Distillation transfer

Alternatively, use the following procedure in which triethylamine replaces potassium acetate as the basic catalyst. Place 2 1 g. (2-0 ml.) of purified benzaldehyde, 2 0 ml. of anhydrous triethylamine and 5 0 ml. of A.R. acetic anhydride in a 200 ml. round-bottomed flask, equipped with a short reflux condenser and a calcium chloride drying tube. Boil the solution gently for 24 hours—heating may be interrupted. Incorporate a steam distillation apparatus in the flask and steam distil until the distillate is no longer cloudy (about 100 ml.) and then collect a further 50 ml. of the distillate di ard the steam distillate. Transfer the residue in the flask to a 400 ml. beaker, add water until the vplume is about 200 ml., then 0 2 g. of decolourising carbon, and boil for a few minutes. Filter the hot solution, and acidify the hot filtrate with 1 1 hydrochlorioiaoid... 

Evaporation and Distillation. Steam is used to supply heat to most evaporation (qv) and distillation (qv) processes, such as ia sugar-juice processiag and alcohol distillation. In evaporation, pure solvent is removed and a low volatiUty solute is concentrated. Distillation transfers lower boiling components from the Hquid to the vapor phase. The vapors are then condensed to recover the desired components. In steam distillation, the steam is admitted iato direct coatact with the solutioa to be evaporated and the flow of steam to the condenser is used to transport distillates of low volatiHty. In evaporation of concentrated solutions, there may be substantial boiling poiat elevation. For example, the boiling poiat of an 80% NaOH solution at atmospheric pressure is 226°C. 

With conductive heating, several factors militate against efficient distillation. Transferal of heat to the liquid usually occurs from the inner surfaces of the vessel. Vaporization from the surface and convection preclude a uniform temperature within the liquid. To achieve distillation under those circumstances, the pot temperature must be considerably higher than that of the distillate. With microwaves, energy is absorbed more uniformly, a larger volume of the sample in the pot is heated simultaneously, convection is reduced and distillation is more rapid. 

Sulfur Dioxide Determine as directed in the general method, Appendix X, using the following method under Sample Introduction and Distillation Transfer about 20 g of the sample, accurately weighed, into flask C, and add 20 mL of ethanol to moisten the sample. Add 400 mL of water, swirling vigorously to... 

In order to solve the MDPE, it is further required to model how the retentate flow R) is changing as a function of position, since material is being transferred monodirectionally (from R to P only). Note that in distillation, transfer between phases occurs bidirectionally as liquid evaporates to the vapor stream and vapor condenses in the liquid stream. Consider a strip membrane area, as shown in Figure 9.2, where J is a vector containing the fluxes of all the components. It can be shown that... 

Carefully transfer the hot contents of the extraction tube into a 1 litre, three-necked round-bottomed flask. Wash the interior of the tube with 25 ml hot water and two 25 ml portions of cold ether and transfer the washings to the 1 litre flask. Connect a separatory funnel containing distilled water, and a horizontally clamped Liebeg condenser with a suitable adaptor to the flask and distill until the distillate has no odour of ethyl alcohol. Add water to the flask when necessary to keep up the volume to a minimum of 200 ml. Ensure that the flask contains between 700 and 800 ml of liquid at the end of the distillation. Transfer the hot distillation residue into a 1 litre capacity liquid-liquid extractor. Wash the interior of the flask and the condenser with 25 ml hot water and two 25 ml portions of cold ether and transfer the washings to the extractor. Proceed as described next. 

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