Chlorocarbons removal from water

B. Distillation and Purging. The great efficiency of fractional distillation for the removal of water from hydrocarbon and chlorocarbon solvents is often not well appreciated. The physical origin of this good separation is in part the large positive deviation of the water vapor pressure from Raoult s law because of the lack of affinity of water for these liquids. Typically, the distillation of a simple hydrocarbon solvent with a column of 100 plates and discarding the first two... 

The pink colour of crystal violet is known to be due to resonance between the electron system of the phenyl groups and the free electron pairs of the three dimethylamino-nitrogen atoms. By coordination of one proton the electron pair of one dimethylamino group is removed from the resonance system so that the spectrum of malachite green is produced. By coordination of two further protons the spectrum is changed to that of the triphenyl carbonium ion. The reactions are reversible and known to occur not only in water but also in acetic anhy-dride i , acetic acid-dioxane mixtures o in thionyl chloride, chlorocarbons, phosphorus oxychloridei2i,i22 and acetyl chlorideii . 

Methyl Allophanate. Three hundred five milliliters of methyl chlorocarbonate (4.0 mols) and 480 g. of finely powdered urea (8.0 mols) are placed in a 2-1. standard-taper round-bottomed flask equipped with a 60-cm. reflux condenser. The mixture is heated on a steam bath for 90 minutes. Four hundred milliliters of water is added to the warm reaction cake to decompose any unreacted chlorocarbonic ester and to remove by solution both unchanged urea and urea hydrochloride, t Methyl allophanate remains behind as a relatively water-insoluble residue. The suspension is filtered and the white product washed with three 250-ml. portions of water, then with 95% ethanol (two 250-ml. portions), and finally with 500 ml. of ethyl ether. It is air-dried. The yield of product will vary from 227 to 274 g. (48 to 58%). The product thus obtained is pure enough to use as the starting material for other reactions. It can be further purified by recrystallization from hot water using 27.5 ml. of water per gram of compound (85% recovery m.p. 215 to 216° with decomposition). 

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