US2255230A - Preparing fatty acid compounds - Google Patents

Description

Patentedsept. 9, 1941 2,255,230 PREPARING FATTY acm oom'ormns John Ross, New York, N. Y., and Hans George Kirschenbauer, Bidgefleld, N. J., assig'norl to Colgate-Palmolive-Peet Company, Jersey City, N. 1., a corporation of Delaware No Drawing. Application April 13, 1939,

Serial No. zc'mzs 12 Claims. (01. 260-408) This invention relatesto the concentration of certain individual organicacids occurring in various mixturesof such acids and to the controlled halogenation of individual carboxylic acids.

It is often desirable to obtain relatively pure fatty acids or their derivatives for specific .purposes, but it is generally a diflicult task to pro-" cure such materials directly, since fatty acids usually occur in complex mixtures of their glycerides in oils or fats. The boiling points, melting points, solubilities, and other physical properties of the fatty acids in these mixtures are such tion of one acid from another.

Furthermore, it is often necessary to use the mono-halogenated derivatives of these fatty acids, for example, in the preparation of monothat they do not readily permit direct separap stearic acid. Upon further chlorination, the monochloropalmitic acid will be largely converted to dichloropalmitic acid and leave the maior portion of the stearic acid non-halogenated. The

formation of uniformly monochlorinated, high molecular weight long-chain fatty acids in such a mixture is not a simple problem.

It has also been found that the monohalogenated acids are very different in their physical properties from the non-halogenated fatty acids,

thus affording means for the separation of the individual acids.

By the process of the present invention, it is possibleto prepareuniformly halogenated fractions of fatty acids. It is also possible to prepare relatively pure aiiphaticcarboxylic acids, and I halogenated aliphatic carboxylicacids from comolefinic unsaturated fatty acids by a method'dia scribed in the copending application Serial No. 267,608, filed April 13, 1939. It has been found, however, that if a mixture of fatty acids, such as is normally obtainedfrom fatty oils, is chlorinated to the proper chlorine percentage corresponding to completely monochlorinated fatty acids; actually a mixture of polychlorinated fatty acids, monochlorinated fatty acids, and nonchlorinated fatty acids results. Such amixture is unsuitable-for many purposes where a relatively uniform product is required. For example, if a mixture of this type is treated in the process of the copending application Serial No. 267,608, filed April 13, 1939, a mixture containin saturated fatty acids, mono-olefinic fatty acids,

and polyoleflnic fatty acids would be obtained.

It has now been found that the reactivity withhalcgens of the diflerent fatty acids varies greatly, depending on the stereo-chemical structure of the acid. Ithas been further discovered that between two ormore aliphatic acids under the same or equivalent conditions, the more reactive aliphatic acidafter monobalogenation is oftenstill relatively more reactive, than the other non-halogenated acid or-acids, and will tend to be poly-halogenated before the less reactive nonhalogenated acid or acids will be monohalogenat- .ed. For example, in a mixture of stearic and palmitic acids, chlorine will substitute the palmitic acid first to produce monochlorcpalmitic acid, andleave substantially non-chlorinated plex mixtures of aliphatic carboxylic acids.

The process of this invention comprises the direct halogenation of amixture of aliphatic carboxylic acids until the most reactive acid is monohalogenated. This halogen -containing acid is then separatedfrom the non-halogenated. lessreactive acids byany suitable'm'eans, such as by fractional crystallization from organic solvents. The remaining unreacted acid may then again be treated with halogen to produce the monohal'ogen derivative of the aliphatic acid of next order of reactivity. This monohalo'genated acid is removed and the above procedure repeat ed to the desired degree of separation. The individual fractions may then-be recombined to obtains mixture of uniformly monohalcgenated fatty acids, or they may be used in their relatively pure state for specific purposes.

It isclear that this procedure may individual. For example, pure stearic acid may be obtained from a triple-pressed stearie acid "containing about equal parts of palmitic and stearic acids by separation of monochloropalmitic acid from the unreacted stearic acid, according eprocedure described in Example I.

- The degree of halogenation of the individual acids in each of the process steps need notbe monohalogenation as indicated above, but may be utilized to prepare a monohalogen acid of one chemical individual which can be separated from another non-halogenated fatty acid, thus obtaining the latter in a substantially pure state as a chemical be dior polyhalogenatlon with the same or dif- Pure stearic acid has acid value 197.3, equivalent ferent halogens. However, it ispreferred to monor molecular weight 284.4, and titer point of 69 to ohalogenate in this treatment. since monohal- 71 C.

ogenated acids are the most diilicult, or even im- The mother liquor C was successively concen- 1 possible, to prepare from mixed fatty acids by 5 trated and cooled, and in turn deposited in solid any means heretofore described. and by this proacids F, K and M. The final mother liquor N cedure the individual acids are most readily sepwas mainly monochloropalmitic acid containing arated. The individual products in the monosome admixed dichloro-acid. FractionM, pos

halogenated state can then be: further halogenatsessing an acid value of 187.1, equivalent or moed with the same or different halogens if delecular weight 299.8, is essentially pure monoing of the present invention, but in no way limsired. 'chloropalmitic acid (acid value 192.9, equivalent For the purpose of giving a better understandor molecular weight 290.8)

E I II iting the scope thereof, the following examples mmpe are given: 200 grams triple-pressed stearic acid were Example; chlorinated at a temperature of 90 C. until the gain in weight was equal to 27 grams chlorine. 2000 grams of triple-pressed commercial stearic The product was washed with water (med,

acid, titer 55.7 C., were meltedand chlorine gas and was found to have a chlorine cgntent of The 2000 grams of chlorinated triple-pressed aci bubbled into the liquid d until the 811111 111 11.6%. Recrystallization from acetone gave 53 W i h t this temperature was equal to 128 grams of substantially pure stearic acid and grams. The product was washed with water and grams of dichloropalmitic acid (acid value 177.3, dried. Itwas found to contain 5.6% chlorine by equivalent or molecular weight 316.4). Theory weight. Fractional crystallization of this materequires acid value 172.5, equivalent or molecular rial from acetone solution gave the following .weight 325.3.

A 200 gms. (11.6%)

Db8gms. E20gms. Flbgms. G104gms. H/ 1 J/ x L/ \M 0100 gms. 17.3% on its ti'it er;-

Q 1 (11 d1 d1 c1 0'1 0'1) ('11) 20 ms. 80gms.

12.05.01 (18.6% on yields of acids which contained the percentage Example III chlorine mdlmed mmwmg -1 738 grams of stearlc acid ((21 content 0.9%)

I purified as described in Example I were treated with chlorine at 90 C. until the gain in weight was'107 grams. The product was washed with E F 40 water and dried. Analysis showed the product D G to have a chlorine content of 12.4%. Recrystallization from acetone showed that the product consisted of approximately 20% unchanged (737%) j CD stearic acid, 20% monochlorostearic acid, and m 5 50% dichlorostearic acid.

- (13.82 1) (16.9% 01) Fractional crystallization of chlorinated stearic Away; 01

- 11 mm. 5.1% 01) c 440mm. 11.3% 01) v a r G$I a H/ \J x/ :L 43M/ 2:118 328m! 340P s 1 ,01' $3 53 251 25%|) (13.15% c (0.1% (14.3%(59 11.4% ('11) na$ 0'1 stearic acid (A) (Cl=6.6%) were dissolved in an Example IV q l Weight 1 W m o and upon 60011118 264 grams of triple-pressed stearlc acid were to 0 C., 1200 grams 01 solid crystalline acid (B) n i t d by th Hell-Volhgrdt-Zelingky was d posited and subsequently filtered on from method until the bromine content was 14.2%. the mother liquor which contains a mixture of The product was washed and dried, and was then acids designated as (C). This solid acid 13 was submitted to fractional crystallization from aceredissolved in fresh acetone and crystallized to tone according to the following scheme:

. A mogms. 14.2% bromine) 1371 2111 v 1) 40ml. 1: 12m F757: 0 a

O83gms.

Eg -32 d z gg a {23:32: Fraction H a titer point of 64.8 C., an,

we 755 acid value of 198.3, and an equivalent or molecugifigj ifg fgf fig gg ig pun lar weight of 285.8. (The theoretical figures roisteam, acid (acid value 301,1 mm t pure stearic acid are: Acid value 197.3, equivalent lecular weight 279 and a titer point of 64.1 0.). or molecular weight 284.4.) The fractions Q and tion to form alpha monohalogenated higher mixtur generally occur is a function P, containing approximately 25% bromine, essentially consist of monobromopalmitic acid.

The above examples illustrate the chief features and advantages of the present invention, but are not limiting on the scope thereof. Although chlorinated acids are-preferred for convenience and economical purposes, the corresponding bromiiiated and/or other halogenated derivatives can be similarly prepared by treatment with bromine, iodine chloride, and the like. Solvents may'alsobe present during the halogenation treatment, such as carbon tetrachloride, other halogenated hydrocarbons, acetic acid, and the like.

The solubilities of the sodium salts of chlorinated fatty acids in water at 28 C. are as follows:

Liquid at the following limiting high concentrations acid sodium soap per cent Chlorinated triple-pressed stearic acid sodium soap. Chlorine content 5.9%

Triple-pressed stearic per cent 0.4 Chlorinated triple-pressed stearic acid sodium soap. Chlorine content 10.1%

' per cent..- 1.0

Chlorinated triple-pressed stearic acid sodium soap. Chlorine content 21.4%

. percent... 13

Chlorinated triple-pressed stearic acid sodium soap. Chlorine content 25.1%

per cent" 20 Chlorinated triple-pressed stearic acid sodium soap. Chlorine content 27.% per cent.;. 23' Palmitic acid sodium soap do.. 0.3 Chlorinated palmitic acid sodium soap.

Chlorine content 13.8% per cent 12.2

The solubility tests werecarried out by pro-- paring successive dilutions until the concentrations were just low enough so that the solutions on cooling to 28 C. would be liquids and would not assume a pasty or solid character. On direct halogenation of fatty acids, it is known that the action first takes place on the alpha carbon atom of the fatty acid, but, as indicated hereinbefore, applicants are theflrst to control the halogenafatty acids from the normally-occurring es of these acids. This is true of other salts of these acids as well as their solubilitie's in organic solvents.

Normal fatty acids are the substances which in mixtures and to which the present invention is particularly adapted. However, it is also possible to-apply the process to straight or branched chain saturated aliphatic monoand poly-basic oarbonlic acids.' The process likewise may be applied to other derivatives of the acids, such as chain substituted acids including hydroxy, acyl, alkoxy, and acyloxy substituted acids of the above class, as well as carboxyl group functional derivatives of any sulphur, antimony, and

temperature, intensity, andtype of light radiation, and concentration in the given solvent, we have found that the rate given acid, and therefore the course of halogenation of a mixture of fatty acids, depends to a hitherto unsuspected degree upon the stereochemical structure of the acid. I

The relative rate of halogenation (relative reactivity) in the even carbon chain fatty acids is a function of the number of carbon atoms. As

one proceeds fromshort-chain fatty .acids to long-chain fatty acids, the reactivity alternates. to be connected with the hypothetical helical structure which is a possible configuration for any given straight-chain fatty acid to assume in the molten or dissolved state. In the case of chlorination, under equivalent conditions of temperature and light radiation,

table, for fatty acids reacting of these acids, for example, acid halides, monohydric alcohol esters, and p yhydric alcohol full and partial esters.

The rate of halogenation of a given fatty acid of the temperature at which the halosenation is carried out, the nature andintensity of the photocatalytic light radiation to which the acid is exposed, the concentration of the acid in solution, the nature of the solvent, and to a minor degree the relative rate of monochlorination of straight. chain fatty acids having an even number of carbon atoms has been found to be as follows: Palmitic acid capric acid laurlc acid caprylic acid stearlc acid myristic acid.

Since each acid has its own specific rate of reaction with a halogen, as shown'by the above with a single chlorine, it is possible by the method of this inve tion to monoor di-halogenate one or more acids in a mixture thereof and to separate the individual halogenated and non-halogenated acids by anyconvenient or desirable procedure.

The products of the process of this invention are particularly deslrablefor preparation of unsaturated fatty acids by the method described in the copending application Serial No. 267,608.

They may be converted td the corresponding hydroxy carbowlic acid. Suitable derivatives, such as the salts of 'the acids, may be reacted at the halogen substituents with other substances, such as alcoholates and thioalcoholates to form ethers, salts to form esters, ammonia and amines to form amines or ammonium compounds. For example, they can be reacted with sodium sulphite to prepare sulphonated derivatives thereof, with or without remaining halogen and/or hydroxy groups. They may be reacted with sodium or potassium cyanide to form-acid nitriles which may be hydrolyzed to yield 'polybasic carboxylic acids useful in the preparation of plastics by reaction with polyamines or polyhydric alcohols. They can be condensed with aromatic or sulphonated aromatic nuclei by the Friedel-Crafts synthesis. The various derivatives such as glycerides and other esters, acid halides, ketones, soaps, and related substances can be prepared from the halogenated fatty acids, or in some cases they can be formed those of the original fatty acids. The halogenated products, preferably chlorinated, are suitable as plasticizers or for lubricating purposes, either alone or in addition to mineral or vegetable oils.

The acids or their derivatives, such as their esthe presence of so-called 7 ters, may be so employed in preparing metal such as halogen derivaof halogenation of a working or cutting lubricants, as well as-lubricants for engines. The products 13088658861311- cidal properties and can be used in various bactericidal and/or insecticidal compositions. They are highly resistant to rancidity and serve as valuable addition agents to other fatty acids, soaps, or other derivatives thereof which tend to become rancid, to prevent these materials from separating the monochloropalmitic acid'fr stearic acid.

2. The process of separating individual fatty acid compounds from mixtures thereof which cm the comprises treating a composition containing a mixture of fatty acid compounds with a halogenating agent in a quantity sumcient and under I 3. The process of separating individual fattyacld compounds from mixtures thereof which comprises treating a composition containing a mixture of fatty acid compounds with a chicents into their structure, it is possible to apply any of the numerous physical methods of separation, either to the fatty acids or to their derivatives', such as the esters (e. g., methyl, ethyl or glyceryl) and salts. These methods take advantage of the differences in boiling points, melting points, and relative solubilities of the various acids and derivatives so that the individual materials may be more readily separated into relatively pure fractions.

The process may be applied to any source of fatty acid or derivative thereof such as fats, fatty oils, oxidized mineral oil, by-products of paper manufacture, ester-waxes, and the like. Among the materials which may be treated by the present process are tallow, palm oil, olive oil, coconut oil, certain grades of Chinese vegetable tallow, cottonseed oil, whale oilyflsh oils, and garbage grease; castor oil, montan wax, sperm oil, carnauba wax, opal wax, Japan wax, Chinese wax, tall oil, and the like; as well as the fatty. acid mixtures derived from these compositions. The term fatty acid compound" as used in this specification and the appended claims is to be understood to include the fatty acids as well as the suitable derivatives thereof. It is often desirable in the treatmentpi' these fatty acid compounds, especially those containing other constituents than fatty acid derivatives, such as tall oil, to fractionate the product to concentrate the desired fraction of individual fatty acids.' This may be accomplished by straight fractional distillation to remove undesired heads and/or tails which may" adversely affect the halogenation reactions, or it may include a fractionation treatment to remove unsaponiflables such as those methods described in detail in the U. 8. Patents 1,918,603 and 1,951,511 to Ittner. These fracrinating agent until substantially all of the most reactive individual fatty acid compound in the mixture is substantially solely chlorinated, and then separating said chlorinated compound from said "mixture.

4. The process of separating individual fatty acids from mixtures thereof which comprises treating a composition containing a mixture of fatty acids with a halogenating agent until substantially all of the most reactive individual fatty acid in the mixture is substantially solely halogenated, and then separating said halogenated fatty acid from said mixture. v

5. The process of separting individual fatty acids from mixtures thereof which comprises treating a composition containing a mixture of fatty acids with a chlorinating agent until sub-.

tlcnation processes may also be used in combination in either order to remove unsaponifiable constituents and other acids of appreciably different properties.

As many apparently widely different embodiments of this invention may be made without departing from the spirit thereof, it'is to be understood that we do not intend to limit ourselves to the specific embodiments thereof except as indicated in'the appended claims.

We claim: 1.,I'he method of preparing relatively pure stearic acid and monoohlorinated palmitic acid from a mixture containing stearic acid and palmitic acid which comprises treating such a mixture with a chlorinating agent in a quantity lust sufficient to monochlorinate substantially all of the palmitic acid in the mixture, and then stantially all of the most reactive individual fatty acid in the mixture is substantially solely chicrinated, and then separating said chlorinated fattyacid from said mixture.

6. The process of separating individual fatty acid esters from mixtures thereof which comprises treating a composition containing a mixture of fatty acid esters with a halogenating agent until substantially all of the most reactive individual fatty acid ester in the mixture is substantially solely. halogenated, and then separating said halogenated fatty acid ester fromsaid mixture.

7. The process of separating individual fatty acid compounds from mixtures thereof which comprises fractionatinga composition containing a mixture of fatty acid compounds to concentrate the individual compounds desired, treating a fraction containing a mixture of the desired fatty acid compounds with a halogenating agent'until substantially all of the most reactive .individual fatty acid compound in the mixture is substantially solely halogenated, and then separating said halogenated compound from said mixture.

8. The process of separating individual fatty acidsfrom mixtures containing fatty acids which comprises fractionating a composition containing a mixture of fatty acids to concentrate the individual compounds .desired, treating a fracacids with a halogenating agent until substantiallyall of the most reactive individual fatty acid,in. the mixture is substantially solely halogenated, and then separating said halogenated compound from said mixture.

9. The'process of separating individual fatty 5 containing a mixture r the desired fatty acids tion containing a mixture of the desired fatty with a chlorinating agent until substantially all of the most reactive individual fatty acid in the mixture is substantially solely chlorinated, and

then separating said chlorinated fatty acid from said mixture. v

10. The process of separating individual fatty acid compounds from mixtures thereof which comprises treating a composition containing a chlorinated, separating said. chlorinated fatty mixture of'fatty acid compounds with a halog'enating agent until substantially all of the most reactive individual fatty acid compound in the mixture is substantially solely halogenated. separating said halogenated compound from said mixture, again treating the remaining mixture with a halogenating agent until substantially all of the next most reactive individual fatty acid compound in the mixture is substantially solely halogenated, separating said halogenated compound from the mixture, repeating this procedure until the mixture has been separated into the individual fatty acid compounds.

11. The process of separating individual fatty acids from mixtures thereof which comprises treating a-composition containing a mixture of fatty acids with a chlorinating agent until substantially all of the most reactive individual fatty acids in the mixture is substantially solely acid from said mixture, again treating the remaining mixture with a chlorinating agent until substantially all of the next most reactive individual fatty acid in the mixture is substantially solely chlorinated, separating said chlorinated fatty acid from the mixture, repeating this procedure until the mixture has been separated into the individual fatty acid constituents.

. 12. The process of separating individual fatty acid esters from mixtures thereof which comprises treating a composition containing a mixture of fatty acid esters with a halogenating agent until substantially all of the most reactive individual fatty acid ester in the mixture is substantially solely halogenated, separating said halogenated fatty acid ester from said mixture,

again treating the remaining mixture with a.