DE764487C - Process for the production of fatty acids with 10 to 20 carbon atoms in the molecule - Google Patents

Description

It has been found necessary in the art to prevent the oxidation of paraffins, e.g. B. von Gatsch from the Fischer synthesis, with oxygen or oxygen-containing gases, yes to break off after conversion of some of the hydrocarbons into fatty acids in order to to avoid further degradation of the latter. As a result, it remains after removal an unsaponifiable proportion of the fatty acids due to saponification, the so-called back paraffin, left over.

It is known to re-oxidize this back paraffin with oxygen or oxygen To subject gases, but this is the yield of fatty acids with io to 20 carbon atoms, the actual soap-forming fatty acids, less than with oxidation the same amount of fresh paraffin, while the accumulation of low molecular weight fatty acids is bigger. so

It has now been found that this disadvantage can encounter characterized in that only after distilling off ⁰ to about 350, preferably from ⁰ to about 320, boiling proportions as a residue remaining part of the return paraffin, expediently in a manner known per

Way, together with fresh paraffin, subjected to the same oxidation and processing of the oxidation products as the original paraffin.

The process significantly increases the capacity of the oxidation apparatus achieved in terms of the yield of soap-forming fatty acids.

Although it is known, before the oxidation of the fresh paraffins to 300 or 310 ⁰ boiling fractions to lower molecular weight hydrocarbons by distillation to remove. But this it could be removed not mean that it is expedient prior to the oxidation of return paraffin to increase the yield of fatty acids having 10 to 20 carbon atoms existing in large part from oxygen-containing neutral products, up to about 350 ⁰ boiling fractions removed by distillation. To prove the difference in the yield of fatty acids with 10 to 20 carbon atoms between the total back paraffin and the higher-boiling portion of the same, the following examples are subjected to air oxidation from a boiling point of 225 to 450 "and once from a boiling point of 320 to 450 ³ .

Comparative examples

Experiment 1:
Rückgatsch total
mixture
Kp. 225 to 450 ³ Experiment 2:
Back gossip
Kp. 320 to 450 ⁰ paraffin
SZ of the paraffin
VZ of the paraffin
KMnO ₄ 100 parts by weight
0.4
4.4
0.2 parts by weight 100 parts by weight
o, 7
6.5
0.2 parts by weight Oxidation process:
SZ after one hour
SZ after 25 hours
VZ after 25 hours
Yield of reaction product 44
73
137
98.5 parts by weight 47
70
130
99.75 parts by weight Yields after separation of the reaction
Products:
Yield of back paraffin
Paraffin consumption
Yield of water-insoluble crude fatty acid ...
Yield of water-insoluble crude fatty acid,
based on paraffin consumed
SZ of the crude fatty acid
VZ of the crude fatty acid 58.9 parts by weight
41.1
29.8
72.5%
238
276 60.3 parts by weight
39.7
3! .O
78, i%
222
258 Distillation of 100 parts by weight each
Crude fatty acid provides:
Fraction C ₄ to C ₃
Fraction C ₁₀ to Ci ₀
Distillation residue
Yield of fatty acid from fraction C ₁₀ to C ₂₀ ,
based on paraffin consumed 17.5%
75.5%
6.3%
54.7% 12.8%
79.1%
7.6%
61.8%

Two paraffin samples were subjected to air oxidation under the same conditions.

1. Rückgatsch total mixture, as it is obtained in the technical implementation of the air oxidation of hydrocarbons from the carbon oxide hydrogenation according to Fischer-Tropsch for the purpose of obtaining synthetic fatty acids. The Rückgatsch total mixture boils ^225-450: and contains 26 _cent, lower than the starting material boiling components.

2. Rückgatsch, over 320 ^: boiling, which was obtained from the above total ^{mixture by distilling off the up to 320:} boiling portion.

The air oxidation conditions were the same for both products, namely temperature HO ", air volume 100 1 / hour, catalyst 0.2% KMnO ₄ , oxidation vessel, cylindrical aluminum container with a perforated tube as an air distributor.

The reaction products were worked up by saponification and subsequent gasoline extraction carried out in a known manner.

The result of the two tests is shown in the following table:

Claims (2)

Claim: A process for the production of fatty acids with 10 to 20 carbon atoms in the molecule by reusing the back paraffin obtained during the oxidation of paraffin with oxygen or molecular oxygen and the usual processing of the oxidation products, characterized in that only the back paraffin is obtained from this back paraffin after distilling off up to about 350 ⁰ , preferably of up to about 320 ⁰ , boiling fractions remaining as residue, expediently in a manner known per se together with fresh paraffin, subjected to the same oxidation and processing of the oxidation products as the original paraffin. To differentiate the subject matter of the invention from the state of the art, the granting procedure the following publications have been considered: British Patent No. 491,927; French patents No. 818 796, 852 597; Angewandte Chemie, Vol. 51, p. 707;
Chemiker-Zeitung, Vol.20, p.227U.Bd.3i, p.277; Seifensieder-Zeitung, Vol. 66, pp. 666 to 668; Hefter-Schönfeld, 1937, vol. 2, pp. 664, 667 and 668;
Wittke, The synthesis of fatty acids, pp. 29 and 666 to 668. 5028 5.