IiVD USTRIAL A N D EiVGIiVEERIlVG CHEMISTRY
Mav. 1927
63.5
Determination of Methanol in the Presence of Ethyl Alcohol’ By F. Spencer Mortimer ILLI\OIS
xI’ESLEY4B
UNIVERSITY,
EVERAL methods have been proposed for the determination of methanol in the presence of ethyl alcohol and water. Practically all of these methods depend upon the oxidation of methanol to formaldehyde and the subsequent determination of this substance. Leach and Lythgoe, however, have proposed a method by which both methyl and ethyl alcohols may be found by a determination of two physical properties. These investigators have pointed out that equal weight concentrations of these two alcohols in water have nearly the same density; hence a determination of the density makes possible the estimation of the total alcoholic content of the mixture. I n order to determine the relative amounts of each alcohol present, it was assumed that “addition of methyl to ethyl alcohol decreases the refraction in direct proportion to the amount present.”
S
of Ternary Mixtures of Methyl and Ethyl Alcohols with Water
Table I-Refractivities
I
SOLUTION I Total per cent of alcohol
Scale reading of refractometer
0.0 4.26 6.93 13.3 16.5 26.5 34.1 45.7
14.5 19.1 22.6 31.1 35.7 50.0 59.3 68.5
1
SOLUTION JI Total per cent of alcohol
Scale reading of refractometer
0.0 4.62 8.85 16,25 22.6 27.95 36.8
14.5 18.0 21.7 28.4 34.8 39.6 46.0
Leach and Lythgoe gave no data (except analyses of some synthetic mixtures) for the refraction of ternary mixtures of water, methanol, and ethyl alcohol. It was the purpose of the present writer to determine this data and t o attempt thereby t o develop a graphical method for the analysis of methyl and ethyl alcohols in the presence of water or, for that matter, any nonvolatile impurity. It soon became apparent that the results, especially those for the refractive index, are much more regular for mixtures containing less than 40 per cent of alcohol by weight than for those which contain more than this amount. Since all mixtures may readily be brought within this range of concentration, only this portion of the system has been investigated. Procedure
The samples of alcohol used in this investigation were treated to remove impurities, but they were not rendered absolutely dry. The amount of water present was determined and allowance made for it in calculating the concentrations. Two stock solutions, each containing the two alcohols, were made up. Solution I contained 38.68 parts of methyl to 61.32 parts of ethyl and solution I1 contained 73.97 parts of methyl to 26.03 parts of ethyl alcohol, the solutions being made up on the weight basis. Appropriate mixtures of each of these stock solutions were then made up with water in small glass-
’ Received 2
December 20, 1926 J. A m . Chem. S o c , 27, 964 (1905).
B L O O ~ I h G T O V , ILL
stoppered bottles. The refractivities of these mixtures were determined a t 20” C. by means of the Zeiss immersion refractometer using the standard procedure. The results obtained are shown in Table I. Table 11-Refractometer Scale Readings of Ternary Mixtures of Water, Methyl a n d Ethyl Alcohols
SCALE
WEIGHT P E R C E N T O F
F2$gN;,1000 Ethyl Methyl
TOTAL -4LCOHOL
IN
MIXTURE
80 Ethyl 20 Methyl
.50 Ethyl 50 Methyl
20 Ethyl 80 Methyl
0 Ethyl 100 Methyl
0.00 1.15 2.60 4.05 5.50 6.80 8.10 9.40 10.70 11.95 13.15 14.35 15.6 16.8 18.0 19.15 20.3 21.5 22.7 24.0 25.2 26.4 27.7 29.0 30.3 31.8 33.4 35.15 37.0 39.2
0.00 1.50 3.45 5.35 7.15 8.85 10.60 12.20 13.80 15.4 16.9 18.5 20.0 21.6 23.2 24.7 26.1 27.8 29.5 31.4 33.3 35.4 37.7 40.4
0.00 2.13; 4.90 7.50 9.90 12.30 14.70 17.00 19.20 21.4 23.5 25.8 28.2 30.8 33.4 36.3 39.5
0.00 3.00 6.35 9.65 13.00 16.15 19.30 22.45 25.50 28.65 31.85 35.40 39.60
-
14.5 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 38.0 40.0 42.0 44.0 46.0 48.0 50.0 52.0 54.0 56.0 58.0 60.0 62.0 64.0 66.0 68.0 70.0 72.0 74.0 76.0 78.0 80.0
0.00 1.00 2.25 3.55 4.80 5.95 7.05 8.10 9.25 10.35 11.45 12,55 13.65 14.75 15.75 16.75 17.75 18.75 19.75 20.8 21.8 22.85 23.9 24.95 26.05 27.15 28.3 29.45 30.7 32.15 33.7 35.3 37.0 38.6
100%
Y O
These results were plotted to a large scale and the concentrations for even refrac-
INDUSTRIAL A N D ENGINEERIXG CHEMISTRY
636
nary diagram easily, the values for sereral even concentration ratios of the two alcohols were read off and recorded, together with similar values for the pure alcohols taken from the paper of Leach and Lythgoe, in Table 11. I t will be noted from the ternary diagram that the lines of equal refraction, although nearly straight, are not quite parallel, neither are they equally spaced. All these conditions would have to obtain in order for the method of Leach and Lythgoe to give exact results in the analysis of samples containing methanol. However, the deviation is not large and in any case, with the density and refractivity determined, it is an easy matter to determine from the ternary diagram the relative amount of each of the three substances present in a mixture, provided, of course, that there are not more than traces of other volatile substances present to interfere. The density data for the solutions of these two alcohols
Vol. 19, No. 5
in water which have been used for the determination of the total alcoholic percentage were taken from a bulletin of the Bureau of standard^,^ which may be found in almost any of the recent handbooks. Accuracy of Method I n order to test this method of analysis a number of synthetic mixtures of known composition of methanol with pure grain alcohol and of methanol with illicit liquor obtained from the sheriff were made up and analyzed. I n every case the methanol found was within *O.l per cent of that known to be present. Likewise it was found that the data for the synthetic mixtures of Leach and Lythgoe, when located upon our ternary diagram, gave results which in every case were more nearly correct than those calculated by the method of the original observers. 3
BUY S t a n d a r d s
Bull
9, No
3
Cheap Ethylene Dichloride’ By D. H . Killeffer, Associate Editor
Improvements i n the method qf preparation and changed industrial conditions have now made this materia2 available in quantit-v at a. low price, and thus haae greatly extended t h e j e l d .f its usefulness. Some of its commercial possibilities are discussed. COiYOpV.IIC considerations exercise a prime influence on the possibilities of use of chemical raw materials. Sulfuric acid, when first commercially available in the United States, was probably viewed askance by the financiers of a hundred and thirty odd years ago, who thought they had no use for it! Within a bare decade the same cycle of strangeness, cheapness, and utility has been repeated for numerous aliphatic alcohols, normal, secondarjr, and tertiary, for nitrocellulose lacquers, for rayons, for furfural, and for no end of other materials now of established value, and it has been profitable to many to keep up with these developments. Ethylene dichloride is a particularly good example of the effect of price on utility. A very short time ago ethylene dichloride was to be had neither in the quantities nor a t the price required by industry, and it was unprofitable to use so expensive and so scarce a material for doing things which might be more cheaply accomplished otherwise. However, improved methods of preparation adapted to large-scale plant operation, instead of the mere laboratory procedures previously practiced, and industrial readjustments, now constantly occurring, have made quantity production of ethylene dichloride both desirable and economical, and it is now available in quantities and a t a price hitherto out of the question. The effect has been to put what amounts to an entirely new material upon the market. Ethylene dichloride possesses certain fixed physical and chemical characteristics which cannot be changed by mere juggling of price, but nevertheless cheapening of the material greatly extends the field of its usefulness. It is of no commercial significance that ethylene dichloride will condense with ammonia to form ethylene diamine, for instance, unless the cost of the two plus the cost of the condensation is less than the selling price of the product. However, when the cost of raw materials goes down far enough to make this reaction cheap enough to yield cheap ethylene diamine and that shows itself valuable, the situation is distinctly different. Although its original discovery was announced in 1795,
E
1
Received February 11, 1927.
no quantities of this “oil of the Dutch chemibti” worthy of consideration were to be had in any market before 1923. During that year the first commercial offerings were made a t 35 cents per pound in not too great amounts. I n 1924 it was possible to reduce this price to 25 cents per pound, and in the spring of 1926 demand had grown and production costs had diminished to the point of allowing a price of 10 cents per pound. I n November, 1926, 6 cents per pound was first quoted for ethylene dichloride in tank-car lots, and industry was given a plentiful supply of a comparatively new material with which t o work. The present situation is such that any practicable demand may be met a t this figure. Price Reduction Brings New Solvent
When ethylene dichloride is scarce and costs 35 cents or more per pound, industries are not interested in the fact that it is a good solvent for oils, fats, and waxes. Carbon tetrachloride, if not identical with it as a solvent, is too nearly so to justify the difference between 7 and 35 cents per pound. However, ethylene dichloride becomes a serious competitor when its price goes down to 6 cents per pound. As a matter of fact, solvents are bought and used on a volume rather than a weight basis and the difference between the specific gravities of these two is such that ethylene dichloride a t 6 cents per pound becomes the practical equivalent of carbon tetrachloride a t 4.75 cents per pound, other things being equal. On a similar volumetric basis of comparison, ethylene dichloride is equivalent to trichloroethylene a t 5.27 cents per pound and acetylene tetrachloride a t 4.65 cents per pound, whereas the present prices of these two are 10.5 and 11.5 cents per pound, respectively. A calculation of this kind can only hold in fields where these four materials are strictly competitive on a basis of volume, which in general is that of “non-flammable” solvents, but with such a comparison before him the chemical engineer can easily choose the one best suited to his purpose. If no property peculiar to one or the other nullifies the price criterion, as it may easily do, the selection is simple. Solvent ability, relative flammability, latent heat, and other
