US2696500A

US2696500A - Production of sebacic acid

Info

Publication number: US2696500A
Application number: US297760A
Authority: US
Inventors: Stein Werner
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1951-07-11
Filing date: 1952-07-08
Publication date: 1954-12-07
Anticipated expiration: 1971-12-07

Description

United States Patent PRODUCTION OF SEBACIC ACID Werner Stein, Dusseldorf-Holthausen, Germany, assignor to Henkel & Cie., G. m. b. H., Dusseldorf-Holthausen, Germany, a corporation of Germany No Drawing. Application July 8, 1952,

Serial No. 297,760

Claims priority, application Germany July 11, 1951 7 Claims. (Cl.260--537) In the conventional methods for the production of sebacic acid by oxidative cleavage of castor oil with caustic alkalis at increased temperatures, the resulting 'ICECiiOIl product constitutes a relatively heavily viscous mass by reason of the high melting points of the alkali salts of sebacic acid. For this reason the working up of the reaction products presents certain difficulties that are not too easily overcome.

One object of the invention comprises the elimination of the aforementioned difiiculties and at the same time the obtaining of a more efficient reaction of the initial reaction components. This and further objects of the invention will be apparent from the following description.

In accordance with the invention, alkali soaps of fatty acids which are substantially liquid at the temperature of reaction are added to the initial reaction mix to be treated for the production of sebacic acid salts.

Castor oil or the therefrom obtained ricinoleic acid constitutes at the moment the raw material of largest practical significance for the obtaining of sebacic acid or acid salt. If castor oil is used as the immediate starting material, it is necessary to add to the initial reaction mix the water which will be consumed during the reaction. Such water is automatically produced when using ricinoleic acid by reason of the neutralization thereof with caustic alkali. Where reference is therefore made hereinto proceeding in the absence of water or the substantial absence thereof there is to be understood in accordance with the foregoing the use of the aforementioned minimum amount of water.

Caustic alkalis useful in the practice of the process are principally caustic soda and in many cases also caustic potash.

For the purpose of reducing the consistency of the reaction mix primarily additions of the alkali salts of the soap forming straight or branched chained, natural or synthetic fatty acids may be used within the scope of the invention. The fatty acids to be used may contain at least 8 carbon atoms in their molecule. The melting points of fatty acids or fatty acid mixtures, as they are I preferably used in the process of this invention do. not change very much with the increasing chain length of the fatty acids. Therefore, the upper limit of chain length depends only by the chain length of the available acids. Wool wax and montan wax contain fatty acids with 25-30 carbon atoms in their molecule. Such high fatty acids may also be produced in synthetic way e. g. by the catalytic reaction between carbon oxyde and hydrogen and olefins, known oxo process, and by subsequent conversion of the alcohols or aldehydes into fatty acids.

It is sometimes desirable and may be of advantage to produce the soaps within the course of the sebacic acid production such as by alkali oxidation of corresponding alcohols. If unsaturated fatty acids free of oxy groups are added to the initial reaction mix, it is also possible to obtain with such additions the results in accordance with the invention by reasonof the decomposition of these fatty acids into suitable products by the action of alkali as part of the reaction leading to sebacic acid or acid salts. inasmuch as these reactions, such as the alkali oxidation of alcohols, and the decomposition of unsaturated'fa'tty acids proceeds with consumption of alkali,

it is necessary to take this into account when calculating the alkali requirements of the initial reaction components .for the'productiqupf sebacicacid or acid salts.

2,696,500 Patented Dec. 7, 1954 The amount of alkali soaps to be added may be at least one half of the alkali soap of the ricinoleic acid. The amount may be increased and if the production of sebacic acid is combined with the alkali decomposition of unsaturated fatty acids into soaps of saturated fatty acids of lower chain length, or with the alkali oxidation of fatty alcohols to salts of the fatty acids, the amount of added soap may be increased to four times the amount of ricinoleic acid soap.

The formation of sebacic acid proceeds already at temperatures of approximately 200 C. plus or minus; for the practical, large scale operation of the process preferred temperatures of above about 235 C. are recommended which may be increased to above about 350 C. up to the temperature at which appreciable decomposition of reactants or reaction products would occur which temperature may be modified or influenced to reduce decomposition or the danger thereof by the addition of, for instance water. The maximum amount of water may be limited so that it forms a 50% by weight alkali lye with the caustic alkali, added to the starting materials. This limitation is given only by economical reasons. The reaction is possible even with greater amounts of water. Under such circumstances it is necessary to observe every necessary precaution when blowing off the hydrogen produced during the reaction which is carried out either continuously or in batch portions during the reaction or only after the completion of the reaction, so as to avoid a sudden pressure drop and resultant boiling and foaming of the reactant which in turn may entail losses of materials and the clogging of reaction apparatuses. Such boiling of the reaction mix may be avoided by maintaining in the apparatus a pressure above the saturation pressure of the water. This is the only reason, why the maintaining of a certain pressure in the reaction vessel is commendable. Its amount depends on the amount of water, the amount ofhydrogen, formed during the reaction and the contents of the reaction vessel. The reaction itself does not depend on the pressure.

It has been further discovered within the scope of the invention and as an embodiment thereof that the speed of reaction may be increased by effecting the reaction in the presence of cadmium or cadmium additions. In a certain case, when a heating of two hours were necessary to obtain a formation of sebacic acid 84% of theory at 275 C. without presence of cadmium, the addition of 5% cadmium oxide, calculated upon the amount of ricinoleic acid, increased the velocity of reaction in such a manner, that the 84% of sebacic acid had already formed, when the vessel was opened after a reaction time of one hour. The cadmium which may be added to the initial reaction components in any desired form whether substantially free or chemically bound, would eventually become de posited in the form of a cadmium. layer on the walls of the autoclave. These little amounts of cadmium are sufficient to catalyze the reaction, so that in later runs the special addition of cadmium may become unnecessary. It is alternatively possible to use autoclaves initially providedwith a cadmium lining.

Upon completion of the reaction, the reaction mix, if necessary, is dissolved in or diluted with water whereafter the monobasic fatty acids are separated from the sebacic acid, preferably by fractionated precipitation with acids which constitutes a relatively simple recovery procedure. If the solution of sebacic salt, remaining after the precipitation of the first separated monobasic acids, is acidified while hot there is obtained upon cooling a crystallizate which is particularly well filterable.

The separation of the sebacic acid or sebacic acid salts from the monocarbonic acids present in the reaction product may be, however effected also in different manner such as by solvent extraction or treatment with organic solvents for the monocarbonic acids.

The addition of alkali soaps to the reaction mixture in accordance with the invention effects a liquification or thinning of this mixture and beneficially influences the efficiency of the reaction itself, as well as the workability of the reaction product. The substantially liquid initial reaction mixpe'rmits a thorough mixture of reaction components andassures a far reaching thorough substantially complete reaction of the materials. Furthermore, the

initial reaction mix and the reaction products in various stages of completeness of reaction possess a materially superior flowability as compared with reaction mixes only composed of castor oil or ricinoleic acid and caustic alkali. The invention makes it thus :possible for the Lfirst time to operate in a relatively simple, substantially continuous mannenusing duct systems-or similar apparatuses for thesubstantially continuous transportuof reaction componentinto and through a reaction zone ifor the substantially continuous production :of sebaci'c .acid or isebacic acid salts.

A still further liquification or reduction in consistency of materials may be obtained by .th'esaddition of Water which, however, in the presence of the fatty facidlsoap addition in accordance with the invention may be Jkept substantially -so low that any resultant pressures will remain moderate.

The increase in 1 speed of reaction by theme oficadmium within the scope of one embodiment of the invention permits shorter reaction periods andlor l'ower :rea'ction temperatures for the *production of sebacic acid tor sebacic acid salts and thus more :efiicient, more :advantageous operations as well :as a saving in wear of materials.

In the herein after set forth examples furnished by way of illustration and not by way iOf limitation, the following procedural steps were involved. The initial reaction mixes were heated in an autoclave of stainless steel 316 and provided with a stirrer arrangement. Heating was carried to the reaction temperature and was maintained for a predetermined period of time. When adding cadmium compounds a copper insert was used which in the course of time became coated with a cadmium layer. "Pressure was released sometimes during the reaction, so that the pressure was not-higher than this one, given in the examples. After completed reaction and a certain dropping of temperature of the reaction mix, the pressure was completely released and the autoclave contents were dissolved in water or diluted with water and the octanol and 'octanone, if any, produced during the reaction were driven oif with steam after the acidification of the solution with sulfuric acid to a pH of about 6. Sebacic acid remaining in solution after the separation of the precipitated fatty acids was obtained in readily fi-lterable form by further acidification of the hot solution and permitting the same to cool. The melting'point of the sebacic acid was 130-132 C.

Example I Starting materials: 339 g. castor oil, 300 g. soy fatty acid (JV=108), 205 g. NaOH,'205 g. water, 18g. CdO. Autoclave: Copper clad. Reaction: '2 hours at 300320 C., pressure not higher than 144 kg./cm Yields:

172 g. sebacic acid=5l% of an castor oil=88% of theory. '70 g. octanol. 340 g. fatty acids.

' By partial decomposition of the unsaturated soy fatty acids into saturated fatty acids the idoine value of .the fatty acids after the reaction was 45. .By prolonged reaction time, the decomposition completed and the iodine value of the fatty acids lowered.

Example 11 Starting materials: 339 g. castor oil, 300 g. soy fatty acid, 205 g. NaOH, 27 g. water, 18 g. CdO. Autoclave: Copper clad. Reaction: 4% hours 250'300 C., pressure .not higher than 136 kg./cm Yields:

150 g. sebacic acid=44% of the castor oil:. 76% of theory. 48.5 g. octanol. 356 g. fatty acids.

Example 111 Starting materials: 339 g. castor oil, 300 g. of a mixture of fatty alcoh ls from sperm oil, 160 g. NaOH, 27 g. water, 18 g. CdO.

Autoclave: Copper clad.

Reaction: 3 hours at.270-'300 C., pressure not higher than 168 kg./cm

Yields:

18 7 -'g. -sebacic acid=40.-2% -of-the*eastor -oil=70-% of theory.

21 g. octanol.

352 g. fatty acids small amounts of unsaponifiable, consisting tessentially of unreacted fatty alcohols.

-Example IV The additional "fatty acid .mix, .used in this example, was produced by air oxidation of a solid paratfin, obtained by catalytic hydrogenation of carbon monoxide. The chaindength .of the .fatty acids was .from 16 to 26 carbon atoms, the 1208.and.the .SV 220.

Starting materials: 600 ,g. fatty acids from castor oil, 2400 g. additional fatty acids, *600 g. of a technical caustic soda, containing .about 10% of water. No additional water, no additional cadmium.

Autoclave: Copper clad .with a cadmium lining, formed during foregoing reactions. p Reaction: .5 hours at 280-300 C., .Zpressure not higher than 3.0 "kg/cm? p I p v Yields: 296 1g. tsebacica'cid=8 t% of theory. Theyie'lds .in octanol and .mono'basic *fatty 'acids were not de- 'termined.

The sebacic acid referred toxhereinlis intended-'Ito'desig .nate nhe .acid typified :by 1&8 .octanedicarboxylic tacid. Fatty acids :as .used .herein :are intended atO designate organic acids within the broad connotation of that term and substantially liquid at the operati'onal temperature of sebacic acid formation within the scope of "this invention. The fatty acids within the broad scope of the invention include as herein. above pointed out those of straight or branched chain configurations .tincluding *o'lefinic :acids and regardless of whether of natural 'or synthetic origin. Within the preferred scope of the invention the .so-called .fat acids thaviing melting points below .1 00" C. :fnrnish suitable additives in the practice of the invention. The term ffat racids here used is intended to designate :those acids normally occurring in animal or vegetable :fats, waxes :and oils, or, the otherwise, .inclnding synthetically produced, equivalents thereof.

1. In the method for the production of sebacic acid by the treatment of the alkali maps of castor oil and ricinoleic acid with caustic alkafis at increased tern .peratures, the improvement which comprises conducting said caustic alkali treatment in the presence of an additional alkali soap of a fatty acid substantially :liquid at the said treating temperature and thereafter recovering sebacic acid from the reaction mix.

2. Improvement in accordance with claim 1 in which a fatty alcohol corresponding to said fatty acid is added to the reaction mix to thereby produce during said treatment the said ifatty acid alkali soap.

3. Improvement in accordance with claim 1 in which there .is added to the reaction :mix an unsaturated fatty acid .free from. hydroxyl groups to thereby obtain said fatty acid soap during said treatment.

4. Improvement in accordance with claim 1 in which :said treatment is carried out in the presence of at least one member of the group consisting of cadmium and cadmium containing materials.

5. Improvement in accordance with claim 1 in which treatment is carried out at a temperature of from substantially 200 C. to below the decomposition temperature of the reactants and said sebacic acid and the salts thereof.

6. Improvement in accordance with claim 5 in which said treatment is carried out in the presence of at least :one :member of the group consisting of cadmium and cadmium containing materials.

7. Improvement in accordance with claim 6 in which said treatment is carried out in the presence of water.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date [2,182.056 Bruson et a1 Dec; 5 1939 2.217.516 Houpt Oct. '8, 1940 2.318.762 Davis et al. May ll, 1943 2.384.811 Chitwood Sept. 18, 1945 2,580,931 Lane Ian-1, 1952

Claims

1. IN THE METHOD FOR THE PRODUCTION OF SEBACIC ACID BY THE TREATMENT OF THE ALKALI SOAPS OF CASTOR OIL AND RICINOLEIC ACID WITH CAUSTIC ALKALIS AT INCREASED TEMPERTURES, THE IMPROVEMENT WHICH COMPRISES CONDUCTING SAID CAUSTIC ALKALI TREATMENT IN THE PRESENCE OF AN ADDITIONAL ALKLI SOAP OF A FATTY ACID SUBSTANTIALLY LIQUID AT THE SAID TREATING TEMPERATURE AND THEREAFTER RECOVERING SEBACIC ACID FROM THE REACTION MIX.