US1931859A - Process for the recovery of organic acids from oxidized nonaromatic hydro carbons - Google Patents

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Oct. 24, 1933. H. BELLER ET AL PROCESS FOR THE RECOVERY OF ORGANIC ACIDS FROM OXIDIZED NONAROMATIC HYDROCARBONS Filed 0G13. 2l. 1951 Tow M MJ E? KEEP# wm.. m nu By M gu Al Patented Oct. 24, 1933 UNITED STATES PATENT OFFICE PROCESS FOR THE RECOVERY OF ORGANIC ACIDS FROM OXIDIZED NONAROMATIC HYDROCARBONS Application October 21,1931, Serial No. 570,128, and in Germany October 22, 1930 6 Claims.

The present invention relates to improvements in the recovery of organic acids from products of the destructive oxidation of liquid and solid, non-aromatic hydrocarbons.

It is already known that the destructive oxidation of non-aromatic hydrocarbons, such as mineral oil, paraffin wax, parailin oil or oils containing the same, with the aid of oxygen, air or other oxygen bearing oxidizing agents at temperatures between about 130 and 180 C. results not only in acid products containing oxygen, as for example carboxylic acids and hydroxy-carboxylic acids, but also greater or less amounts of neutral compounds containing oxygen, such as alcohols, aldehydes, ketones, esters, laetones, estolides, lactides, aldehyde-alcohols and ketone-alcohols. In order to recover the valuable acid constituents, especially those which are present in the combined or modified form, namely esters and estolides, it has beenv necessary hitherto to saponify the oxidation product with caustic alkalies or oxides or hydroxides of the alkaline earth metals.

We have now found that the organic acids, especially those present in the combined or modified form as esters, estolides, lactones and lactides, are recovered in an advantageous manner from products of the destructive oxidation of liquid to solid non-aromatic hydrocarbons by treatingthe oxidation products in a closed vessel and at a temperature, which is at least 75 C. but is always kept below the boiling temperature of water at the pressure employed, which is produced both by heating and by the evolution of carbon dioxide, with an aqueous solution of an amount of alkali metal carbonate, as for example sodium, potassium or ammonium carbonate, at least corresponding to the .saponiiication value of the oxidation product, preferably in excess thereof, the resulting alkali metal salts being worked up into free fatty acids by acidification after the removal of the unsaponiable constituents. Contrary to expectation, not only the free carboxylic acids but also those which are present in the oxiv dation products in a combined form, such as (Cl. 26o-116) temperature, especially those above 100 C., with the simultaneous. employment of elevated pressure. When working in this manner more carboxylic acids are obtained from the reaction mixture when working up the reaction mixture than corresponds to the' acid value of the oxidation product employed.

The amount o1 alkali metal carbonate (which term is intended to include ammonium carbonate) is preferably calculated on the saponification value of the oxidation product, which is usually considerably greater than, as for example twice as great as, the acid value. It is, however, advantageous to use an amount of alkali carbonate slightly in excess, as for example from about 5 to about 10 per cent in excess, of the amount so calculated for complete saponiiication. Still higher quantities may be employed but an excess of more than 10 per cent is superuous and unduly expensive. The alkali carbonate can be employed in the form of from 5 per cent aqueous solutions to hot saturated solutions and is preferably employed in the form of an about 20 per cent aqueous solution, the product to be saponiiied being slowly introduced into the hot solution of carbonate. At the commencement of the treatment the temperature is kept usually between and 100 C., preferably between about and about 95 C., until the 'greater part of the carbon dioxide formed by the conversion of the free carboxylic acids present has been evolved. Towards the end of the reaction, the temperature is preferably raised above 100 C. up to say 350 C., generally, however, to from about 160 to about 185 C., and the pressure increased above l'atmosphere, usually from 8 to 9 atmospheres, or even to 15 or more atmospheres. Care should be taken for a uniform removal of the carbon dioxide evolved. It is of special advantage thoroughly to mix the reaction mass during the treatment, as for example by means of a highspeed stirrer. For example, the saponiiication may be carried out in a turbo-mixer or vessel provided With turbo-stirrers, in which process the time required for saponiflcation is very short. By suitable arrangement of the inlet and outlet devices and by continuous withdrawal of the saponified product while introducing fresh initial material, the saponiiication in the turbo-mixer may readily be rendered continuous. Processes for carrying out the saponication are further illustrated by the diagrams in Figures 1 and 2 annexed hereto, Figure 1 showing continuous working in a direct ilow and Figure 2 showing a modification of this process in which the final saponiication may be carried out in a cycle.

When the saponication is completed the unsaponiable constituents separate out from the soap solution, if necessary after diluting the reaction product with water, when a concentrated carbonate solution has been used for the reaction, as the upper layer which is removed. Any remaining unsaponiable constituents in the solution may be completely removed by extraction with organic solvents, as for example gasoline, carbon tetrachloride, other chlorinated hydrocarbons and ethyl ether. If desired, the unsaponiilable constituents may be subjected lto oxidation again, if necessary after washing for a short time with dilute alkali carbonate solution or water in order to remove small quantities of soap contained therein.

The following examples will further illustrate the nature of this invention, but the invention is not restricted to these examples.

Eample 1 100 kilograms of a crude oxidation product having an acid value of 100 and a saponifcation value of 150, obtainable by the destructive oxidation of hard paraiiin wax by blowing it for several hours with air at about 150 C. in the presence of 0.1 per cent by weight of the wax of sodium carbonate in the form of a concentrated aqueous solution, is allowed to ow in a thin stream at C. into a solution of 15.6 kilograms of anhydrous sodium carbonate in '70 kilograms of Water while stirring vigorously under atmospheric pressure. AfterY the initial turbulent evolution of carbon dioxide has ceased, the mixture is transferred to a stirring autoclave and further treated for about an hour at 120 C., whereby the carbon dioxide set free is removed by frequently releasing the pressure in the autoclave down to 3 atmospheres. The soap solution obtained is diluted with water and extracted with benzine. Then byacidication with sulphuric acid about 50 kilograms of pure fatty acids are obtained.

Example 2 100 kilograms of an oxidation product having an acid value of '75 and a saponification value of 140 and obtained from soft paraiiin wax by blowing it for several hours with air at about 150 C. are stirred together with a solution of 14.3 kilograms of anhydrous sodium carbonate in 60 kilograms of water at about C. under atmospheric pressure. After the initial turbulent evolution of carbon dioxide has ceased, the mixture is charged several times at 170 C. through a turbomixer (3000 revolutions per minute) provided with a circulating vessel, whereby a pressure of about 9 atmospheres is maintained. After a few minutes the saponication is almost completely effected and the treatment is terminated after about 15 minutes. The reaction mixture is worked up into free fatty acids in the manner described in Example 1.

What we claim isz- 1. In the separation of organic acids from products of the destructive oxidation of from liquid to solid, non-aromatic hydrocarbons, the step which comprises heating such oxidation product in a closed, pressure-tight vessel to a temperature between 75 C. and the bc-iling point of water at the pressure employed together with an at least 5 per cent aqueous solution of a quantity of an alkali metal carbonate at least corresponding to the saponication value of said oxidation product.

2. In the separation of organic acids from products of the destructive oxidation of from liquid to solid, non-aromatic hydrocarbons, the step which comprises heating such oxidation product in an open vessel together with an at least 5 per cent aqueous solution of a quantity of an alkali metal carbonate at least corresponding to the saponication value of said oxidation product, to a temperature below the boiling point of water until the evolution of carbon dioxide has ceased and then heating the whole in a closed pressure-tight vessel to a temperature between 75 C. and the boiling point of water at the pressure employed.

3. In the separation of organic acids from products of the destructive oxidation of from liquid to solid, non-aromatic hydrocarbons, the step which comprises heating such oxidation product in an open vessel together with an at least 5 per cent aqueous solution of a quantity of an alkali metal carbonate at least corresponding to the saponication value of said oxidation product, to a temperature below the boiling point of water until the evolution of carbon dioxide has ceased and then heating the whole in a pressure-tight turbomixer to a temperature between 100 C. and the boiling point of water atv the pressure employed.

4. In the separation of organic acids from products of the destructive oxidation of parailin wax, the step which comprises heating such oxidation product in an open vessel to a temperature between 60 and 95 C. with an at least 5 per cent aqueous solution of a quantity of an alkali metal carbonate at least corresponding to the saponification value of said oxidation product until the evolution of carbon dioxide has ceased and then heating the whole in a closed, pressure- .tight vessel to a temperature between 100 and about 185 C.

5. In the separation of organic acids from products of the destructive oxidation of parafn wax, the step which comprises heating such oxidation product in an open vessel to a temperature between about 60 and about 95 C. with an aqueous solution of a quantity of sodium carbonate, exceeding that theoretically required for complete saponication by from about 5 to about 10 per cent, until the evolution of carbon dioxide has ceased and then heating the whole in a closed, pressure-tight vessel to a temperature between 100 and about 185 C.

6. In the separation of organic acids from products of the destructive oxidation of parain wax, the step which comprises heating such oxidation product in an open vessel to a temperature between about 60 and about 95 C. with a quantity of an about 20 per cent aqueous solution of sodium carbonate, exceeding that theoretically required for complete saponication by from about 5 to about 10 per cent, until the evolution of carbon dioxide has ceased, and then heating the whole in a closed, pressure-tight vessel to a temperature between 100 and about 185 C.

HANS BELLER. MARTIN LUTHER.

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