DE1266747B - Process for the preparation of sodium epoxypropionate - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

C07d

German class: 12 ο -11

Number: 1266 747

File number: St 19757IV b / 12 ο

Filing date: September 25, 1962

Opening day: April 25, 1968

The invention relates to the production of epoxypropionic acid Sodium by oxidation of epoxypropionaldehyde in an alkaline solution.

According to a known process, the sodium salt of epoxypropionic acid is obtained in that epoxypropionaldehyde is ^{oxidized with a dilute solution of hydrogen peroxide in water at a temperature of 30 to 45 0} C, while the pH value during the reaction is increased to 8.5 by adding sodium hydroxide 9 ("Journal of Organic Chemistry", Vol. 26, p. 2984 [1961]). Here, however, a relatively expensive oxidising agent is used, and the yield is only 65 ° / _0th

The purpose of the invention is to provide a cheaper method for To create production of sodium epoxypropionate. The invention also contemplates one substantial increase in yield.

The process according to the invention for the preparation of sodium epoxypropionate by oxidation of epoxypropionaldehyde in alkaline solution is characterized in that the oxidation is carried out in aqueous sodium hydroxide solution at a pH of 7 to 11, preferably 8 to 10.5, in the presence of metallic silver or a Silver salt, such as silver nitrate or acetate, with oxygen or an oxygen-containing gas at 15 to 55 ⁰ C is carried out.

The gas used as an oxidizing agent can be pure oxygen as well as air or another mixture of oxygen with one or more other gases which are inert under the reaction conditions. If necessary, it is possible to work under pressure, which accelerates the oxidation.

Because, on the one hand, epoxyaldehyde hydrolyses very quickly at a pH value above 11 and, on the other hand If the pH value is very slowly oxidized below 7, it is necessary to precisely match the claimed pH range to be observed.

Free epoxypropionic acid can then be prepared in a customary manner from the salt obtained.

Finely divided metallic silver or a silver salt, ζ. B. silver nitrate or silver acetate, find application. Metallic silver obtained by reducing silver oxide is preferably used. This has the advantage that the oxidation of the epoxyaldehyde can be carried out at a lower temperature and with considerably smaller amounts of catalyst than when using catalysts prepared by reducing other silver compounds. The reduction of the silver oxide can be carried out separately in the usual way, but can also take place excellently "in situ" by using the epoxyaldehyde as a reduction process for the production of
sodium epoxypropionate

Applicant:

Stamicarbon N.V., Heerlen (Netherlands)

Representative:

Dr. F, Zumstein,

Dipl.-Chem. Dr. rer. nat. E. Assmann

and Dipl.-Chem. Dr. R. Koenigsberger,

Patent attorneys,

8000 Munich 2, Bräuhausstr. 4th

Named as inventor:

Johannes Wilhelmus Gielkens, Sittard;

Johannes Henricus Catharma Beek,

Marie-Aim6e Gregoiree,

Franciscus Albertus Busschers, Geleen

(Netherlands)

Claimed priority:

Netherlands of October 2, 1961 (269 793) - -

acts medium. If the reduction is carried out "in situ," one can use a silver salt with the same result, from which silver oxide is formed under these conditions.
The reaction can be carried out in a simple manner by, for. B. an aqueous suspension of metallic silver or silver oxide or a solution of the silver salt in water, a solution of the epoxyaldehyde in water gradually adds while the oxidizing gas is passed through and at the same time an aqueous alkali is added at such a rate that the pH of the solution is kept at the required value.

The sodium salt of epoxypropionic acid can be obtained from the aqueous solution obtained in this way retire by z. B. the solution evaporated and then by adding alcohol or Acetone drops the salt. The free acid can be produced from this by dissolving the salt in water, the solution acidified, saturated with ammonium sulfate and the

Acid extracted with ether. In this way, the acid can also be separated out directly from the aqueous oxidation solution.

- 809 5Φ0 / 438

The free epoxypropionic acid was prepared under the conditions of the reaction according to the prior art regarded as unstable because the reaction medium was considered too alkaline (see U.S. Patent 2,930,801, Column 2, lines 59 to 61. pH = 12.5 or higher). That's why Only a pH above 11 is to be avoided in the process according to the invention.

Due to the high reactivity of the epoxy oxygen atom, the free epoxy propionic acid is important as an intermediate for various syntheses. You can z. B. converted into glyceric acid by hydrolysis which is used to stabilize the water resistance of leather.

For example _χ .

A solution of 72 g (1 mol) of epoxypropionaldehyde in 11 of water was with constant stirring within 4.5 hours gradually added to a suspension of 5 g of silver oxide in 40 ml of water while at the same time ao oxygen was passed through the mixture at a rate of 401 per hour. Simultaneously a solution of 40 g of sodium hydroxide in 150 ml of water was added at such a rate that that the pH of the reaction mixture was kept at a level of 9-10. Afterward the mixture was stirred for a further 1 hour while passing through oxygen. The temperature was kept at about 20 ° C. throughout the reaction.

The reaction solution was filtered off from the catalyst and at 35 ° C in vacuo to a volume of Evaporated 200 ml. Acetone was then added to form a white precipitate. This was filtered off, washed with ether and dried. The product obtained consisted of 115 g of the hemihydrate of the sodium salt of epoxypropionic acid (yield 97%). The purity was according to a determination of the content of epoxy oxygen 90%. The product can optionally be recrystallized from a mixture of 80% alcohol and ether (1: 1) subjected to further purification and then converted into the free epoxycarboxylic acid.

Example2

The test conditions were the same as in Example 1, with the difference that a suspension of 100 g of silver powder was used, which was obtained by reducing silver nitrate with zinc in 250 ml Water had been prepared and that it was operated at a temperature of 50 ° C. In this case 113 g of sodium epoxypropionate was obtained (yield: 95%).

Claims (2)

Patent claims:: 1. Process for the preparation of sodium epoxypropionate by oxidation of epoxypropionaldehyde in alkaline solution, characterized in that the oxidation in aqueous sodium hydroxide solution at a pH of 7 to 11, preferably 8 to 10.5, in the presence of metallic silver or a silver salt such as silver nitrate or acetate, with oxygen or a oxygen-containing gas at 15 to 55 ° C. 2. The method according to claim 1, characterized in that metallic silver is used as the catalyst obtained by reducing silver oxide. Considered publications:
U.S. Patent No. 2,887,496. 809 540/438 4.68 © Bundesdruckerei Berlin