The Mercurous Acetate Method. This method of Nicolardot and Clement3) depends on the same principle on which the detection of petroleum or benzene by means of nitric acid or sulphuric acid depends. The natural constituents of turpentine oil are removed by oxidation, whereas the mineral oil constituents which are not attacked are determined quantitatively. For the purpose of carrying out this test, 70 g. of mercurous acetate are dissolved in 150 cc. of acetic acid, 50 cc. of the oil to be tested are added, and the mixture is heated in a flask, connected with a reflux condenser, on a water bath for 1/2 hr. The reaction mixture is distilled with steam and the volume of the distilled oil ascertained. Inasmuch as pure turpentine oil is thus completely oxidized without yielding a volatile residue, any distillate represents adulteration. "White spirit" is not volatilized quantitatively since it is partly attacked by the acetates of mercury. However, the deviation is small.
1) Pharm. Weekblad 8 (1911), No. 35.
2) By hydrocarbons the author here evidently means petroleum hydrocarbons.
3) Bull. Soc. chim. IV. 7 (1910), 173.
Detection of Rosin Oil and Rosin Essences. The distillates obtained by the destructive distillation of colophony are used extensively for the adulteration of turpentine oil. According to the temperature employed during the distillation or the type of apparatus used (distillation over direct heat, with superheated steam, or vacuum) different products are obtained which upon fractionation can be resolved into distillates with greatly differing properties. Additional changes are produced by chemical treatment, such as that with alkalies and acids, bleaching, decoloration or aeration. The nomenclature of these products is not uniform. Hence, for this reason alone it is not surprising that the opinions of analysts concerning the detection of these products is at variance.
In general the lowest fractions of the colophony distillation are designated pinolin or resin spirit, rosin essence, turpentine essence and rosin spirit, whereas the higher boiling products are known as rosin oils. Of these distinction is made between light blue and green rosin oils, pitch oil, retinol, viscid rosin oil, etc. Inasmuch as the specific gravity of the rosin oils varies between 0,945 and 1,0101) the lighter pinolin only comes into consideration as an adulterant for turpentine oil.
Thus far the following hydrocarbons have been found in rosin essence: cymene2), and the terpenes a-pinene, camphene and dipentene3).
The properties of these products actually vary as much as the concept "resin essence". A resin essence from Kahlbaum4) had the following properties: d15o 0,8656; nD15o1,4826 (hence the index of refraction is higher than that of turpentine oil); 8 p.c. distilled over between 118 and 150°, 51 p.c. between 150 and 180°, 27 p.c. between 180 and 220°, 10 p.c. between 220 and 295°. The residue amounted to 10 p.c.
1) Bottler, Harze u. Harzindustrie. Hannover 1907, p. 208. 2) Kelbe, Liebig's Annalen 210 (1881), 10.
3) Wallach and Rheindorff, Liebig's Annalen 271 (1892), 311. - Grimaldi, Chem. Ztg. 33 (1909), 1157.
4) R. Adan, Chem. Zentralbl. 1908, II. 1749.
The examination of several rosin distillates in the laboratory of Schimmel $ Co. yielded the following results: -
Rosin oil, crude1)
Rosin essence after removal of the acids and phenols and rectification with water vapor.
Boiling temperature of the rosin essence freed from acids and phenols.
100 to 120° 6%
+ 39° 10'
+ 3° 30'
120 „ 130° 18%
130 „ 140°15°/o
140 „ 150°13%
150 „ 160°10°/o
in 4,5 vols.
and more of abs. ale.
in abt.25 vols.
of 80 % alcohol in abt. 7 vols, of 90 % alcohol
in abt. 15 vols.
of 80 % alcohol in abt.3,5vols. of 90 % alcohol
160 „ 170°14°/o
170 „ 180°10°/o
180 „ 190° 6% Residue 8 %
According to Aignan2), the specific angle of rotation [a]D, of these varieties of rosin oil was as follows: 1. Huile blanche de choix rectifiee - 36°
2. Huile blanche fine rectifiee . . - 16°
3. Huile blanche rectifiee . . . - 10°30.
According to Worstall3) rosin essence has an iodine value of about 185, rosin oil one of about 97, whereas that of turpentine oil (see p. 30) is above 370.
According to Utz4), the absorption of bromine diminishes with the degree of rectification.
1) With water vapor about 10 p.c. distil over: d15° 0,9237; aD + 21°10'.
2) In the original [Compt. rend. 109 (1889), 944] the values are again as large. According to Vezes und Mouline (Sur l'essai technique de l'essence de te're'benthine des Landes. Bordeaux 1902, p. 2) these observations were made with a 200 mm. tube.
3) Journ. Soc. chem. Industry 23 (1904), 302; Chem. Zentralbl. 1904,1.1676.
4) Chem. Rev. Fett- u. Harzind. 13 (1906), 161; Chem. Zentralbl. 1906, II. 636.
Inasmuch as resin essence usually contains portions that boil below 155° (see above) these should be isolated by fractional distillation. The identification of resin essence is brought about mostly by color reactions, which, however, do not always yield corresponding and unquestionable results when applied by different analysts to the several products used as adulterants. However, since better methods are wanting, the principal color reactions may here be mentioned.
According to Herzfeld, pinolin produces a yellowish-green color when shaken with an aqueous solution of sulphur dioxide. The same color reaction is also produced by Kieno/, a pine tar oil.
In order to demonstrate the presence of pinolin in turpentine oil, according to Valenta1) the oil is fractionated and fraction - 160° is utilized for the following reactions: With acetic acid anhydride and a drop of sulphuric acid it produces an intensively green color. Further, if 1 part of this fraction is carefully heated with 1 to 2 parts of a 6 p. c. solution of iodine in chloroform or carbon tetrachloride in a water bath or in the flame of a Bunsen burner, an intensively green or olive color is produced.
For the distinction of rosin essence (pinolin), more particularly of that fraction thereof boiling up to 170° (Terpentin-essenz) and for distinguishing between it and similar oils, such as turpentine oil, pine tar oil, camphor oil and mineral oil, Grimaldi2) recommends a color reaction which depends on the characteristic green color produced by the action of tin and concentrated hydrochloric acid with the rosin essence. For the purpose of carrying out this test, 100 g. of the oil to be investigated are fractionated so that at first five fractions of 3 cc. each are collected, then fractions of 5° each up to 170°. To 3 cc. of each fraction an equal volume of concentrated hydrochloric acid is added without shaking and a piece of metallic tin as large as a grain of rice. The test tubes are heated for five minutes in a boiling water bath, shaken, and heated another five minutes. According to the amount of rosin essence or similar low-boiling substance present, an intensively emerald green color is produced more or less readily. If the reaction is but faint, it is recommended to use 200 to 400 cc. for the test, to collect fractions of 30 cc. each and to re-fractionate these as recorded above. The other oils, viz. turpentine oil, pine tar oil, camphor oil and mineral oil yield a straw-yellow to brownish color with tin and concentrated hydrochloric acid. It is claimed that the presence of five per cent, of rosin essence in its mixtures with turpentine oil, and of 10 p. c. with pine tar oil can be detected.