I N D U S T R I A L A N D ENGINEERING CHEMISTRY
November, 1923
Indene and Styrene-Constituents Water-Gas Tar’
1147
of Carbureted
By Ralph L. Brown and Roscoe D. Howard PITTSBURGH EXPERIMENT STATION, BUREAUOR MINES, PITTSBURGH, PA.
HE list of constituents which have been identified and may normally be expected to be present in coal tar is a long one. The compounds comprising this list have been discussed in the authoritative work of Lunge,2 in which the literature had been well reviewed. I n the case of carbureted water-gas tar but little work has apparently been clone towards the identification of constituents. I n a recent publication, B a t e m q 3 in speaking of water-gas tar, states that “benzol, toluol, xylol, naphthalene, phenanthrene, and methyl anthracene have been identified.” Downs and Dean4 reported the identification of thiophene, benzene, toluene, 0-, m-, and p-xylenes, mesitylene, naphthalene, and anthracene. I n 1893, Deunstedt and Ahrens6 reported an examination of condensate from the illuminating gas of the City of Hamburg, in which they found about 1 per cent of styrene and an unstated quantity of indene, but from their original paper the amount is judged to be only a few per cent. I n a previous paper6 it was pointed out that the natural condensate, “drip-oil,” taken from the distributing systems of carbureted water-gas plants in the United States contained these two hydrocarbons-namely, indene and styrene-in amounts totaling 40 to 50 per cent of the condensate. It follows as a corollary that these two hydrocarbons should be found in water-gas tar, It is the belief of the writers that the most intelligent and profitable utilization of this byproduct of the “gross’1industry of gas manufacture is possible when it is based upon the fundamental information of molecular composition of the tar, and the physical and chemical
T
-----PBRCENTAGE
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OR
Oils Boiling r Fractions Sample below 1’30’ C. 1 2 1.4 A 5.3 1.0 1.5 2 .1 B 5.5
properties of the constituents. With this point of view, and in the interests of the dissemination of knowledge, the writers have isolated, identified, and measured the indene and styrene in two typical samples of water-gas tar. The experimental data in their essentials are given below.
1
ISOLATIONAND DETERMINATION The method employed in removing the oils boiling below 200” C. was to pass steam through 1000-cc. samples of the tar maintained a t 150” C. The oil thus separated was distilled over a 14-inch bead column and collected in three fractions-namely, (1) boiling up to 130” C., (2) boiling between 130” and 160” C., and (3) boiling 16O”to 190’ C. Fraction 2 was titrated with bromine (in carbon tetrachloride solution), and the styrene content was calculated 1 Received
June 8, 1923.
Published by permission of the Director,
U.S. Bureau of Mines. “Coal T a r and Ammonia,” 5th ed., 1916. U. S. Dept. A g r . , Bull. 1036, 73. 4 Txrs JOURNAL, 6, 366 (1914). 6 “Jahrbiich der. Hamburgerschen wissenschaftlichen Anstalten,” 1893, p. 132. 6 Brown, Chairman of Committee on Deposits in Gas Pipes and Meters; “Deposits in Gas Pipes and Meters,” American Gas Association, Proceedings Technical Section, 1922. 2
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DETERMINATION OR STYRENE AND INDENE MELTINGPOINTS-O ---C . ---Styrene Dibromide-----Indene Oxybromide-Styrene Indene From Fraction 2 Pure Mixture From Fraction 3 Pure Mixture 130.5 130 72.Rto73 130 73.5 1.9 72.5 0.7 73 129 t o 130 130 5 130 73.5 1.2 73 0.9
TARSAMPLE3 2.9 1.9
from the bromine used. The styrene dibromide so formed ‘ and recovered by the evaporation of the hydrocarbons other than styrene was found to be practically pure, and amounted to over 95 per cent of the amount calculated from the titration. Fraction 3 was similarly titrated with bromine, and the indene content calculated from the bromine taken up. The indene was isolated as the oxybromide by gentle steam distillation of the titrated fraction, which removed the other hydrocarbons of the fraction and hydrolyzed the indene dibromide formed during the titration. The crude oxybromide so recovered was approximately equal to that calculated from the amount of bromine used. The purified oxybromide recovery amounted to 60 per cent of the amount calculated from the bromine titration. No other compound was separated from the residual resinous material resulting from the steam distillation of the crude indene dibromide. The writers have always found this resinous material left as a residue when the dibromide is so treated. IDENTIFICATION The identification of the styrene was made through the melting point of its dibromide following recrystallization from alcohol, and by the method of mixed melting points. Pure styrene dibromide was prepared from styrene and bromine. The identification of indene was effected through its oxybromide, which melts a t 130” to 131” C. and is otherwise __.-
characteristic. Melting points of mixtures of equal parts of the crystals isolated and the oxybromide derivative prepared from indene were taken, and are reported below. Sample A was a wat,er-gas tar of specific gravity (20” C.) 1.058 and low naphthalene, free carbon, and water content. It was taken from tar storage, and was typical for the plant. Sample B was a water-gas tar of specific gravity (20” C.) of 1.176, and contained in comparison with Sample A much naphthalene, free carbon, and water. It was taken from the works separator of the plant in which it was produced. I n the table which follows is given the experimental data pertinent to the purpose of the paper. The percentages are all based on 1000-cc. of tar as sampled, and are in terms of volume throughout. The temperatures are corrected values. The Department of Commerce has announced t h a t after January 1, 1924, “too many asphalt grades” no longer will be the complaint, and that on the date mentioned the recommendations adopted a t its recent asphalt paving conference will become effective and the number of asphalt grades for use in the construction of sheet asphalt, asphaltic concrete, asphalt macadam, and surface-treated pavements will be reduced from eighty-eight to nine. The number of asphalt grades used as joint filler in the construction of brick and block pavements and various other types has been reduced from fourteen to four.
