Oleic acid

“ Pure almond or olive-oil soap is decomposed by a dilute acid, and the resulting oily acid is digested in a water bath with half its weight of litharge (in very fine powder) for some hours, constantly stirring; the mixture is then agitated with twice its volume of ether in a close vessel, and in 24 hours the clear ethereal solution is decanted, and decomposed with dilute hydrochloric acid; the oleic acid separates, and the ether mixed with it is expelled by evaporation. ”

“ The fatty acid method adopted is sufficiently accurate for commercial purposes. In many routine laboratories the fat or oil is measured and not weighed, but the committee recommends weighing the sample in all cases. For scientific purposes the result is often expressed as "acid number," meaning the number of milligrams of KOH required to neutralize the free acids in one gram of fat, but the commercial practice has been, and is, to express the fatty acids as oleic acid or in the case of palm oil, as palmitic acid, in some instances. ”

“ From oxide of glycyl ensues acroline; oleic acid affords a fatty acid, and among the decomposition products of fats containing stearine and margarine are found pure margaric acid, and, at the same time, some hydro-carbons are formed. When exposed quickly to a high temperature, fats are completely decomposed. (Oil gas.) In closed vessels the pure fats undergo no change, but, placed in thin layers in the air, the fats containing oleine and oline rapidly absorb oxygen under the strong evolution of heat, which will inflame porous bodies, as cotton wool. ”

“ Syn. Elain; Huile absolue, Fr. The liquid portion of the fixed oils and fats. By saponification it yields oleic acid.
Prep. 1. Olive oil or almond oil is digested for 24 hours with a quantity of caustic soda lye, only sufficient to saponify one half of the oil, and the undecomposed oily portion (olein) is then separated from the alkaline solution and newly formed stearine soap.
2. The saponified mixture of oil and alkali (see No. 1) is digested with proof spirit until all the soap is dissolved out, and the olein separates and floats on the surface ”

“ Oils.—For very many years all oils were considered to be composed of olein, that is to say, the triglyceride of oleic acid, with small quantities of impurities; chemists, therefore, to distinguish oils of various origin, confined themselves to tests for these impurities, employing so-called colour reactions based upon the change of colour of the oil by various reagents such as sulphuric, nitric or phosphoric acids. These reactions were exceedingly indefinite and unsatisfactory and oil adulteration was prevalent and almost undiscoverable. ”

“ The crude oil increases in weight 11 to 12 per cent., although at the same time its glycerin is destroyed by oxidation.
By saponification, linseed oil yields glycerin, and 95 per cent. of fatty acids, consisting chiefly of Linoleic Acid, C16H26O2, accompanied by some oleic, palmitic, and myristic acid. The action of the air transforms linoleic acid into the resinoid Oxylinoleic Acid, C16H26O5. Linoleic acid appears to be contained in all drying oils, notably in that of poppy seed. It is not homologous either with ordinary fatty acids or with the oleic acid of oil of almonds, C18H34O2. ”

“ The largest number of high-grade oils contain less than three percent of free fatty acid, but a larger quantity, as has been stated, does not render the oil inedible unless actual fermentation has taken place producing rancidity. Rancidity appears to be the result of the generation of other acids than oleic, and also aldehyds, formic, butyric, acetic, and œnanthylic acids have been found. Olive oil is a typical non-drying oil and therefore shows a less rise in temperature when mixed with sulfuric acid than other vegetable oils. ”

“ A 10 per cent solution of aluminum oleate in petroleum is a very excellent agent for preserving the soles, a single saturation of the soles sufficing forever. The sole will last about 1 year.
III.—The following mixture is prepared by melting together over the fire in an enameled iron vessel: Vaseline, 400 parts; ceresine, 100 parts. The melted mass, which is used as a grease, is filled in wooden boxes or tin cans.
IV.—The oleic acid of the stearine factories is heated with strong alcohol and sulphuric acid. ”

“ Acids of Series II. may also be converted into saturated acids by heating to 300°C. with solid caustic potash, which decomposes them into acids of the stearic series with liberation of hydrogen. This reaction, with oleic acid, for example, is generally represented by the equation—
C18H34O2 + 2KOH = KC2H3O2 + KC16H31O2 + H2,
though it must be really more complex than this indicates, for, as Edmed has pointed out, oxalic acid is also formed in considerable quantity. ”

“ When ground-nut oil is treated with hyponitric acid, which may be most conveniently evolved by heating nitric acid with a little starch, a solid mass is obtained, which yields by crystallization from alcohol Elaïdic and Gæidinic acids, the former isomeric with oleic, the latter with hypogæic acid.
Production and Commerce—The pods are exported on an immense and ever increasing scale from the West Coast of Africa. ”

“ Rosin oil is a deleterious adulterant, but one which may be more readily detected than cotton-seed oil. Rosin is [332] added to boiled oil to hasten its drying; this also is an injurious substance. Of late years glycerine has become an article of greater value than formerly, and this may account for the manufacture of linoleic acid and its use as an adulterant of oleic acid and of linseed oil.
Lastly, it may be mentioned that certain samples of “pale boiled oil” have been found to contain what is practically a raw oil mixed with dryers. ”

“ When nine parts of cod-liver oil are saponified with five parts of oxide of lead, with the necessary quantity of distilled water, in a porcelain vessel, by the heat of a water bath, the oil is decomposed into oleic and margaric acids, and a new acid propylic acid. ”

“ When fats are saponified by an alkali, stearate, palmitate, and oleate of potassa or soda, as the case may be, are produced and glycerin is set free. On decomposing either of these compounds with sulphuric acid a sulphate of the alkali is formed, and the fatty acid is precipitated. Some of the fatty acids, as stearic, cerotic, palmitic, and lauric, are solid at ordinary temperatures; others, as oleic, are liquid. The hard fatty acids are extensively used as candle materials, being superior in every respect to the natural fats from which they are derived. ”

“ Fats of the third order, the stearic group, are called "saturated" because they have taken up all the hydrogen they can hold. Fats of the other two groups are called "unsaturated." The first, which have the least hydrogen, are the most eager for more. If hydrogen is not handy they will take up other things, for instance oxygen. Linseed oil, which consists largely, as the name implies, of linoleic acid, will absorb oxygen on exposure to the air and become hard. ”

“ Writers seem to disagree as to what the acids are, and in what respect they differ from the acid properties of the non-drying fixed oils, but that is a question which need not be discussed here. The glycerine base of linolein seems to be common to all fixed oils, and is set down as an oxide consisting of one equivalent of water and five of oxygen; hence the affinity between the linoleic acid and its glycerine base.
Linoleic acid, like other acids, has an affinity for alkalies and the ordinary metallic oxides. It unites with them, forming neutral compounds. ”

“ Other oils do not grow dry, though they turn thick, become less combustible, and assume an offensive smell. They are then called rancid. In this state, they exhibit an acid reaction, and irritate the fauces when swallowed, in consequence of the presence of a peculiar acid, which may be removed in a great measure by boiling the oil along with water and a little common magnesia for a quarter of an hour, or till it has lost the property of reddening litmus. While oils undergo the above changes, they absorb a quantity of oxygen equal to several times their volume. ”

“ The crude oil, as is well known, consists principally of hydrated oxide of amyl, mixed with more or less alcohol, and small quantities of other substances, the nature of which is not generally known, though it has been asserted that œnanthic ether and œnanthic acid may be found among them. ”

“ The impurities, such as mucilage and albuminous matters, are thus deprived of water, and more or less charred, and along with them the colouring matters are destroyed by the acid. It is essential for the success of the process that the oil and the acid be not long in contact without undergoing dilution, otherwise the oil itself may become charred. ”

“ It must be observed, that an essential Oil, combined with an acid strong enough to dissolve it, immediately becomes as thick and resinous, in consequence of this union, as if it had been long exposed to the air: which proves the consistence an Oil acquires by long keeping to be owing to this, that its lightest and less acid parts being evaporated, the proportion of its acid to the remainder is so increased, that it produces therein the same change, as an additional acid mixed with the Oil would have wrought before the evaporation. ”

“ Its solubility in alcohol (·794) appears to depend in great measure on the age of the oil, and the greater or less freshness of the seeds from which it was expressed,—oxidized or resinified oil dissolving the most readily. [2101] We found the oil which one of us had extracted by means of bisulphide of carbon to be levogyre.
Croton oil consists chiefly of the glycerinic ethers of the common fatty acids, such as stearic, palmitic, myristic and lauric acids. They partly separate in the cold; the acids also may partly be obtained by passing nitrous acid through croton oil. ”

“ When one drop of sulphuric acid is added to eight or ten drops of tea oil on a white plate, the change of color observed is more like that when almond oil is similarly treated than with any other oil, olive oil coming next in order of similarity.
When a few drops of tea oil are boiled with thirty drops or so of nitric acid in a small tube, the layer of oily matter, when the brisk action has moderated, is of a light yellow color, similar in tint to that produced from almond and olive oil under similar circumstances. When the oil is digested with an equal volume of nitric acid (1.2 sp. gr.) ”

“ This oil somewhat resembles the fat oils of vegetables; for like them it is mild, unctuous, indissoluble in spirit of wine, and is subtilized and attenuated by the action of fire. But there is not in animals, as in vegetables, any light essential oil, which rises with the heat of boiling water; so that, properly speaking, animals contain but one sort of oil.
Few animal substances yield a perceptible acid. Ants and bees are almost the only ones from which any can be obtained: and indeed the quantity they yield is very small, as the acid itself is extremely weak. ”

“ To solve this problem, the oil employed in the experiments was obtained by means of ether. The seeds of croton yield by expression 35 per cent.; treated by ether, they yield from 52 to 55 per cent. If treated by ether, the ether obtained by distillation is free from acid, all the acid remaining in the oil. When a certain fixed quantity of this oil is put in contact with ten times its weight of strong alcohol, the alcohol dissolves 6 per cent. of its own weight, and the oil 50 per cent. ”

“ The Acids also suffer a considerable alteration by contracting an union with Oils. They become much milder, and lose almost all their strength. If the mixture described in the process be distilled, there will come over a great quantity of an empyreumatic acidulated phlegm, that smells strong of Sulphureous Spirit; an Oil thinner than the original saponaceous mixture; a weak Oily Acid, and a very thick, black Oil. If the fire be made very strong, when the Oil ceases to rise, it sometimes happens that a little Sulphur sublimes into the neck of the retort. ”

“ This substance is not fusible, and, [278] when burned, diffuses the same odour as animal bodies do. It is insoluble in cold water, very soluble in alcohol and ether, but, after the evaporation of these liquids, it is recovered unchanged. Fats and unctuous oils both dissolve it. It is soluble in carbonated and caustic alkaline lyes, from which it is precipitated by the acids without alteration. An excess of alkali, however, speedily decomposes it. Nitric acid transforms it into oxalic acid, and a bitter matter. Chlorine makes it white. ”

“ These esters of the fatty acids give the characteristic savor to many of our favorite fruits, candies and beverages. The pear flavor, amyl acetate, is made from acetic acid and amyl alcohol—though amyl alcohol (fusel oil) has a detestable smell. Pineapple is ethyl butyrate—but the acid part of it (butyric acid) is what gives Limburger cheese its aroma. These essential oils are easily made in the laboratory, but cannot be extracted from the fruit for separate use.
If the carbon chain contains one or more double linkages we get the "flowery" perfumes. ”

“ For each oil the iodine absorption is a fairly constant quantity; this number, together with the determination of the amount of caustic alkali needed for complete saponification, the thermal rise with strong sulphuric acid or with bromine, the refraction of light and the specific gravity, now enable the analyst to form a fair idea of the nature of any sample under examination, and, in consequence of this advance in knowledge, adulteration of oils has much declined. The most common adulterant of the more valuable oils, like olive oil, is cotton-seed oil. ”