A concentrated fraction of highly unsaturated acids has been separated from sardine oil by means of sodium-soap-acetone method. It was converted into methyl esters and the latter subjected to a fractional distillation which yielded a fraction consisting of the methyl esters of C22-acids. This fraction and the free fatty acids liberated from it showed iodine values which were close to those of methyl clupanodonate and clupanodonic acid respectively, but on separating the fatty acids of this fraction by a fractional precipitation of sodium soap in acetone solution, they were found to contain, in addition to clupanodonic acid, some acids of different degrees of unsaturation. After a repeated separation, clupanodonic acid has been separated in much purer state than prepared hitherto, and also a more highly unsaturated portion consisting chiefly of docosahexenoic acid C22H32O2 has been separated. There was obtained also a less unsaturated portion than clupanodonic acid; this was, however, found to be a mixture contaminated with cetoleic acid C22H42O2, though in a minor amount. Docosatetraenoic acid C22H36O2 was not separated, although this acid could not be altogether deemed to be absent.
1. Amyl clupanodonate was subjected to ozonolysis. Among the products of ozonolysis were found propyl aldehyde, acetaldehyde, carbon dioxide, succinic acid, amyl hydrogen succinate and also lower acids which were deemed to consist of propionic and acetic acids. Of these compounds, acetaldehyde, acetic acid and carbon dioxide are attributable to the secondary decomposition of the products of ozonolysis primarily derived from the group =CH· CH2·CH=. Accordingly clupanodonic acid was shown to contain the following groups: CH3·CH2·CH=, =CH·(CH2)2·COOH, =CH·CH2·CH= and =CH·(CH2)2·CH=, of which clupanodonic acid contains three of the last named group. 2. The dibromo-derivative of clupanodonic acid was separated as the chief constituent of the product which was obtained by adding 1 mol bromine to 1 mol clupanodonic acid. Similarly tetrabromo- and hexa-bromo-derivatives of clupanodonic acid were separated, respectively, as the chief constituents of the product obtained by adding 2 mols and 3 mols bromine, respectively, to 1 mol clupanodonic acid. It is seen from the following results obtained by the ozonolysis of these bromo-derivatives that, in these partial brominations, bromine adds selectively first to the ethylenic linking which is more distant from the carboxyl group. Though this selectivity is not a complete one, any of the above-mentioned bromoderivatives contains as its chief constituent the product formed in accordance to this selectivity. 3. Ozonolysis of dibromo-derivative of clupanodonic acid thus obtained gave a bromo-compound which on debromination and subsequent hydrogenation yielded, as an acidic product, heptoic acid. This fact, coupled with the results obtained by the ozonolysis of amyl clupanodonate, indicated that clupanodonic acid had the group CH3·CH2·CH=CH·(CH2)2·CH=. 4. Ozonolysis of tetrabromo-derivative of clupanodonic acid gave a bromo-compound which on debromination and subsequent hydrogenation yielded capric acid, and consequently clupanodonic acid was shown to contain the group CH3·CH2·CH=CH·(CH2)2·CH=CH·CH2·CH=. 5. Ozonolysis of hexabromo-derivative of clupanodonic acid gave a bromo-compound which on debromination and subsequent hydrogenation yielded myristic acid, and consequently clupanodonic acid was shown to contain the group CH3·CH2·CH=CH·(CH2)2·CH=CH·CH2·CH=CH·(CH2)2·CH=. 6. From the foregoing results, the constitution of clupanodonic acid has been established as Δ4:5,8:9,12:13,15:16,19:20-docosapentenoic acid which is expressed by the following formula: CH_3·CH_2·CH=CH·(CH_2)_2·CH=CH·CH_2·CH=CH·(CH_2)_2·CH=CH·(CH_2)_2·CH=CH·(CH_2)_2·COOH.
(1) Gas—liquid interfacial potential difference of fatty acid film was measured by using the method of ionizing air gap between the electrode and the surface of the liquid with X-ray. (2) Various factors which affect the measurements were studied at first. (3) Under the most favourable conditions the measurements of the surface potentials were carried out with four fatty acids, i.e. myristic, palmitic, stearic, and oleic acids. (4) The surface potential difference attains a maximum or a saturation value at a certain definite surface concentration. This value is nearly equal for three saturated fatty acids and is about 350 mv. The value for oleic acid, however, is about 240 mv. (5) The (surface potential)—(surface concentration)-curves were plotted and the mean vertical component of dipole moment was calculated for these fatty acids by applying Helmholtz’s formula. (6) The break point of the curve or the saturation point of fatty acid is nearly similar for four acids, and the area occupied by a molecule at this point is about 27 sq. Å.