INDUSTRIAL AND ENGINEERING CHEMISTRY
250
TABLEIV. COMPARATIVE VISCOSITIES~ Thinner Commercial C Synthetic C Commeroial D Synthetic D Commercial F Synthetic F
(Cooperators 1 to 6) 2 3 4 5 6 50% ._Solution of Modified Phenolic Resin F+ E E++ E+ E FD CSt 1
.. ‘C
B
T+2B T+3B
D+ C-
.. .C.
u
82
x x+
....
:+
B+iB 60% Solution of Alkyd Resin
C
B/C
Commercial C Synthetic C Commercial D Synthetio D Commercial F Synthetic F 37.5% 0.5-Second Nitrocellulose Solution Thinned 60/40 with Thinners Commercial C Synthetic C Commeroial D Synthetic D Commercial F Synthetic F Aniline Points 40.5 40.6 59.0 59.0 24.6 25.4
39.4 39.6
..
25: 0 25.4
a “F+” indicates a viscosity heavier than tube F. “ F f t B ” , one quarter bubble heavier than F; “F-+B”, one quarter lighter than F.
naphtha whose straight aniline point is 60” C., and 10 cc. of anhydrous aniline (4). Each cooperator’s data should be considered per se, since the viscosity of a synthetic resin solution is affected not only by the heat treatment received during solution, but also by the time and method of agitation. Viscosities, expressed in terms of Gardner-Holdt bubble-tube letters, were determined with each cooperator’s own set of standards.
VOL. 11, NO. 5
I n considering the comparative viscosities of resin solutions, the differences in average boiling points shown in Table I11should be noted. The higher molecular weights indicated by the higher boiling ranges of the commercial solvents makes for a higher molal resin concentration in a given resin solution made on a weight basis.
Conclusion The refractive index-sulfuric acid extraction method for determining the aromaticity of commercial high-solvency hydrocarbon thinners, whose evaporation rates are similar to that of toluene and which are substantially olefin-free, provides results which are reasonably accurate, as shown by comparison with synthetic blends, and can be duplicated by several cooperating laboratories with a precision of *0.5 per cent. Although the method, as it stands, does not determine the naphthenic or paraffinic contents with the accuracy or precision which may be desired, the relatively greater importance of aromaticity is demonstrated by a reasonably good concordance in the viscosities of solutions of film-forming materials in the commercial thinners and their synthetic matches.
Literature Cited Baldesohwieler, E. L., Morgan, M. D., and Troeller, W. J., Jr., IND.ENG.CHEY.,Anal. Ed., 9, 540 (1937). Baldeschwieler, E. L., Troeller, W. J., Jr., and Morgan, M. D.,
Ibbid., 7, 374 (1935). Kurtz, S. S., and Headington, C. E., Ibid., 9,21 (1937). McArdle, E. H., Chem. & Met. Eng., 44, 598 (1937). McFarlane and Wright, J . Chem. Soc., 1933,114-18. PhiIadelphia Paint and Varnish Production Club, “Proximate Analysis of Hydrocarbon Thinners”, Circ. 568, Scientific Section, National Paint, Varnish & Lacquer Association (November, 1938). Thomas, C. L.,Bloch, H. S., and Hoekstra, J., IND. ENQ.C ~ n n i . , Anal. Ed., 10, 153 (1938).
A Modified Beilstein Test for Halogens in Volatile Organic Compounds WM. L. RUIGH,’ Merck & Co., Inc., Rahway, N. J.
D
URING an investigation of the low-boiling fraction obtained in the commercial production of divinyl ether, vinyl chloride was isolated. The need arose for a rapid sensitive test to detect this impurity in the finished product. The well-known Beilstein test (1) for detecting halogens in organic compounds, either with copper oxide in a platinum loop or with plain copper wire, is inapplicable to highly volatile substances and in order to detect vinyl chloride (b. p. -13.9’ C.) in divinyl ether (b. p. 28.3’ C.) the following modification was developed. A piece of clean copper screen 10 cm. square, with about 8 meshes to the inch of fairly heavy wire, is clamped 4 cm. above an ordinary Bunsen burner. The flame is allowed to burn on both sides of the gauze until all trace of green color disappears. The liquid to be tested for halogen is then added drop by drop from ti separatory funnel to a warmed 125-cc. flask through which the gas supply to the burner passes. The presence of halogens is evidenced by the appearance of a green color in the flame. 1 Present address: Department of Physiological Chemistry, University of Pennsylvania, Philadelphia, Penna.
With careful observation in a darkened room the limit of sensitivity was found to be 0.005 per cent of vinyl chloride which corresponds to about 30 parts per million of chlorine. Under the same conditions 0.025 per cent of vinyl chloride gave a strong green flame. Since this paper was submitted, Stenger, Shrader, and Beshgetoor (2) have described a modified Beilstein test which is ideally adapted to the detection of volatile halogen compounds in the air, particularly under the conditions found when leakappear in refrigerator pumping systems. The author’s modification, which was completed in March, 1934, was designed primarily for laboratory use to determine halogens in volatile liquids, but it could also be used to determine halos gens in samples of a gas or air. The sensitivity of both tests is of the same order of magnitude.
Literature Cited (1) Meyer, H., “Analyse und Konatitutionsermittlung organischen Verbindungen”, 6th ed., p. 132,Berlin, Julius Springer, 1931. (2) Stenger, Shrader, and Beshgetoor, IND. ENQ. CFXEM., Anal. Ed., 11, 121 (1939).
