无水氯仿的处理操作

来去

无水氯仿怎么处理？用熔融的氯化钙处理？

桃源佬

Chloroform [67-66-3] M 119.4, b 61.2°, d15 1.49845, d10 1.47060, n15 1.44858. Reacts
slowly with oxygen or oxidising agents, when exposed to air and light, giving, mainly, phosgene, Cl2 and HCl.
Commercial CHCH3 is usually stabilized by addn of up to 1% EtOH or of dimethylaminoazobenzene. Simplest purifications involve washing with water to remove the EtOH, drying with K2CO3 or CaCl2, refluxing with P2O5, CaCl2, CaSO4 or Na2SO4, and distilling. It must not be dried with sodium. The distd CHCH3 should be stored in the dark to avoid photochemical formation of phosgene. As an alternative purification, CHCH3 can be shaken with several small portions of cone H2SO4, washed thoroughly with water, and dried with CaCl2 or K2COs before filtering and distilling. EtOH can be removed from CHCH3 by passage through a column of activated alumina, or through a column of silica gel 4-ft long by 1.75-in diameter at a flow rate of 3mL/min. (The column, which can hold about 8% of its weight of EtOH, is regenerated by air drying and then heating at 600° for 6h. It is pre-purified by washing with CHCH3, then EtOH, leaving in cone H2SO4 for about 8hr, washing with water until the washings are neutral, then air drying, followed by activation at 600° for 6h. Just before use it is reheated for 2h to 154°.) [McLaughlin, Kaniecki and Gray Anal Chem 30 1517 1958].
Carbonyl-containing impurities can be removed from CHCH3 by percolation through a Celite column impregnated with 2,4-dinitrophenylhydrazine, phosphoric acid and water. (Prepared by dissolving 0.5g DNPH in 6mL of 85% H3PO4 by grinding together, then mixing with 4mL of distilled water and 1Og of Celite.) [Schwartz and Parks Anal Chem 33 1396 1961]. Chloroform can be dried by distn from powdered type 4A Linde molecular sieves. For use as a solvent in IR spectroscopy, chloroform is washed with water (to remove EtOH), then dried for several hours over anhydrous CaCl2 and fractionally distd. This treatment removes material absorbing near 1600 cm'1. (Percolation through activated alumina increases this absorbing impurity). [Goodspeed and Millson Chem lnd (London) 1594 1967].
Rapid purification: Pass through a column of basic alumina (Grade I, lOg/mL of CHCl3), and either dry by standing over 4A molecular sieves, or alternatively, distil from P2O5 (3% w/v). Use immediately.