| dc.description.abstract | Anthracene oil was first distilled in a single lot up to 360°C, and the total quantity of solids that separated out on cooling at ordinary temperature (room temperature), and on cooling at 0°C for a week and for a month in a cold room, were noted. There was more separation of solids on cooling to 0°C.
Next, the oil was fractionally distilled and collected into various fractions within a range of 20°C, as shown below:
Fraction No.Temperature Range(a)Up to 220°CI (A)220–240°CII (B)240–260°CIII (C)260–280°CIV (D)280–300°CV (E)300–320°CVI (F)320–360°C
There was separation of solids in all fractions except the middle one (C). The solids obtained in the first three fractions (a, A, and B) showed, from their melting points, that they contained mostly naphthalene. The separation of crude anthracene began only at higher temperatures, i.e., from 280–360°C.
The total quantity of solids that separated in this case (at a 20°C range) at ordinary temperature and on cooling to 0°C for about a week or a month was noted. The amount of solids that separated in this case was more than twice the amount that had separated previously when the oil was distilled in one lot up to 360°C, without fractionation.
Further fractionation of the filtrates within a narrower range of 5°C again gave solids in quantities higher than those obtained by ordinary cooling or by cooling to 0°C for a week or a month. Hence, fractional distillation of the oil at higher temperatures within a narrow range (say 5°C) gives more separation of solids on cooling to 0°C for a week than by fractional distillation within a wider range (say 20°C).
The filtrates, after the separation of solids from distillates collected within 5°C, were mixed together and subjected to fractional distillation at 2°C intervals. The fractions were collected separately and kept at 0°C for about a week, when more solids separated out. All these solids were worked up for the isolation of the various ingredients.
After establishing the optimum conditions for the isolation of anthracene in maximum yield, the next procedure was to purify the crude products to obtain the maximum yield of pure anthracene, phenanthrene, and carbazole by employing solvent methods.
The same procedure was followed for the purification of solids obtained at the 5°C range. As the 2°C range solids contained very little anthracene (from their melting points and other experimental data), fractional distillation of the mixed solids and fractional crystallization from alcohol were adopted for isolating the individual solids. | |
