Carbon disulphide, purification

A solution of sodium methoxide, prepared from sodium (23 g) and dry methanol (500 mL), was added drop-wise at 0 °C to a stirred suspension of aminoacetonitrile hydrochloride (18, 100 g, 1.08 mol) in dry methanol (100 rnL). After stirring for 2 h at rt the precipitated sodium chloride was filtered off and the filtrate concentrated in vacuo. EtOAc (20 mL) was added and evaporated under reduced pressure to remove all traces of methanol. The oily residue was dissolved in dry EtOAc (100 mL) and anhydrous sodium sulfate added. After cooling, the precipitate was filtered off. The solution of crude aminoacetonitrile was used without further purification. This solution was added drop-wise during a period of 1 h to a vigorously stirred, ice-cooled solution of carbon disulphide (100 mL, 1.66 mol) in dry EtOAc (100 mL) under an N2 atmosphere. Continued mechanical stirring and water-free conditions were essential. The mixture was stirred at 0 °C for 1 h. The resultant precipitate was filtered off, washed with EtaO and dried, giving the product 50 as yellow crystals (99 g, 75 % on amount of sodium), m.p. 131 °C dec. IR (KBr) v max 1630, 1500 cm. ... 

Carbon dioxide, 184, 358, 359 solid see Dry Ice Carbon disulphide, 767 purification of, 175 Carbon monoxide, 185, 1003, 1004 Carbon, decolourising, 127, 128 Carbon tetrachloride, 733, 815 drying of, 734 purification of, 176 Carbonyl chloride, 185 Carborundum chips, 4 Carboxylic acids, equivalent weights of, 1071 ... 

The iron oxide used in the purification of coal gas gradually becomes richer in sulphur and can repeatedly be revivified by exposure to air until the sulphur amounts to about 40 per cent., of the whole the mixture is then of greater value as a source of sulphur. The spent oxide, as it is commonly termed, is frequently applied to the production of sulphur dioxide or sulphuric acid, but the extraction of its sulphur by carbon disulphide has been effected as a successful commercial process using the system of counter-currents the mass is exhausted of sulphur, whilst a saturated solution of sulphur is obtained, from which the solvent can be distilled and returned to the extraction process. 

Purification may also be effected by oxidation to selenious acid, e.g. by heating with dilute nitric acid. On evaporation the solid selenium dioxide may be obtained, and this can be purified by repeated sublimation in a current of dust-free dry air.3 It may then be redissolved in water, the solution acidified with hydrochloric acid, and the selenium precipitated by passing in sulphur dioxide.4 For further purification the element can be sublimed in a current of carbon dioxide, and after heating for some time at 100° C. to convert it into the crystalline condition, it may be heated with carbon disulphide to extract any traces of residual sulphur. 

Ultra-violet and visible spectrophotometry can be effectively used for the control of purification and specification of purity of compounds. If a compound is transparent in the near ultra-violet and the visible regions, the purification is continued until the absorbancy is reduced to a minimum (e < 1). Traces of impurities present in pure transparent organic compounds can be readily detected and estimated, provided the impurities themselves have fairly intense, absorption bands. Before a liquid is used as a spectroscopic solvent, it should be tested for spectrophotometric purity. For example, commercial absolute alcohol usually contains benzene as impurity. The absence of benzene in the Alcohol should be confirmed spectrophoto-metrically by using sufficiently large cells (4 or 10 cm cells), before using the alcohol as a solvent. The presence of carbon disulphide in carbon tetrachloride may be detected by the presence of the disulphide absorption tend at 318 mytt. The detection of the characteristic benzenoid absorption in the spectra of many organic compounds (e.g. diethyl ether, cyclohexene) showed that the bands attributed to these compounds earlier were only due to the contamination by benzene1. 

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