The latter, C2H,PtCl2, KCl,H,O, yields on heating ethylene gas, whilst potassic platinous chloride remains. Propylene and isoamylene also yield similar compounds; C3H,PtCl2,KCl, H2O crystallises in yellow tables; CH10PtCl2, KCl, H2O, in golden yellow scales resembling plumbic iodide.

Ethylene iron chloride, C2H,FeCl2,2H2O. This body is obtained on heating a solution of ferric chloride in ether to 140°-150°, better if some phosphorus dissolved in carbonic disulphide be added, the heat of the water bath then sufficing. The liquid fills with hard, nearly colourless crystals of the above formula. These become somewhat damp in the air, and oxidise, turning yellow. They dissolve readily in water, and lose their water of crystallisation at 100°. Their whole behaviour characterises them as a ferrous compound, so that their CH

composition cannot be expressed by the formula |

CI

Fe

but is

CH2

Cl

Their formation is expressed by the

equation:

2(C2H)2O + Fe2Cl = 2C2H,FeCl2 + 2C2H ̧.OH + 2C12,

the chlorine acting on the resulting alcohol or the excess of ether either directly or after combination with phosphorus.

TRIPLE SUBSTITUTION PRODUCTS OF THE

PARAFFINS.

DERIVATIVES OF THE TRIVALENT RADICALS, CnH2n- 1o

1.

534. The replacement of three hydrogen atoms in a paraffin by other elements or compound radicals yields, in accordance with the chemical position of the replacement, the following groups of compounds :

1. If the three substitution positions are on a single, necessarily terminal carbon atom, there occur derivatives of the hydrocarbon radical:

whose simplest oxygen compounds are the organic acids CnH2nO2 or

CnH2n+1

مين

он

The first member of the series is the mono-carbonide formyl H.C:

2. If two substitution positions occur on one, the third on a second carbon atom, two cases may occur.

a. The double replacement occurs, as in the aldehydes, on a terminal carbon atom:

CnH2n'
H

The compounds of this class are those of the mono-substituted aldehyde radicals. The first member of the series is a dicarbonide :

CH2.
CH:

b. In the derivatives of the mono-substituted ketone radicals the

double substitution has occurred on an intermediate secondarily united carbon atom:

CnH2n

یا

CnH2n+1

All compounds of this class must contain more than two carbon

atoms.

3. If, finally, all these substitution positions occur on three different carbon atoms, there result derivatives of the trivalent alcohol radicals, whose first member is the tricarbonide glyceryl or allyl :

DERIVATIVES OF THE ACID RADICALS, CnH2n+1.C;.

535. The first member of this series, strictly speaking, is the radical of acetic acid, CH3.C:(acetyl), but that of formic acid, H.C: (formyl), shows such analogy that it must be included in the group. Up to the tricarbon radical of propionic acid, CH3.CH2.C:, no isomerism occurs, this commencing only with a carbon contents of four atoms:

Their number is always equal to the number of primary alcohols of equal carbon contents.

536. By far the larger number of the acid radical derivatives contain an oxygen atom in divalent union, oxidised radicals, CnH2n+1.CO, acidoxyls, thereby resulting, whose hydrates are the monobasic organic acids, CnH2n+1.CO.OH. In these hydrates not only the halogen atom, but also the whole hydroxyl group is readily replaced by other elements, whilst the oxygen atom in diad union is only eliminated or replaced with difficulty.

Halogen and Nitryl Compounds.

537. The number of known halogen compounds of the acidyl residue CnH2n-1 is very small, consisting of the trihaloids of formyl and acetyl.

The trichlorides and tribromides are obtained directly by the action of the respective halogens upon the paraffins, but are more readily prepared from the chlorides and bromides of the respective primary alcohols and the dihaloids of the aldehyde radicals:

CnH2n+1.CH2Cl + 2C12 = CnH2n+1.CCl3 + 2HC1

CnH2n+1.CHC12 + Cl2 = CnH2n+1.CCl3 + HCl.

They can be partly obtained from the acidoxyl chlorides, CnH2n+1.COC1, by heating with excess of phosphoric chloride : CnH2n+1.COC1 + PC15 = POCl3 + CnH2n‍+1. 1.CC13.

The yield, however, is but small, the high temperature required for the reaction leading to further decompositions.

Formyl Compounds.

538. Formyl trichloride, or chloroform, CHCl3, trichlor methane. Chloroform is obtained by the direct action of chlorine gas on methane, methylic chloride, and methene dichloride, and further by the distillation of wood spirit, alcohol, acetone, acetates, and several other organic bodies with chloride of lime, also, together with potassic formate, by heating chloral with solution of potassic hydrate:

CC1,.CHO + HOK = CC1,H + CHO.OK.

The latter method has been employed of late for the manufacture of pure chloroform; in large quantity it is still obtained from alcohol. For this purpose three parts of alcohol, 100 parts of water, and fifty parts of chloride of lime are submitted to distillation. In the receiver, which must be kept well cooled, two layers of liquid collect, the under consisting mainly of chloroform. This is shaken with water and then purified by distillation over concentrated sulphuric acid.

Chloroform is a colourless, strongly refractive liquid, not miscible with water, of sp. gr. 1.52 at 0°, boiling point 61°, and of vapour density 4.199. It is uninflammable in air, has an agreeable odour, a sweet taste, and on long inhaling of its vapour produces loss of consciousness and insensibility to pain. It is therefore employed as an anæsthetic agent.

Chloroform is further employed as a solvent for fats, resins, caoutchouc, &c. Sulphur, phosphorus, and iodine also dissolve in it, the latter with violet colour.

Ammonia converts chloroform at 180° into ammonic chloride and cyanide :

HCC13+5NH2 = 3NH4Cl + (NH1)CN ;

by addition of potassic hydrate ammonic cyanide is obtained at considerably lower temperatures :

HCC1, + 2NH3 + 3KOH = 3KCl + (NH1)CN + 3H2O. Alcoholic potassic hydrate converts it into potassic chloride and formate:

HCC1, + 4HOK =3KCl + HCO.OK + 2H2O,

or in presence of alkylamines gives the alkyl isocyanates (§ 278).

The chloroform of commerce, especially when prepared from alcohol, is frequently contaminated with other bodies, such as alcohol, aldehyde, ethylidene dichloride, &c., and then readily becomes useless on keeping. Pure chloroform must be without action on vegetable colours, must not colour a mixture of sulphuric and chromic acids

green, must not turn brown with sulphuric acid or potassic hydrate, and must not suddenly evolve inflammable gases (monochlor ethylene) when heated with alcoholic potassic hydrate.

By the action of chlorine on boiling chloroform in sunlight

Carbonic tetrachloride, or tetrachlor methane, CCl4, is obtained as a colourless oil of ethereal odour, of sp. gr. 1.56 and of boiling point 78°. The same compound is formed by passing chlorine into a heated mixture of carbonic disulphide and antimonic chloride :

The product is distilled, and that portion passing over below 100° treated with solution of potassic hydrate in order to decompose the sulphur chloride.

Potassic hydrate decomposes an alcoholic solution of carbonic tetrachloride into potassic chloride and carbonate :

CC1, + 6KOH= 4KCl + K2CO2+ 3H2O;

and nascent hydrogen converts it into chloroform, methene dichloride, methylic chloride, and even methane:

CC1, + 2H = CHCl3 + HCl, &c.

Methane is also obtained when the vapour of tetrachlor methane mixed with hydrogen is passed through red-hot tubes :

CCl4 + 4H2 = CH1 + 4HCl.

539. Formyl tribromide, bromoform, CHBr3, is obtained, similarly to chloroform, by the action of bromine and potassic hydrate upon methylic and ethylic alcohols, acetone, &c. It closely resembles chloroform, but has a higher sp. gr. (2·9), boils between 150° and 152°, and solidifies at 9° to a colourless crystalline mass.

On heating bromoform or carbonic disulphide with bromine, carbonic tetrabromide, CBr4, is obtained; it melts at 92.5°, is insoluble in water, and forms tabular crystals.

540. Formyl triiodide, or iodoform, CH,I, is obtained by heating methylic and ethylic alcohols, ether, acetone, sugar, dextrine, albuminoids, &c., with potassic hydrate and iodine. It separates thereby in yellow leafy crystals, which on recrystallisation from ether form large, citron-yellow, brilliant, hexagonal tables. It is insoluble in water, but readily soluble in alcohol and ether. At ordinary temperatures it evaporates slowly and smells like saffron. It evaporates readily and unchanged with aqueous vapour and melts at 119°. Its reactions resemble those of chloroform. Its convertibility into methene compounds has been already mentioned (§ 380).

If iodoform be distilled with plumbic, mercuric, or zinic chlorides, formyl dichloroiodide, or dichloriodoform, CHC1,I, passes over as a yellow-coloured oil, boiling at 131°. Bromine converts iodoform into formyl dibromiodide, or dibromiodoform, CHBr2I.

541. Nitroform, or trinitro-methane, CH(NO2)3, is formed by the action of the most concentrated nitric acid upon the bile acids, upon œnanthol, and some organic bodies. It is usually prepared from triaceto-nitrile (see later). On boiling this with water or alcohol, carbonic anhydride is evolved, and the solution evaporated on com