ISDUSTRIAL AND EArGILVEERIAVG CHE-VISTRY
May, 1930 Silica Iron Calcium Magnesium Sodium and potassium, calculated Bicarbonate radical
P. p . m. 6 8 0 7 47 26
254 "
P.9 . m. Sulfate radical 7 3 Chloride radical 1 8 Nitrate radical 0 15 Total dissolved solids Total hardness as CaC03, 210 calculated 222 201 Soap hardness
Conclusion
The glass-covered sludge beds are a great success and even though sludge was drawn in January, cracking and drying are progressing slowly.
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Acknowledgment
The writer wishes to acknowledge the suggestions of Richard Messer, Wellington Donaldson, and A. M. Buswell, as well as the assistance of the Chemistry Department, the Engineering Experiment Station, and the Civil Engineering Department of Virginia Polytechnic Institute. Literature Cited (1) Buswell, IND.s N GcHEM, . 21, 322 (1929). (2) Donaldson, Sewage Works J , 1, 609 (1929).
New Industrial Solvents' Ethylene Dichloride, Dichloroethyl Ether, and Isopropyl Ether H. R. Fife and E. W. Reid MELLONINSTITUTE OF IXDUSTRIAL RESEARCH, UNIVERSITY OF PITTSBURGH, PITTSBURGH, PA.
HE rapid growth of the chemical industry during the past few years has been notable for the commercial development of a number of new products formerly classed as fine chemicals. Among these products ethylene dichloride, dichloroethyl ether, and isopropyl ether are of special interest to the industrial chemist and chemical engineer. Their unique solvent properties, ease of recovery, and low cost promise economies of operation which command attention. The general physical properties of these products are given in Table I, while the solubility of various materials is shown in Table 11. A study of these properties will indicate their value as general and specific solvents.
T
Ethylene Dichloride
Ethylene dichloride has been the subject of academic investigations for a number of years, but it was not available in quantity and a t a l o ~ vprice until 1927. As its properties and usefulnebs become more generally known, it finds more diversified uses in the chemical industry. It is the most stable chlorinated hydrocarbon available and may be handled in the presence of water a t boiling temperatures in metal vessels without danger of corrosion. I t s stability is also hhown in its re.zistance to oxidation. As a result, it may be used in the extraction of edible oils and medicinal products where the highe>t purity is required. I n the extraction of vegetable oils from oil-beaiing seeds by the "cupeller" method, approximately 10 to 15 per cent of the oil remains in the cake. This residual oil represents 1 Received March 24, 1930 Presented before the Division of Industrial and Engineering Chemistry a t the 79th Meeting of t h e American Chemical Societ) A t l a n t a , G a , April 7 to 11, 1930.
a definite loss since the value of the cake is much less than that of the oil. One method of extraction consists of treating the press cake with ethylene dichloride to remove the residual oil. The more commonly used method is the extraction of the ground seeds by percolation or digestion followed by the evaporation of the solvent and subsequent refining of the oil in the usual manner. The usual chlorinated solvents are not satisfactory for this purpose because of their tendency to hydrolyze and/or oxidize, producing hydrochloric acid which not only corrodes the iron or steel equipment but lowers the quality of the oil. The use of benzene and gasoline is attended by extreme fire hazard. Ethylene dichloride is not classed as a non-flammable liquid, but is on the border line between a flammable and non-flammable solvent. When the liquid is ignited, it will burn, but the flame is extinguished by the force of its own draft. I t s lower explosive limit in air is 6.2 per cent as compared with 1.4 per cent for benzene and 1.5 per cent for gasoline. Ethylene dichloride is of value in the separation of mineral oil and paraffin v a x . Mineral oils are miscible with this solvent in all proportions, while paraffin wax is immiscible a t temperatures below 25" F. This solvent has found a wide use in dry cleaning and for the removal of oil and grease stains from textiles. It.: value in the fumigation of grains, flour, rugs, clothing, and upholstered furniture is well known. For this purpose. a mivture of three parts of ethylene dichloride and one part of carbon tetrachloiide is normally u?ed. This mixture is non-flammable, non-injurious to grains or fabrics, is simple to use, and is not dangerous to human life when used in the proper manner.
Table I-Physical
Properties of Ethylene Dichloride, Dlchloroethyl Ether, a n d Isoprop! il Ether ETHYLESE DICHLORIDE DICHLOROETHYL ETHER ISOPROPYL ETHER PROPERTY Cl-CHZ-CHrC1 CI-CHrCH~-O-CHz-CH?-Cl (CH~Z-CH-O-CH(CH~)I Molecular weight 98.95 142.98 102.11 Boiling point (7!0 mm.), ' C. 83.5 178.0 67.5 Freezing point, C. -36.0 -51.7 < -60 Specific gravity 1.2569 (2Oo/4O C.) 1 . 2 2 (200/200 C.) 0.7247 (2Oo/2O0 C.) Weight per gallon, pounds 1 0 . 5 3 (15'C.j 1 0 . 1 (200 C.) 6 . 0 4 (25' C . ) Specific gravity and weight per gallon at various temp. See Chart 1 See Chart 1 See Chart 2 Refractive index 1 . 4 4 4 (200 C.) 1 , 4 3 7 (200 C.) 1 . 3 6 7 8 (23' C.) Surface tension, dynes/sq. cm. 3 7 . 5 ( 2 5 0 c.j 4 1 . 8 (25' C.)-o 32 (23' C.) Viscosity centipoises 0 . 7 8 (25" C.) 2 . 0 6 5 3 ( 2 5 J C.) 0 . 3 7 9 (250 C.) Vapor pressure, mm. (200 c.) 61.6 (Approx.) 0 . 7 3 m m . 15s ' Vapor pressures at various temperatures See Chart 3 See Chart 3 See Chart 3 Specific heat, calories per gram 0 . 3 0 5 4 (30' C.) 0 369 (30" C.) 0 . 5 2 6 (22-27' C.) Flash point (closed cup), F. R 8 121 ._ -6.7 Apparent ignition temperature in air C. 449 369 ... Latent heat of evaporation, calories ber gram 7 7 . 3 4 (82.20 C.) 6 4 . 1 (178' C.) 6 8 . 2 (67.5'C.j Comparative rate of evaporation See Chart 4 See Chart 5 See Chart 4 Solubility Practically insoluble in water, soluble in most organic liquids
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11VDUSTRIAL A-VD EXGINEERIIYG CHEMISTRY
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T'ol. 22, No. 5
properties, stability, low toxicity and 1017 flammability, and its availability in large quantity. Dichloroethyl Ether
SPECIFIC GR4VlTY+&
Figure 1-Specific
Gravity a n d Weight per Gallon of E t h y l e n e Dichloride a n d Dichloroethyl E t h e r a t Various Temperatures
Ethylene dichloride lends itself to the synthesis and production of a new series of industrial chemical compounds. The replacement of the t v o chlorine atoms with ammonia yields ethylene diamine. Condensation with sodium acetate produces the ethylene glycol acetates. Succinic acid may be prepared by reacting two mols of sodium cyanide with one mol of ethylene dichloride and hydrolyzing the resulting ethylene dicyanide to succinic acid. These characteristic reactions suggest other syntheses that are economically
This solvent possesses to a marked extent the combined solvent properties of ethyl ether and ethylene dichloride with a low vapor pressure and fairly high boiling point. It is a stable compound and may be handled in iron equipment without danger of corrosion and is of value in hightemperature extraction processes. Dichloroethyl ether is not a solvent for the cellulose esters, but in conjunction with 10 to 30 per cent alcohol it becomes an active solvent. It has been used as a high-boiling diluent in lacquers with complete satisfaction. Both cellulose acetate and nitrocellulose lacquers containing this solvent have been stored in tin containers for two gears without any indication of corrosion or discoloration. Table 11-Solubility of F a t s Oils Waxes Resins Balsams a n d Dyee in Commercial Isopropyl E i h e r , b i c h l o r b e t h y l E t h e r , and Ethylene Dichloride
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PROPYL ETHYL CHLOSOLUTE ETHERETHER RIDE SOLUTE Crisco S S S Laculose(A) Vaseline S SH SH Gilsonite s s s Sandarac Mazola Wessonoil S S S Montol resin Mineraloil S SH S Pontianac Citronella S S S Gum mastic S S S Benzyl Juniper Coriander S S S abietate Sweet birch S S S Shellac Menthol S S S Vinylite80 Castoroil S S S VinyliteA S S S Casein Linseedoil Cottonseedoil S S S (rennet) Venetian h'itrocellulose turpentine S S S Cellulose Japanwax S SH S acetate Carnaubawax SS SH PSH Benzyl Beeswax SH SH SH cellulose Paraffinwax S S S Ethylcellulose Amberol S S S Camphor Albertol S S S Spirit-soluble Aroclar1254 S S S yellow Rezylbalsam S S S Spirit-soluble S S PS red, Rezylresins Varnish-type Sp+t-soluble glyptals S S S nigrosene SS PSH SSH Water-soluble Sarpee East India PSH PSH PSH Bakelite R. nigrosene s s~ s 352 G ~ ~ - sL ~ SH s Oil-soluble Coumarone SH S S blue s s s Oil-soluble Cumar yellow Manilla SSH SSH S Ester gum S S S black Ester gum (oxidized) S S S Indigosol SH Spirit-soluble Rosin black Abietic acid s SH SH Spirit-soluble (purified) blue Beckacite PSH PSH S G . P. 0.Resin S S S oil-soluble green Ester gum Indigo (acetylated) S S S B ~ G. E. Resin 36A (Bakelite type)S s Alizarine sky hlantagum S SSH SSH blue Dammar SH SH S Victoriablue B Congo S PSH PSH Diazobrown Kauri SH SH PSH Zopal s s s scarlet (S B P extra) Zincresinate S S S S = Soluble at room temperature SS = Slightly soluble at room temperature S H = Solublehot P S = Partially soluble PSH = Partially soluble hot I = insoluble
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Figure 2-Specific
Gravity a n d Weight per Gallon of Isopropyl E t h e r a t Various T e m p e r a t u r e s
possible with raw materials of low cost. Ethylene dichloride is a suitable solvent or reacting medium in reactions involving the use of such products as thionyl chloride, sulfuryl chloride, chlorine, hydrochloric acid, sulfur chlorides, and hydrogen peroxide. The chlorinated solvents have not been used to a n appreciable extent in nitrocellulose or cellulose acetate lacquer on account of their tendency to hydrolyze. For use in fast drying lacquers, ethylene dichloride has proved quite satisfactory, and lacquer containing this solvent has been stored in tin containers over long periods of time without discoloration of the lacquer or container. The outstanding characteristics of ethylene dichloride which recommend its use are: its low cost, excellent solvent
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The chlorinated hydrocarbons have not been used in quantity in the textile industry owing to the unstability of most solvents of this nature. The stability of dichloroethyl ether and ethylene dichloride permit their use in a number of applications where their active solvent power for tars, fats, waxes, oils, resins, pectins, and the like is of major importance. They are used in scouring for the removal of paint and tar brand marks from raw wool; and oil
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I.YDCISTRI-4L A S D EiYGISEERISG CHEMISTRY
May, 1930
and grease spots from cloth. Dichloroethyl ether is indicated where high temperatures are necessary and the loss of the active solvent is a n economic consideration. Hand spotting may be largely eliminated by incorporating it in fulling and scouring soaps. The exact amount required depends largely upon the colidition of the woo1 or cloth to be treated, but normally approxiinately 2 per cent, based on
515
antioxidants, antiknock compounds, and intermediates. With sodium alcoholates the chloroalkyloxy or chloroaryloxy ethers and the dialkyl or diary1 ethers are formed. Isopropyl Ether
Isopropyl ether has only quite recently become available in commercial quantities. I t s properties are somewhat similar t o those of ethyl ether with the added advantage of lower vapor pressure, higher boiling point, higher flash point, less solubility in water, and somewhat higher solvent power. It is a n excellent solvent for animal, vegetable, and mineral oils, and certain maYes and resins. It is of value in extraction processes where a solvent of this nature is indicated. The solubility of paraffin wax in isopropyl ether decreases rapidly with the addition of isopropanol and also with a decrease in temperature, while that of mineral oil remains fairly constant. For example, a t 50' C. paraffin wax is 100
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the weight of the soap stock, is effective. This solvent is often used with diethylene glycol, soaps, and sulfonated oils in the compounding of wetting-out agents and penetrants. This type of product is especially applicable to cotton because of the solvent action of dichloroethyl ether on the cotton waxes which more readily permits the penetration of the water and conditioning agent into the cotton fiber. Dichloroethyl ether is being investigated in various typss of scouring solutions for textile fibers. The chemical structure of dichloroethyl ether suggests its use in the syntheses of new compounds. I t s reactions are somewhat similar to those of ethylene dichloride and they can usually be carried out in a similar manner. For
40
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Figure 5-Comparative R a t e s of Evaporation of Solvents a t 2 5 O C. i n Circulating Air
miscible in all proportions and at 0' C. its solubility decreases t o 2.6 per cent by weight. The addition of 30 per cent isopropanol decreases the solubility of the wax to 0.6 per cent by weight at 0" C. The mixtures of isopropyl ether and isopropanol may be adapted t o certain processes in the de-waxing of oil or the de-oiling of wax. The present experimental work indicates that this product is of special value when used in conjunction with ketones, alcohols, and other ethers in this process. This solvent is well adapted t o the extraction of 100 acetic acid from aqueous solutions. Acetic acid is miscible with isopropyl ether in all proportions, $0 while the latter is practically insoluble in water. BO As with ethyl ether, the presence of a small amount 10 of alcohol increases the efficiency of the process. Ethyl ether normally contains sufficient alcohol -g60 as an impurity, but the high purity of the isoE50 propyl ether requires the addition of 5 to 10 per cent of alcohol in this process. $40 The table of solubilities indicates that practically e30 all the natural and synthetic resins are either totally 20 or partially soluble in isopropyl ether. The majoiity of organic solyents are miscible, although the ethanolamines, glycols, glycerol, and their mono30 60 30 120 150 I80 210 240 210 300 330 360 330 420 450 480 SI0 540 570 600 esters have a limited solubility, while the di-esters TIMEIN MINUTES F i g u r e 4-Comparative R a t e s of Evaporation of Solvents a t 2 5 O C. in S t i l i Air are soluble. The organic dyes are generally insoluble in the pure solvent but are soluble in the example, the amino ethers and substituted amino ethers may presence of a small amount of alcohol. The esters and ethers be prepared by reacting dichloroethyl ether with ammonia. of cellulose, with the exception of ethyl cellulose, are insoluThe resulting compounds are of practical value as inhibitors, ble in mixtures of isopropyl ether and ethyl or methyl alcohol.
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