Distillation solvent effects

Solvent Effects m Extractive Distillation In the distillation of ideal or nonazeotropic mixtures, the component with the lowest pure-component boihng point is always recovered primarily in the distillate, while the highest boiler is recovered primarily in the bottoms. The situation is not as straightforward for an extractive-distillation operation. With some solvents, the component with the lower pure-component boiling point wih be recovered in the distillate as in ordinaiy distillation. For another solvent, the expected order is reversed, and the component with the higher pure-component boiling point wih be... 

The authors reported an example of such solvent effects in the catalytic two-step denitrogenation of coal liquid distillates. With large quantities of added 1-methylnaphthalene or 20% added pyrene or fluoranthene, no additional catalyst is necessary for the second step to achieve high levels of denitrogenation. 

Most researchers distil solvents for radical reactions in the same manner as they might for use with a reactive organometallic. This practice is recommended to ensure that solvents are sufficiently pure. That the solvents are simultaneously dried during purification is of little consequence. Water is a much poorer hydrogen atom donor than any common solvent (conversely, the hydroxyl radical is a powerful hydrogen atom abstractor). Thus, the presence of trace quantities of water will have no adverse effect on most radical reactions. As a corollary, water can be a useful solvent or cosolvent provided that the reagents or substrates are not susceptible to hydrolysis or protonolysis. 

Stage 2 Preparation of l-[2-Phenyl-2-Methoxy]-Ethyl-Piperazine - 210 grams of 2-phenyl-2-methoxy-ethyl bromide and 260 grams of anhydrous piperazine are heated for 5 to 6 hours to reflux in 600 ml of ethanol, 500 ml of ethanol is then distilled off and finally the solvent is removed in vacuo. The residue is taken up in 250 ml of benzene and the piperazine hydrobromide is filtered off. The benzene is removed in vacuo. The oily residue is taken up by 450 ml of water and acidification is effected up to pH = 1 by concentrated HCI. The aqueous solution is filtered the latter is then made alkaline by 50% aqueous NaOH. The liberated base is decanted, the alkaline aqueous solution is washed twice by 150 ml ether. After distillation of the ether, the previously decanted oil is added to the residue and distillation is effected in vacuo. Thus,135 grams of a colorless viscous oil, becoming carbonated in air, is obtained. 

The use of digital computers to carry out complete calculations in the design of separation processes has been the goal of many. To do this effectively, suitable methods for phase equilibria and tray-to-tray distillation calculations are required. Results calculated by the application of such methods to dehydrate aqueous ethanol mixtures using ethylene glycol as the extractive distillation solvent is discussed below. A brief review of the methods used for phase equilibria and enthalpies is followed by a discussion of the results from distillation calculations. These are compared for extractive distillation with corresponding results obtained by azeotropic distillation with n-pentane. 

There are many different approaches for in situ ethanol removal during fermentation. These approaches include vacuum distillation, solvent extraction, membrane reactors, and gas stripping (see 114] for review). Gas stripping of ethanol during fermentation offers advantages in terms of its effectiveness and ease of operation [15]. Ethanol can be recovered from the carrier gas stream by adsorbing onto activated carbon [16] or by condensation of the recycled gas stream under low temperatures [17]. 

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