloride solution in hydrochloric acid was impregnated and then subjected to a reduction treatment with formaldehyde would.

The lactic acid used was obtained by hydrolysis of the product of the oxidation of propylene with Nitric acid and removal of the oxygen-containing nitrogen (II-IV) compounds formed in the course of the hydrolysis in proportion to their formation (addendum 92 116 to the French patent specification 1465 460) received. The lactic acid is isolated from the solution obtained by distillation.

Example 2

The procedure described in Example 1 is followed, except that the pressure is increased Bringing 50 bar and varying the temperature and the duration of treatment. One obtains those in the following Results given in the table:

0.057%

Example 3

ίο You work according to the method of example 1, but under a hydrogen pressure of 10 bar. After 30 minutes of reaction, the total level is on Nitrogen dropped to 0.036%, this nitrogen being in the form of ammonium ions.

Example 4

The procedure described in Example 1 is used at a hydrogen pressure of 50 bar and with a water content of lactic acid

ao of 10 ⁰ O, but the palladium is replaced by 0.1 percent by weight (corresponding to 2 g of platinum-carbon catalyst with a content of 5%> metal). After 30 minutes of reaction, a lactic acid is obtained which contains a total of 0.13% nitrogen,

»5 being this nitrogen in the form of quaternary Ammonium ions are present.

Claims (1)

_to 510) applied, under which one pfianz patent claim: ... _{h oc] er} animal "types of coal, which possibly Process for the purification of lactic acid, which can be activated κ ° ^ηη ^ ^η · pylene with nitric acid and / or nitrogen- 5 asbestos, pumice stone, quartz,
intermediate products formed by the dioxide are obtained from diatomaceous earth and sand
had been, after partial or complete mixtures of silica and a
Removal of the nitric acid, thereby ge or Alunimosihka ej «™« ™ ** - The content of the ke η η ζ cich η et that the raw lactic acid carrier of metal is not critical,
at a temperature of 20 to 250 ° C and xo The amount of metal used has in general a pressure of 1 to 200 bar in the presence of over 0.001 percent by weight based on the lactic acid subjected to a hydrogenation catalyst on the basis of a treatment and can be up to noble metal of group VIII of the periodic to 5 »/«. VerSystems can treat quantities over i / o with hydrogen. can be applied without going beyond the scope of However, this does not provide any particular advantages. Sufficient in practice Metallmemx-ii / gave way to P.05 and 0.5 »V The UehaiKHung temperature of lactic acid κ- The present invention relates to a method carries forward / ug, wipe 50 and 180_ C. Ii ler for the purification of lactic acid, which ugnen through oxidation 20 Praxis s.ch in general between ■ nd of propylene with nitric acid and / or nitrogen - 100 bar. Dioxide to intermediate products and associated with the implementation of the invention \ _-r- Hydrolysc of these oxidation products is obtained. fahieiis can a hydrogen stream in d.e kn According to de: French patent 1465 640 catalyst containing, anhydrous or in v.aLi- and their additives 90 556 and 92 116 and the lactic acid present in the solution. Man French patent specification 1500 619 represents lactic acid can also be fed through a column, In Let lactic acid by oxidation of propylene, which contains packing and the catalyst Nitric acid and / or nitrogen dioxide, given and in the hydrogen in cocurrent or in de- if in the presence of oxygen, the lactic acid stream is introduced with the formation of a gene stream. of intermediates mainly composed of 30 The process according to the invention is special. rs Λ-nitratopropionic acid, which is then connected advantageously, which sticks out almost all of the > lf- ßend a hydrolysis with water, optionally containing impurities with removal of the is destroyed in the presence of an acid such as nitric acid or nitrogen in gaseous form (e.g. N ₂ , N _? O), undergoes. In the course of the reaction one sets the It can happen that part of the nitrogen, Nitric acid in freedom and at the end of 35 receives its level according to the treatment conditions Treatment an aqueous solution of lactic acid, which is variable, is converted into ammonium ions, which which contains nitric acid. These two acids stay dissolved in the lactic acid. An additional can be separated according to various methods, treatment with cation exchange resins or which, for example, by treating the reaction by electrodialysis, allows these remaining mixture with tertiary or secondary amines 40 to remove nitrogen. or more simply by azeotropic distillation of the process according to the invention enables in Nitric acid (French patent 1,500,619) easily adds lactic acid of high purity or obtained by extraction of the lactic acid with butanol, which is less than 15% nitrogen in the form (Belgian patent 707 424). of ammonium ions and in particular These pre-separation operations result in a 45 for use in the food industry and Lactic acid, which, even if it is free from nitric- pharmaceutical industry, acid is, nor nitrogen-containing impurities Di "the following examples illustrate the invention, contains indefinite nature. . -I ₁ A method for purifying Example has now been established Lactic acid, which is produced by hydrolysis of the oxy-50 In a 5 () 0-cm ^{: I} autoclave made of stainless steel, dalion of propylene with nitric acid and / or the intermediate products shaken by means of a shaker, one brings 300 g of nitric acid-free milk had been kept, after partial or complete acid with a content of 0.34 percent by weight removal of the nitric acid, which is characterized by nitrogen, determined by the method of, that the crude lactic acid at 55 Dewarda, and 6 g a palladium-carbon Katalyeincr temperature of 20 h * s 250 ° C and a sators with a content of 10% metal in. The pressure of I to 200 bar in the presence of a hydrogen autoclave is closed and gerungskalysators based on a hydrogen Precious metal that washes. Then brought, after having brought the contents of group VIII of the periodic system with water of the autoclave to 120 ⁰ C, treated fabric to a. 60 hydrogen pressure of 50 bar. After 5 minutes, the pressure to 40 bar can be used in particular as a catalyst. Hydrogen is introduced to bring metals, such as ruthenium and palladium, to a pressure of 50 bar. After 5 minutes, use rhodium and platinum. These metals adjust the pressure to 40 bar. This can be maintained alone in the form of a powder with variable conditions for 20 minutes. The contents of the particle size or in the form of spheres or autoclave are cooled to 20 ° C. Then the grains will be used. They can also be degassed on apparatus. The catalyst is separated off by the supports customarily used in catalysis. The lactic acid obtained contains (see S. Berkman and coworkers, Catalysis, p. 426 only 0.04 percent by weight nitrogen in the form