Carbon disulphide, solubility

The solubility of cyclonite (in g per 100 g of solution) in other solvents as reported by various other authors is given in Table 17. It is insoluble in carbon disulphide, soluble in hot aniline and phenol. 

When sulphur is melted viscosity changes occur as the temperature is raised. These changes are due to the formation of long-chain polymers (in very pure sulphur, chains containing about 100 (X)0 atoms may be formed). The polymeric nature of molten sulphur can be recognised if molten sulphur is poured in a thin stream into cold water, when a plastic rubbery mass known as plastic sulphur is obtained. This is only slightly soluble in carbon disulphide, but on standing it loses its plasticity and reverts to the soluble rhombic form. If certain substances, for example iodine or oxides of arsenic, are incorporated into the plastic sulphur, the rubbery character can be preserved. 

Like bromine, iodine is soluble in organic solvents, for example chloroform, which can be used to extract it from an aqueous solution. The iodine imparts a characteristic purple colour to the organic layer this is used as a test for iodine (p. 349). NB Brown solutions are formed when iodine dissolves in ether, alcohol, and acetone. In chloroform and benzene a purple solution is formed, whilst a violet solution is produced in carbon disulphide and some hydrocarbons. These colours arise due to charge transfer (p. 60) to and from the iodine and the solvent organic molecules. 

Selection of solvents. The choice of solvent will naturally depend in the first place upon the solubility relations of the substance. If this is already in solution, for example, as an extract, it is usually evaporated to dryness under reduced pressure and then dissolved in a suitable medium the solution must be dilute since crystallisation in the column must be avoided. The solvents generally employed possess boiling points between 40° and 85°. The most widely used medium is light petroleum (b.p. not above 80°) others are cycZohexane, carbon disulphide, benzene, chloroform, carbon tetrachloride, methylene chloride, ethyl acetate, ethyl alcohol, acetone, ether and acetic acid. 

Pheiiyl iso-thiocyanate may be prepared in quantity directly from aniline. Aniline, carbon disulphide and concentrated aqueous ammonia react to form the sparingly soluble ammonium phenyldithiocarbamate this is decomposed by lead nitrate to produce phenyl iso-thiocyanate ... 

The commercial product, m.p. 53-55°, may be used. Alternatively the methyl -naphthyl ketone may be prepared from naphthalene as described in Section IV,136. The Friedel - Crafts reaction in nitrobenzene solution yields about 90 per cent, of the p-ketone and 10 per cent, of the a-ketone in carbon disulphide solution at — 15°, the proportions ore 65 per cent, of the a- and 35 per cent, of the p-isomer. With chlorobenzene ns the reaction medium, a high proportion of the a-ketone is also formed. Separation of the liquid a-isomer from the solid p-isomer in Such mixtures (which remain liquid at the ordinary temp>erature) is readily effected through the picrates the picrate of the liquid a-aceto compound is less soluble and the higher melting. 

Immiscible Liquids (i.c.,liquids very sparingly soluble in each other, such as water with carbon disulphide), in which the total pressure is equal to the sum of the pressures of the pure liquids. 

Alkyl and glycosyl isocyanates and isothiocyanates are produced in good yield under phase-transfer catalytic conditions using either conventional soluble catalysts or polymer-supported catalysts [32, 33]. Acyl isothiocyanates are obtained under similar conditions [34]. A-Aryl phosphoramidates are converted via their reaction with carbon disulphide under basic conditions into the corresponding aryl isothiocyanates, when the reaction is catalysed by tetra-n-butylammonium bromide [35]. 

The more powerful the solvent-solute interaction, the more pronounced will solvent broadening be for this reason, saturated hydrocarbons are preferred as solvents for spectroscopy, and such strongly interacting media as methylene chloride and chloroform are to be avoided. It is obvious that the requirements of spectroscopy and those of solubility are in direct conflict. Carbon tetrachloride and carbon disulphide are often used as compromise solvents ) (although both of these react thermally or photochemically with many carbonyl complexes) but are generally inferior spectroscopically to alkanes. 

Quinoline, when exposed to light, forms first a yellow liquid, and slowly a hrown liquid. It is only slightly soluble in water hut dissolves readily in many organic solvents. Isoquinoline crystallizes to platelets and is sparingly soluble in water but dissolves well in ethanol, acetone, diethyl ether, carbon disulphide and other common organic solvents. It is also soluble in dilute... 

The increase in the solubility of bromine in soln. of ammonium salts is very marked, as is also the case with the alkali chlorides. The case with the alkali bromides is specially interesting. The solubilities by F. P. Worley are indicated in Table IX. The marked increase in the solubility of bromine in soln. of potassium bromide was attributed by M. Roloff to the formation of molecules of KBr3. He shook up a soln. of bromine in carbon disulphide with water and with an aq. soln. of potassium biomide, and measured the concentration of the bromine in the two layers. M. Wildermann has shown that the density of bromine vapour over a soln. of potassium bromide sat. with bromine is the same as over water sat. with bromine, indicating that the cone, of the free bromine in all the aq. soln. is the same, and any excess in the presence of potassium bromide must be united with the potassium bromide. All the bromine dissolved by a soln. of potassium bromide can be removed... 

When iodine is dissolved in hydriodic acid or a soln. of a metallic iodide, there is much evidence of chemical combination, with the formation of a periodide. A. Baudrimont objected to the polyiodide hypothesis of the increased solubility of iodine in soln. of potassium iodide, because he found that an extraction with carbon disulphide removed the iodine from the soln. but S. M. Jorgensen showed that this solvent failed to remove the iodine from an alcoholic soln. of potassium iodide and iodine in the proportion KI I2, and an alcoholic soln. of potassium iodide decolorized a soln. of iodine in carbon disulphide. The hypothesis seemed more probable when, in 1877, G. S. Johnson isolated cubic crystals of a substance with the empirical formula KI3 by the slow evaporation of an aqueous-alcoholic soln. of iodine and potassium iodide over sulphuric acid. There is also evidence of the formation of analogous compounds with the other halides. The perhalides or poly halides—usually polyiodides—are products of the additive combination of the metal halides, or the halides of other radicles with the halogen, so. that the positive acidic radicle consists of several halogen atoms. The polyiodides have been investigated more than the other polyhalides. The additive products have often a definite physical form, and definite physical properties. J. J. Berzelius appears to have made the first polyiodide—which he called ammonium bin-iodide A. Geuther called these compounds poly-iodides and S. M. Jorgensen, super-iodides. They have been classified 1 as... 

Nitrogen sulphide is insoluble in water, slightly soluble in alcohol and ether, somewhat soluble in carbon disulphide and benzene. At room temperature it is hydrolysed to some extent by water to form free sulphur, sulphur dioxide and ammonia. Its specific gravity is 2.22. 

By rapidly cooling the fluid mixture it is possible to minimise the readjustment of the equilibrium and to attain a solid condition in which tire original proportions of the mixture are approximately retained in the solid state tire allotropic change is so very slow as to allow careful and fairly prolonged examination of the mixture. It is then found that, the normal mobile liquid constituent (S ) has given rise to crystalline sulphur, soluble in carbon disulphide, whereas the dark-coloured viscous constituent (S ) has produced an amorphous solid, insoluble in this solvent4 (see also p. 10). A rough analysis of molten sulphur in... 

If sulphur is heated to 180° C. and then cooled, it becomes more soluble in carbon disulphide also a saturated solution of sulphur chloride in toluene at the ordinary temperature will, after being heated to the neighbourhood of 180° C. and cooled again, dissolve yet more sulphur. These observations led to the discovery of a third modification in molten sulphur. This form of sulphur, distinguished as n-sulplmr, is formed to some extent when ordinary sulphur is heated to 125° C. The optimum temperature for its formation is near 180° C., when the liquid contains approximately 6-5 per cent, of S with 20-5 per cent, of... 

Carbon disulphide is an excellent solvent for rhombic sulphur, the proportions soluble in 100 parts by weight of the solvent at different temperatures being given in the following table the highest temperature is the boiling-point of the saturated solution under ordinary atmospheric pressure.4... 

Insoluble Amorphous Sulphur is produced, usually together with some sulphur soluble in carbon disulphide, by many reactions in which sulphur is set free. The slow decomposition of sulphur chloride or bromide by water, which may require several days for completion, gives a very stable form of insoluble sulphur.8 The action of mineral acids on... 

When prepared by chemical methods, y-sulphur is frequently accompanied by an apparently amorphous powder which is readily soluble in carbon disulphide. This has been regarded, by some investigators, as a definite form of sulphur and given the name soluble amorphous sulphur 2 in reality, however, it consists of minute spheroidal crystals of rhombic sulphur possibly together with nacreous sulphur.3 Another so-called modification of amorphous sulphur, described 4 as soluble in carbon disulphide but becoming insoluble on evaporation of the solvent, is probably no distinct form, but only a mixture of y-sulphur with finely divided crystalline sulphur. 

TT-Sulphur, a deep yellow amorphous form of sulphur soluble in carbon disulphide, has already been described (p. 17). 

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