THE ANALYST. 139 ON OXIDIZED OILS. BY J. LEWICOWITSCH, PH.D. (Read at the Meeting, March 5, 1902.) IN my last paper, read before this Society a t a meeting, November 1, 1899,’ I pointed out that the examination of the (‘ oxidized acids ” occurring in blown oils and solid linseed oil had been taken in hand by me. This investigation has made very slow progress, and I should not have published the .following incomplete results had not a paper appeared by Em. Lecocq and * ANALYST, 1899, p. 319.TABLE 1.- Blown .Oils. Value after Acetyla- tion. XI1.- 'I' Ravison rape.. . East India rape Cottonseed ... Solid linseed oil I I I ---I-- I Mgrms. Mgrms. Mgrms. I Per ' Mgrms. KOH. KOH. KOH. j Cent. KOH. 10.47 198-31 187.841 72.66 35.89 13.25 21557 202.32 61.92 56-26 9.41 224.59 215.18' 65.74 I 46.49 i (linoleummass) * 287.47 Maize ...1 7.33 208-63 - ' 52.2 k36.9 201.30' 90.7 1 49.13 Blown Ravison rape oil ... ... ... Blown East India rapeIooil ... ... ... Blown cottonseed oil ... ... Solid linseed oil (linoleum masg) . . . Blown maize oil ... ... ... ... ... ... 175-14/ 191.7 16.56 171.931 190.0 i 18.07 66.2 55.5 237.8 194.79 210-46 15.67 209.63 248.741 39.11 192.8 209.93; 17.13 XII. XIII. XIV. 1 xv. VII. VI. I-- Hehner 1 True Acetyl Value 0 $5. X 29.11 25.63 35.36 - 34.85 __- sap. Value of Acetyl- t t d Oil, Mgrms. KOH. 243 -2 253.33 273.30 367.75 268.75 Unsa- ponifi- able. Specific Gravity, 3 xidi zec Acids. Per Cent. 21.22 20.74 Value. 1 Ap- True. Mgrms. KOH. 52.93 46.61 64.29 - 63-37 --I-- Mgrms. 1 KOH. 83.52 I 88-37 Per Cent. 1.23 0.93 1.37 44.9 37.76 48.71 0.9685 0.9623 0.9785 102.87 110.73 82.18 29.39 1 82.59 - 83-85 53.01 53.92 31.93 82.34 - - __ - .- 1.33 2.28 - 113.16 - 0.9806 * u * * Acid value waa difficult to take.Experiments made by adding excew of alkalies and titrating back led to the impossible value 369.9 ( 9 ) . TABLE 11 . - To tal Fatty Acids. -_ -. - 11. 7- Sap. Value. -- Mgrms. KOH. * A VI. VII. 1 VIII. I IX. 1 x. I XI. * - -- -- -- III' I IV' I v* -- Hehner Value of the Ace tyl- ated Acids. Per Cent. - Total Soluble Acids. I-- I Mgrms. Per Mums. KOH. I Cent. KOH. ___ --- -- , Mgrms. I KOH.I Acetyl Value. *p- 1 True. Hehner - parent. vE:'of I Acetyl- IX.-II. ated 1 Acids. I -- -._,_ - Mgrms. ~ Mgrms. I Mgrms. KOH. I KOH. 1 KOH. 102:5 I 80-0 i 307.5 128.0 105.65 315-9 154.4 118.28 322.69 164.67 104.991 341.43 173.581 126.681 326.45 -- 99-5 104.6 101.98 86.29 111.11 KOH.208.0 211.3 220.71 -- KOH. 36.5 38.0 46-01 _ _ Acid 1 Sap. Value. I Value. II,-I Hehner Value. Per Cent. - - - - 85.54 Soluble Acids. --- Mgrms. KOH. 6-75 8-85 7-27 I 7.54 ~ _ _ Mgrms. KOH. 188.6 176.8 196.15 187-58 177.68 Mgrms. KOH. 11.8 10.2 8.15 7.61 5.31 219.2 232.0 246.11 42.95 33.6 58.53 IV. v. VI, VII. 1 VIII. [- IX. j x. ~ ~ _ _ _ _ - - - - - XI. .. - XII. Hehner Value of Acetyl- ated Acids. -- - .- - -- 83-85 76-38 -_ M b Z P t-' * ___ XIII. Hehner Value of Ace t yl- ated Acids. -- - - 96.17 96.05 .~ 11. 111. I, -- Acid Value. -- Mgrms. KOH, 171.5 Acetyl True Value 0.55. X -- 44.0 58.1 65.02 57.74 69.67 Total Soluble Acids. _- Mrgms. KOH. 22.56 22.35 36-12 59.68 48.0 Iodine Value.-- Per Cent. 49.14 39.79 48.6 46.49 70.87 Blown Ravison rme oil . . . ... ' . . . 171.94, 215.741 43-60 - -_ _ ~ _ _ Blown maize oil ' . . . I_-_p TABLE 1V.-Fatty Acids freed from Oxidized Acids. - XII. True Acetyl Value X 0.55. -- 19.54 20.64 12.49 17.24 20.18 _I__ V. --- Total soluble Acids. Mgrms. KOH. 6.97 10.09 11.0 18.89 6.14 _ _ _ - ~ Blown Ravison rape oil ... Blown East India rape oil ... Blown cottonseed oil ... Solid linseed oil (linoleum mass) ... ... ... Blown maize oil . . . ... -- - - VIII. I IX. -- - Acetyl Value. IV. --- Iodine Value. Per Cent. 61-88 55.93 56.02 61.31 85.52 . I I AP- parent. Slgrms, KOH. -L- 42.5 47.13 33.69 50.25 43.8 - . True. Hgrms. KOH. 35.53 37-54 22.69 31-36 36.7 Mgrms. KOH. 176.8 166.6 188.0 179.97 172.37142 THE ANALYST.H. Dandervoort (Chem. Revue, 1902, 13), which partly covers the same subject, although it refers to blown colza oil only. The oils I chose for examination were : Commercial blown Ravison oil, com- mercial blown East India rape oil, commercial blown cottonseed oil, solid linseed oil (so-called ‘( scrim ” oil), and blown maize oil. All the values that have been determined in these oils are set out in Table No. I., headed ‘‘ Blown Oils ” (see p. 140). For the preparation of the oxidized acids, 100 grammes were saponified in the usual manner, the total fatty acids separated, and the separation of the oxidized acids from the other acids effected by means of petroleum ether. The total fatty acids as well as their components-viz., the oxidized acids and the acids freed from oxidized acids-were examined, and the values so obtained are set out in Tables II., III., and IV.(see p. 141). On acetylating the original oils, it was found that emulsions were formed in the washing-out process in the case of blown Ravison oil, rape, cottonseed oil, and maize oil. This has been pointed out already by Archbutt, but the separation caused little trouble. The blown Ravison oil formed the strongest emulsion ; the scrim oil caused more trouble, the acetylated product separating as a sticky mass denser than water. I n contradistinction to the behaviour of the oils, the total fatty acids, which were also acetylated, did not give emulsions, as has also been pointed out by Archbutt. Oxidized Acids.-The values obtained on examination are set out in Table No.111. The acetyl values were determined by the filtration method. As found before in the case of the oxidized acids from solid linseed oil, all the oxidized acids showed considerably higher saponification values than acid values. The surmise that these acids would be saturated acids is not borne out by experiment, for the iodine values are comparatively high. A difficulty arose in the determination of the iodine values, inasmuch as the oxidized acids were found to be practically insoluble in carbon tetrachloride, hence strong alcohol was used as a solvent, The error, if any, introduced thereby cannot have been a considerable one, for while a blank test with carbon tetrachloride required 50.6 C.C. of thiosulphate, the alcoholic solution took 50.00 C.C.To obtain the true acetyl value the total soluble acids had to be determined. Naturally one would have expected to find no soluble acids, as they should all have been washed away or dissolved out in the treatment with petroleum spirit. However, considerable quantities were found in each case. The explanation suggested itself that these soluble acids were formed on treatment with the alcoholic potash by the action of the latter on the oxidized acids, for the soluble acids were determined after the original substance had been boiled with excess of alcoholic potash for the deter- mination of the saponification value. If this explanation be the true one, then a check experiment with the oxidized fatty acids as they were obtained originally should give no soluble acids on washing, but the actual experiment gave considerable amounts of soluble acids, in some cases almost approaching those obtained after treatment with alcoholic potash.This is shown in the following table :THE ANALYST. 143 - ... ... ... ... ... ... ... ... ... ... ... ... ... ... SOLUBLE ACIDS IN OXIDIZED ACIDS. 21-38 9-5 22.56 22-35 36-12 16-36 26.30 21-39 59.68 24.11 Oil. ... ... ... ... 1 46.90 Blown Ravison rape ,, East India rape ,, cottonseed I. 11. Blown maize ... Sdiid linseei ..- 19-20 Blown Ravison rape ... j 7-26 ? ? cottonseed ... ... 1 12.94 ,, East India rape ... j 10.71 ,, maize ... ... 1 29.4 No such differences were observed in the cases of the total fatty acids and the fatty acids freed from oxidized acids, as will be seen from the following table : -- - 7.09 6-97 6.75 9.84 10.09 8.85 12.99 11.0 7-27 24-8 , 6.08 7.54 SOLUBLE ACIDS IN OIL. 1 FATTY ACIDS FREED FROM OXIDIZED ACIDS.i TOTAL FATTY AUIDS. ! ~ _ _ _ I After boiling After boiling 1 KOH. Unfortunately, the soluble acids in the solidified linseed oil oxidized acids hme not been determined, as it was taken for granted at the time that they were free from soluble acids, which now appears to be very doubtful. The values obtained by multiplying the true acetyl values by 0.55 are again remarkably low, as they should have been, of course, 100 per cent. This proves that the molecular weight of 300 is not to be taken without further evidence. The differences between the saponification and acid values point to the presence of lactones.Further investigation is in hand, but so far it appears pretty certain that the oxidized acids are not insoluble in water, and it is not unlikely that they split off volatile fatty acids when treated in a current of steam. Acids freed from Oxidized Acids.-It was to be expected that these acids would have no acetyl value. If such a one were obtained, it would perhaps point to the presence of hydroxy-acids, which are soluble in petroleum ether. The considerable aoetyl values found and set out in Table IV. mcy be due to oxidation having taken plaoe after isolation, although free access of air had been guarded against. The acids still possessed considerable iodine values, and the differences between saponification and acid values again point to the presence of lactones, although their proportion can be only very small, not amounting to more than 4 to 6 per cent.Even these acids contain small amounts of soluble acid, as shown in the table. Further axamination must show whether, under the conditions I worked with, the oxidized adds are completely insoluble in petroleum ether, for small experiments144 THE ANALYST. Blown Ravison rape ... ... cottonseed ... ... ,, East India rape ... ... SdGd linseed ... ... 117.8 1 125.3 42.72 I 80.25 72-116 86.6 The aqueous soap solution of the oxidized acids after the removal of the lactones was treated with mineral acid under ether, so that the separating fatty acids were immediately dissolved. The following table shows that in the fatty matter so obtained some lactonic substances had been formed again, as evidenced by Columns I.and 11: : OXIDIZED ACIDS FREED FROM LACTONES. Blown Ravison rape . . . ,, East India rape cottonseed . . . Blown maize . . . ... SoEd linseed . . . ... Acid Value. I. -- 172 -2-175.6 194.0-195.4 177.9- 204.5 190.8-194.5 182.2-284'3 Fatty Matter recovered from Soap Solution, obtained sub. 11. Saponification 1 -'--I ~- 38.9 220.6-221-5 184.8 1 223.7 237.7-247.6 ' 198.5 1 234.1 35.6 215.1-22269 190.2 1 221.7 1 31.5 37.9 255 *5 216.0-217.7 ' 185.8 1 218.8 1 33.0 212.9 249.8 The solutions were very dark, so that it was very difficult to titrate accurately, somewhat considerable differences between duplicate determinations.THE ANALYST. 145 The solutions containing the completely saponified mass were treated with mineral acid, and the fatty matter so recovered again examined for acid and saponifi- cation values, with the results set out in Columns 111.and IV. of the last table. Allowing for the errors caused by the very dark solution, the numbers giveu under Columns 111. and IV. may perhaps be looked upon as giving practically the same values as those stated in Columns I. and II., with the exception of solid linseed oil. The process of re-extracting the lactonic substances, etc., was repeated once or twice, but lactonic substances were always formed again. My thanks are due to Messrs. C. D. Robertshaw and George Warburton for the numerous analyses made in the preparation of this paper. The practically constant differences in Column V, are notable. DISCUSSION.Mr. JENKINS said that in dealing with blown cotton oil of about 0.975 specific gravity he had found that the fatty acids from such oil were distinctly more soluble in methylated ether than in petroleum spirit, which appeared to confirm the author's experience. I t was a rather peeuliar fact that the blowing of these oils decreased their miscibility with petroleum compounds. The blown oil could be mixed or blended only to a slight extent with American petroleum ; it mixed, however, a little more freely with Scotch petroleum, and comparatively easily with Russian petroleum. Another peculiarity, probably due to the oxidized condition of the fatty acids, was that the sulphuric acid reaction increased out of proportion to the iodine value, whereas in the case of most oils a certain ratio existed between these two factors.The bromine thermal rise also did not bear a normal relationship to the iodine value; there was generally a low Hehner value and a low flash-point. The flash-point might be 100" lower than that of the original oil. Mr. ALLEN said that although the author had stated that at present the exact bearing of all these figures could not be definitely laid down, nevertheless, the accumulation of data of this kind was extremely valuable, and would probably be followed by the removal of the difficulties which at present existed, and by a consequent better understanding of the chemistry of blown oils. These oils were of an extremely complex nature, and any method by which a proximate analysis of their constituents could be made was of great value.Mr. HORATIO BALLANTYNE said that he waB pleased to see that in their general aspect these figures accorded with the results obtained by Mr. R. T. Thomson and himself some ten yeara previously. One most interesting point was the very high percentage of soluble fatty acids which blown oils contained. In testing for the presence of blown oil in castor oils of doubtful purity, the percentage of soluble fatty acids-determined just as in the case of butter analysis-was probably the very best criterion by which to judge. Dr. LEWKOWITSCH said that the miscibility of blown oils with petroleum dis- tillates showed that, after all, in some sehse the surmise was correct that these oxidized acids were hydroxy acids, because in that respect these oils approached castor oil, and, in fact, were known, when first brought into the market, as L c soluble146 THE ANALYST. castor oil.” In regard to solubility, they evidently took an intermediate position between castor oil and the other fatty oils. That Russian petroleum behaved some- what differently from American petroleum could only be due to a difference in composition. Whilst the American petroleum distillates consisted chiefly of hydro- carbons of the paraffin series, the hydrocarbons of Russian petroleum largely belonged to the naphthene series, and must therefore exhibit a different solubility. He was afraid that he had not a very frtvourable opinion of the usefulness of the Maumene test and the bromine thermal test. It seemed to him much better to determine the iodine value itself. The low flash-point of blown oil was due to the considerable amount of volatile acids. Of course, the acetyl value, which might be indicative of the presence of castor oil, would break down in these cases. No doubt the deter- mination of the percentage of volatile acids was & very good test indeed. It was somewhat puzzling to find such a large amount of volatile or soluble fatty &cia8 in a product which from its treatment would hardly be expected to contain any volatile fatty acids at all.