INDUSTRIAL A N D ENGINEERING CHEMISTRY
728 Screen size, inches Pusher end, cumulative per cent Middle cumulative per cent Coke eAd, cumulative per cent
2.0 3.6 3.1 2.8
1.5 26.3 21.3 17.3
1.0
55.7 50.7 47.8
0.5 67.2 66.7 64.5
0.26 69.2 68.9 67.2
I n this case the stability factor varies 8 per cent between samples of coke from the same oven. Since the preliminary drying of the coke is an extra step in the procedure, some tests were made to determine the necessity of this. A typical test between coke with a moisture content of 9.5 per cent and the same coke subjected to the usual preliminary drying gave the following results : Screen size, inches Coke dry, cumulative per cent Coke: wet, cumulative per cent
2.0 3.9 6.8
1.5
1.0
0.5
0.25
52.0 65.6 68.2 57.0 75.1 7 8 . 1 Although the wet coke in this case has a moisture content considerably above normal, it indicates the necessity of drying all coke before it is submitted to the tumbler test. The effect of tumbling coke which has not been given preliminary #drying is to cause abrasion of fine material which clings to $he larger pieces and cushions their fall. 24.3
19.9
Practical Value of Tumbler Test Judging by the results obtained from a great many tests, it is believed that the stability factor, as determined by the
Vol. 20, No. 7
tumbler test, has considerable value as an indicator of the extent to which size degradation will occur in the handling of coke. Unfortunately, it is impossible to give a quantitative comparison between tumbler test results and the actual degradation results occurring between point of production and point of use. I n the handling and transportation of coke, it is subjected to so many variables that it would be useless to try to compare such practice with the results from the closely controlled conditions of the tumbler test. However, there are many indications that tumbler test results correlate with actual practice. For instance, it is well known that the handling qualities of coke are usually greatly improved by the addition of low volatile (semi-bituminous) coal to the high volatile coal used in making the coke. I n several cases it has been possible to study series of cokes, ranging from that made from 100 per cent high-volatile coal, to that made with 30 per cent low-volatile coal in the mix. In such cases the addition of a small percentage of lowvolatile coal causes a decided increase in the stability factor of the coke, and each addition of low-volatile coal further increases the stability factor, but a t a decreasing rate. This corresponds to facts that are well known in coke technology.
Physical Properties of o-Dichlorobenzene' T. S. Carswell MONSANTO CHEMICAL
HE data for common organic compounds given in the literature often show marked discrepancies, particularly in the case of compounds which may contain as impurities isomers of very similar properties. o-Dichlorobenzene is an excellent example of such a compound, because the para and mpta isomers are so closely related in physical and chemical properties that it is practically impossible to prepare pure ortho from a mixkure of the isomers. Other authors have overcome this difficulty by synthesizing the o-dichlorobenzene in such a way that no other isomers can be formed. However, even then great care must be taken to use purified reagents throughout the synthesis, in order to avoid contamination of the product.
T
Schmidt and Ladner2 heated o-bromonitrobenzene with ammonium chloride, and obtained o-dichlorobenzene, boiling a t 179" to 180" C. under 755 mm. Holleman3 reduced o-nitrochlorobenzene, of crystallizing point 29.0' C., with tin and acid to o-chloroaniline, and fractionated the latter. The fraction boiling below 225" C. was purified by crystallization of the picrate and the purified o-chloroaniline was transformed to o-chlorobenzene through the diazonium compound. The product boiled a t 178" C. under, 762.5 mm., and a t 86" C. under 18 mm., and had a specific gravity a t 19.1" C. of 1.3039. Holleman and Van der Linden4 reduced o-nitrochlorobenzene, the purity of which is not stated, with iron and acid to o-chloroaniline, diazotized the hydrochloride of the latter, and added the diazonium chloride to boiling cuprous chloride. The product was steamdistilled and redistilled under vacuum and atmospheric pressure, after which it boiled a t 179' C. under atmospheric pressure, at 65.8" C. under 14 mm., and had crystallizing point -17.6" C., n: 1.5532, and specific gravity 1.3039 a t 19.1' C. Narbutt5 fractionated o-CsHaC12 from Kahlbaum twice a t 49 mm.; the product was partially crystallized and the liquid drained off. The crystals then had crystallizing point -17.5" C., n: 1.5524, Presented before the Division of Dye Chemistry a t the 75th Meeting of the American Chemical Society, St. Louis, Mo., April 16 to 19, 1928. 2 Ber., 37, 4402 (1904). 3 Rec. trav. chim., 23, 358 (1904). 4 Ibid., 90, 305 (1911). 5 Ber., 62B, 1028 (1919).
WORXS, S T .
LOUIS,MO.
1.3104, and dno 1.3048. The International Critical Tables (1926) give for o-CBH4C11 a melting point of -17.6" C., boiling point 179" C., density 1.298, and TZ? 1.549. dla
The writer followed essentially the same method as that of Holleman, with certain modifications. The o-nitrochlorobenzene used to start with had a crystallizing point of 32" C. This was reduced in the usual way with iron and hydrochloric acid. Reduction with iron is better than with tin, since chlorinated by-products are liable to be formed with the tin. The chloroaniline was fractionated in vacuum, and the distillate was dissolved in hot, dilute hydrochloric acid. On cooling, crystals of the hydrochloride separated, and were filtered off and washed. The purified hydrochloride was diazotized, and was added at 0" C. to a solution of cuprous chloride in hydrochloric acid. Decomposition in the cold rather than at the boiling temperature minimizes the chance of by-product formation. The decomposition was complete in a few minutes at 0-10" C., and the product was removed by steam distillation. The oil was washed with dilute sodium hydroxide to remove any phenols, and the washed oil was fractionated first under vacuum and then under atmospheric pressure. The product so obtained had the following properties: Density Crystallizing 18°/150 point, C. C. Density' 20°/200 C. Boiling boint, 757.4 mm., Boiling point, 745.2 mm., Refractive index,
%?
0
c.
c.
-16.7 1.3112 1.3088 180.2 179.5 1.5818
From the two boiling-point readings, the barometric correction for the boiling point at atmospheric pressure is 0.058" C. per millimeter. Applying this correction, the boiling point at 760 mm. is 180.3' C. All temperatures were taken with thermometers standardized by the Bureau of Standards. The densities were taken in a bottle-type pycnometer, and the refractive index was determined with an Abbe type refractometer.
