distilled over. Smooth, semirapid, and consistent distillation (approximately 20 minutes) is essential. Rinse the adapter tube with 10 ml. of monochlorobenzene and titrate the distillate with the 0.1N hydrogen bromide in glacial acetic acid, using O.lyo crystal violet indicator in glacial acetic acid. Calculations : Milligrams of epoxide recovered per gram of sample material = nil. H l h X K X E.W. - wt. of sample ml. IIEr X N X E.W. wt. of blank sample Refer to calibration graph for total absorbed epoxide. Notes. T h e condenser is air cooled. Glassware must be scrupulously clean and d r y ; d o not use other glass joint lubricants. Glacial acetic acid is used in the receiving flask to prevent obscure end1)oints caused by traces of moisture in the sample. Small amounts of moisture do not otherwise interfere except for increased blank titers. For each different material that is tested for epoxide, it is necessary to determine blank values. Calibration. Several 2-gram samples of the adsorbent in question are exposed to the pure epoxide in a disiccator, for different lengths of time, to adsorb varying quantities of gas and are weighed t o determine the amount of gas adsorbed in each. A minimum of three samples, and pref-
erably five or six, should be run, covering the complete range of the expected epoxide concentration. The amount of epoxide recovered (a blank determination is run on several unexposed samples, and this average value subtracted from the value found on exposed samples is the amount recovered) from each sample by distillation and titration is then plotted against the amount adsorbed as determined by weight. I n subsequent determinations then, the total adsorbed epoxide is found by referring the amount recovered to this calibration graph.
Table II.
mg./gram found; 2-gram samples Polyethylene 0.2 0.2 Rubber
0.2 0.2 0.4 0.3
0.5 (0.9)o (0.9) Vinyl
RESULTS AND DISCUSSION
The unrecovered epoxide is presumed to be due to a reaction between the adsorbed epoxide and the adsorbent during distillation; the reaction product thus formed (unrecovered epoxide in milligram per gram of sample) increases with the epoxide concentration and is dependent on the nature of a given adsorbent. With controlled distillation for a specific period of time, recovery from the different adsorbents was consistent over a wide range of concentration, and with the construction of a calibration graph, is considered to be complete. Relative standard deviations for the determinations of ethylene and propylene oxides in gum rubber are 2.2% and 1.3%, respectively. Deviation in less reactive adsorbents is smaller. The detection limits of ethy-
Blank Determinations (calcd. as ethylene oxide)
a
0.1
0.2
5-gram samples.
lene and propylene oxides are 0.04 mg. and 0.06 mg., respectively. Data are presented in Table I. Table I1 gives the values obtained on conducting blank distillations and titrations. LITERATURE CITED
(1) Durbetaki, A. J., ANAL. CHEM.28,
2000 (1956).
(2) Durbetaki, A. J., Ibid., 30, 2024 fl%W. (3) Jay, R. R., Ibid., 36, 667 (1964). \ - - - - ,
(4)Schecter, L., Wynstra, J., Kurkjy, R. P., Znd. Eng. Chem. 48, 94 (1956).
Deot. of Research Aierican Sterilizer Co. Erie, Pa.
DONA. GUNTHER
N e w Method for Determination of Hydrocarbon-in-Water Solubilities Edward J. Forkas,' Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Mass.
IN
CONNECTION with a study of the bubble column slurry reactor (0, data on solubility of cyclohexene in water a t room conditions became necessary. No results were found in the literature. Published experimental methods applicable to hydrocarbonwater systems either required complex, expensive equipment or were suitable only for compounds much more soluble than cyclohexene. Against this background, a new method was developed as part of the reactor work. This technique requires only commonly available, inexpensive apparatus and yet is suitable for determination of extremely minute solubilities of hydrocarbons in water. During preparation of this report, the literature was thoroughly rechecked
1 Present address, Esso Research and Engineering Co., Florham Park, N. J.
for solubility methods applicable to gas-liquid and water-hydrocarbon systems. Among the additional references obtained were disclosures (8,
