282

ETHYLENE, TRITYLENE, TETRYLENE.

4

2. Ethylene, Olefiant Gas, or Elayl (Є2H, or CH; Rel. wt. 14; Sp. gr. 0978) has already been described (487). It is produced, abundantly mixed with other hydrocarbons, during the dry distillation of pit coal, and of many fatty and resinous bodies. It is also present in small quantity, amongst other bodies, in the product of the dry distillation of baric formiate (Ba 2 ЄHO). Olefiant gas is the principal luminous constituent of coal gas. When required in a state of purity it is always obtained by decomposing alcohol by means of sulphuric acid in excess.

Berthelot has shown that olefiant gas and marsh gas, in small quantity, diluted largely with free hydrogen, may be obtained by passing a current of sulphuretted hydrogen mixed with the vapour of carbonic disulphide over finely divided copper heated to dull redness; a process which possesses some interest from the circumstance that it indicates a method, though an imperfect one, for procuring from compounds of inorganic origin, hydrocarbons, which previously had been obtained only by the decomposition of organic products.

6

6

(1210) 3. Tritylene or Propylene (H ̧ or CH ̧), Sp. gr. 1'498; Rel. wt. 21.-Reynolds obtained this gas mixed with marsh gas and some other compounds, by decomposing the vapours of fousel oil by transmission through a porcelain tube heated to redness; but it is best procured by the action of phosphorus diniodide (PI) upon glycerin. Pure tritylene is readily obtained for laboratory use by distilling 1 part of allyl iodide (1472) with 5 parts of mercury and 2 of concentrated hydrochloric acid. An ounce of allyl iodide treated thus yields more than 150 cubic inches of the gas; ЄHI+HCl+2 Hg=Є2Hq+HgI+HgCl. Tritylene remains gascous at -40°, but it may be liquefied under pressure. Its odour resembles that of olefiant gas. It is dissolved to some extent by essence of turpentine, ether, chloroform, and benzol, each of which absorbs from 13 to 18 times its volume of this gas.

6

Oil of vitriol readily takes up about 200 times its volume of the gas, converting it into trityl-sulphuric acid. Hydrochloric acid also absorbs it, and forms trityl-hydrochloric ether or trityl chloride, HCl. The action of iodine and of bromine upon tritylene yields compounds of considerable interest in connexion with the allylic series (1469).

4

(1211) 4. Tetrylene, Butylene, or Oil Gas [(EH ̧); Sp. gr. 1854; Rel. wt. 28], has been already described (496). This gas was ascertained by Faraday to be one of the products furnished by the destructive distillation of oil; and it appears also to be contained amongst the products of the distillation of caoutchouc.

AMYLENE, HEXYLENE, HEPTYLENE, ETC.

283

It was afterwards obtained by Kolbe during the voltaic decomposition of potassic valerate; and by Wurtz as one of the compounds produced by the action of zincic chloride upon tetrylic alcohol; and it has been procured from erythrite (1243) by decomposing it with hydriodic acid, and treatment of the distillate with oxide of silver (v. Luynes).

5. Amylene [(ЄH10), Boiling pt. 102° (39° C.)] may be procured by decomposing amyl chloride with fused caustic potash, or by distilling a concentrated solution of zincic chloride with fousel oil; or by acting upon amyl iodide in a sealed tube with an amalgam of zinc in the latter case it is mixed with amyl hydride. Amylene is a colourless, very mobile liquid, with the odour of decaying cabbage. An attempt was made to substitute it for chloroform as an anesthetic in surgical operations; but its use has been abandoned, as in some cases its employment has occasioned fatal results.

(1212) 6. Hexylene or Caproylene (EH); Boiling pt. 160° (71° C.) (G. Williams). This compound is a colourless liquid, lighter than water, of a nauseous, penetrating, alliaceous odour. It is scarcely soluble in water, but freely so in alcohol and in ether. It appears to act injuriously when respired. It is procured during the destructive distillation of several fatty acids (Fremy), and is stated by G. Williams to be one of the products obtained from the distillation of the Boghead cannel, and may be procured by acting upon mannite with hydriodic acid, decomposing the ẞ hexyl-iodide so obtained, by acting upon it with

oxide of silver :

2ЄH1I + Ag20 = 2 AgI + H20 + 2¤ ̧H,

6 13

6 12.

7. Heptylene or Enanthylene (E,H14); Sp. gr. of liquid 0718; of vapour 332; Rel. wt. 49; Boiling pt. 210° (99° C.)—This body was also reported by Williams to occur in the Boghead distillate; and was likewise obtained by Bouis from the distillation of œnanthol (1255) with phosphoric anhydride.

8. Octylene or Caprylene [(E,H16), Boiling pt. 257° (125° C.)] was obtained as a colourless liquid, insoluble in water, by distilling the castor oil (octylic) alcohol with sulphuric acid, or with zincic chloride. The action of potassium or of mercury on chloride or iodide of octyl gives rise to the same compound :

2 ¤ ̧H1I+2 Hg=2 €2H16+2 HgI+ H2.

16

9. Nonylene, or Elaene (Є,H18), was obtained mixed with hexylene, by Fremy, during the distillation of several fatty acids. 10. Paramylene (E10H20) is procured by the distillation of

284

DIATOMIC ALCOHOLS, OR GLYCOLS.

fousel oil with phosphoric anhydride in excess. Its boiling point is as high as 320° (160° C.), that of amylene being only 102°. Fousel oil, it will be seen, gives rise to at least three isomeric hydrocarbons of this series, viz., to tritylene, amylene, and paramylene, and even, as Balard believes, to one of still greater density. Cerene (CH) and Melene (Hoo), two solid hydrocarbons, obtained by Brodie from wax, probably belong to this series (1226).

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60

(B.) DIATOMIC ALCOHOLS, OR GLYCOLS.

(1213) THE GLYCOLS, as it has already been stated, are a purely artificial class of compounds, the existence of which, as an intermediate series between the monobasic alcohols and the glycerins, was inferred by Wurtz. They are formed from ethylene and its homologous dyad hydrocarbons, by preparing the dibromide or the diniodide of the olefine, and decomposing it with potassic or argentic acetate, and obtaining the monacetate or diacetate of the glycol (1217), and on distilling these compounds with baric hydrate, or caustic potash, the corresponding glycol is liberated :—

DIATOMIC ALCOHOLS, OR GLYCOLS.

285

Each of these glycols corresponds to a monatomic alcohol

which contains 1 atom less of oxygen :

In the monatomic alcohols, a single typical atom of hydrogen only admits of displacement by an acid radicle; whereas in the diatomic alcohols, or glycols, two typical atoms of hydrogen may be displaced by a corresponding number of atoms of an acid radicle. The glycols are therefore to be regarded as formed upon the type of 2 atoms of water, the two atoms being bound into a single molecule by the displacement of two atoms of hydrogen by one atom of the dyad hydrocarbon; as for example :—

Glycolic acid.
H

:

Ꮎ

Ꮎ

H

H

H

The glycols when exposed to the action of air or oxygen under the influence of platinum black, or when heated with caustic potash, speedily become oxidized, and furnish acids which belong either to the lactic or to the oxalic acid series ::

The glycols exhibit an anomaly in their boiling points; as in the first four terms, instead of rising, the boiling point becomes progressively lower. It will be unnecessary to enter minutely into a description of the glycols, as the general properties of these compounds will be sufficiently understood from the following account of

It is indeed probable that there is a class of compounds represented by glyoxal, intermediate between these glycols and the glycolic or lactic acid series, corresponding to the aldehyds of the monobasic alcohols (Debus); and the researches of Debus have further rendered it not unlikely that between the lactic

286

GLYCOL, OR ETHYLENE ALCOHOL.

ethylic glycol; for further details the reader is referred to Wurtz's papers on the subject. (Ann. de Chimie, III. lv. 400, IV. iii. 129.)

(1214) Glycol or Ethylene Alcohol, [Є,H ̧Ð ̧= H,

Boiling pt. 387° (197° C.); Sp. gr. of liquid 1125; of vapour 2164; Rel. wt. 31.-When ethylene diniodide (Є,H,I,) is triturated with anhydrous silver acetate, in the proportion of 10 'parts or one atom of the former to 12 parts or 2 atoms of the latter, and the mixture is introduced into a flask, a brisk reaction speedily begins to take place; the temperature rises, and the mass becomes yellow, owing to the formation of silver iodide; while carbonic anhydride and olefiant gas, the result of a secondary decomposition, are evolved in abundance. The product of this reaction is then to be submitted to distillation, and the portions which come over between 320° and 400°, are to be collected separately, and rectified from litharge. By repeating the distillation and collecting the product in separate portions, a liquid is at length obtained which boils at 365° (185° C.), and may be distilled without undergoing decomposition. This liquid is the diacetate of glycol, and if the secondary products of the reaction be neglected, its formation may be thus represented :

and the oxalic series of acids is a third intermediate group of acids, the representative of which is the glyoxalic (1151), so that the different stages of the oxidation of glycol would be the following:

The relation of these bodies may further be thus represented :