C36H33CH  :

CH2+R•COOH ; from tertiary alcohols .by the action of acetic anhydride in the presence of a small quantity of sulphuric acid (L . Henry, Comptes rendus, 1907, 144, p . 552) : (CH3)2.C(OH)•CH(CH3)2-->(CH3)2C:C(CH3)2+CH2:C(CH3)•CH (CH3)2; from unsaturated alcohols by the action of metal-ammonium compounds (E . Chablay, Comptes rendus, 1906, 143, p . 123) : 2CH2:CH•CH2OH+2NH3•Na = CH2:CH.CHs +CH2:CH . CH2ONa +NaOH+2NH3; from the lower members of the series by heating them with alkyl halides in the presence of lead oxide or lime: C5H1o+2CH3I=2H1+ C7H14; and by the action of the zinc alkyls upon the halogen substituted olefines . A . Mailhe (Chem . Zeit., 1906, 30, p . 37) has shown that on passing the monohalogen derivatives of the paraffins through a glass tube containing reduced nickel, copper or cobalt at 250° C., olefines are produced, together with the halogen acids, and recombination is prevented by passing the gases through a solution of potash . The reaction probably proceeds thus: MC12+Cn.H2,~1Cl-HCI-i-Cl•M•C„H2„Cl—)MC12+C„H2,,, since the haloid derivatives of the monovalent metals do not act similarly . The anhydrous chlorides of nickel, cobalt, cadmium, barium, iron and lead act in the same way as catalysts at about 300° C., and the bromides of lead, cadmium, nickel and barium at about 320° C .

In their

physical properties, the olefines resemble the normal paraffins, the lower members of the series being inflammable gases, the members from C5 to C,4 liquids insoluble in water,and from C16 upwards of solids . The chief normal members of the series are shown in the table . Name . Formula. point. cg- Boiling-point . C . . C Ethylene . . CH2:CH2 -169° -102.7° (757 mm.) Propylene . . CH3CH:CH2 .. -50.2° (749 mm.) Butylene . . C2H5•CH:CH2 .. -5° Amylene . . C3H7•CH:CH2 ..

39°—40° Hexylene . . C4H9CH:CH2 .. 68°—7o° Heptylene . . C&H11CH:CH2 .. 95° Octylene . . C6H13CH:CH2 .. 122°—123° Decylene . C5H1,CH:CH2 I .. 172° Undecylene . . C5 H19CH :CH2: 84° (18 mm.) Duodecylene . C1oH21CH:CH2 -31° 96° (15 mm.) In chemical properties, however, they differ very markedly from the paraffins . As unsaturated compounds they can combine with two monovalent atoms .

Hydrogen is absorbed readily at ordinary temperature in the presence of platinum black, and paraffins are formed; the halogens (chlorine and bromine) combine directly with them, giving dihalogen substituted compounds; the halogen halides to form monohalogen derivatives (hydriodic acid reacts most readily, hydrochloric acid, least); and it is to be noted that the haloid acids attach themselves in such a manner that the halogen atom unites itself to the carbon atom which is in combination with the fewest hydrogen atoms (W . Markownikow, Ann., 1870, 153, p . 2561 . They combine with hypochlorous acid to form chlorhydrins; and are easily soluble in concentrated sulphuric acid, giving rise to sulphuric acid esters; consequently if the solution be boiled with water, the alcohol from which the olefine was in the first place derived is regenerated . The oxides of nitrogen convert them into nitrosites and nitrosates (0 . Wallach, Ann., 1887, 241, p . 288, &c.; J . Schmidt, Bet., 1902, 35. pp . 2323 et seq.) . They also combine with nitrosyl bromide and chloride, and with many metallic haloid salts (platinum bichloride, iridium chloride), with mercury salts (see K . A . Hofmann and J .

Sand, Ber., 1900, 33, pp . 1340 et seq.), and those with a tertiary carbon atom yield double salts with zinc chloride . Dilute potassium permanganate oxidizes the olefines to glycols (G . Wagner, Ber., 1888, 21, p . 3359) . With ozone they form ozonides (C . Harries, Ber., 1904, 37, p . 839) . The higher members of the series readily polymerize in the presence of dilute sulphuric acid, zinc chloride, &c . For the first member of the series see ETHYLENE . Propylene, C3H6, may be obtained by passing the vapour of trimethylene through a heated tube (S . M .

Tanatar, Ber., 1899, 32, pp . 702, 1965) . It is a colourless

gas which may be liquefied by a pressure of 7 to 8 atmospheres . Butylene, C4H3, exists in three Isomeric forms: normal butylene, C2H5•CH:CH2; pseudo-butylene, CH3.CH:CH•CH3;andisobutylene, (CH3)2C:CH2 . Normal butylene is a readily condensible gas . Two spatial modifications of pseudobutylene, CH3•CH:CH•CH3,are known, the cis and the trans; they are prepared by heating the sodium salts of hydro-iodo-tiglic and hydro-iodo-angelic acids respectively (J . Wislicenus, Ann., 1900, 313, p . 228) . Isobutylene, (CH3)2C: CH2, is formed in the dry distillation of fats, and also occurs among the products obtained when the vapour of fusel oil is led through a heated tube . It is a gas at ordinary temperature, and may be liquefied, the liquid boiling at -5° C . It combines with acetyl chloride in the presence of zinc chloride to form a ketone, which on warming breaks down into hydrochloric acid and mesityl oxide (I . L .

Kondakow, Jour . Russ. phys. chem .

Soc . 26, p . 12) . It polymerizes, giving isodibutylene, C3H16, and isotributylene, C12H24, liquids which boil at 110-113° and 178-181° C . Amylene, CSHlo, exists in five isomeric forms, viz . (n) propylethvlene, CH3•CH2•CH2•CH: CH2; isopropylethylene, (CH3)2CH • CIS : CH2; symmetrical methyl-ethyl-ethylene, CH, . CH : CH • C2H6; unsymmetrical methyl-ethyl-ethylene, (CH3)(C2H5)C:CH2; and trimethyl ethylene, (CH3)2C:CH(CH3) . The highest members of the series as yet known are cerotene, C26H62, which is obtained by the distillation of Chinese wax and is a paraffin-like solid which melts at 57° C., and melene, C3oH60(?), which is obtained by the distillation of bees'-wax . It melts at 62° C . (B .

J .

Brodie, Ann., 1848, 67, p . 210; 1849, 71, p . 156) .