Vanadium dichloride, VC12, is a green crystalline solid obtained when the tetrachloride is reduced with hydrogen at a dull red heat.
Molybdenum monoxide, MoO.n(H 2 O), is a black powder obtained when the dichloride is boiled with concentrated potash solution.
Molybdenum dichloride (MoC1 2) 3 or Cl 4 Mo 3 C1 2 (chlormolybdenum chloride), is prepared (together with some tetrachloride) by heating the trichloride in a stream of carbon dioxide (C. W.
Germanium dichloride, GeCl2, and germanium chloroform, GeHCl3, have also been described.
Thionyl chloride, SOC1 21 may be obtained by the action of phosphorus pentachloride on sodium sulphite; by the action of sulphur trioxide on sulphur dichloride at 75 -80° C. (Journ.
Disulphuryl chloride, S 2 O 5 C1 2, corresponding to pyrosulphuric acid, is obtained by the action of sulphur trioxide on sulphur dichloride, phosphorus oxychloride, sulphuryl chloride or dry sodium chloride: 650 3- + 2POC1 3 = P 2 O 5 + 3S 2 O 5 C1 2; S2C12+ 5503 = S 2 0 5 C1 2 + 550 2; SO 3 + SO 2 C1 2 = S 2 0 5 C1 2; 2NaC1 + 3SO 3 = S 2 0 5 C1 2 -1 Na 2 SO 4.
Ruthenium dichloride, RuC1 2, is obtained (in solution) by reducing the sesquichloride by sulphuretted hydrogen or zinc. It is stable in the cold.
Instances had already been recorded of cases where a halogen element replaced hydrogen with the production of a closely allied substance: Gay Lussac had prepared cyanogen chloride from hydrocyanic acid; Faraday, hexachlorethane from ethylene dichloride, &c. Here the electronegative halogens exercised a function similar to electro-positive hydrogen.
This tetrahedral configuration is based on the existence of only one methylene dichloride, two being necessary if the carbon valencies were directed from the centre of a plane square to its corners, and on the existence of two optical isomers of the formula C. A.
It is remarkable that the position of the halogen in the molecule has no effect on the heat of formation; for example, chlorpropylene and allylchloride, and also ethylene dichloride and ethylidene dichloride, have equal heats of formation.
If a suspension of lead dichloride in hydrochloric acid be treated with chlorine gas, a solution of lead tetrachloride is obtained; by adding ammonium chloride ammonium plumbichloride, (NH 4) 2 PbC1 6, is precipitated, which on treatment with strong sulphuric acid yields lead tetrachloride, PbC1 4, as a translucent, yellow, highly refractive liquid.
Titanium dichloride, TiC1 21 obtained by passing hydrogen over the trichloride at a dull red heat, is a very hygroscopic brown powder which inflames when exposed to air, and energetically decomposes water.
On heating piperidine with phosphorus pentachloride to 200°C. in a sealed tube pentamethylene dichloride is obtained, and this on treatment with potassium phthalimide gives a condensation product of composition, C 6 H 4 [CO] 2 N(CH 2) 5 N[CO] 2 C 6 H 4, which is finally hydrolysed by hydrochloric acid.
Gold dichloride, probably Au 2 C1 4, =Au.AuC1 4, aurous chloraurate, is said to be obtained as a dark-red mass by heating finely divided gold to 140°- 170° in chlorine.
The dichloride, BiC1 2, is obtained as a brown crystalline powder by fusing the metal with the trichloride, or in a current of chlorine, or by heating the metal with calomel to 250°.
Two chlorides are known, the dichloride, TeC121 and the tetrachloride, TeCl 4.
The dichloride is an amorphous, readily fusible, almost black solid.
The tetrachloride is a white crystalline solid which is formed by the action of chlorine on the dichloride or by sulphur chloride on the element.
By heating with sodium amalgam and separating with hydrochloric acid, the dichloride, TaC1 2.2H 2 O, is obtained as emerald green hexagonal crystals.
Osmium dichloride, OsC1 21 is obtained as a dark coloured powder when the metal is heated in a current of chlorine.
The tetrachloride, OsC1 41 is obtained as a dark red sublimate (mixed with the dichloride) when osmium is l}eated in dry chlorine.
It readily forms addition products with chlorine and with hydrogen; the dichloride, C10H8C12, is obtained as a yellow liquid by acting with hydrochloric acid and potassium chlorate; the solid tetrachloride, C,o 11 8 C1 4, results when chlorine is passed into naphthalene dissolved in chloroform.
By heating gallium in a regulated stream of chlorine the dichloride GaC1 2 is obtained as a crystalline mass, which melts at 164° C. and readily decomposes on exposure to moist air.
The dichloride, WC1 2, is an amorphous grey powder obtained by reducing the hexachloride at a high temperature in hydrogen, or, better, by heating the tetrachloride in a current of carbon dioxide.
Braun (Ber., 1904, 37, p. 2915) showed that benzoyl piperidine, when heated with phosphorus pentachloride to 200° C. in sealed tubes, yields benzonitrile, and pentamethylene dichloride, thus leading to a simple method of preparing pentamethylene compounds.
Fournier (Comptes rendus, 1901, 150, p. 102) obtained phosphorus dichloride, P2C14, as a colourless, oily, strongly fuming liquid, freezing at -28° and boiling at 180° with decomposition.
The pure metal may be obtained by reducing vanadium dichloride in hydrogen, the operation being exceedingly difficult (for details, see Roscoe's original papers).
Three chlorides of indium are known: the trichloride, InC13j a deliquescent salt, formed by heating a mixture of the oxide and carbon in a current of chlorine; the dichloride, InCl2, obtained by heating the metal in hydrochloric acid gas; and the monochloride, InCl, which is prepared by distilling the vapour of the dichloride over metallic indium.