February, 1925
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Chemical Examination of Dissolved Tars
The 13 per cent distillate'and 87 per cent residue obtained by distilling the 20-mm. tar were examined by the general method of dissolving in organic solvent, washing the solution first with sodium carbonate and then with sodium hydroxide solution, and precipitating these with acid. These and similar manipulations gave the quantitative results shown in Table IV. Since no well defined compound was separated or identified, it is unnecessary to describe in detail all the steps. Of especial interest was the precipitate formed when sodium hydroxide was added to the ether solution of the distillate a t this step (Item 3, Table IV). This precipitate, after purification, was an oil a t room temperature, but on being cooled slightly it formed waxy crystals. Evaporation following the sodium carbonate and sodium hydroxide treatments of the ether solution of the distillate also yielded an oil which formed waxy crystals on cooling. A special examination of the solution obtained from the sodium hydroxide treatment was also made (Item 4, Table IV). Upon acidification no oil precipitate was obtained, but by extracting with ether and evaporating the extract 5 grams of oil were left. This oil on distillation in vacuo gave 3 grams of an oil light yellow in color with a strong phenolic odor, which when treated with benzoyl chloride by the SchottenBaumann method yielded a white, crystalline derivative having a melting point of 120' to 120.5' C. The crystals contained 1.35 per cent methoxyl, but their small quantity prevented further examination. In the course of the manipulation of the distillation residue it was found that the acid filtrates resulting from the treatment of the alkaline solutions with sulfuric acid (Items 8 and 9, Table IV) could be extracted with amyl alcohol and expecially amyl acetate, and that such extractions removed a large portion of the material which caused the orange color in the acid condition and the blue-black color in the neutral condition. Table IV--Products from Alkallna Treatment of Dissolved Tars (Figures in per cent) -VACUUM TARConDistilResidue trolled late in in chlotar in OF ITSM ether roform ether Item DESCRIPTION Material taken into solution by 1 58.6 7 9 . 9 100.0 the solvent Soluble material dissolved by car2 57.7 1 9 . 9 46.7 bonate solution Soluble material precipitated by 3 37.8 3.7 NaOH solutiono (a) 4 Soluble material dissolved by 5.2 3 3 . 5 1 5 . 2 NaOH solution Material precipitated from car5 2.4 7.4 2.4 bonate solution by acid 6 Soluble material in acid filtrate 55.3 38.2 17.5 from Item 5 Material in Item 1 not removed by 7 1.4 11.0 3.7 carbonate and NaOH Material in acid filtrate from €5 13.1 33.5 Item 4 (a) 9 Material in acid filtrate from 13.6 3.7 Item 3 (a) Material precipitated by adding 10 CsHs t o CHCh solution of tar (b) residue 22.5 Total volatile acids from Item 6 11 Material precipitated from solvent 12 (b) by carbonate solutionc 24.2 Item 3 insoluble in acid 13 Material precipitated from NaOH 14 (b) solution by ac!d Material precipitated from Item 15 13.2 3 by C02 Material precipitated from Item 3 16 11.0 after COI bv His04 (I A product of this description could not be isolated although it was obtained. b No product of this description was obtained. o This means a precipitate, soluble in neither the aqueous nor organic solvent, which formed a layer a t the dividing line.
The chloroform solution of the distillation residue after extraction with carbonate and caustic (Item 7, Table IV) was evaporated for separation of the chloroform. The residue was heated under 18 mm. pressure without producing any distillate until 220' C. was reached. Then, with slight
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decomposition, a dark red oil came over which rapidly turned black and solidified. The dissolved tar obtained by distilling a t 740 mm. was examined by much the same methods and the quantitative results are shown in Table IV, last column. Especially noticeable was the large amount of the ether solution which was extracted by the sodium carbonate solution (Item 2). That the extracted material was largely water-soluble acid appeared from the fact that very little was precipitated on acidifying the carbonate extract (Item 5); about 40 per cent of this acid, 22.5 parts out of 55.3, was volatile (Item 11). An effort to show the presence of hydroxy acids in the insoluble material from the acidulation of the sodium carbonate extract by the method of Marcusson and Picard4gave negative results. A large amount of precipitate was formed when the ether solution, after the carbonate extraction, was treated with caustic soda solution (Item 3). The precipitate was apparently composed of the sodium salts of phenol methyl ethers and of phenols of high molecular weight, since it was soluble in water and after precipitation by carbon dioxide the phenols were found soluble in dilute caustic and concentrated sulfuric aaid but not in alcohol or water. Summary
1-The solubility of dissolved tar in water is much less than in pyroligneous acid, a fact showing the positive effect of acetic acid and methanol on the solubility. 1 2-Dissolved tar is much more readily soluble in pyroligneous acid than is settled tar, showing that the two kinds of tar differ in composition and that the amount of dissolved tar is controlled by the conditions of distillation of the wood rather than by the amount or composition of the pyroligneous acid. 3-Benzene and chloroform dissolve large proportions of the dissolved tar from pyroligneous acid, but not enough to justify their use in a commercial process of refining. 4-Dissolved tar can be distilled only in small part a t atmospheric pressure without decomposition, but at reduced pressures (20 mm.) about 45 per cent is volatile without noticeable decomposition. In this respect also it differs greatly from settled tar, which is about 45 per cent volatile a t atmospheric pressure. 5-The dissolved tar contains a large proportion of materials of acidic and phenolic character which can be separated from ether solution by sodium carbonate and sodium hydroxide, respectively. 6-The dissolved tar is sensitive to the decomposing or polymerizing action of heat a t temperatures far below those a t which parts of the settled tar distil without decomposition. 7-Certain fractions of the dissolved tar manifest chromotropic properties, being of a deep orange color in acid solutions and an intense blue black in alkali. These constituents can best be separated by extraction from acid solution with amyl acetate. 8-This work has been of a preliminary character. Only crude groups of products have been separated, and no identifications of single substances or significant quantitative determinations have been made. Further work is now under way, and with larger amounts of material more definite and detailed results may be expected. 4
2. angew. Chem., 84, 203 (1921).
Production of Arsenic in Brazil-The annual report of the workings of the St. John del Rey mines states that a new roasting furnace in the course of construction should enable the company to double its output of arsenic, which amounted to 162 tons in the year ended February 29, 1924. The total exports of white arsenic from Brazil in 1922 were 52,888 kilos.
