Ethylene

“ Acetylene is readily decomposed by heat, polymerizing under its influence to form an enormous number of organic compounds; indeed the gas, which can itself be directly prepared from its constituents, carbon and hydrogen, under the influence of the electric arc, can be made the starting point for the construction of an enormous number of different organic compounds of a complex character. In contact with nascent hydrogen it bunds up ethylene; ethylene acted upon by sulphuric acid yields ethyl sulphuric acid ”

“ The specific gravity of liquid ethylene is 0.386 (3° C.) . Ethylene burns with a bright luminous flame, and forms a very explosive mixture with oxygen. For the combustion of ethylene see Flame. On strong heating it decomposes, giving, among other products, carbon, methane and acetylene (M. Berthelot, Ann., 1866, 139, p. 277) . Being an unsaturated hydrocarbon, it is capable of forming addition products, e.g. ”

“ Ethane, when heated to this degree, splits up into ethylene and hydrogen, whilst ethylene decomposes to methane and acetylene, and the acetylene at once polymerizes to benzene, styrolene, retene, &c. A portion also condenses, and at the same time loses some hydrogen, becoming naphthalene; and the compounds so formed by interactions amongst themselves build up the remainder of the hydrocarbons present in the coal tar, whilst the organic substances containing oxygen in the coal break down, and cause the formation of the phenols in the tar. ”

“ The most delicate test for alcohol is, however, the iodoform test fully described in “Foods,” p. 375. [161] Dichloride of ethylene is detected by shaking up the chloroform with dry potassic carbonate, and then adding metallic potassium. This does not act on pure chloroform, but only in presence of ethylene dichloride, when the gaseous chlor-ethylene (C2H3Cl) is evolved. Ethyl-chloride is detected by distilling the chloroform and collecting the first portions of the distillate; it will have a distinct odour of ethyl-chloride should it be present. ”

“ The effects of the products of the polymerisation of acetylene on the flame produced when the gas is burnt at the ordinary acetylene burners have been stated in Chapter VIII., where the reasons therefor have been indicated. The chief primary product of the polymerisation of acetylene by heat appears to be benzene. But there are also produced, in some cases by secondary changes, ethylene, methane, naphthalene, styrolene, anthracene, and homologues of several of these hydrocarbons, while carbon and hydrogen are separated. ”

“ The conversion of acetylene into ethylene, and the synthesis of alcohol were also important reactions. Acetylene polymerizes, under the influence of the electric spark, into benzene, and many of its derivations were formed by Berthelot. He also formed methane by passing the vapour of carbon disulphide and sulphuretted hydrogen over hot copper; and by the action of carbon monoxide on a hot solution of caustic potash, potassium formate was produced, the formate yielding formic acid on distillation with hydrochloric acid. ”

“ M. Wroblewski, of Cracow, who had witnessed some of M. Cailletet's experiments, and obtained his apparatus, and M. Olzewski, in association with him, also experimented with ethylene, and had the pleasure of recording their first complete success early in April, 1883. Causing liquid ethylene to boil in an air-pump vacuum at -103° C., they were able to produce a temperature of -150° C. (-238° Fahr.) , the lowest that had ever been observed. Oxygen, having been previously compressed in a glass tube, became a permanent liquid, with a clearly defined meniscus. ”

“ Properties of the hydrocarbons. The lower members of the first two series of hydrocarbons mentioned are all gases; the succeeding members are liquids. In some series, as the methane series, the higher members are solids. The preparation and properties of methane and acetylene have been discussed in a previous chapter. Ethylene is present in small quantities in coal gas and may be [Pg 401] obtained in the laboratory by treating alcohol (C2H6O) with sulphuric acid:
C2H6O = C2H4 + H2O.
Benzene, the first member of the benzene series, is a liquid boiling at 80°. ”

“ These paraffins, under the influence of heat, split up into simpler members of the same series and into olefines; and if we imagine the action in its simplest form, we should have the gases, as they were evolved, consisting of (say) ethane and ethylene. These have now to pass down the heated retort on their way to the ascension pipe, and the contact with the heated sides of the retort, and the baking from the radiant heat in the retort, set up an infinity of changes. ”

“ Several compounds of ethylene and metallic 852 chlorides are known; e.g. ferric chloride in the presence of ether at 150° C. gives C2H4·FeCl3·2H2O (J. Kachtler, Ber., 1869, 2, p. 510) , while platinum bichloride in concentrated hydrochloric acid solution absorbs ethylene, forming the compound C2H4·PtCl2 (K. Birnbaum, Ann., 1868, 145, p. 69) . ”

“ STANDARDIZATION OF ETHYLENE OXIDE STOCK SOLUTION [7] 1. 2. 3.
4. 5. 6. 7.
Pipet 20.0 mL standardized HCl-pyridine solution into a 100-mL round bottom flask. Add 2.0 mL EtO stock solution. Attach the flask to the condenser. Reflux for 20 min. NOTE: The reaction is: EtO + HCl (xs) chloroethanol. The excess HCl is back-titrated in step D-6. Cool to near room temperature. Add 5 mL distilled H 2O through the condenser, collecting washings in the flask. Remove the condenser and add a drop of phenolphthalein solution to the flask. ”

“ Ethylene glycol. 2-Propanol/water, 2% (v/v) . Add 2 volumes 2-propanol to 98 volumes freshly distilled water. Helium or nitrogen, purified. Hydrogen, prepurified. Air, filtered. Calibration stock solution, 10 mg/mL, in 2% 2-propanol/water.
1. Sampler: 13-mm glass fiber filter, free of binders, in filter holder (Cat. No. SX00 013 00, Millipore Corp. or equivalent) followed by glass tube, 8 cm long, 8-mm OD, 6-mm ID; two sections of 20/40 mesh silica gel (d = 0.72 g/cm 3; surface area, 720 to 760 m 2/g) separated by 3-mm urethane foam plug (front = 520 mg; backup = 260 mg) . ”

“ Volumetric flasks, 25-, 100-, 200- and 250-mL capacity. 13. Miscellaneous: tweezers, microspatula, rubber suction bulb, wood applicator stick weighing paper, filter paper and filter funnel with stand.
SPECIAL PRECAUTIONS: Bromine is very SAMPLING: corrosive and causes severe burns; vapors are extremely irritating and toxic. Wear gloves and 1. Calibrate each personal sampling pump handle only in a hood. with a representative sampler in line. 2. Sample at an accurately known flow rate Ethylene thiourea is an animal teratogen and between 1 and 3 L/min for a total sample carcinogen [3,4] . ”

“ As explained in the last chapter, after-generation is the secondary production of acetylene which takes place more or less slowly after the primary reaction is finished, proceeding either between calcium hydroxide, merely damp lime, or damp gas and calcium carbide, with an evolution of more acetylene. As it is possible, and indeed usual, to fit a holder of some capacity even to an automatic generator, the simple fact that more acetylene is liberated after the main reaction is over does not matter, for the gas can be safely stored without waste and entirely without trouble or danger. ”

“ Nevertheless, although satisfactory medium-sized vehicular lamps for the generation of acetylene have been constructed, the best way of using acetylene for all such employments as these is to carry it ready made in a state of compression. For railway purposes, where an oil-gas plant is in existence, and where it is merely desired to obtain a somewhat brighter light, the oil-gas may be enriched with 20 per cent. of acetylene, and the mixed gas pumped into the same cylinders to a pressure of 10 atmospheres, as mentioned in Chapter XI. ”

“ If a mixture of acetylene with either of the oxides of carbon is led through a red-hot tube, or if a similar mixture is submitted to the action of electric sparks when confined within a closed vessel at some pressure, a decomposition occurs, the whole of the carbon is liberated in the free state, while the hydrogen and oxygen combine to form water. Analogous reactions take place when either oxide of carbon is led over calcium carbide heated to a temperature of 200° or 250° C., the second product in this case being calcium oxide. ”

“ Looked at from one aspect the holder of a fixed apparatus is merely an economical substitute for the wasteful vent- pipe, because it is a place in which acetylene can be held in reserve whenever the make exceeds the consumption in speed. It is perhaps possible to conceive of a large table acetylene lamp fitted with a water- sealed rising holder; but for vehicular purposes the displacement holder is practically the only one available, and in small apparatus it becomes too minute in size to be of much service as a store for the gas produced by after-generation. ”

“ It is manifest that, where space is to spare, purifiers containing the materials mentioned in Chapter V. can be added to any portable acetylene apparatus, provided also that the extra weight is not prohibitive. Cycle lamps and motor lamps must burn an unpurified gas unpurified from phosphorus and sulphur; but it is always good and advisable to filter the acetylene from dust by a plug of cotton wool or the like, in order to keep the burners as clear as may be. A burner with a screwed needle for cleaning is always advantageous. ”

“ It will be seen that a sufficient removal of these generator impurities need throw no appreciable extra labour upon the consumer of acetylene, for he can readily select a type of generator in which their production is reduced to a minimum; while a cotton-wool or coke filter for the gas, a water washer, which is always useful in the plant if only employed as a non-return valve between the generator and the holder, and the indispensable chemical purifiers, will take out of the acetylene all the remaining generator impurities which need, and can, be extracted. ”

“ The high proportion of carbon dioxide and the low proportion of oxygen in chimney gases makes a mixture of acetylene and chimney gases non-explosive in any proportions, and hence if the air is first wholly or to a large extent expelled from a pipe, main, or apparatus, by means of chimney gases, acetylene may be admitted, and a much shorter time allowed for the expulsion by it of the contents of the pipe, before a light is applied at the burners, &c. ”

“ Since acetylene is more soluble in water than any of its diluents or impurities, sulphuretted hydrogen and ammonia excepted, and since the solubility of all gases increases as the pressure at which they are stored rises, the true acetylene in an acetylene holder dissolves in the water more rapidly and comparatively more copiously than the impurities; and thus the acetylene tends to disappear and the impurities to become concentrated within the bell. Simultaneously at the outer part of the seal, air is dissolved in the water ”

“ One peculiar and noteworthy feature of acetylene, often overlooked, is that the apparatus is constructed by men who may have been accustomed to gas-making plant all their lives, and who may understand by mere habit how to superintend a chemical operation; but the same apparatus is used by persons who generally have no special acquaintance with such subjects, and who, very possibly, have not even burnt coal-gas at any period of their lives. ”

“ During the operation of an acetylene generator a large amount of heat is produced, the quantity of which is beyond human control. It is desirable, for various reasons, that the temperature shall be kept as low as possible. There are three substances present to which the heat may be compelled to transfer itself until it has opportunity to pass into the surrounding atmosphere: the material of which the apparatus is constructed, the gas which is in process of evolution, and whichever of the two bodies-- calcium carbide or water--is in excess in the generator. ”

“ In the United States, at least one railway system (The Great Northern) has a number of its passenger coaches lighted by means of plain acetylene carried in a state of compression in cylinders without porous matter. The gas is generated, filtered from dust, and stored in an ordinary rising holder at a factory alongside the line; being drawn from this holder through a drier to extract moisture, and through a safety device, by a pump which, in three stages, compresses the acetylene into large storage reservoirs. ”

“ For example, in a district to which coal and oil must be brought great distances, the freight on them may be so heavy that--regarding the question as simply one of obtaining light in the cheapest manner--it may be more economical to bring calcium carbide an equal or even greater distance and generate acetylene from it on the spot, than to use oil or make coal-gas for lighting purposes, notwithstanding that acetylene may not be able to compete on equal terms with oil--or coal-gas at the place from which the carbide is brought. ”

“ Once the gas is set free it ranks simply as an inflammable, moisture-laden, somewhat impure, illuminating and heat-giving gas, which has to be dried, purified, stored, and led to the place of combustion; it is in this respect precisely analogous to coal- gas. Even the actual generation is only an exothermic, or heat-producing, reaction between a solid and a liquid, in which rise of temperature and pressure must be prevented as far as possible. Accordingly there is no fundamental or indispensable portion of an acetylene apparatus which lends itself to the protection of the patent laws ”