Petroleum disulphides

The base lubricant is usually a petroleum oil while the thickener usually consists of a soap or soap mixture. In addition they may contain small amounts of free alkali, free fatty acid, glycerine, anti-oxidant, extreme-pressure agent, graphite or molybdenum disulphide. 

The inflammable solvents most frequently used for reaction media, extraction or recrystallisation are diethyl ether, petroleum ether (b.p. 40-60° and higher ranges), carbon disulphide, acetone, methyl and ethyl alcohols, di-Mo-propyl ether, benzene, and toluene. Special precautions must be taken in handling these (and other equivalent) solvents if the danger of Are is to be more or less completely eliminated. It is advisable to have, if possible, a special bench in the laboratory devoted entirely to the recovery or distillation of these solvents no flames are permitted on this bench. 

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. 

For petroleum spirit, a petroleum mixture or carbon disulphide, check the road tanker for compliance with Schedule 2 Construction of Road Tankers. ... 

Molybdenum is also used as a catalyst in petroleum refining, as a pigment for paints and printer s ink, and as a high-temperature lubricant (molybdenum disulphide-MoS ) for use by spacecraft and high-performance automobiles. 

Petroleum ether with acetic acid, acetone, benzene, carbon disulphide or ethyl ether. 

Methanol with carbon disulphide, cyclohexane or petroleum ether. 

Di-m-tolyl tellurium dichloride, (CH3.C6H4)2TeCl2,3 is formed when di-m-tolyl telluride in ether solution is chlorinated. The product appears as needles, sintering at 128° C. and melting at 131° to 132° C., readily soluble at the ordinary temperature in benzene, toluene, xylene, carbon disulphide, chloroform or carbon tetrachloride, less soluble in methyl or ethyl alcohol, insoluble in petroleum. When the dichloride is boiled with water a white powder separates on cooling this melts at 87° C. to a viscous oil which gradually becomes watery. Analysis shows this product to be a basic salt and not the anhydride. 

This is isolated in the usual manner from di-p-anisyl telluride. It sinters at 180° C. and melts at 183° to 184° C. The crystals consist of four-sided columns, easily soluble in warm benzene, toluene, xylene or chloroform, less soluble in alcohols, carbon disulphide or carbon tetrachloride, insoluble in petroleum ether. Boiling with water for a prolonged period yields a product of which the tellurium content lies between that of the dichloride and that of the oxide. 

Di-m-xylyl tellurium di-iodide, [(CH3)2C6H3]2TeI2, forms ruby-red columns, sintering at 179° C. and melting at 181° to 182° C. It dissolves in benzene, toluene, xylene, chloroform or carbon disulphide, is sparingly soluble in ether or ethyl alcohol, and insoluble in methyl alcohol or petroleum ether. 

Great care is necessary in the use of ether, light petroleum, carbon disulphide, acetone, alcohol, benzene, etc., as the vapours of these are highly inflammable. They should always be distilled from a water bath and be collected in the apparatus shown on p. 20. Special care is necessary with carbon disulphide, as its vapour inflames in contact with a warm surface, even in the absence of a flame. 

Chromatographic Analysis.—Chromatographic adsorption-analysis, the most delicate method of separation of closely related compounds, depends on the simultaneous adsorption and separation of mixtures of organic compounds, such as natural dyes, biochemical products, isomerides, hydrocarbons, etc., in suitable solvents such as petroleum, ether, chloroform, carbon disulphide and water. 

This is the solid residue left when turpentine is distilled for the preparation of oil of turpentine. It consists essentially of resin acids and their oxidation products and forms brittle, translucent masses with a peculiar resinous odour and a colour varying from pale yellow to dark brown D = 1 05-1 085. It is readily soluble in alcohol (1 part in 10 parts of 70% alcohol) and dissolves also in methyl or amyl alcohol, ether, acetone, benzene, chloroform, carbon disulphide or oil of turpentine in petroleum ether it is not completely soluble. It is easily and completely saponified by caustic soda solution. Addition of a drop of concentrated sulphuric add to a solution of a small quantity of colophony in acetic anhydride produces an intense violet-red or purple coloration, soon changing to yellowish-brown. Different types or grades of colophony are sold, distinguished mainly by the colour and origin. 

It is insoluble in water and partially soluble in anhydrous alcohol or ether it dissolves in benzene, carbon disulphide or chloroform and, less easily, in petroleum ether. 

Notes. (1) Pyridine was stored over potassium hydroxide and distilled immediately before use. The tris(cyclohexyl)phosphine-carbon disulphide complex is prepared by the method of K. Issleib and A. Brack.9 This involves the addition of carbon disulphide to an ethereal solution of tricyclohexylphosphine, the precipitate is washed with light petroleum (b.p. 50-60 °C), and recrystallised under a nitrogen atmosphere from either methanol, ethanol or dioxane the complex has m.p. 118 °C. 

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